Use glamour and termev to render/colorize content (#181)

Merge branch 'master' into use-glamour

select Glamour Theme based on BackgroundColor

Merge branch 'master' into use-glamour

Merge branch 'master' into use-glamour

update termev

update go.mod

label color colorate

use glamour for issue content

Vendor: Add glamour

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: 6543 <6543@obermui.de>
Reviewed-on: https://gitea.com/gitea/tea/pulls/181
Reviewed-by: techknowlogick <techknowlogick@gitea.io>
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>

vendor/github.com/yuin/goldmark/.gitignore

@@ -0,0 +1,19 @@
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, build with `go test -c`
+*.test
+*.pprof
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+.DS_Store
+fuzz/corpus
+fuzz/crashers
+fuzz/suppressions
+fuzz/fuzz-fuzz.zip

vendor/github.com/yuin/goldmark/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2019 Yusuke Inuzuka
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/yuin/goldmark/Makefile

@@ -0,0 +1,16 @@
+.PHONY: test fuzz
+
+test:
+	go test -coverprofile=profile.out -coverpkg=github.com/yuin/goldmark,github.com/yuin/goldmark/ast,github.com/yuin/goldmark/extension,github.com/yuin/goldmark/extension/ast,github.com/yuin/goldmark/parser,github.com/yuin/goldmark/renderer,github.com/yuin/goldmark/renderer/html,github.com/yuin/goldmark/text,github.com/yuin/goldmark/util ./...
+
+cov: test
+	go tool cover -html=profile.out
+
+fuzz:
+	which go-fuzz > /dev/null 2>&1 || (GO111MODULE=off go get -u github.com/dvyukov/go-fuzz/go-fuzz github.com/dvyukov/go-fuzz/go-fuzz-build; GO111MODULE=off go get -d github.com/dvyukov/go-fuzz-corpus; true)
+	rm -rf ./fuzz/corpus
+	rm -rf ./fuzz/crashers
+	rm -rf ./fuzz/suppressions
+	rm -f ./fuzz/fuzz-fuzz.zip
+	cd ./fuzz && go-fuzz-build
+	cd ./fuzz && go-fuzz

vendor/github.com/yuin/goldmark/README.md

@@ -0,0 +1,403 @@
+goldmark
+==========================================
+
+[![http://godoc.org/github.com/yuin/goldmark](https://godoc.org/github.com/yuin/goldmark?status.svg)](http://godoc.org/github.com/yuin/goldmark)
+[![https://github.com/yuin/goldmark/actions?query=workflow:test](https://github.com/yuin/goldmark/workflows/test/badge.svg?branch=master&event=push)](https://github.com/yuin/goldmark/actions?query=workflow:test)
+[![https://coveralls.io/github/yuin/goldmark](https://coveralls.io/repos/github/yuin/goldmark/badge.svg?branch=master)](https://coveralls.io/github/yuin/goldmark)
+[![https://goreportcard.com/report/github.com/yuin/goldmark](https://goreportcard.com/badge/github.com/yuin/goldmark)](https://goreportcard.com/report/github.com/yuin/goldmark)
+
+> A Markdown parser written in Go. Easy to extend, standards-compliant, well-structured.
+
+goldmark is compliant with CommonMark 0.29.
+
+Motivation
+----------------------
+I needed a Markdown parser for Go that satisfies the following requirements:
+
+- Easy to extend.
+    - Markdown is poor in document expressions compared to other light markup languages such as reStructuredText.
+    - We have extensions to the Markdown syntax, e.g. PHP Markdown Extra, GitHub Flavored Markdown.
+- Standards-compliant.
+    - Markdown has many dialects.
+    - GitHub-Flavored Markdown is widely used and is based upon CommonMark, effectively mooting the question of whether or not CommonMark is an ideal specification.
+        - CommonMark is complicated and hard to implement.
+- Well-structured.
+    - AST-based; preserves source position of nodes.
+- Written in pure Go.
+
+[golang-commonmark](https://gitlab.com/golang-commonmark/markdown) may be a good choice, but it seems to be a copy of [markdown-it](https://github.com/markdown-it).
+
+[blackfriday.v2](https://github.com/russross/blackfriday/tree/v2) is a fast and widely-used implementation, but is not CommonMark-compliant and cannot be extended from outside of the package, since its AST uses structs instead of interfaces.
+
+Furthermore, its behavior differs from other implementations in some cases, especially regarding lists: [Deep nested lists don't output correctly #329](https://github.com/russross/blackfriday/issues/329), [List block cannot have a second line #244](https://github.com/russross/blackfriday/issues/244), etc.
+
+This behavior sometimes causes problems. If you migrate your Markdown text from GitHub to blackfriday-based wikis, many lists will immediately be broken.
+
+As mentioned above, CommonMark is complicated and hard to implement, so Markdown parsers based on CommonMark are few and far between.
+
+Features
+----------------------
+
+- **Standards-compliant.**  goldmark is fully compliant with the latest [CommonMark](https://commonmark.org/) specification.
+- **Extensible.**  Do you want to add a `@username` mention syntax to Markdown?
+  You can easily do so in goldmark. You can add your AST nodes,
+  parsers for block-level elements, parsers for inline-level elements,
+  transformers for paragraphs, transformers for the whole AST structure, and
+  renderers.
+- **Performance.**  goldmark's performance is on par with that of cmark,
+  the CommonMark reference implementation written in C.
+- **Robust.**  goldmark is tested with [go-fuzz](https://github.com/dvyukov/go-fuzz), a fuzz testing tool.
+- **Built-in extensions.**  goldmark ships with common extensions like tables, strikethrough,
+  task lists, and definition lists.
+- **Depends only on standard libraries.**
+
+Installation
+----------------------
+```bash
+$ go get github.com/yuin/goldmark
+```
+
+
+Usage
+----------------------
+Import packages:
+
+```go
+import (
+    "bytes"
+    "github.com/yuin/goldmark"
+)
+```
+
+
+Convert Markdown documents with the CommonMark-compliant mode:
+
+```go
+var buf bytes.Buffer
+if err := goldmark.Convert(source, &buf); err != nil {
+  panic(err)
+}
+```
+
+With options
+------------------------------
+
+```go
+var buf bytes.Buffer
+if err := goldmark.Convert(source, &buf, parser.WithContext(ctx)); err != nil {
+  panic(err)
+}
+```
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `parser.WithContext` | A `parser.Context` | Context for the parsing phase. |
+
+Context options
+----------------------
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `parser.WithIDs` | A `parser.IDs` | `IDs` allows you to change logics that are related to element id(ex: Auto heading id generation). |
+
+
+Custom parser and renderer
+--------------------------
+```go
+import (
+    "bytes"
+    "github.com/yuin/goldmark"
+    "github.com/yuin/goldmark/extension"
+    "github.com/yuin/goldmark/parser"
+    "github.com/yuin/goldmark/renderer/html"
+)
+
+md := goldmark.New(
+          goldmark.WithExtensions(extension.GFM),
+          goldmark.WithParserOptions(
+              parser.WithAutoHeadingID(),
+          ),
+          goldmark.WithRendererOptions(
+              html.WithHardWraps(),
+              html.WithXHTML(),
+          ),
+      )
+var buf bytes.Buffer
+if err := md.Convert(source, &buf); err != nil {
+    panic(err)
+}
+```
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `goldmark.WithParser` | `parser.Parser`  | This option must be passed before `goldmark.WithParserOptions` and `goldmark.WithExtensions` |
+| `goldmark.WithRenderer` | `renderer.Renderer`  | This option must be passed before `goldmark.WithRendererOptions` and `goldmark.WithExtensions`  |
+| `goldmark.WithParserOptions` | `...parser.Option`  |  |
+| `goldmark.WithRendererOptions` | `...renderer.Option` |  |
+| `goldmark.WithExtensions` | `...goldmark.Extender`  |  |
+
+Parser and Renderer options
+------------------------------
+
+### Parser options
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `parser.WithBlockParsers` | A `util.PrioritizedSlice` whose elements are `parser.BlockParser` | Parsers for parsing block level elements. |
+| `parser.WithInlineParsers` | A `util.PrioritizedSlice` whose elements are `parser.InlineParser` | Parsers for parsing inline level elements. |
+| `parser.WithParagraphTransformers` | A `util.PrioritizedSlice` whose elements are `parser.ParagraphTransformer` | Transformers for transforming paragraph nodes. |
+| `parser.WithASTTransformers` | A `util.PrioritizedSlice` whose elements are `parser.ASTTransformer` | Transformers for transforming an AST. |
+| `parser.WithAutoHeadingID` | `-` | Enables auto heading ids. |
+| `parser.WithAttribute` | `-` | Enables custom attributes. Currently only headings supports attributes. |
+
+### HTML Renderer options
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `html.WithWriter` | `html.Writer` | `html.Writer` for writing contents to an `io.Writer`. |
+| `html.WithHardWraps` | `-` | Render newlines as `<br>`.|
+| `html.WithXHTML` | `-` | Render as XHTML. |
+| `html.WithUnsafe` | `-` | By default, goldmark does not render raw HTML or potentially dangerous links. With this option, goldmark renders such content as written. |
+
+### Built-in extensions
+
+- `extension.Table`
+    - [GitHub Flavored Markdown: Tables](https://github.github.com/gfm/#tables-extension-)
+- `extension.Strikethrough`
+    - [GitHub Flavored Markdown: Strikethrough](https://github.github.com/gfm/#strikethrough-extension-)
+- `extension.Linkify`
+    - [GitHub Flavored Markdown: Autolinks](https://github.github.com/gfm/#autolinks-extension-)
+- `extension.TaskList`
+    - [GitHub Flavored Markdown: Task list items](https://github.github.com/gfm/#task-list-items-extension-)
+- `extension.GFM`
+    - This extension enables Table, Strikethrough, Linkify and TaskList.
+    - This extension does not filter tags defined in [6.11: Disallowed Raw HTML (extension)](https://github.github.com/gfm/#disallowed-raw-html-extension-).
+    If you need to filter HTML tags, see [Security](#security).
+- `extension.DefinitionList`
+    - [PHP Markdown Extra: Definition lists](https://michelf.ca/projects/php-markdown/extra/#def-list)
+- `extension.Footnote`
+    - [PHP Markdown Extra: Footnotes](https://michelf.ca/projects/php-markdown/extra/#footnotes)
+- `extension.Typographer`
+    - This extension substitutes punctuations with typographic entities like [smartypants](https://daringfireball.net/projects/smartypants/).
+
+### Attributes
+The `parser.WithAttribute` option allows you to define attributes on some elements.
+
+Currently only headings support attributes.
+
+**Attributes are being discussed in the
+[CommonMark forum](https://talk.commonmark.org/t/consistent-attribute-syntax/272).
+This syntax may possibly change in the future.**
+
+
+#### Headings
+
+```
+## heading ## {#id .className attrName=attrValue class="class1 class2"}
+
+## heading {#id .className attrName=attrValue class="class1 class2"}
+```
+
+```
+heading {#id .className attrName=attrValue}
+============
+```
+
+### Table extension
+The Table extension implements [Table(extension)](https://github.github.com/gfm/#tables-extension-), as
+defined in [GitHub Flavored Markdown Spec](https://github.github.com/gfm/).
+
+Specs are defined for XHTML, so specs use some deprecated attributes for HTML5.
+
+You can override alignment rendering method via options.
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `extension.WithTableCellAlignMethod` | `extension.TableCellAlignMethod` | Option indicates how are table cells aligned. |
+
+### Typographer extension
+
+The Typographer extension translates plain ASCII punctuation characters into typographic-punctuation HTML entities.
+
+Default substitutions are:
+
+| Punctuation | Default entity |
+| ------------ | ---------- |
+| `'`           | `&lsquo;`, `&rsquo;` |
+| `"`           | `&ldquo;`, `&rdquo;` |
+| `--`       | `&ndash;` |
+| `---`      | `&mdash;` |
+| `...`      | `&hellip;` |
+| `<<`       | `&laquo;` |
+| `>>`       | `&raquo;` |
+
+You can override the default substitutions via `extensions.WithTypographicSubstitutions`:
+
+```go
+markdown := goldmark.New(
+    goldmark.WithExtensions(
+        extension.NewTypographer(
+            extension.WithTypographicSubstitutions(extension.TypographicSubstitutions{
+                extension.LeftSingleQuote:  []byte("&sbquo;"),
+                extension.RightSingleQuote: nil, // nil disables a substitution
+            }),
+        ),
+    ),
+)
+```
+
+### Linkify extension
+
+The Linkify extension implements [Autolinks(extension)](https://github.github.com/gfm/#autolinks-extension-), as
+defined in [GitHub Flavored Markdown Spec](https://github.github.com/gfm/).
+
+Since the spec does not define details about URLs, there are numerous ambiguous cases.
+
+You can override autolinking patterns via options.
+
+| Functional option | Type | Description |
+| ----------------- | ---- | ----------- |
+| `extension.WithLinkifyAllowedProtocols` | `[][]byte` | List of allowed protocols such as `[][]byte{ []byte("http:") }` |
+| `extension.WithLinkifyURLRegexp` | `*regexp.Regexp` | Regexp that defines URLs, including protocols |
+| `extension.WithLinkifyWWWRegexp` | `*regexp.Regexp` | Regexp that defines URL starting with `www.`. This pattern corresponds to [the extended www autolink](https://github.github.com/gfm/#extended-www-autolink) |
+| `extension.WithLinkifyEmailRegexp` | `*regexp.Regexp` | Regexp that defines email addresses` |
+
+Example, using [xurls](https://github.com/mvdan/xurls):
+
+```go
+import "mvdan.cc/xurls/v2"
+
+markdown := goldmark.New(
+    goldmark.WithRendererOptions(
+        html.WithXHTML(),
+        html.WithUnsafe(),
+    ),
+    goldmark.WithExtensions(
+        extension.NewLinkify(
+            extension.WithLinkifyAllowedProtocols([][]byte{
+                []byte("http:"),
+                []byte("https:"),
+            }),
+            extension.WithLinkifyURLRegexp(
+                xurls.Strict(),
+            ),
+        ),
+    ),
+)
+```
+
+Security
+--------------------
+By default, goldmark does not render raw HTML or potentially-dangerous URLs.
+If you need to gain more control over untrusted contents, it is recommended that you
+use an HTML sanitizer such as [bluemonday](https://github.com/microcosm-cc/bluemonday).
+
+Benchmark
+--------------------
+You can run this benchmark in the `_benchmark` directory.
+
+### against other golang libraries
+
+blackfriday v2 seems to be the fastest, but as it is not CommonMark compliant, its performance cannot be directly compared to that of the CommonMark-compliant libraries.
+
+goldmark, meanwhile, builds a clean, extensible AST structure, achieves full compliance with
+CommonMark, and consumes less memory, all while being reasonably fast.
+
+```
+goos: darwin
+goarch: amd64
+BenchmarkMarkdown/Blackfriday-v2-12                  326           3465240 ns/op         3298861 B/op      20047 allocs/op
+BenchmarkMarkdown/GoldMark-12                        303           3927494 ns/op         2574809 B/op      13853 allocs/op
+BenchmarkMarkdown/CommonMark-12                      244           4900853 ns/op         2753851 B/op      20527 allocs/op
+BenchmarkMarkdown/Lute-12                            130           9195245 ns/op         9175030 B/op     123534 allocs/op
+BenchmarkMarkdown/GoMarkdown-12                        9         113541994 ns/op         2187472 B/op      22173 allocs/op
+```
+
+### against cmark (CommonMark reference implementation written in C)
+
+```
+----------- cmark -----------
+file: _data.md
+iteration: 50
+average: 0.0037760639 sec
+go run ./goldmark_benchmark.go
+------- goldmark -------
+file: _data.md
+iteration: 50
+average: 0.0040964230 sec
+```
+
+As you can see, goldmark's performance is on par with cmark's.
+
+Extensions
+--------------------
+
+- [goldmark-meta](https://github.com/yuin/goldmark-meta): A YAML metadata
+  extension for the goldmark Markdown parser.
+- [goldmark-highlighting](https://github.com/yuin/goldmark-highlighting): A syntax-highlighting extension
+  for the goldmark markdown parser.
+- [goldmark-mathjax](https://github.com/litao91/goldmark-mathjax): Mathjax support for the goldmark markdown parser
+
+goldmark internal(for extension developers)
+----------------------------------------------
+### Overview
+goldmark's Markdown processing is outlined in the diagram below.
+
+```
+            <Markdown in []byte, parser.Context>
+                           |
+                           V
+            +-------- parser.Parser ---------------------------
+            | 1. Parse block elements into AST
+            |   1. If a parsed block is a paragraph, apply 
+            |      ast.ParagraphTransformer
+            | 2. Traverse AST and parse blocks.
+            |   1. Process delimiters(emphasis) at the end of
+            |      block parsing
+            | 3. Apply parser.ASTTransformers to AST
+                           |
+                           V
+                      <ast.Node>
+                           |
+                           V
+            +------- renderer.Renderer ------------------------
+            | 1. Traverse AST and apply renderer.NodeRenderer
+            |    corespond to the node type
+
+                           |
+                           V
+                        <Output>
+```
+
+### Parsing
+Markdown documents are read through `text.Reader` interface.
+
+AST nodes do not have concrete text. AST nodes have segment information of the documents, represented by `text.Segment` .
+
+`text.Segment` has 3 attributes: `Start`, `End`, `Padding` .
+
+(TBC)
+
+**TODO**
+
+See `extension` directory for examples of extensions.
+
+Summary:
+
+1. Define AST Node as a struct in which `ast.BaseBlock` or `ast.BaseInline` is embedded.
+2. Write a parser that implements `parser.BlockParser` or `parser.InlineParser`.
+3. Write a renderer that implements `renderer.NodeRenderer`.
+4. Define your goldmark extension that implements `goldmark.Extender`.
+
+
+Donation
+--------------------
+BTC: 1NEDSyUmo4SMTDP83JJQSWi1MvQUGGNMZB
+
+License
+--------------------
+MIT
+
+Author
+--------------------
+Yusuke Inuzuka

vendor/github.com/yuin/goldmark/ast/ast.go

@@ -0,0 +1,492 @@
+// Package ast defines AST nodes that represent markdown elements.
+package ast
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+
+	textm "github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+// A NodeType indicates what type a node belongs to.
+type NodeType int
+
+const (
+	// TypeBlock indicates that a node is kind of block nodes.
+	TypeBlock NodeType = iota + 1
+	// TypeInline indicates that a node is kind of inline nodes.
+	TypeInline
+	// TypeDocument indicates that a node is kind of document nodes.
+	TypeDocument
+)
+
+// NodeKind indicates more specific type than NodeType.
+type NodeKind int
+
+func (k NodeKind) String() string {
+	return kindNames[k]
+}
+
+var kindMax NodeKind
+var kindNames = []string{""}
+
+// NewNodeKind returns a new Kind value.
+func NewNodeKind(name string) NodeKind {
+	kindMax++
+	kindNames = append(kindNames, name)
+	return kindMax
+}
+
+// An Attribute is an attribute of the Node
+type Attribute struct {
+	Name  []byte
+	Value interface{}
+}
+
+var attrNameIDS = []byte("#")
+var attrNameID = []byte("id")
+var attrNameClassS = []byte(".")
+var attrNameClass = []byte("class")
+
+// A Node interface defines basic AST node functionalities.
+type Node interface {
+	// Type returns a type of this node.
+	Type() NodeType
+
+	// Kind returns a kind of this node.
+	Kind() NodeKind
+
+	// NextSibling returns a next sibling node of this node.
+	NextSibling() Node
+
+	// PreviousSibling returns a previous sibling node of this node.
+	PreviousSibling() Node
+
+	// Parent returns a parent node of this node.
+	Parent() Node
+
+	// SetParent sets a parent node to this node.
+	SetParent(Node)
+
+	// SetPreviousSibling sets a previous sibling node to this node.
+	SetPreviousSibling(Node)
+
+	// SetNextSibling sets a next sibling node to this node.
+	SetNextSibling(Node)
+
+	// HasChildren returns true if this node has any children, otherwise false.
+	HasChildren() bool
+
+	// ChildCount returns a total number of children.
+	ChildCount() int
+
+	// FirstChild returns a first child of this node.
+	FirstChild() Node
+
+	// LastChild returns a last child of this node.
+	LastChild() Node
+
+	// AppendChild append a node child to the tail of the children.
+	AppendChild(self, child Node)
+
+	// RemoveChild removes a node child from this node.
+	// If a node child is not children of this node, RemoveChild nothing to do.
+	RemoveChild(self, child Node)
+
+	// RemoveChildren removes all children from this node.
+	RemoveChildren(self Node)
+
+	// SortChildren sorts childrens by comparator.
+	SortChildren(comparator func(n1, n2 Node) int)
+
+	// ReplaceChild replace a node v1 with a node insertee.
+	// If v1 is not children of this node, ReplaceChild append a insetee to the
+	// tail of the children.
+	ReplaceChild(self, v1, insertee Node)
+
+	// InsertBefore inserts a node insertee before a node v1.
+	// If v1 is not children of this node, InsertBefore append a insetee to the
+	// tail of the children.
+	InsertBefore(self, v1, insertee Node)
+
+	// InsertAfterinserts a node insertee after a node v1.
+	// If v1 is not children of this node, InsertBefore append a insetee to the
+	// tail of the children.
+	InsertAfter(self, v1, insertee Node)
+
+	// Dump dumps an AST tree structure to stdout.
+	// This function completely aimed for debugging.
+	// level is a indent level. Implementer should indent informations with
+	// 2 * level spaces.
+	Dump(source []byte, level int)
+
+	// Text returns text values of this node.
+	Text(source []byte) []byte
+
+	// HasBlankPreviousLines returns true if the row before this node is blank,
+	// otherwise false.
+	// This method is valid only for block nodes.
+	HasBlankPreviousLines() bool
+
+	// SetBlankPreviousLines sets whether the row before this node is blank.
+	// This method is valid only for block nodes.
+	SetBlankPreviousLines(v bool)
+
+	// Lines returns text segments that hold positions in a source.
+	// This method is valid only for block nodes.
+	Lines() *textm.Segments
+
+	// SetLines sets text segments that hold positions in a source.
+	// This method is valid only for block nodes.
+	SetLines(*textm.Segments)
+
+	// IsRaw returns true if contents should be rendered as 'raw' contents.
+	IsRaw() bool
+
+	// SetAttribute sets the given value to the attributes.
+	SetAttribute(name []byte, value interface{})
+
+	// SetAttributeString sets the given value to the attributes.
+	SetAttributeString(name string, value interface{})
+
+	// Attribute returns a (attribute value, true) if an attribute
+	// associated with the given name is found, otherwise
+	// (nil, false)
+	Attribute(name []byte) (interface{}, bool)
+
+	// AttributeString returns a (attribute value, true) if an attribute
+	// associated with the given name is found, otherwise
+	// (nil, false)
+	AttributeString(name string) (interface{}, bool)
+
+	// Attributes returns a list of attributes.
+	// This may be a nil if there are no attributes.
+	Attributes() []Attribute
+
+	// RemoveAttributes removes all attributes from this node.
+	RemoveAttributes()
+}
+
+// A BaseNode struct implements the Node interface.
+type BaseNode struct {
+	firstChild Node
+	lastChild  Node
+	parent     Node
+	next       Node
+	prev       Node
+	childCount int
+	attributes []Attribute
+}
+
+func ensureIsolated(v Node) {
+	if p := v.Parent(); p != nil {
+		p.RemoveChild(p, v)
+	}
+}
+
+// HasChildren implements Node.HasChildren .
+func (n *BaseNode) HasChildren() bool {
+	return n.firstChild != nil
+}
+
+// SetPreviousSibling implements Node.SetPreviousSibling .
+func (n *BaseNode) SetPreviousSibling(v Node) {
+	n.prev = v
+}
+
+// SetNextSibling implements Node.SetNextSibling .
+func (n *BaseNode) SetNextSibling(v Node) {
+	n.next = v
+}
+
+// PreviousSibling implements Node.PreviousSibling .
+func (n *BaseNode) PreviousSibling() Node {
+	return n.prev
+}
+
+// NextSibling implements Node.NextSibling .
+func (n *BaseNode) NextSibling() Node {
+	return n.next
+}
+
+// RemoveChild implements Node.RemoveChild .
+func (n *BaseNode) RemoveChild(self, v Node) {
+	if v.Parent() != self {
+		return
+	}
+	n.childCount--
+	prev := v.PreviousSibling()
+	next := v.NextSibling()
+	if prev != nil {
+		prev.SetNextSibling(next)
+	} else {
+		n.firstChild = next
+	}
+	if next != nil {
+		next.SetPreviousSibling(prev)
+	} else {
+		n.lastChild = prev
+	}
+	v.SetParent(nil)
+	v.SetPreviousSibling(nil)
+	v.SetNextSibling(nil)
+}
+
+// RemoveChildren implements Node.RemoveChildren .
+func (n *BaseNode) RemoveChildren(self Node) {
+	for c := n.firstChild; c != nil; {
+		c.SetParent(nil)
+		c.SetPreviousSibling(nil)
+		next := c.NextSibling()
+		c.SetNextSibling(nil)
+		c = next
+	}
+	n.firstChild = nil
+	n.lastChild = nil
+	n.childCount = 0
+}
+
+// SortChildren implements Node.SortChildren
+func (n *BaseNode) SortChildren(comparator func(n1, n2 Node) int) {
+	var sorted Node
+	current := n.firstChild
+	for current != nil {
+		next := current.NextSibling()
+		if sorted == nil || comparator(sorted, current) >= 0 {
+			current.SetNextSibling(sorted)
+			if sorted != nil {
+				sorted.SetPreviousSibling(current)
+			}
+			sorted = current
+			sorted.SetPreviousSibling(nil)
+		} else {
+			c := sorted
+			for c.NextSibling() != nil && comparator(c.NextSibling(), current) < 0 {
+				c = c.NextSibling()
+			}
+			current.SetNextSibling(c.NextSibling())
+			current.SetPreviousSibling(c)
+			if c.NextSibling() != nil {
+				c.NextSibling().SetPreviousSibling(current)
+			}
+			c.SetNextSibling(current)
+		}
+		current = next
+	}
+	n.firstChild = sorted
+	for c := n.firstChild; c != nil; c = c.NextSibling() {
+		n.lastChild = c
+	}
+}
+
+// FirstChild implements Node.FirstChild .
+func (n *BaseNode) FirstChild() Node {
+	return n.firstChild
+}
+
+// LastChild implements Node.LastChild .
+func (n *BaseNode) LastChild() Node {
+	return n.lastChild
+}
+
+// ChildCount implements Node.ChildCount .
+func (n *BaseNode) ChildCount() int {
+	return n.childCount
+}
+
+// Parent implements Node.Parent .
+func (n *BaseNode) Parent() Node {
+	return n.parent
+}
+
+// SetParent implements Node.SetParent .
+func (n *BaseNode) SetParent(v Node) {
+	n.parent = v
+}
+
+// AppendChild implements Node.AppendChild .
+func (n *BaseNode) AppendChild(self, v Node) {
+	ensureIsolated(v)
+	if n.firstChild == nil {
+		n.firstChild = v
+		v.SetNextSibling(nil)
+		v.SetPreviousSibling(nil)
+	} else {
+		last := n.lastChild
+		last.SetNextSibling(v)
+		v.SetPreviousSibling(last)
+	}
+	v.SetParent(self)
+	n.lastChild = v
+	n.childCount++
+}
+
+// ReplaceChild implements Node.ReplaceChild .
+func (n *BaseNode) ReplaceChild(self, v1, insertee Node) {
+	n.InsertBefore(self, v1, insertee)
+	n.RemoveChild(self, v1)
+}
+
+// InsertAfter implements Node.InsertAfter .
+func (n *BaseNode) InsertAfter(self, v1, insertee Node) {
+	n.InsertBefore(self, v1.NextSibling(), insertee)
+}
+
+// InsertBefore implements Node.InsertBefore .
+func (n *BaseNode) InsertBefore(self, v1, insertee Node) {
+	n.childCount++
+	if v1 == nil {
+		n.AppendChild(self, insertee)
+		return
+	}
+	ensureIsolated(insertee)
+	if v1.Parent() == self {
+		c := v1
+		prev := c.PreviousSibling()
+		if prev != nil {
+			prev.SetNextSibling(insertee)
+			insertee.SetPreviousSibling(prev)
+		} else {
+			n.firstChild = insertee
+			insertee.SetPreviousSibling(nil)
+		}
+		insertee.SetNextSibling(c)
+		c.SetPreviousSibling(insertee)
+		insertee.SetParent(self)
+	}
+}
+
+// Text implements Node.Text  .
+func (n *BaseNode) Text(source []byte) []byte {
+	var buf bytes.Buffer
+	for c := n.firstChild; c != nil; c = c.NextSibling() {
+		buf.Write(c.Text(source))
+	}
+	return buf.Bytes()
+}
+
+// SetAttribute implements Node.SetAttribute.
+func (n *BaseNode) SetAttribute(name []byte, value interface{}) {
+	if n.attributes == nil {
+		n.attributes = make([]Attribute, 0, 10)
+	} else {
+		for i, a := range n.attributes {
+			if bytes.Equal(a.Name, name) {
+				n.attributes[i].Name = name
+				n.attributes[i].Value = value
+				return
+			}
+		}
+	}
+	n.attributes = append(n.attributes, Attribute{name, value})
+}
+
+// SetAttributeString implements Node.SetAttributeString
+func (n *BaseNode) SetAttributeString(name string, value interface{}) {
+	n.SetAttribute(util.StringToReadOnlyBytes(name), value)
+}
+
+// Attribute implements Node.Attribute.
+func (n *BaseNode) Attribute(name []byte) (interface{}, bool) {
+	if n.attributes == nil {
+		return nil, false
+	}
+	for i, a := range n.attributes {
+		if bytes.Equal(a.Name, name) {
+			return n.attributes[i].Value, true
+		}
+	}
+	return nil, false
+}
+
+// AttributeString implements Node.AttributeString.
+func (n *BaseNode) AttributeString(s string) (interface{}, bool) {
+	return n.Attribute(util.StringToReadOnlyBytes(s))
+}
+
+// Attributes implements Node.Attributes
+func (n *BaseNode) Attributes() []Attribute {
+	return n.attributes
+}
+
+// RemoveAttributes implements Node.RemoveAttributes
+func (n *BaseNode) RemoveAttributes() {
+	n.attributes = nil
+}
+
+// DumpHelper is a helper function to implement Node.Dump.
+// kv is pairs of an attribute name and an attribute value.
+// cb is a function called after wrote a name and attributes.
+func DumpHelper(v Node, source []byte, level int, kv map[string]string, cb func(int)) {
+	name := v.Kind().String()
+	indent := strings.Repeat("    ", level)
+	fmt.Printf("%s%s {\n", indent, name)
+	indent2 := strings.Repeat("    ", level+1)
+	if v.Type() == TypeBlock {
+		fmt.Printf("%sRawText: \"", indent2)
+		for i := 0; i < v.Lines().Len(); i++ {
+			line := v.Lines().At(i)
+			fmt.Printf("%s", line.Value(source))
+		}
+		fmt.Printf("\"\n")
+		fmt.Printf("%sHasBlankPreviousLines: %v\n", indent2, v.HasBlankPreviousLines())
+	}
+	for name, value := range kv {
+		fmt.Printf("%s%s: %s\n", indent2, name, value)
+	}
+	if cb != nil {
+		cb(level + 1)
+	}
+	for c := v.FirstChild(); c != nil; c = c.NextSibling() {
+		c.Dump(source, level+1)
+	}
+	fmt.Printf("%s}\n", indent)
+}
+
+// WalkStatus represents a current status of the Walk function.
+type WalkStatus int
+
+const (
+	// WalkStop indicates no more walking needed.
+	WalkStop WalkStatus = iota + 1
+
+	// WalkSkipChildren indicates that Walk wont walk on children of current
+	// node.
+	WalkSkipChildren
+
+	// WalkContinue indicates that Walk can continue to walk.
+	WalkContinue
+)
+
+// Walker is a function that will be called when Walk find a
+// new node.
+// entering is set true before walks children, false after walked children.
+// If Walker returns error, Walk function immediately stop walking.
+type Walker func(n Node, entering bool) (WalkStatus, error)
+
+// Walk walks a AST tree by the depth first search algorithm.
+func Walk(n Node, walker Walker) error {
+	_, err := walkHelper(n, walker)
+	return err
+}
+
+func walkHelper(n Node, walker Walker) (WalkStatus, error) {
+	status, err := walker(n, true)
+	if err != nil || status == WalkStop {
+		return status, err
+	}
+	if status != WalkSkipChildren {
+		for c := n.FirstChild(); c != nil; c = c.NextSibling() {
+			if st, err := walkHelper(c, walker); err != nil || st == WalkStop {
+				return WalkStop, err
+			}
+		}
+	}
+	status, err = walker(n, false)
+	if err != nil || status == WalkStop {
+		return WalkStop, err
+	}
+	return WalkContinue, nil
+}

vendor/github.com/yuin/goldmark/ast/block.go

@@ -0,0 +1,474 @@
+package ast
+
+import (
+	"fmt"
+	"strings"
+
+	textm "github.com/yuin/goldmark/text"
+)
+
+// A BaseBlock struct implements the Node interface.
+type BaseBlock struct {
+	BaseNode
+	blankPreviousLines bool
+	lines              *textm.Segments
+}
+
+// Type implements Node.Type
+func (b *BaseBlock) Type() NodeType {
+	return TypeBlock
+}
+
+// IsRaw implements Node.IsRaw
+func (b *BaseBlock) IsRaw() bool {
+	return false
+}
+
+// HasBlankPreviousLines implements Node.HasBlankPreviousLines.
+func (b *BaseBlock) HasBlankPreviousLines() bool {
+	return b.blankPreviousLines
+}
+
+// SetBlankPreviousLines implements Node.SetBlankPreviousLines.
+func (b *BaseBlock) SetBlankPreviousLines(v bool) {
+	b.blankPreviousLines = v
+}
+
+// Lines implements Node.Lines
+func (b *BaseBlock) Lines() *textm.Segments {
+	if b.lines == nil {
+		b.lines = textm.NewSegments()
+	}
+	return b.lines
+}
+
+// SetLines implements Node.SetLines
+func (b *BaseBlock) SetLines(v *textm.Segments) {
+	b.lines = v
+}
+
+// A Document struct is a root node of Markdown text.
+type Document struct {
+	BaseBlock
+}
+
+// KindDocument is a NodeKind of the Document node.
+var KindDocument = NewNodeKind("Document")
+
+// Dump implements Node.Dump .
+func (n *Document) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// Type implements Node.Type .
+func (n *Document) Type() NodeType {
+	return TypeDocument
+}
+
+// Kind implements Node.Kind.
+func (n *Document) Kind() NodeKind {
+	return KindDocument
+}
+
+// NewDocument returns a new Document node.
+func NewDocument() *Document {
+	return &Document{
+		BaseBlock: BaseBlock{},
+	}
+}
+
+// A TextBlock struct is a node whose lines
+// should be rendered without any containers.
+type TextBlock struct {
+	BaseBlock
+}
+
+// Dump implements Node.Dump .
+func (n *TextBlock) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindTextBlock is a NodeKind of the TextBlock node.
+var KindTextBlock = NewNodeKind("TextBlock")
+
+// Kind implements Node.Kind.
+func (n *TextBlock) Kind() NodeKind {
+	return KindTextBlock
+}
+
+// NewTextBlock returns a new TextBlock node.
+func NewTextBlock() *TextBlock {
+	return &TextBlock{
+		BaseBlock: BaseBlock{},
+	}
+}
+
+// A Paragraph struct represents a paragraph of Markdown text.
+type Paragraph struct {
+	BaseBlock
+}
+
+// Dump implements Node.Dump .
+func (n *Paragraph) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindParagraph is a NodeKind of the Paragraph node.
+var KindParagraph = NewNodeKind("Paragraph")
+
+// Kind implements Node.Kind.
+func (n *Paragraph) Kind() NodeKind {
+	return KindParagraph
+}
+
+// NewParagraph returns a new Paragraph node.
+func NewParagraph() *Paragraph {
+	return &Paragraph{
+		BaseBlock: BaseBlock{},
+	}
+}
+
+// IsParagraph returns true if the given node implements the Paragraph interface,
+// otherwise false.
+func IsParagraph(node Node) bool {
+	_, ok := node.(*Paragraph)
+	return ok
+}
+
+// A Heading struct represents headings like SetextHeading and ATXHeading.
+type Heading struct {
+	BaseBlock
+	// Level returns a level of this heading.
+	// This value is between 1 and 6.
+	Level int
+}
+
+// Dump implements Node.Dump .
+func (n *Heading) Dump(source []byte, level int) {
+	m := map[string]string{
+		"Level": fmt.Sprintf("%d", n.Level),
+	}
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindHeading is a NodeKind of the Heading node.
+var KindHeading = NewNodeKind("Heading")
+
+// Kind implements Node.Kind.
+func (n *Heading) Kind() NodeKind {
+	return KindHeading
+}
+
+// NewHeading returns a new Heading node.
+func NewHeading(level int) *Heading {
+	return &Heading{
+		BaseBlock: BaseBlock{},
+		Level:     level,
+	}
+}
+
+// A ThematicBreak struct represents a thematic break of Markdown text.
+type ThematicBreak struct {
+	BaseBlock
+}
+
+// Dump implements Node.Dump .
+func (n *ThematicBreak) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindThematicBreak is a NodeKind of the ThematicBreak node.
+var KindThematicBreak = NewNodeKind("ThematicBreak")
+
+// Kind implements Node.Kind.
+func (n *ThematicBreak) Kind() NodeKind {
+	return KindThematicBreak
+}
+
+// NewThematicBreak returns a new ThematicBreak node.
+func NewThematicBreak() *ThematicBreak {
+	return &ThematicBreak{
+		BaseBlock: BaseBlock{},
+	}
+}
+
+// A CodeBlock interface represents an indented code block of Markdown text.
+type CodeBlock struct {
+	BaseBlock
+}
+
+// IsRaw implements Node.IsRaw.
+func (n *CodeBlock) IsRaw() bool {
+	return true
+}
+
+// Dump implements Node.Dump .
+func (n *CodeBlock) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindCodeBlock is a NodeKind of the CodeBlock node.
+var KindCodeBlock = NewNodeKind("CodeBlock")
+
+// Kind implements Node.Kind.
+func (n *CodeBlock) Kind() NodeKind {
+	return KindCodeBlock
+}
+
+// NewCodeBlock returns a new CodeBlock node.
+func NewCodeBlock() *CodeBlock {
+	return &CodeBlock{
+		BaseBlock: BaseBlock{},
+	}
+}
+
+// A FencedCodeBlock struct represents a fenced code block of Markdown text.
+type FencedCodeBlock struct {
+	BaseBlock
+	// Info returns a info text of this fenced code block.
+	Info *Text
+
+	language []byte
+}
+
+// Language returns an language in an info string.
+// Language returns nil if this node does not have an info string.
+func (n *FencedCodeBlock) Language(source []byte) []byte {
+	if n.language == nil && n.Info != nil {
+		segment := n.Info.Segment
+		info := segment.Value(source)
+		i := 0
+		for ; i < len(info); i++ {
+			if info[i] == ' ' {
+				break
+			}
+		}
+		n.language = info[:i]
+	}
+	return n.language
+}
+
+// IsRaw implements Node.IsRaw.
+func (n *FencedCodeBlock) IsRaw() bool {
+	return true
+}
+
+// Dump implements Node.Dump .
+func (n *FencedCodeBlock) Dump(source []byte, level int) {
+	m := map[string]string{}
+	if n.Info != nil {
+		m["Info"] = fmt.Sprintf("\"%s\"", n.Info.Text(source))
+	}
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindFencedCodeBlock is a NodeKind of the FencedCodeBlock node.
+var KindFencedCodeBlock = NewNodeKind("FencedCodeBlock")
+
+// Kind implements Node.Kind.
+func (n *FencedCodeBlock) Kind() NodeKind {
+	return KindFencedCodeBlock
+}
+
+// NewFencedCodeBlock return a new FencedCodeBlock node.
+func NewFencedCodeBlock(info *Text) *FencedCodeBlock {
+	return &FencedCodeBlock{
+		BaseBlock: BaseBlock{},
+		Info:      info,
+	}
+}
+
+// A Blockquote struct represents an blockquote block of Markdown text.
+type Blockquote struct {
+	BaseBlock
+}
+
+// Dump implements Node.Dump .
+func (n *Blockquote) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindBlockquote is a NodeKind of the Blockquote node.
+var KindBlockquote = NewNodeKind("Blockquote")
+
+// Kind implements Node.Kind.
+func (n *Blockquote) Kind() NodeKind {
+	return KindBlockquote
+}
+
+// NewBlockquote returns a new Blockquote node.
+func NewBlockquote() *Blockquote {
+	return &Blockquote{
+		BaseBlock: BaseBlock{},
+	}
+}
+
+// A List struct represents a list of Markdown text.
+type List struct {
+	BaseBlock
+
+	// Marker is a marker character like '-', '+', ')' and '.'.
+	Marker byte
+
+	// IsTight is a true if this list is a 'tight' list.
+	// See https://spec.commonmark.org/0.29/#loose for details.
+	IsTight bool
+
+	// Start is an initial number of this ordered list.
+	// If this list is not an ordered list, Start is 0.
+	Start int
+}
+
+// IsOrdered returns true if this list is an ordered list, otherwise false.
+func (l *List) IsOrdered() bool {
+	return l.Marker == '.' || l.Marker == ')'
+}
+
+// CanContinue returns true if this list can continue with
+// the given mark and a list type, otherwise false.
+func (l *List) CanContinue(marker byte, isOrdered bool) bool {
+	return marker == l.Marker && isOrdered == l.IsOrdered()
+}
+
+// Dump implements Node.Dump.
+func (l *List) Dump(source []byte, level int) {
+	m := map[string]string{
+		"Ordered": fmt.Sprintf("%v", l.IsOrdered()),
+		"Marker":  fmt.Sprintf("%c", l.Marker),
+		"Tight":   fmt.Sprintf("%v", l.IsTight),
+	}
+	if l.IsOrdered() {
+		m["Start"] = fmt.Sprintf("%d", l.Start)
+	}
+	DumpHelper(l, source, level, m, nil)
+}
+
+// KindList is a NodeKind of the List node.
+var KindList = NewNodeKind("List")
+
+// Kind implements Node.Kind.
+func (l *List) Kind() NodeKind {
+	return KindList
+}
+
+// NewList returns a new List node.
+func NewList(marker byte) *List {
+	return &List{
+		BaseBlock: BaseBlock{},
+		Marker:    marker,
+		IsTight:   true,
+	}
+}
+
+// A ListItem struct represents a list item of Markdown text.
+type ListItem struct {
+	BaseBlock
+
+	// Offset is an offset position of this item.
+	Offset int
+}
+
+// Dump implements Node.Dump.
+func (n *ListItem) Dump(source []byte, level int) {
+	m := map[string]string{
+		"Offset": fmt.Sprintf("%d", n.Offset),
+	}
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindListItem is a NodeKind of the ListItem node.
+var KindListItem = NewNodeKind("ListItem")
+
+// Kind implements Node.Kind.
+func (n *ListItem) Kind() NodeKind {
+	return KindListItem
+}
+
+// NewListItem returns a new ListItem node.
+func NewListItem(offset int) *ListItem {
+	return &ListItem{
+		BaseBlock: BaseBlock{},
+		Offset:    offset,
+	}
+}
+
+// HTMLBlockType represents kinds of an html blocks.
+// See https://spec.commonmark.org/0.29/#html-blocks
+type HTMLBlockType int
+
+const (
+	// HTMLBlockType1 represents type 1 html blocks
+	HTMLBlockType1 HTMLBlockType = iota + 1
+	// HTMLBlockType2 represents type 2 html blocks
+	HTMLBlockType2
+	// HTMLBlockType3 represents type 3 html blocks
+	HTMLBlockType3
+	// HTMLBlockType4 represents type 4 html blocks
+	HTMLBlockType4
+	// HTMLBlockType5 represents type 5 html blocks
+	HTMLBlockType5
+	// HTMLBlockType6 represents type 6 html blocks
+	HTMLBlockType6
+	// HTMLBlockType7 represents type 7 html blocks
+	HTMLBlockType7
+)
+
+// An HTMLBlock struct represents an html block of Markdown text.
+type HTMLBlock struct {
+	BaseBlock
+
+	// Type is a type of this html block.
+	HTMLBlockType HTMLBlockType
+
+	// ClosureLine is a line that closes this html block.
+	ClosureLine textm.Segment
+}
+
+// IsRaw implements Node.IsRaw.
+func (n *HTMLBlock) IsRaw() bool {
+	return true
+}
+
+// HasClosure returns true if this html block has a closure line,
+// otherwise false.
+func (n *HTMLBlock) HasClosure() bool {
+	return n.ClosureLine.Start >= 0
+}
+
+// Dump implements Node.Dump.
+func (n *HTMLBlock) Dump(source []byte, level int) {
+	indent := strings.Repeat("    ", level)
+	fmt.Printf("%s%s {\n", indent, "HTMLBlock")
+	indent2 := strings.Repeat("    ", level+1)
+	fmt.Printf("%sRawText: \"", indent2)
+	for i := 0; i < n.Lines().Len(); i++ {
+		s := n.Lines().At(i)
+		fmt.Print(string(source[s.Start:s.Stop]))
+	}
+	fmt.Printf("\"\n")
+	for c := n.FirstChild(); c != nil; c = c.NextSibling() {
+		c.Dump(source, level+1)
+	}
+	if n.HasClosure() {
+		cl := n.ClosureLine
+		fmt.Printf("%sClosure: \"%s\"\n", indent2, string(cl.Value(source)))
+	}
+	fmt.Printf("%s}\n", indent)
+}
+
+// KindHTMLBlock is a NodeKind of the HTMLBlock node.
+var KindHTMLBlock = NewNodeKind("HTMLBlock")
+
+// Kind implements Node.Kind.
+func (n *HTMLBlock) Kind() NodeKind {
+	return KindHTMLBlock
+}
+
+// NewHTMLBlock returns a new HTMLBlock node.
+func NewHTMLBlock(typ HTMLBlockType) *HTMLBlock {
+	return &HTMLBlock{
+		BaseBlock:     BaseBlock{},
+		HTMLBlockType: typ,
+		ClosureLine:   textm.NewSegment(-1, -1),
+	}
+}

vendor/github.com/yuin/goldmark/ast/inline.go

@@ -0,0 +1,548 @@
+package ast
+
+import (
+	"fmt"
+	"strings"
+
+	textm "github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+// A BaseInline struct implements the Node interface.
+type BaseInline struct {
+	BaseNode
+}
+
+// Type implements Node.Type
+func (b *BaseInline) Type() NodeType {
+	return TypeInline
+}
+
+// IsRaw implements Node.IsRaw
+func (b *BaseInline) IsRaw() bool {
+	return false
+}
+
+// HasBlankPreviousLines implements Node.HasBlankPreviousLines.
+func (b *BaseInline) HasBlankPreviousLines() bool {
+	panic("can not call with inline nodes.")
+}
+
+// SetBlankPreviousLines implements Node.SetBlankPreviousLines.
+func (b *BaseInline) SetBlankPreviousLines(v bool) {
+	panic("can not call with inline nodes.")
+}
+
+// Lines implements Node.Lines
+func (b *BaseInline) Lines() *textm.Segments {
+	panic("can not call with inline nodes.")
+}
+
+// SetLines implements Node.SetLines
+func (b *BaseInline) SetLines(v *textm.Segments) {
+	panic("can not call with inline nodes.")
+}
+
+// A Text struct represents a textual content of the Markdown text.
+type Text struct {
+	BaseInline
+	// Segment is a position in a source text.
+	Segment textm.Segment
+
+	flags uint8
+}
+
+const (
+	textSoftLineBreak = 1 << iota
+	textHardLineBreak
+	textRaw
+	textCode
+)
+
+func textFlagsString(flags uint8) string {
+	buf := []string{}
+	if flags&textSoftLineBreak != 0 {
+		buf = append(buf, "SoftLineBreak")
+	}
+	if flags&textHardLineBreak != 0 {
+		buf = append(buf, "HardLineBreak")
+	}
+	if flags&textRaw != 0 {
+		buf = append(buf, "Raw")
+	}
+	if flags&textCode != 0 {
+		buf = append(buf, "Code")
+	}
+	return strings.Join(buf, ", ")
+}
+
+// Inline implements Inline.Inline.
+func (n *Text) Inline() {
+}
+
+// SoftLineBreak returns true if this node ends with a new line,
+// otherwise false.
+func (n *Text) SoftLineBreak() bool {
+	return n.flags&textSoftLineBreak != 0
+}
+
+// SetSoftLineBreak sets whether this node ends with a new line.
+func (n *Text) SetSoftLineBreak(v bool) {
+	if v {
+		n.flags |= textSoftLineBreak
+	} else {
+		n.flags = n.flags &^ textHardLineBreak
+	}
+}
+
+// IsRaw returns true if this text should be rendered without unescaping
+// back slash escapes and resolving references.
+func (n *Text) IsRaw() bool {
+	return n.flags&textRaw != 0
+}
+
+// SetRaw sets whether this text should be rendered as raw contents.
+func (n *Text) SetRaw(v bool) {
+	if v {
+		n.flags |= textRaw
+	} else {
+		n.flags = n.flags &^ textRaw
+	}
+}
+
+// HardLineBreak returns true if this node ends with a hard line break.
+// See https://spec.commonmark.org/0.29/#hard-line-breaks for details.
+func (n *Text) HardLineBreak() bool {
+	return n.flags&textHardLineBreak != 0
+}
+
+// SetHardLineBreak sets whether this node ends with a hard line break.
+func (n *Text) SetHardLineBreak(v bool) {
+	if v {
+		n.flags |= textHardLineBreak
+	} else {
+		n.flags = n.flags &^ textHardLineBreak
+	}
+}
+
+// Merge merges a Node n into this node.
+// Merge returns true if the given node has been merged, otherwise false.
+func (n *Text) Merge(node Node, source []byte) bool {
+	t, ok := node.(*Text)
+	if !ok {
+		return false
+	}
+	if n.Segment.Stop != t.Segment.Start || t.Segment.Padding != 0 || source[n.Segment.Stop-1] == '\n' || t.IsRaw() != n.IsRaw() {
+		return false
+	}
+	n.Segment.Stop = t.Segment.Stop
+	n.SetSoftLineBreak(t.SoftLineBreak())
+	n.SetHardLineBreak(t.HardLineBreak())
+	return true
+}
+
+// Text implements Node.Text.
+func (n *Text) Text(source []byte) []byte {
+	return n.Segment.Value(source)
+}
+
+// Dump implements Node.Dump.
+func (n *Text) Dump(source []byte, level int) {
+	fs := textFlagsString(n.flags)
+	if len(fs) != 0 {
+		fs = "(" + fs + ")"
+	}
+	fmt.Printf("%sText%s: \"%s\"\n", strings.Repeat("    ", level), fs, strings.TrimRight(string(n.Text(source)), "\n"))
+}
+
+// KindText is a NodeKind of the Text node.
+var KindText = NewNodeKind("Text")
+
+// Kind implements Node.Kind.
+func (n *Text) Kind() NodeKind {
+	return KindText
+}
+
+// NewText returns a new Text node.
+func NewText() *Text {
+	return &Text{
+		BaseInline: BaseInline{},
+	}
+}
+
+// NewTextSegment returns a new Text node with the given source position.
+func NewTextSegment(v textm.Segment) *Text {
+	return &Text{
+		BaseInline: BaseInline{},
+		Segment:    v,
+	}
+}
+
+// NewRawTextSegment returns a new Text node with the given source position.
+// The new node should be rendered as raw contents.
+func NewRawTextSegment(v textm.Segment) *Text {
+	t := &Text{
+		BaseInline: BaseInline{},
+		Segment:    v,
+	}
+	t.SetRaw(true)
+	return t
+}
+
+// MergeOrAppendTextSegment merges a given s into the last child of the parent if
+// it can be merged, otherwise creates a new Text node and appends it to after current
+// last child.
+func MergeOrAppendTextSegment(parent Node, s textm.Segment) {
+	last := parent.LastChild()
+	t, ok := last.(*Text)
+	if ok && t.Segment.Stop == s.Start && !t.SoftLineBreak() {
+		t.Segment = t.Segment.WithStop(s.Stop)
+	} else {
+		parent.AppendChild(parent, NewTextSegment(s))
+	}
+}
+
+// MergeOrReplaceTextSegment merges a given s into a previous sibling of the node n
+// if a previous sibling of the node n is *Text, otherwise replaces Node n with s.
+func MergeOrReplaceTextSegment(parent Node, n Node, s textm.Segment) {
+	prev := n.PreviousSibling()
+	if t, ok := prev.(*Text); ok && t.Segment.Stop == s.Start && !t.SoftLineBreak() {
+		t.Segment = t.Segment.WithStop(s.Stop)
+		parent.RemoveChild(parent, n)
+	} else {
+		parent.ReplaceChild(parent, n, NewTextSegment(s))
+	}
+}
+
+// A String struct is a textual content that has a concrete value
+type String struct {
+	BaseInline
+
+	Value []byte
+	flags uint8
+}
+
+// Inline implements Inline.Inline.
+func (n *String) Inline() {
+}
+
+// IsRaw returns true if this text should be rendered without unescaping
+// back slash escapes and resolving references.
+func (n *String) IsRaw() bool {
+	return n.flags&textRaw != 0
+}
+
+// SetRaw sets whether this text should be rendered as raw contents.
+func (n *String) SetRaw(v bool) {
+	if v {
+		n.flags |= textRaw
+	} else {
+		n.flags = n.flags &^ textRaw
+	}
+}
+
+// IsCode returns true if this text should be rendered without any
+// modifications.
+func (n *String) IsCode() bool {
+	return n.flags&textCode != 0
+}
+
+// SetCode sets whether this text should be rendered without any modifications.
+func (n *String) SetCode(v bool) {
+	if v {
+		n.flags |= textCode
+	} else {
+		n.flags = n.flags &^ textCode
+	}
+}
+
+// Text implements Node.Text.
+func (n *String) Text(source []byte) []byte {
+	return n.Value
+}
+
+// Dump implements Node.Dump.
+func (n *String) Dump(source []byte, level int) {
+	fs := textFlagsString(n.flags)
+	if len(fs) != 0 {
+		fs = "(" + fs + ")"
+	}
+	fmt.Printf("%sString%s: \"%s\"\n", strings.Repeat("    ", level), fs, strings.TrimRight(string(n.Value), "\n"))
+}
+
+// KindString is a NodeKind of the String node.
+var KindString = NewNodeKind("String")
+
+// Kind implements Node.Kind.
+func (n *String) Kind() NodeKind {
+	return KindString
+}
+
+// NewString returns a new String node.
+func NewString(v []byte) *String {
+	return &String{
+		Value: v,
+	}
+}
+
+// A CodeSpan struct represents a code span of Markdown text.
+type CodeSpan struct {
+	BaseInline
+}
+
+// Inline implements Inline.Inline .
+func (n *CodeSpan) Inline() {
+}
+
+// IsBlank returns true if this node consists of spaces, otherwise false.
+func (n *CodeSpan) IsBlank(source []byte) bool {
+	for c := n.FirstChild(); c != nil; c = c.NextSibling() {
+		text := c.(*Text).Segment
+		if !util.IsBlank(text.Value(source)) {
+			return false
+		}
+	}
+	return true
+}
+
+// Dump implements Node.Dump
+func (n *CodeSpan) Dump(source []byte, level int) {
+	DumpHelper(n, source, level, nil, nil)
+}
+
+// KindCodeSpan is a NodeKind of the CodeSpan node.
+var KindCodeSpan = NewNodeKind("CodeSpan")
+
+// Kind implements Node.Kind.
+func (n *CodeSpan) Kind() NodeKind {
+	return KindCodeSpan
+}
+
+// NewCodeSpan returns a new CodeSpan node.
+func NewCodeSpan() *CodeSpan {
+	return &CodeSpan{
+		BaseInline: BaseInline{},
+	}
+}
+
+// An Emphasis struct represents an emphasis of Markdown text.
+type Emphasis struct {
+	BaseInline
+
+	// Level is a level of the emphasis.
+	Level int
+}
+
+// Dump implements Node.Dump.
+func (n *Emphasis) Dump(source []byte, level int) {
+	m := map[string]string{
+		"Level": fmt.Sprintf("%v", n.Level),
+	}
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindEmphasis is a NodeKind of the Emphasis node.
+var KindEmphasis = NewNodeKind("Emphasis")
+
+// Kind implements Node.Kind.
+func (n *Emphasis) Kind() NodeKind {
+	return KindEmphasis
+}
+
+// NewEmphasis returns a new Emphasis node with the given level.
+func NewEmphasis(level int) *Emphasis {
+	return &Emphasis{
+		BaseInline: BaseInline{},
+		Level:      level,
+	}
+}
+
+type baseLink struct {
+	BaseInline
+
+	// Destination is a destination(URL) of this link.
+	Destination []byte
+
+	// Title is a title of this link.
+	Title []byte
+}
+
+// Inline implements Inline.Inline.
+func (n *baseLink) Inline() {
+}
+
+// A Link struct represents a link of the Markdown text.
+type Link struct {
+	baseLink
+}
+
+// Dump implements Node.Dump.
+func (n *Link) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Destination"] = string(n.Destination)
+	m["Title"] = string(n.Title)
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindLink is a NodeKind of the Link node.
+var KindLink = NewNodeKind("Link")
+
+// Kind implements Node.Kind.
+func (n *Link) Kind() NodeKind {
+	return KindLink
+}
+
+// NewLink returns a new Link node.
+func NewLink() *Link {
+	c := &Link{
+		baseLink: baseLink{
+			BaseInline: BaseInline{},
+		},
+	}
+	return c
+}
+
+// An Image struct represents an image of the Markdown text.
+type Image struct {
+	baseLink
+}
+
+// Dump implements Node.Dump.
+func (n *Image) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Destination"] = string(n.Destination)
+	m["Title"] = string(n.Title)
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindImage is a NodeKind of the Image node.
+var KindImage = NewNodeKind("Image")
+
+// Kind implements Node.Kind.
+func (n *Image) Kind() NodeKind {
+	return KindImage
+}
+
+// NewImage returns a new Image node.
+func NewImage(link *Link) *Image {
+	c := &Image{
+		baseLink: baseLink{
+			BaseInline: BaseInline{},
+		},
+	}
+	c.Destination = link.Destination
+	c.Title = link.Title
+	for n := link.FirstChild(); n != nil; {
+		next := n.NextSibling()
+		link.RemoveChild(link, n)
+		c.AppendChild(c, n)
+		n = next
+	}
+
+	return c
+}
+
+// AutoLinkType defines kind of auto links.
+type AutoLinkType int
+
+const (
+	// AutoLinkEmail indicates that an autolink is an email address.
+	AutoLinkEmail AutoLinkType = iota + 1
+	// AutoLinkURL indicates that an autolink is a generic URL.
+	AutoLinkURL
+)
+
+// An AutoLink struct represents an autolink of the Markdown text.
+type AutoLink struct {
+	BaseInline
+	// Type is a type of this autolink.
+	AutoLinkType AutoLinkType
+
+	// Protocol specified a protocol of the link.
+	Protocol []byte
+
+	value *Text
+}
+
+// Inline implements Inline.Inline.
+func (n *AutoLink) Inline() {}
+
+// Dump implements Node.Dump
+func (n *AutoLink) Dump(source []byte, level int) {
+	segment := n.value.Segment
+	m := map[string]string{
+		"Value": string(segment.Value(source)),
+	}
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindAutoLink is a NodeKind of the AutoLink node.
+var KindAutoLink = NewNodeKind("AutoLink")
+
+// Kind implements Node.Kind.
+func (n *AutoLink) Kind() NodeKind {
+	return KindAutoLink
+}
+
+// URL returns an url of this node.
+func (n *AutoLink) URL(source []byte) []byte {
+	if n.Protocol != nil {
+		s := n.value.Segment
+		ret := make([]byte, 0, len(n.Protocol)+s.Len()+3)
+		ret = append(ret, n.Protocol...)
+		ret = append(ret, ':', '/', '/')
+		ret = append(ret, n.value.Text(source)...)
+		return ret
+	}
+	return n.value.Text(source)
+}
+
+// Label returns a label of this node.
+func (n *AutoLink) Label(source []byte) []byte {
+	return n.value.Text(source)
+}
+
+// NewAutoLink returns a new AutoLink node.
+func NewAutoLink(typ AutoLinkType, value *Text) *AutoLink {
+	return &AutoLink{
+		BaseInline:   BaseInline{},
+		value:        value,
+		AutoLinkType: typ,
+	}
+}
+
+// A RawHTML struct represents an inline raw HTML of the Markdown text.
+type RawHTML struct {
+	BaseInline
+	Segments *textm.Segments
+}
+
+// Inline implements Inline.Inline.
+func (n *RawHTML) Inline() {}
+
+// Dump implements Node.Dump.
+func (n *RawHTML) Dump(source []byte, level int) {
+	m := map[string]string{}
+	t := []string{}
+	for i := 0; i < n.Segments.Len(); i++ {
+		segment := n.Segments.At(i)
+		t = append(t, string(segment.Value(source)))
+	}
+	m["RawText"] = strings.Join(t, "")
+	DumpHelper(n, source, level, m, nil)
+}
+
+// KindRawHTML is a NodeKind of the RawHTML node.
+var KindRawHTML = NewNodeKind("RawHTML")
+
+// Kind implements Node.Kind.
+func (n *RawHTML) Kind() NodeKind {
+	return KindRawHTML
+}
+
+// NewRawHTML returns a new RawHTML node.
+func NewRawHTML() *RawHTML {
+	return &RawHTML{
+		Segments: textm.NewSegments(),
+	}
+}

vendor/github.com/yuin/goldmark/extension/ast/definition_list.go

@@ -0,0 +1,83 @@
+package ast
+
+import (
+	gast "github.com/yuin/goldmark/ast"
+)
+
+// A DefinitionList struct represents a definition list of Markdown
+// (PHPMarkdownExtra) text.
+type DefinitionList struct {
+	gast.BaseBlock
+	Offset             int
+	TemporaryParagraph *gast.Paragraph
+}
+
+// Dump implements Node.Dump.
+func (n *DefinitionList) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindDefinitionList is a NodeKind of the DefinitionList node.
+var KindDefinitionList = gast.NewNodeKind("DefinitionList")
+
+// Kind implements Node.Kind.
+func (n *DefinitionList) Kind() gast.NodeKind {
+	return KindDefinitionList
+}
+
+// NewDefinitionList returns a new DefinitionList node.
+func NewDefinitionList(offset int, para *gast.Paragraph) *DefinitionList {
+	return &DefinitionList{
+		Offset:             offset,
+		TemporaryParagraph: para,
+	}
+}
+
+// A DefinitionTerm struct represents a definition list term of Markdown
+// (PHPMarkdownExtra) text.
+type DefinitionTerm struct {
+	gast.BaseBlock
+}
+
+// Dump implements Node.Dump.
+func (n *DefinitionTerm) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindDefinitionTerm is a NodeKind of the DefinitionTerm node.
+var KindDefinitionTerm = gast.NewNodeKind("DefinitionTerm")
+
+// Kind implements Node.Kind.
+func (n *DefinitionTerm) Kind() gast.NodeKind {
+	return KindDefinitionTerm
+}
+
+// NewDefinitionTerm returns a new DefinitionTerm node.
+func NewDefinitionTerm() *DefinitionTerm {
+	return &DefinitionTerm{}
+}
+
+// A DefinitionDescription struct represents a definition list description of Markdown
+// (PHPMarkdownExtra) text.
+type DefinitionDescription struct {
+	gast.BaseBlock
+	IsTight bool
+}
+
+// Dump implements Node.Dump.
+func (n *DefinitionDescription) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindDefinitionDescription is a NodeKind of the DefinitionDescription node.
+var KindDefinitionDescription = gast.NewNodeKind("DefinitionDescription")
+
+// Kind implements Node.Kind.
+func (n *DefinitionDescription) Kind() gast.NodeKind {
+	return KindDefinitionDescription
+}
+
+// NewDefinitionDescription returns a new DefinitionDescription node.
+func NewDefinitionDescription() *DefinitionDescription {
+	return &DefinitionDescription{}
+}

vendor/github.com/yuin/goldmark/extension/ast/footnote.go

@@ -0,0 +1,125 @@
+package ast
+
+import (
+	"fmt"
+	gast "github.com/yuin/goldmark/ast"
+)
+
+// A FootnoteLink struct represents a link to a footnote of Markdown
+// (PHP Markdown Extra) text.
+type FootnoteLink struct {
+	gast.BaseInline
+	Index int
+}
+
+// Dump implements Node.Dump.
+func (n *FootnoteLink) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Index"] = fmt.Sprintf("%v", n.Index)
+	gast.DumpHelper(n, source, level, m, nil)
+}
+
+// KindFootnoteLink is a NodeKind of the FootnoteLink node.
+var KindFootnoteLink = gast.NewNodeKind("FootnoteLink")
+
+// Kind implements Node.Kind.
+func (n *FootnoteLink) Kind() gast.NodeKind {
+	return KindFootnoteLink
+}
+
+// NewFootnoteLink returns a new FootnoteLink node.
+func NewFootnoteLink(index int) *FootnoteLink {
+	return &FootnoteLink{
+		Index: index,
+	}
+}
+
+// A FootnoteBackLink struct represents a link to a footnote of Markdown
+// (PHP Markdown Extra) text.
+type FootnoteBackLink struct {
+	gast.BaseInline
+	Index int
+}
+
+// Dump implements Node.Dump.
+func (n *FootnoteBackLink) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Index"] = fmt.Sprintf("%v", n.Index)
+	gast.DumpHelper(n, source, level, m, nil)
+}
+
+// KindFootnoteBackLink is a NodeKind of the FootnoteBackLink node.
+var KindFootnoteBackLink = gast.NewNodeKind("FootnoteBackLink")
+
+// Kind implements Node.Kind.
+func (n *FootnoteBackLink) Kind() gast.NodeKind {
+	return KindFootnoteBackLink
+}
+
+// NewFootnoteBackLink returns a new FootnoteBackLink node.
+func NewFootnoteBackLink(index int) *FootnoteBackLink {
+	return &FootnoteBackLink{
+		Index: index,
+	}
+}
+
+// A Footnote struct represents a footnote of Markdown
+// (PHP Markdown Extra) text.
+type Footnote struct {
+	gast.BaseBlock
+	Ref   []byte
+	Index int
+}
+
+// Dump implements Node.Dump.
+func (n *Footnote) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Index"] = fmt.Sprintf("%v", n.Index)
+	m["Ref"] = fmt.Sprintf("%s", n.Ref)
+	gast.DumpHelper(n, source, level, m, nil)
+}
+
+// KindFootnote is a NodeKind of the Footnote node.
+var KindFootnote = gast.NewNodeKind("Footnote")
+
+// Kind implements Node.Kind.
+func (n *Footnote) Kind() gast.NodeKind {
+	return KindFootnote
+}
+
+// NewFootnote returns a new Footnote node.
+func NewFootnote(ref []byte) *Footnote {
+	return &Footnote{
+		Ref:   ref,
+		Index: -1,
+	}
+}
+
+// A FootnoteList struct represents footnotes of Markdown
+// (PHP Markdown Extra) text.
+type FootnoteList struct {
+	gast.BaseBlock
+	Count int
+}
+
+// Dump implements Node.Dump.
+func (n *FootnoteList) Dump(source []byte, level int) {
+	m := map[string]string{}
+	m["Count"] = fmt.Sprintf("%v", n.Count)
+	gast.DumpHelper(n, source, level, m, nil)
+}
+
+// KindFootnoteList is a NodeKind of the FootnoteList node.
+var KindFootnoteList = gast.NewNodeKind("FootnoteList")
+
+// Kind implements Node.Kind.
+func (n *FootnoteList) Kind() gast.NodeKind {
+	return KindFootnoteList
+}
+
+// NewFootnoteList returns a new FootnoteList node.
+func NewFootnoteList() *FootnoteList {
+	return &FootnoteList{
+		Count: 0,
+	}
+}

vendor/github.com/yuin/goldmark/extension/ast/strikethrough.go

@@ -0,0 +1,29 @@
+// Package ast defines AST nodes that represents extension's elements
+package ast
+
+import (
+	gast "github.com/yuin/goldmark/ast"
+)
+
+// A Strikethrough struct represents a strikethrough of GFM text.
+type Strikethrough struct {
+	gast.BaseInline
+}
+
+// Dump implements Node.Dump.
+func (n *Strikethrough) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindStrikethrough is a NodeKind of the Strikethrough node.
+var KindStrikethrough = gast.NewNodeKind("Strikethrough")
+
+// Kind implements Node.Kind.
+func (n *Strikethrough) Kind() gast.NodeKind {
+	return KindStrikethrough
+}
+
+// NewStrikethrough returns a new Strikethrough node.
+func NewStrikethrough() *Strikethrough {
+	return &Strikethrough{}
+}

vendor/github.com/yuin/goldmark/extension/ast/table.go

@@ -0,0 +1,157 @@
+package ast
+
+import (
+	"fmt"
+	gast "github.com/yuin/goldmark/ast"
+	"strings"
+)
+
+// Alignment is a text alignment of table cells.
+type Alignment int
+
+const (
+	// AlignLeft indicates text should be left justified.
+	AlignLeft Alignment = iota + 1
+
+	// AlignRight indicates text should be right justified.
+	AlignRight
+
+	// AlignCenter indicates text should be centered.
+	AlignCenter
+
+	// AlignNone indicates text should be aligned by default manner.
+	AlignNone
+)
+
+func (a Alignment) String() string {
+	switch a {
+	case AlignLeft:
+		return "left"
+	case AlignRight:
+		return "right"
+	case AlignCenter:
+		return "center"
+	case AlignNone:
+		return "none"
+	}
+	return ""
+}
+
+// A Table struct represents a table of Markdown(GFM) text.
+type Table struct {
+	gast.BaseBlock
+
+	// Alignments returns alignments of the columns.
+	Alignments []Alignment
+}
+
+// Dump implements Node.Dump
+func (n *Table) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, func(level int) {
+		indent := strings.Repeat("    ", level)
+		fmt.Printf("%sAlignments {\n", indent)
+		for i, alignment := range n.Alignments {
+			indent2 := strings.Repeat("    ", level+1)
+			fmt.Printf("%s%s", indent2, alignment.String())
+			if i != len(n.Alignments)-1 {
+				fmt.Println("")
+			}
+		}
+		fmt.Printf("\n%s}\n", indent)
+	})
+}
+
+// KindTable is a NodeKind of the Table node.
+var KindTable = gast.NewNodeKind("Table")
+
+// Kind implements Node.Kind.
+func (n *Table) Kind() gast.NodeKind {
+	return KindTable
+}
+
+// NewTable returns a new Table node.
+func NewTable() *Table {
+	return &Table{
+		Alignments: []Alignment{},
+	}
+}
+
+// A TableRow struct represents a table row of Markdown(GFM) text.
+type TableRow struct {
+	gast.BaseBlock
+	Alignments []Alignment
+}
+
+// Dump implements Node.Dump.
+func (n *TableRow) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindTableRow is a NodeKind of the TableRow node.
+var KindTableRow = gast.NewNodeKind("TableRow")
+
+// Kind implements Node.Kind.
+func (n *TableRow) Kind() gast.NodeKind {
+	return KindTableRow
+}
+
+// NewTableRow returns a new TableRow node.
+func NewTableRow(alignments []Alignment) *TableRow {
+	return &TableRow{}
+}
+
+// A TableHeader struct represents a table header of Markdown(GFM) text.
+type TableHeader struct {
+	gast.BaseBlock
+	Alignments []Alignment
+}
+
+// KindTableHeader is a NodeKind of the TableHeader node.
+var KindTableHeader = gast.NewNodeKind("TableHeader")
+
+// Kind implements Node.Kind.
+func (n *TableHeader) Kind() gast.NodeKind {
+	return KindTableHeader
+}
+
+// Dump implements Node.Dump.
+func (n *TableHeader) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// NewTableHeader returns a new TableHeader node.
+func NewTableHeader(row *TableRow) *TableHeader {
+	n := &TableHeader{}
+	for c := row.FirstChild(); c != nil; {
+		next := c.NextSibling()
+		n.AppendChild(n, c)
+		c = next
+	}
+	return n
+}
+
+// A TableCell struct represents a table cell of a Markdown(GFM) text.
+type TableCell struct {
+	gast.BaseBlock
+	Alignment Alignment
+}
+
+// Dump implements Node.Dump.
+func (n *TableCell) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, nil)
+}
+
+// KindTableCell is a NodeKind of the TableCell node.
+var KindTableCell = gast.NewNodeKind("TableCell")
+
+// Kind implements Node.Kind.
+func (n *TableCell) Kind() gast.NodeKind {
+	return KindTableCell
+}
+
+// NewTableCell returns a new TableCell node.
+func NewTableCell() *TableCell {
+	return &TableCell{
+		Alignment: AlignNone,
+	}
+}

vendor/github.com/yuin/goldmark/extension/ast/tasklist.go

@@ -0,0 +1,35 @@
+package ast
+
+import (
+	"fmt"
+	gast "github.com/yuin/goldmark/ast"
+)
+
+// A TaskCheckBox struct represents a checkbox of a task list.
+type TaskCheckBox struct {
+	gast.BaseInline
+	IsChecked bool
+}
+
+// Dump implements Node.Dump.
+func (n *TaskCheckBox) Dump(source []byte, level int) {
+	m := map[string]string{
+		"Checked": fmt.Sprintf("%v", n.IsChecked),
+	}
+	gast.DumpHelper(n, source, level, m, nil)
+}
+
+// KindTaskCheckBox is a NodeKind of the TaskCheckBox node.
+var KindTaskCheckBox = gast.NewNodeKind("TaskCheckBox")
+
+// Kind implements Node.Kind.
+func (n *TaskCheckBox) Kind() gast.NodeKind {
+	return KindTaskCheckBox
+}
+
+// NewTaskCheckBox returns a new TaskCheckBox node.
+func NewTaskCheckBox(checked bool) *TaskCheckBox {
+	return &TaskCheckBox{
+		IsChecked: checked,
+	}
+}

vendor/github.com/yuin/goldmark/extension/definition_list.go

@@ -0,0 +1,270 @@
+package extension
+
+import (
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type definitionListParser struct {
+}
+
+var defaultDefinitionListParser = &definitionListParser{}
+
+// NewDefinitionListParser return a new parser.BlockParser that
+// can parse PHP Markdown Extra Definition lists.
+func NewDefinitionListParser() parser.BlockParser {
+	return defaultDefinitionListParser
+}
+
+func (b *definitionListParser) Trigger() []byte {
+	return []byte{':'}
+}
+
+func (b *definitionListParser) Open(parent gast.Node, reader text.Reader, pc parser.Context) (gast.Node, parser.State) {
+	if _, ok := parent.(*ast.DefinitionList); ok {
+		return nil, parser.NoChildren
+	}
+	line, _ := reader.PeekLine()
+	pos := pc.BlockOffset()
+	indent := pc.BlockIndent()
+	if pos < 0 || line[pos] != ':' || indent != 0 {
+		return nil, parser.NoChildren
+	}
+
+	last := parent.LastChild()
+	// need 1 or more spaces after ':'
+	w, _ := util.IndentWidth(line[pos+1:], pos+1)
+	if w < 1 {
+		return nil, parser.NoChildren
+	}
+	if w >= 8 { // starts with indented code
+		w = 5
+	}
+	w += pos + 1 /* 1 = ':' */
+
+	para, lastIsParagraph := last.(*gast.Paragraph)
+	var list *ast.DefinitionList
+	status := parser.HasChildren
+	var ok bool
+	if lastIsParagraph {
+		list, ok = last.PreviousSibling().(*ast.DefinitionList)
+		if ok { // is not first item
+			list.Offset = w
+			list.TemporaryParagraph = para
+		} else { // is first item
+			list = ast.NewDefinitionList(w, para)
+			status |= parser.RequireParagraph
+		}
+	} else if list, ok = last.(*ast.DefinitionList); ok { // multiple description
+		list.Offset = w
+		list.TemporaryParagraph = nil
+	} else {
+		return nil, parser.NoChildren
+	}
+
+	return list, status
+}
+
+func (b *definitionListParser) Continue(node gast.Node, reader text.Reader, pc parser.Context) parser.State {
+	line, _ := reader.PeekLine()
+	if util.IsBlank(line) {
+		return parser.Continue | parser.HasChildren
+	}
+	list, _ := node.(*ast.DefinitionList)
+	w, _ := util.IndentWidth(line, reader.LineOffset())
+	if w < list.Offset {
+		return parser.Close
+	}
+	pos, padding := util.IndentPosition(line, reader.LineOffset(), list.Offset)
+	reader.AdvanceAndSetPadding(pos, padding)
+	return parser.Continue | parser.HasChildren
+}
+
+func (b *definitionListParser) Close(node gast.Node, reader text.Reader, pc parser.Context) {
+	// nothing to do
+}
+
+func (b *definitionListParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *definitionListParser) CanAcceptIndentedLine() bool {
+	return false
+}
+
+type definitionDescriptionParser struct {
+}
+
+var defaultDefinitionDescriptionParser = &definitionDescriptionParser{}
+
+// NewDefinitionDescriptionParser return a new parser.BlockParser that
+// can parse definition description starts with ':'.
+func NewDefinitionDescriptionParser() parser.BlockParser {
+	return defaultDefinitionDescriptionParser
+}
+
+func (b *definitionDescriptionParser) Trigger() []byte {
+	return []byte{':'}
+}
+
+func (b *definitionDescriptionParser) Open(parent gast.Node, reader text.Reader, pc parser.Context) (gast.Node, parser.State) {
+	line, _ := reader.PeekLine()
+	pos := pc.BlockOffset()
+	indent := pc.BlockIndent()
+	if pos < 0 || line[pos] != ':' || indent != 0 {
+		return nil, parser.NoChildren
+	}
+	list, _ := parent.(*ast.DefinitionList)
+	if list == nil {
+		return nil, parser.NoChildren
+	}
+	para := list.TemporaryParagraph
+	list.TemporaryParagraph = nil
+	if para != nil {
+		lines := para.Lines()
+		l := lines.Len()
+		for i := 0; i < l; i++ {
+			term := ast.NewDefinitionTerm()
+			segment := lines.At(i)
+			term.Lines().Append(segment.TrimRightSpace(reader.Source()))
+			list.AppendChild(list, term)
+		}
+		para.Parent().RemoveChild(para.Parent(), para)
+	}
+	cpos, padding := util.IndentPosition(line[pos+1:], pos+1, list.Offset-pos-1)
+	reader.AdvanceAndSetPadding(cpos, padding)
+
+	return ast.NewDefinitionDescription(), parser.HasChildren
+}
+
+func (b *definitionDescriptionParser) Continue(node gast.Node, reader text.Reader, pc parser.Context) parser.State {
+	// definitionListParser detects end of the description.
+	// so this method will never be called.
+	return parser.Continue | parser.HasChildren
+}
+
+func (b *definitionDescriptionParser) Close(node gast.Node, reader text.Reader, pc parser.Context) {
+	desc := node.(*ast.DefinitionDescription)
+	desc.IsTight = !desc.HasBlankPreviousLines()
+	if desc.IsTight {
+		for gc := desc.FirstChild(); gc != nil; gc = gc.NextSibling() {
+			paragraph, ok := gc.(*gast.Paragraph)
+			if ok {
+				textBlock := gast.NewTextBlock()
+				textBlock.SetLines(paragraph.Lines())
+				desc.ReplaceChild(desc, paragraph, textBlock)
+			}
+		}
+	}
+}
+
+func (b *definitionDescriptionParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *definitionDescriptionParser) CanAcceptIndentedLine() bool {
+	return false
+}
+
+// DefinitionListHTMLRenderer is a renderer.NodeRenderer implementation that
+// renders DefinitionList nodes.
+type DefinitionListHTMLRenderer struct {
+	html.Config
+}
+
+// NewDefinitionListHTMLRenderer returns a new DefinitionListHTMLRenderer.
+func NewDefinitionListHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
+	r := &DefinitionListHTMLRenderer{
+		Config: html.NewConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetHTMLOption(&r.Config)
+	}
+	return r
+}
+
+// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
+func (r *DefinitionListHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindDefinitionList, r.renderDefinitionList)
+	reg.Register(ast.KindDefinitionTerm, r.renderDefinitionTerm)
+	reg.Register(ast.KindDefinitionDescription, r.renderDefinitionDescription)
+}
+
+// DefinitionListAttributeFilter defines attribute names which dl elements can have.
+var DefinitionListAttributeFilter = html.GlobalAttributeFilter
+
+func (r *DefinitionListHTMLRenderer) renderDefinitionList(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<dl")
+			html.RenderAttributes(w, n, DefinitionListAttributeFilter)
+			_, _ = w.WriteString(">\n")
+		} else {
+			_, _ = w.WriteString("<dl>\n")
+		}
+	} else {
+		_, _ = w.WriteString("</dl>\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+// DefinitionTermAttributeFilter defines attribute names which dd elements can have.
+var DefinitionTermAttributeFilter = html.GlobalAttributeFilter
+
+func (r *DefinitionListHTMLRenderer) renderDefinitionTerm(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<dt")
+			html.RenderAttributes(w, n, DefinitionTermAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<dt>")
+		}
+	} else {
+		_, _ = w.WriteString("</dt>\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+// DefinitionDescriptionAttributeFilter defines attribute names which dd elements can have.
+var DefinitionDescriptionAttributeFilter = html.GlobalAttributeFilter
+
+func (r *DefinitionListHTMLRenderer) renderDefinitionDescription(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		n := node.(*ast.DefinitionDescription)
+		_, _ = w.WriteString("<dd")
+		if n.Attributes() != nil {
+			html.RenderAttributes(w, n, DefinitionDescriptionAttributeFilter)
+		}
+		if n.IsTight {
+			_, _ = w.WriteString(">")
+		} else {
+			_, _ = w.WriteString(">\n")
+		}
+	} else {
+		_, _ = w.WriteString("</dd>\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+type definitionList struct {
+}
+
+// DefinitionList is an extension that allow you to use PHP Markdown Extra Definition lists.
+var DefinitionList = &definitionList{}
+
+func (e *definitionList) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(parser.WithBlockParsers(
+		util.Prioritized(NewDefinitionListParser(), 101),
+		util.Prioritized(NewDefinitionDescriptionParser(), 102),
+	))
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewDefinitionListHTMLRenderer(), 500),
+	))
+}

vendor/github.com/yuin/goldmark/extension/footnote.go

@@ -0,0 +1,336 @@
+package extension
+
+import (
+	"bytes"
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+	"strconv"
+)
+
+var footnoteListKey = parser.NewContextKey()
+
+type footnoteBlockParser struct {
+}
+
+var defaultFootnoteBlockParser = &footnoteBlockParser{}
+
+// NewFootnoteBlockParser returns a new parser.BlockParser that can parse
+// footnotes of the Markdown(PHP Markdown Extra) text.
+func NewFootnoteBlockParser() parser.BlockParser {
+	return defaultFootnoteBlockParser
+}
+
+func (b *footnoteBlockParser) Trigger() []byte {
+	return []byte{'['}
+}
+
+func (b *footnoteBlockParser) Open(parent gast.Node, reader text.Reader, pc parser.Context) (gast.Node, parser.State) {
+	line, segment := reader.PeekLine()
+	pos := pc.BlockOffset()
+	if pos < 0 || line[pos] != '[' {
+		return nil, parser.NoChildren
+	}
+	pos++
+	if pos > len(line)-1 || line[pos] != '^' {
+		return nil, parser.NoChildren
+	}
+	open := pos + 1
+	closes := 0
+	closure := util.FindClosure(line[pos+1:], '[', ']', false, false)
+	closes = pos + 1 + closure
+	next := closes + 1
+	if closure > -1 {
+		if next >= len(line) || line[next] != ':' {
+			return nil, parser.NoChildren
+		}
+	} else {
+		return nil, parser.NoChildren
+	}
+	padding := segment.Padding
+	label := reader.Value(text.NewSegment(segment.Start+open-padding, segment.Start+closes-padding))
+	if util.IsBlank(label) {
+		return nil, parser.NoChildren
+	}
+	item := ast.NewFootnote(label)
+
+	pos = next + 1 - padding
+	if pos >= len(line) {
+		reader.Advance(pos)
+		return item, parser.NoChildren
+	}
+	reader.AdvanceAndSetPadding(pos, padding)
+	return item, parser.HasChildren
+}
+
+func (b *footnoteBlockParser) Continue(node gast.Node, reader text.Reader, pc parser.Context) parser.State {
+	line, _ := reader.PeekLine()
+	if util.IsBlank(line) {
+		return parser.Continue | parser.HasChildren
+	}
+	childpos, padding := util.IndentPosition(line, reader.LineOffset(), 4)
+	if childpos < 0 {
+		return parser.Close
+	}
+	reader.AdvanceAndSetPadding(childpos, padding)
+	return parser.Continue | parser.HasChildren
+}
+
+func (b *footnoteBlockParser) Close(node gast.Node, reader text.Reader, pc parser.Context) {
+	var list *ast.FootnoteList
+	if tlist := pc.Get(footnoteListKey); tlist != nil {
+		list = tlist.(*ast.FootnoteList)
+	} else {
+		list = ast.NewFootnoteList()
+		pc.Set(footnoteListKey, list)
+		node.Parent().InsertBefore(node.Parent(), node, list)
+	}
+	node.Parent().RemoveChild(node.Parent(), node)
+	list.AppendChild(list, node)
+}
+
+func (b *footnoteBlockParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *footnoteBlockParser) CanAcceptIndentedLine() bool {
+	return false
+}
+
+type footnoteParser struct {
+}
+
+var defaultFootnoteParser = &footnoteParser{}
+
+// NewFootnoteParser returns a new parser.InlineParser that can parse
+// footnote links of the Markdown(PHP Markdown Extra) text.
+func NewFootnoteParser() parser.InlineParser {
+	return defaultFootnoteParser
+}
+
+func (s *footnoteParser) Trigger() []byte {
+	// footnote syntax probably conflict with the image syntax.
+	// So we need trigger this parser with '!'.
+	return []byte{'!', '['}
+}
+
+func (s *footnoteParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
+	line, segment := block.PeekLine()
+	pos := 1
+	if len(line) > 0 && line[0] == '!' {
+		pos++
+	}
+	if pos >= len(line) || line[pos] != '^' {
+		return nil
+	}
+	pos++
+	if pos >= len(line) {
+		return nil
+	}
+	open := pos
+	closure := util.FindClosure(line[pos:], '[', ']', false, false)
+	if closure < 0 {
+		return nil
+	}
+	closes := pos + closure
+	value := block.Value(text.NewSegment(segment.Start+open, segment.Start+closes))
+	block.Advance(closes + 1)
+
+	var list *ast.FootnoteList
+	if tlist := pc.Get(footnoteListKey); tlist != nil {
+		list = tlist.(*ast.FootnoteList)
+	}
+	if list == nil {
+		return nil
+	}
+	index := 0
+	for def := list.FirstChild(); def != nil; def = def.NextSibling() {
+		d := def.(*ast.Footnote)
+		if bytes.Equal(d.Ref, value) {
+			if d.Index < 0 {
+				list.Count += 1
+				d.Index = list.Count
+			}
+			index = d.Index
+			break
+		}
+	}
+	if index == 0 {
+		return nil
+	}
+
+	return ast.NewFootnoteLink(index)
+}
+
+type footnoteASTTransformer struct {
+}
+
+var defaultFootnoteASTTransformer = &footnoteASTTransformer{}
+
+// NewFootnoteASTTransformer returns a new parser.ASTTransformer that
+// insert a footnote list to the last of the document.
+func NewFootnoteASTTransformer() parser.ASTTransformer {
+	return defaultFootnoteASTTransformer
+}
+
+func (a *footnoteASTTransformer) Transform(node *gast.Document, reader text.Reader, pc parser.Context) {
+	var list *ast.FootnoteList
+	if tlist := pc.Get(footnoteListKey); tlist != nil {
+		list = tlist.(*ast.FootnoteList)
+	} else {
+		return
+	}
+	pc.Set(footnoteListKey, nil)
+	for footnote := list.FirstChild(); footnote != nil; {
+		var container gast.Node = footnote
+		next := footnote.NextSibling()
+		if fc := container.LastChild(); fc != nil && gast.IsParagraph(fc) {
+			container = fc
+		}
+		index := footnote.(*ast.Footnote).Index
+		if index < 0 {
+			list.RemoveChild(list, footnote)
+		} else {
+			container.AppendChild(container, ast.NewFootnoteBackLink(index))
+		}
+		footnote = next
+	}
+	list.SortChildren(func(n1, n2 gast.Node) int {
+		if n1.(*ast.Footnote).Index < n2.(*ast.Footnote).Index {
+			return -1
+		}
+		return 1
+	})
+	if list.Count <= 0 {
+		list.Parent().RemoveChild(list.Parent(), list)
+		return
+	}
+
+	node.AppendChild(node, list)
+}
+
+// FootnoteHTMLRenderer is a renderer.NodeRenderer implementation that
+// renders FootnoteLink nodes.
+type FootnoteHTMLRenderer struct {
+	html.Config
+}
+
+// NewFootnoteHTMLRenderer returns a new FootnoteHTMLRenderer.
+func NewFootnoteHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
+	r := &FootnoteHTMLRenderer{
+		Config: html.NewConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetHTMLOption(&r.Config)
+	}
+	return r
+}
+
+// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
+func (r *FootnoteHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindFootnoteLink, r.renderFootnoteLink)
+	reg.Register(ast.KindFootnoteBackLink, r.renderFootnoteBackLink)
+	reg.Register(ast.KindFootnote, r.renderFootnote)
+	reg.Register(ast.KindFootnoteList, r.renderFootnoteList)
+}
+
+func (r *FootnoteHTMLRenderer) renderFootnoteLink(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		n := node.(*ast.FootnoteLink)
+		is := strconv.Itoa(n.Index)
+		_, _ = w.WriteString(`<sup id="fnref:`)
+		_, _ = w.WriteString(is)
+		_, _ = w.WriteString(`"><a href="#fn:`)
+		_, _ = w.WriteString(is)
+		_, _ = w.WriteString(`" class="footnote-ref" role="doc-noteref">`)
+		_, _ = w.WriteString(is)
+		_, _ = w.WriteString(`</a></sup>`)
+	}
+	return gast.WalkContinue, nil
+}
+
+func (r *FootnoteHTMLRenderer) renderFootnoteBackLink(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		n := node.(*ast.FootnoteBackLink)
+		is := strconv.Itoa(n.Index)
+		_, _ = w.WriteString(` <a href="#fnref:`)
+		_, _ = w.WriteString(is)
+		_, _ = w.WriteString(`" class="footnote-backref" role="doc-backlink">`)
+		_, _ = w.WriteString("&#x21a9;&#xfe0e;")
+		_, _ = w.WriteString(`</a>`)
+	}
+	return gast.WalkContinue, nil
+}
+
+func (r *FootnoteHTMLRenderer) renderFootnote(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	n := node.(*ast.Footnote)
+	is := strconv.Itoa(n.Index)
+	if entering {
+		_, _ = w.WriteString(`<li id="fn:`)
+		_, _ = w.WriteString(is)
+		_, _ = w.WriteString(`" role="doc-endnote"`)
+		if node.Attributes() != nil {
+			html.RenderAttributes(w, node, html.ListItemAttributeFilter)
+		}
+		_, _ = w.WriteString(">\n")
+	} else {
+		_, _ = w.WriteString("</li>\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+func (r *FootnoteHTMLRenderer) renderFootnoteList(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	tag := "section"
+	if r.Config.XHTML {
+		tag = "div"
+	}
+	if entering {
+		_, _ = w.WriteString("<")
+		_, _ = w.WriteString(tag)
+		_, _ = w.WriteString(` class="footnotes" role="doc-endnotes"`)
+		if node.Attributes() != nil {
+			html.RenderAttributes(w, node, html.GlobalAttributeFilter)
+		}
+		_ = w.WriteByte('>')
+		if r.Config.XHTML {
+			_, _ = w.WriteString("\n<hr />\n")
+		} else {
+			_, _ = w.WriteString("\n<hr>\n")
+		}
+		_, _ = w.WriteString("<ol>\n")
+	} else {
+		_, _ = w.WriteString("</ol>\n")
+		_, _ = w.WriteString("</")
+		_, _ = w.WriteString(tag)
+		_, _ = w.WriteString(">\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+type footnote struct {
+}
+
+// Footnote is an extension that allow you to use PHP Markdown Extra Footnotes.
+var Footnote = &footnote{}
+
+func (e *footnote) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(
+		parser.WithBlockParsers(
+			util.Prioritized(NewFootnoteBlockParser(), 999),
+		),
+		parser.WithInlineParsers(
+			util.Prioritized(NewFootnoteParser(), 101),
+		),
+		parser.WithASTTransformers(
+			util.Prioritized(NewFootnoteASTTransformer(), 999),
+		),
+	)
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewFootnoteHTMLRenderer(), 500),
+	))
+}

vendor/github.com/yuin/goldmark/extension/gfm.go

@@ -0,0 +1,18 @@
+package extension
+
+import (
+	"github.com/yuin/goldmark"
+)
+
+type gfm struct {
+}
+
+// GFM is an extension that provides Github Flavored markdown functionalities.
+var GFM = &gfm{}
+
+func (e *gfm) Extend(m goldmark.Markdown) {
+	Linkify.Extend(m)
+	Table.Extend(m)
+	Strikethrough.Extend(m)
+	TaskList.Extend(m)
+}

vendor/github.com/yuin/goldmark/extension/linkify.go

@@ -0,0 +1,303 @@
+package extension
+
+import (
+	"bytes"
+	"regexp"
+
+	"github.com/yuin/goldmark"
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var wwwURLRegxp = regexp.MustCompile(`^www\.[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]+(?:(?:/|[#?])[-a-zA-Z0-9@:%_\+.~#!?&//=\(\);,'">\^{}\[\]` + "`" + `]*)?`)
+
+var urlRegexp = regexp.MustCompile(`^(?:http|https|ftp):\/\/(?:www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]+(?:(?:/|[#?])[-a-zA-Z0-9@:%_+.~#$!?&//=\(\);,'">\^{}\[\]` + "`" + `]*)?`)
+
+// An LinkifyConfig struct is a data structure that holds configuration of the
+// Linkify extension.
+type LinkifyConfig struct {
+	AllowedProtocols [][]byte
+	URLRegexp        *regexp.Regexp
+	WWWRegexp        *regexp.Regexp
+	EmailRegexp      *regexp.Regexp
+}
+
+const optLinkifyAllowedProtocols parser.OptionName = "LinkifyAllowedProtocols"
+const optLinkifyURLRegexp parser.OptionName = "LinkifyURLRegexp"
+const optLinkifyWWWRegexp parser.OptionName = "LinkifyWWWRegexp"
+const optLinkifyEmailRegexp parser.OptionName = "LinkifyEmailRegexp"
+
+// SetOption implements SetOptioner.
+func (c *LinkifyConfig) SetOption(name parser.OptionName, value interface{}) {
+	switch name {
+	case optLinkifyAllowedProtocols:
+		c.AllowedProtocols = value.([][]byte)
+	case optLinkifyURLRegexp:
+		c.URLRegexp = value.(*regexp.Regexp)
+	case optLinkifyWWWRegexp:
+		c.WWWRegexp = value.(*regexp.Regexp)
+	case optLinkifyEmailRegexp:
+		c.EmailRegexp = value.(*regexp.Regexp)
+	}
+}
+
+// A LinkifyOption interface sets options for the LinkifyOption.
+type LinkifyOption interface {
+	parser.Option
+	SetLinkifyOption(*LinkifyConfig)
+}
+
+type withLinkifyAllowedProtocols struct {
+	value [][]byte
+}
+
+func (o *withLinkifyAllowedProtocols) SetParserOption(c *parser.Config) {
+	c.Options[optLinkifyAllowedProtocols] = o.value
+}
+
+func (o *withLinkifyAllowedProtocols) SetLinkifyOption(p *LinkifyConfig) {
+	p.AllowedProtocols = o.value
+}
+
+// WithLinkifyAllowedProtocols is a functional option that specify allowed
+// protocols in autolinks. Each protocol must end with ':' like
+// 'http:' .
+func WithLinkifyAllowedProtocols(value [][]byte) LinkifyOption {
+	return &withLinkifyAllowedProtocols{
+		value: value,
+	}
+}
+
+type withLinkifyURLRegexp struct {
+	value *regexp.Regexp
+}
+
+func (o *withLinkifyURLRegexp) SetParserOption(c *parser.Config) {
+	c.Options[optLinkifyURLRegexp] = o.value
+}
+
+func (o *withLinkifyURLRegexp) SetLinkifyOption(p *LinkifyConfig) {
+	p.URLRegexp = o.value
+}
+
+// WithLinkifyURLRegexp is a functional option that specify
+// a pattern of the URL including a protocol.
+func WithLinkifyURLRegexp(value *regexp.Regexp) LinkifyOption {
+	return &withLinkifyURLRegexp{
+		value: value,
+	}
+}
+
+// WithLinkifyWWWRegexp is a functional option that specify
+// a pattern of the URL without a protocol.
+// This pattern must start with 'www.' .
+type withLinkifyWWWRegexp struct {
+	value *regexp.Regexp
+}
+
+func (o *withLinkifyWWWRegexp) SetParserOption(c *parser.Config) {
+	c.Options[optLinkifyWWWRegexp] = o.value
+}
+
+func (o *withLinkifyWWWRegexp) SetLinkifyOption(p *LinkifyConfig) {
+	p.WWWRegexp = o.value
+}
+
+func WithLinkifyWWWRegexp(value *regexp.Regexp) LinkifyOption {
+	return &withLinkifyWWWRegexp{
+		value: value,
+	}
+}
+
+// WithLinkifyWWWRegexp is a functional otpion that specify
+// a pattern of the email address.
+type withLinkifyEmailRegexp struct {
+	value *regexp.Regexp
+}
+
+func (o *withLinkifyEmailRegexp) SetParserOption(c *parser.Config) {
+	c.Options[optLinkifyEmailRegexp] = o.value
+}
+
+func (o *withLinkifyEmailRegexp) SetLinkifyOption(p *LinkifyConfig) {
+	p.EmailRegexp = o.value
+}
+
+func WithLinkifyEmailRegexp(value *regexp.Regexp) LinkifyOption {
+	return &withLinkifyEmailRegexp{
+		value: value,
+	}
+}
+
+type linkifyParser struct {
+	LinkifyConfig
+}
+
+// NewLinkifyParser return a new InlineParser can parse
+// text that seems like a URL.
+func NewLinkifyParser(opts ...LinkifyOption) parser.InlineParser {
+	p := &linkifyParser{
+		LinkifyConfig: LinkifyConfig{
+			AllowedProtocols: nil,
+			URLRegexp:        urlRegexp,
+			WWWRegexp:        wwwURLRegxp,
+		},
+	}
+	for _, o := range opts {
+		o.SetLinkifyOption(&p.LinkifyConfig)
+	}
+	return p
+}
+
+func (s *linkifyParser) Trigger() []byte {
+	// ' ' indicates any white spaces and a line head
+	return []byte{' ', '*', '_', '~', '('}
+}
+
+var protoHTTP = []byte("http:")
+var protoHTTPS = []byte("https:")
+var protoFTP = []byte("ftp:")
+var domainWWW = []byte("www.")
+
+func (s *linkifyParser) Parse(parent ast.Node, block text.Reader, pc parser.Context) ast.Node {
+	if pc.IsInLinkLabel() {
+		return nil
+	}
+	line, segment := block.PeekLine()
+	consumes := 0
+	start := segment.Start
+	c := line[0]
+	// advance if current position is not a line head.
+	if c == ' ' || c == '*' || c == '_' || c == '~' || c == '(' {
+		consumes++
+		start++
+		line = line[1:]
+	}
+
+	var m []int
+	var protocol []byte
+	var typ ast.AutoLinkType = ast.AutoLinkURL
+	if s.LinkifyConfig.AllowedProtocols == nil {
+		if bytes.HasPrefix(line, protoHTTP) || bytes.HasPrefix(line, protoHTTPS) || bytes.HasPrefix(line, protoFTP) {
+			m = s.LinkifyConfig.URLRegexp.FindSubmatchIndex(line)
+		}
+	} else {
+		for _, prefix := range s.LinkifyConfig.AllowedProtocols {
+			if bytes.HasPrefix(line, prefix) {
+				m = s.LinkifyConfig.URLRegexp.FindSubmatchIndex(line)
+				break
+			}
+		}
+	}
+	if m == nil && bytes.HasPrefix(line, domainWWW) {
+		m = s.LinkifyConfig.WWWRegexp.FindSubmatchIndex(line)
+		protocol = []byte("http")
+	}
+	if m != nil && m[0] != 0 {
+		m = nil
+	}
+	if m != nil && m[0] == 0 {
+		lastChar := line[m[1]-1]
+		if lastChar == '.' {
+			m[1]--
+		} else if lastChar == ')' {
+			closing := 0
+			for i := m[1] - 1; i >= m[0]; i-- {
+				if line[i] == ')' {
+					closing++
+				} else if line[i] == '(' {
+					closing--
+				}
+			}
+			if closing > 0 {
+				m[1] -= closing
+			}
+		} else if lastChar == ';' {
+			i := m[1] - 2
+			for ; i >= m[0]; i-- {
+				if util.IsAlphaNumeric(line[i]) {
+					continue
+				}
+				break
+			}
+			if i != m[1]-2 {
+				if line[i] == '&' {
+					m[1] -= m[1] - i
+				}
+			}
+		}
+	}
+	if m == nil {
+		if len(line) > 0 && util.IsPunct(line[0]) {
+			return nil
+		}
+		typ = ast.AutoLinkEmail
+		stop := -1
+		if s.LinkifyConfig.EmailRegexp == nil {
+			stop = util.FindEmailIndex(line)
+		} else {
+			m := s.LinkifyConfig.EmailRegexp.FindSubmatchIndex(line)
+			if m != nil && m[0] == 0 {
+				stop = m[1]
+			}
+		}
+		if stop < 0 {
+			return nil
+		}
+		at := bytes.IndexByte(line, '@')
+		m = []int{0, stop, at, stop - 1}
+		if m == nil || bytes.IndexByte(line[m[2]:m[3]], '.') < 0 {
+			return nil
+		}
+		lastChar := line[m[1]-1]
+		if lastChar == '.' {
+			m[1]--
+		}
+		if m[1] < len(line) {
+			nextChar := line[m[1]]
+			if nextChar == '-' || nextChar == '_' {
+				return nil
+			}
+		}
+	}
+	if m == nil {
+		return nil
+	}
+	if consumes != 0 {
+		s := segment.WithStop(segment.Start + 1)
+		ast.MergeOrAppendTextSegment(parent, s)
+	}
+	consumes += m[1]
+	block.Advance(consumes)
+	n := ast.NewTextSegment(text.NewSegment(start, start+m[1]))
+	link := ast.NewAutoLink(typ, n)
+	link.Protocol = protocol
+	return link
+}
+
+func (s *linkifyParser) CloseBlock(parent ast.Node, pc parser.Context) {
+	// nothing to do
+}
+
+type linkify struct {
+	options []LinkifyOption
+}
+
+// Linkify is an extension that allow you to parse text that seems like a URL.
+var Linkify = &linkify{}
+
+func NewLinkify(opts ...LinkifyOption) goldmark.Extender {
+	return &linkify{
+		options: opts,
+	}
+}
+
+func (e *linkify) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(
+		parser.WithInlineParsers(
+			util.Prioritized(NewLinkifyParser(e.options...), 999),
+		),
+	)
+}

vendor/github.com/yuin/goldmark/extension/strikethrough.go

@@ -0,0 +1,116 @@
+package extension
+
+import (
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type strikethroughDelimiterProcessor struct {
+}
+
+func (p *strikethroughDelimiterProcessor) IsDelimiter(b byte) bool {
+	return b == '~'
+}
+
+func (p *strikethroughDelimiterProcessor) CanOpenCloser(opener, closer *parser.Delimiter) bool {
+	return opener.Char == closer.Char
+}
+
+func (p *strikethroughDelimiterProcessor) OnMatch(consumes int) gast.Node {
+	return ast.NewStrikethrough()
+}
+
+var defaultStrikethroughDelimiterProcessor = &strikethroughDelimiterProcessor{}
+
+type strikethroughParser struct {
+}
+
+var defaultStrikethroughParser = &strikethroughParser{}
+
+// NewStrikethroughParser return a new InlineParser that parses
+// strikethrough expressions.
+func NewStrikethroughParser() parser.InlineParser {
+	return defaultStrikethroughParser
+}
+
+func (s *strikethroughParser) Trigger() []byte {
+	return []byte{'~'}
+}
+
+func (s *strikethroughParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
+	before := block.PrecendingCharacter()
+	line, segment := block.PeekLine()
+	node := parser.ScanDelimiter(line, before, 2, defaultStrikethroughDelimiterProcessor)
+	if node == nil {
+		return nil
+	}
+	node.Segment = segment.WithStop(segment.Start + node.OriginalLength)
+	block.Advance(node.OriginalLength)
+	pc.PushDelimiter(node)
+	return node
+}
+
+func (s *strikethroughParser) CloseBlock(parent gast.Node, pc parser.Context) {
+	// nothing to do
+}
+
+// StrikethroughHTMLRenderer is a renderer.NodeRenderer implementation that
+// renders Strikethrough nodes.
+type StrikethroughHTMLRenderer struct {
+	html.Config
+}
+
+// NewStrikethroughHTMLRenderer returns a new StrikethroughHTMLRenderer.
+func NewStrikethroughHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
+	r := &StrikethroughHTMLRenderer{
+		Config: html.NewConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetHTMLOption(&r.Config)
+	}
+	return r
+}
+
+// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
+func (r *StrikethroughHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindStrikethrough, r.renderStrikethrough)
+}
+
+// StrikethroughAttributeFilter defines attribute names which dd elements can have.
+var StrikethroughAttributeFilter = html.GlobalAttributeFilter
+
+func (r *StrikethroughHTMLRenderer) renderStrikethrough(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<del")
+			html.RenderAttributes(w, n, StrikethroughAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<del>")
+		}
+	} else {
+		_, _ = w.WriteString("</del>")
+	}
+	return gast.WalkContinue, nil
+}
+
+type strikethrough struct {
+}
+
+// Strikethrough is an extension that allow you to use strikethrough expression like '~~text~~' .
+var Strikethrough = &strikethrough{}
+
+func (e *strikethrough) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(parser.WithInlineParsers(
+		util.Prioritized(NewStrikethroughParser(), 500),
+	))
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewStrikethroughHTMLRenderer(), 500),
+	))
+}

vendor/github.com/yuin/goldmark/extension/table.go

@@ -0,0 +1,446 @@
+package extension
+
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+// TableCellAlignMethod indicates how are table cells aligned in HTML format.indicates how are table cells aligned in HTML format.
+type TableCellAlignMethod int
+
+const (
+	// TableCellAlignDefault renders alignments by default method.
+	// With XHTML, alignments are rendered as an align attribute.
+	// With HTML5, alignments are rendered as a style attribute.
+	TableCellAlignDefault TableCellAlignMethod = iota
+
+	// TableCellAlignAttribute renders alignments as an align attribute.
+	TableCellAlignAttribute
+
+	// TableCellAlignStyle renders alignments as a style attribute.
+	TableCellAlignStyle
+
+	// TableCellAlignNone does not care about alignments.
+	// If you using classes or other styles, you can add these attributes
+	// in an ASTTransformer.
+	TableCellAlignNone
+)
+
+// TableConfig struct holds options for the extension.
+type TableConfig struct {
+	html.Config
+
+	// TableCellAlignMethod indicates how are table celss aligned.
+	TableCellAlignMethod TableCellAlignMethod
+}
+
+// TableOption interface is a functional option interface for the extension.
+type TableOption interface {
+	renderer.Option
+	// SetTableOption sets given option to the extension.
+	SetTableOption(*TableConfig)
+}
+
+// NewTableConfig returns a new Config with defaults.
+func NewTableConfig() TableConfig {
+	return TableConfig{
+		Config:               html.NewConfig(),
+		TableCellAlignMethod: TableCellAlignDefault,
+	}
+}
+
+// SetOption implements renderer.SetOptioner.
+func (c *TableConfig) SetOption(name renderer.OptionName, value interface{}) {
+	switch name {
+	case optTableCellAlignMethod:
+		c.TableCellAlignMethod = value.(TableCellAlignMethod)
+	default:
+		c.Config.SetOption(name, value)
+	}
+}
+
+type withTableHTMLOptions struct {
+	value []html.Option
+}
+
+func (o *withTableHTMLOptions) SetConfig(c *renderer.Config) {
+	if o.value != nil {
+		for _, v := range o.value {
+			v.(renderer.Option).SetConfig(c)
+		}
+	}
+}
+
+func (o *withTableHTMLOptions) SetTableOption(c *TableConfig) {
+	if o.value != nil {
+		for _, v := range o.value {
+			v.SetHTMLOption(&c.Config)
+		}
+	}
+}
+
+// WithTableHTMLOptions is functional option that wraps goldmark HTMLRenderer options.
+func WithTableHTMLOptions(opts ...html.Option) TableOption {
+	return &withTableHTMLOptions{opts}
+}
+
+const optTableCellAlignMethod renderer.OptionName = "TableTableCellAlignMethod"
+
+type withTableCellAlignMethod struct {
+	value TableCellAlignMethod
+}
+
+func (o *withTableCellAlignMethod) SetConfig(c *renderer.Config) {
+	c.Options[optTableCellAlignMethod] = o.value
+}
+
+func (o *withTableCellAlignMethod) SetTableOption(c *TableConfig) {
+	c.TableCellAlignMethod = o.value
+}
+
+// WithTableCellAlignMethod is a functional option that indicates how are table cells aligned in HTML format.
+func WithTableCellAlignMethod(a TableCellAlignMethod) TableOption {
+	return &withTableCellAlignMethod{a}
+}
+
+var tableDelimRegexp = regexp.MustCompile(`^[\s\-\|\:]+$`)
+var tableDelimLeft = regexp.MustCompile(`^\s*\:\-+\s*$`)
+var tableDelimRight = regexp.MustCompile(`^\s*\-+\:\s*$`)
+var tableDelimCenter = regexp.MustCompile(`^\s*\:\-+\:\s*$`)
+var tableDelimNone = regexp.MustCompile(`^\s*\-+\s*$`)
+
+type tableParagraphTransformer struct {
+}
+
+var defaultTableParagraphTransformer = &tableParagraphTransformer{}
+
+// NewTableParagraphTransformer returns  a new ParagraphTransformer
+// that can transform paragraphs into tables.
+func NewTableParagraphTransformer() parser.ParagraphTransformer {
+	return defaultTableParagraphTransformer
+}
+
+func (b *tableParagraphTransformer) Transform(node *gast.Paragraph, reader text.Reader, pc parser.Context) {
+	lines := node.Lines()
+	if lines.Len() < 2 {
+		return
+	}
+	alignments := b.parseDelimiter(lines.At(1), reader)
+	if alignments == nil {
+		return
+	}
+	header := b.parseRow(lines.At(0), alignments, true, reader)
+	if header == nil || len(alignments) != header.ChildCount() {
+		return
+	}
+	table := ast.NewTable()
+	table.Alignments = alignments
+	table.AppendChild(table, ast.NewTableHeader(header))
+	for i := 2; i < lines.Len(); i++ {
+		table.AppendChild(table, b.parseRow(lines.At(i), alignments, false, reader))
+	}
+	node.Parent().InsertBefore(node.Parent(), node, table)
+	node.Parent().RemoveChild(node.Parent(), node)
+}
+
+func (b *tableParagraphTransformer) parseRow(segment text.Segment, alignments []ast.Alignment, isHeader bool, reader text.Reader) *ast.TableRow {
+	source := reader.Source()
+	line := segment.Value(source)
+	pos := 0
+	pos += util.TrimLeftSpaceLength(line)
+	limit := len(line)
+	limit -= util.TrimRightSpaceLength(line)
+	row := ast.NewTableRow(alignments)
+	if len(line) > 0 && line[pos] == '|' {
+		pos++
+	}
+	if len(line) > 0 && line[limit-1] == '|' {
+		limit--
+	}
+	i := 0
+	for ; pos < limit; i++ {
+		alignment := ast.AlignNone
+		if i >= len(alignments) {
+			if !isHeader {
+				return row
+			}
+		} else {
+			alignment = alignments[i]
+		}
+		closure := util.FindClosure(line[pos:], byte(0), '|', true, false)
+		if closure < 0 {
+			closure = len(line[pos:])
+		}
+		node := ast.NewTableCell()
+		seg := text.NewSegment(segment.Start+pos, segment.Start+pos+closure)
+		seg = seg.TrimLeftSpace(source)
+		seg = seg.TrimRightSpace(source)
+		node.Lines().Append(seg)
+		node.Alignment = alignment
+		row.AppendChild(row, node)
+		pos += closure + 1
+	}
+	for ; i < len(alignments); i++ {
+		row.AppendChild(row, ast.NewTableCell())
+	}
+	return row
+}
+
+func (b *tableParagraphTransformer) parseDelimiter(segment text.Segment, reader text.Reader) []ast.Alignment {
+	line := segment.Value(reader.Source())
+	if !tableDelimRegexp.Match(line) {
+		return nil
+	}
+	cols := bytes.Split(line, []byte{'|'})
+	if util.IsBlank(cols[0]) {
+		cols = cols[1:]
+	}
+	if len(cols) > 0 && util.IsBlank(cols[len(cols)-1]) {
+		cols = cols[:len(cols)-1]
+	}
+
+	var alignments []ast.Alignment
+	for _, col := range cols {
+		if tableDelimLeft.Match(col) {
+			alignments = append(alignments, ast.AlignLeft)
+		} else if tableDelimRight.Match(col) {
+			alignments = append(alignments, ast.AlignRight)
+		} else if tableDelimCenter.Match(col) {
+			alignments = append(alignments, ast.AlignCenter)
+		} else if tableDelimNone.Match(col) {
+			alignments = append(alignments, ast.AlignNone)
+		} else {
+			return nil
+		}
+	}
+	return alignments
+}
+
+// TableHTMLRenderer is a renderer.NodeRenderer implementation that
+// renders Table nodes.
+type TableHTMLRenderer struct {
+	TableConfig
+}
+
+// NewTableHTMLRenderer returns a new TableHTMLRenderer.
+func NewTableHTMLRenderer(opts ...TableOption) renderer.NodeRenderer {
+	r := &TableHTMLRenderer{
+		TableConfig: NewTableConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetTableOption(&r.TableConfig)
+	}
+	return r
+}
+
+// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
+func (r *TableHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindTable, r.renderTable)
+	reg.Register(ast.KindTableHeader, r.renderTableHeader)
+	reg.Register(ast.KindTableRow, r.renderTableRow)
+	reg.Register(ast.KindTableCell, r.renderTableCell)
+}
+
+// TableAttributeFilter defines attribute names which table elements can have.
+var TableAttributeFilter = html.GlobalAttributeFilter.Extend(
+	[]byte("align"),       // [Deprecated]
+	[]byte("bgcolor"),     // [Deprecated]
+	[]byte("border"),      // [Deprecated]
+	[]byte("cellpadding"), // [Deprecated]
+	[]byte("cellspacing"), // [Deprecated]
+	[]byte("frame"),       // [Deprecated]
+	[]byte("rules"),       // [Deprecated]
+	[]byte("summary"),     // [Deprecated]
+	[]byte("width"),       // [Deprecated]
+)
+
+func (r *TableHTMLRenderer) renderTable(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		_, _ = w.WriteString("<table")
+		if n.Attributes() != nil {
+			html.RenderAttributes(w, n, TableAttributeFilter)
+		}
+		_, _ = w.WriteString(">\n")
+	} else {
+		_, _ = w.WriteString("</table>\n")
+	}
+	return gast.WalkContinue, nil
+}
+
+// TableHeaderAttributeFilter defines attribute names which <thead> elements can have.
+var TableHeaderAttributeFilter = html.GlobalAttributeFilter.Extend(
+	[]byte("align"),   // [Deprecated since HTML4] [Obsolete since HTML5]
+	[]byte("bgcolor"), // [Not Standardized]
+	[]byte("char"),    // [Deprecated since HTML4] [Obsolete since HTML5]
+	[]byte("charoff"), // [Deprecated since HTML4] [Obsolete since HTML5]
+	[]byte("valign"),  // [Deprecated since HTML4] [Obsolete since HTML5]
+)
+
+func (r *TableHTMLRenderer) renderTableHeader(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		_, _ = w.WriteString("<thead")
+		if n.Attributes() != nil {
+			html.RenderAttributes(w, n, TableHeaderAttributeFilter)
+		}
+		_, _ = w.WriteString(">\n")
+		_, _ = w.WriteString("<tr>\n") // Header <tr> has no separate handle
+	} else {
+		_, _ = w.WriteString("</tr>\n")
+		_, _ = w.WriteString("</thead>\n")
+		if n.NextSibling() != nil {
+			_, _ = w.WriteString("<tbody>\n")
+		}
+	}
+	return gast.WalkContinue, nil
+}
+
+// TableRowAttributeFilter defines attribute names which <tr> elements can have.
+var TableRowAttributeFilter = html.GlobalAttributeFilter.Extend(
+	[]byte("align"),   // [Obsolete since HTML5]
+	[]byte("bgcolor"), // [Obsolete since HTML5]
+	[]byte("char"),    // [Obsolete since HTML5]
+	[]byte("charoff"), // [Obsolete since HTML5]
+	[]byte("valign"),  // [Obsolete since HTML5]
+)
+
+func (r *TableHTMLRenderer) renderTableRow(w util.BufWriter, source []byte, n gast.Node, entering bool) (gast.WalkStatus, error) {
+	if entering {
+		_, _ = w.WriteString("<tr")
+		if n.Attributes() != nil {
+			html.RenderAttributes(w, n, TableRowAttributeFilter)
+		}
+		_, _ = w.WriteString(">\n")
+	} else {
+		_, _ = w.WriteString("</tr>\n")
+		if n.Parent().LastChild() == n {
+			_, _ = w.WriteString("</tbody>\n")
+		}
+	}
+	return gast.WalkContinue, nil
+}
+
+// TableThCellAttributeFilter defines attribute names which table <th> cells can have.
+var TableThCellAttributeFilter = html.GlobalAttributeFilter.Extend(
+	[]byte("abbr"), // [OK] Contains a short abbreviated description of the cell's content [NOT OK in <td>]
+
+	[]byte("align"),   // [Obsolete since HTML5]
+	[]byte("axis"),    // [Obsolete since HTML5]
+	[]byte("bgcolor"), // [Not Standardized]
+	[]byte("char"),    // [Obsolete since HTML5]
+	[]byte("charoff"), // [Obsolete since HTML5]
+
+	[]byte("colspan"), // [OK] Number of columns that the cell is to span
+	[]byte("headers"), // [OK] This attribute contains a list of space-separated strings, each corresponding to the id attribute of the <th> elements that apply to this element
+
+	[]byte("height"), // [Deprecated since HTML4] [Obsolete since HTML5]
+
+	[]byte("rowspan"), // [OK] Number of rows that the cell is to span
+	[]byte("scope"),   // [OK] This enumerated attribute defines the cells that the header (defined in the <th>) element relates to [NOT OK in <td>]
+
+	[]byte("valign"), // [Obsolete since HTML5]
+	[]byte("width"),  // [Deprecated since HTML4] [Obsolete since HTML5]
+)
+
+// TableTdCellAttributeFilter defines attribute names which table <td> cells can have.
+var TableTdCellAttributeFilter = html.GlobalAttributeFilter.Extend(
+	[]byte("abbr"),    // [Obsolete since HTML5] [OK in <th>]
+	[]byte("align"),   // [Obsolete since HTML5]
+	[]byte("axis"),    // [Obsolete since HTML5]
+	[]byte("bgcolor"), // [Not Standardized]
+	[]byte("char"),    // [Obsolete since HTML5]
+	[]byte("charoff"), // [Obsolete since HTML5]
+
+	[]byte("colspan"), // [OK] Number of columns that the cell is to span
+	[]byte("headers"), // [OK] This attribute contains a list of space-separated strings, each corresponding to the id attribute of the <th> elements that apply to this element
+
+	[]byte("height"), // [Deprecated since HTML4] [Obsolete since HTML5]
+
+	[]byte("rowspan"), // [OK] Number of rows that the cell is to span
+
+	[]byte("scope"),  // [Obsolete since HTML5] [OK in <th>]
+	[]byte("valign"), // [Obsolete since HTML5]
+	[]byte("width"),  // [Deprecated since HTML4] [Obsolete since HTML5]
+)
+
+func (r *TableHTMLRenderer) renderTableCell(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	n := node.(*ast.TableCell)
+	tag := "td"
+	if n.Parent().Kind() == ast.KindTableHeader {
+		tag = "th"
+	}
+	if entering {
+		fmt.Fprintf(w, "<%s", tag)
+		if n.Alignment != ast.AlignNone {
+			amethod := r.TableConfig.TableCellAlignMethod
+			if amethod == TableCellAlignDefault {
+				if r.Config.XHTML {
+					amethod = TableCellAlignAttribute
+				} else {
+					amethod = TableCellAlignStyle
+				}
+			}
+			switch amethod {
+			case TableCellAlignAttribute:
+				if _, ok := n.AttributeString("align"); !ok { // Skip align render if overridden
+					fmt.Fprintf(w, ` align="%s"`, n.Alignment.String())
+				}
+			case TableCellAlignStyle:
+				v, ok := n.AttributeString("style")
+				var cob util.CopyOnWriteBuffer
+				if ok {
+					cob = util.NewCopyOnWriteBuffer(v.([]byte))
+					cob.AppendByte(';')
+				}
+				style := fmt.Sprintf("text-align:%s", n.Alignment.String())
+				cob.Append(util.StringToReadOnlyBytes(style))
+				n.SetAttributeString("style", cob.Bytes())
+			}
+		}
+		if n.Attributes() != nil {
+			if tag == "td" {
+				html.RenderAttributes(w, n, TableTdCellAttributeFilter) // <td>
+			} else {
+				html.RenderAttributes(w, n, TableThCellAttributeFilter) // <th>
+			}
+		}
+		_ = w.WriteByte('>')
+	} else {
+		fmt.Fprintf(w, "</%s>\n", tag)
+	}
+	return gast.WalkContinue, nil
+}
+
+type table struct {
+	options []TableOption
+}
+
+// Table is an extension that allow you to use GFM tables .
+var Table = &table{
+	options: []TableOption{},
+}
+
+// NewTable returns a new extension with given options.
+func NewTable(opts ...TableOption) goldmark.Extender {
+	return &table{
+		options: opts,
+	}
+}
+
+func (e *table) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(parser.WithParagraphTransformers(
+		util.Prioritized(NewTableParagraphTransformer(), 200),
+	))
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewTableHTMLRenderer(e.options...), 500),
+	))
+}

vendor/github.com/yuin/goldmark/extension/tasklist.go

@@ -0,0 +1,115 @@
+package extension
+
+import (
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/extension/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+	"regexp"
+)
+
+var taskListRegexp = regexp.MustCompile(`^\[([\sxX])\]\s*`)
+
+type taskCheckBoxParser struct {
+}
+
+var defaultTaskCheckBoxParser = &taskCheckBoxParser{}
+
+// NewTaskCheckBoxParser returns a new  InlineParser that can parse
+// checkboxes in list items.
+// This parser must take precedence over the parser.LinkParser.
+func NewTaskCheckBoxParser() parser.InlineParser {
+	return defaultTaskCheckBoxParser
+}
+
+func (s *taskCheckBoxParser) Trigger() []byte {
+	return []byte{'['}
+}
+
+func (s *taskCheckBoxParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
+	// Given AST structure must be like
+	// - List
+	//   - ListItem         : parent.Parent
+	//     - TextBlock      : parent
+	//       (current line)
+	if parent.Parent() == nil || parent.Parent().FirstChild() != parent {
+		return nil
+	}
+
+	if _, ok := parent.Parent().(*gast.ListItem); !ok {
+		return nil
+	}
+	line, _ := block.PeekLine()
+	m := taskListRegexp.FindSubmatchIndex(line)
+	if m == nil {
+		return nil
+	}
+	value := line[m[2]:m[3]][0]
+	block.Advance(m[1])
+	checked := value == 'x' || value == 'X'
+	return ast.NewTaskCheckBox(checked)
+}
+
+func (s *taskCheckBoxParser) CloseBlock(parent gast.Node, pc parser.Context) {
+	// nothing to do
+}
+
+// TaskCheckBoxHTMLRenderer is a renderer.NodeRenderer implementation that
+// renders checkboxes in list items.
+type TaskCheckBoxHTMLRenderer struct {
+	html.Config
+}
+
+// NewTaskCheckBoxHTMLRenderer returns a new TaskCheckBoxHTMLRenderer.
+func NewTaskCheckBoxHTMLRenderer(opts ...html.Option) renderer.NodeRenderer {
+	r := &TaskCheckBoxHTMLRenderer{
+		Config: html.NewConfig(),
+	}
+	for _, opt := range opts {
+		opt.SetHTMLOption(&r.Config)
+	}
+	return r
+}
+
+// RegisterFuncs implements renderer.NodeRenderer.RegisterFuncs.
+func (r *TaskCheckBoxHTMLRenderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	reg.Register(ast.KindTaskCheckBox, r.renderTaskCheckBox)
+}
+
+func (r *TaskCheckBoxHTMLRenderer) renderTaskCheckBox(w util.BufWriter, source []byte, node gast.Node, entering bool) (gast.WalkStatus, error) {
+	if !entering {
+		return gast.WalkContinue, nil
+	}
+	n := node.(*ast.TaskCheckBox)
+
+	if n.IsChecked {
+		w.WriteString(`<input checked="" disabled="" type="checkbox"`)
+	} else {
+		w.WriteString(`<input disabled="" type="checkbox"`)
+	}
+	if r.XHTML {
+		w.WriteString(" /> ")
+	} else {
+		w.WriteString("> ")
+	}
+	return gast.WalkContinue, nil
+}
+
+type taskList struct {
+}
+
+// TaskList is an extension that allow you to use GFM task lists.
+var TaskList = &taskList{}
+
+func (e *taskList) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(parser.WithInlineParsers(
+		util.Prioritized(NewTaskCheckBoxParser(), 0),
+	))
+	m.Renderer().AddOptions(renderer.WithNodeRenderers(
+		util.Prioritized(NewTaskCheckBoxHTMLRenderer(), 500),
+	))
+}

vendor/github.com/yuin/goldmark/extension/typographer.go

@@ -0,0 +1,323 @@
+package extension
+
+import (
+	"unicode"
+
+	"github.com/yuin/goldmark"
+	gast "github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var uncloseCounterKey = parser.NewContextKey()
+
+type unclosedCounter struct {
+	Single int
+	Double int
+}
+
+func (u *unclosedCounter) Reset() {
+	u.Single = 0
+	u.Double = 0
+}
+
+func getUnclosedCounter(pc parser.Context) *unclosedCounter {
+	v := pc.Get(uncloseCounterKey)
+	if v == nil {
+		v = &unclosedCounter{}
+		pc.Set(uncloseCounterKey, v)
+	}
+	return v.(*unclosedCounter)
+}
+
+// TypographicPunctuation is a key of the punctuations that can be replaced with
+// typographic entities.
+type TypographicPunctuation int
+
+const (
+	// LeftSingleQuote is '
+	LeftSingleQuote TypographicPunctuation = iota + 1
+	// RightSingleQuote is '
+	RightSingleQuote
+	// LeftDoubleQuote is "
+	LeftDoubleQuote
+	// RightDoubleQuote is "
+	RightDoubleQuote
+	// EnDash is --
+	EnDash
+	// EmDash is ---
+	EmDash
+	// Ellipsis is ...
+	Ellipsis
+	// LeftAngleQuote is <<
+	LeftAngleQuote
+	// RightAngleQuote is >>
+	RightAngleQuote
+	// Apostrophe is '
+	Apostrophe
+
+	typographicPunctuationMax
+)
+
+// An TypographerConfig struct is a data structure that holds configuration of the
+// Typographer extension.
+type TypographerConfig struct {
+	Substitutions [][]byte
+}
+
+func newDefaultSubstitutions() [][]byte {
+	replacements := make([][]byte, typographicPunctuationMax)
+	replacements[LeftSingleQuote] = []byte("&lsquo;")
+	replacements[RightSingleQuote] = []byte("&rsquo;")
+	replacements[LeftDoubleQuote] = []byte("&ldquo;")
+	replacements[RightDoubleQuote] = []byte("&rdquo;")
+	replacements[EnDash] = []byte("&ndash;")
+	replacements[EmDash] = []byte("&mdash;")
+	replacements[Ellipsis] = []byte("&hellip;")
+	replacements[LeftAngleQuote] = []byte("&laquo;")
+	replacements[RightAngleQuote] = []byte("&raquo;")
+	replacements[Apostrophe] = []byte("&rsquo;")
+
+	return replacements
+}
+
+// SetOption implements SetOptioner.
+func (b *TypographerConfig) SetOption(name parser.OptionName, value interface{}) {
+	switch name {
+	case optTypographicSubstitutions:
+		b.Substitutions = value.([][]byte)
+	}
+}
+
+// A TypographerOption interface sets options for the TypographerParser.
+type TypographerOption interface {
+	parser.Option
+	SetTypographerOption(*TypographerConfig)
+}
+
+const optTypographicSubstitutions parser.OptionName = "TypographicSubstitutions"
+
+// TypographicSubstitutions is a list of the substitutions for the Typographer extension.
+type TypographicSubstitutions map[TypographicPunctuation][]byte
+
+type withTypographicSubstitutions struct {
+	value [][]byte
+}
+
+func (o *withTypographicSubstitutions) SetParserOption(c *parser.Config) {
+	c.Options[optTypographicSubstitutions] = o.value
+}
+
+func (o *withTypographicSubstitutions) SetTypographerOption(p *TypographerConfig) {
+	p.Substitutions = o.value
+}
+
+// WithTypographicSubstitutions is a functional otpion that specify replacement text
+// for punctuations.
+func WithTypographicSubstitutions(values map[TypographicPunctuation][]byte) TypographerOption {
+	replacements := newDefaultSubstitutions()
+	for k, v := range values {
+		replacements[k] = v
+	}
+
+	return &withTypographicSubstitutions{replacements}
+}
+
+type typographerDelimiterProcessor struct {
+}
+
+func (p *typographerDelimiterProcessor) IsDelimiter(b byte) bool {
+	return b == '\'' || b == '"'
+}
+
+func (p *typographerDelimiterProcessor) CanOpenCloser(opener, closer *parser.Delimiter) bool {
+	return opener.Char == closer.Char
+}
+
+func (p *typographerDelimiterProcessor) OnMatch(consumes int) gast.Node {
+	return nil
+}
+
+var defaultTypographerDelimiterProcessor = &typographerDelimiterProcessor{}
+
+type typographerParser struct {
+	TypographerConfig
+}
+
+// NewTypographerParser return a new InlineParser that parses
+// typographer expressions.
+func NewTypographerParser(opts ...TypographerOption) parser.InlineParser {
+	p := &typographerParser{
+		TypographerConfig: TypographerConfig{
+			Substitutions: newDefaultSubstitutions(),
+		},
+	}
+	for _, o := range opts {
+		o.SetTypographerOption(&p.TypographerConfig)
+	}
+	return p
+}
+
+func (s *typographerParser) Trigger() []byte {
+	return []byte{'\'', '"', '-', '.', '<', '>'}
+}
+
+func (s *typographerParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
+	line, _ := block.PeekLine()
+	c := line[0]
+	if len(line) > 2 {
+		if c == '-' {
+			if s.Substitutions[EmDash] != nil && line[1] == '-' && line[2] == '-' { // ---
+				node := gast.NewString(s.Substitutions[EmDash])
+				node.SetCode(true)
+				block.Advance(3)
+				return node
+			}
+		} else if c == '.' {
+			if s.Substitutions[Ellipsis] != nil && line[1] == '.' && line[2] == '.' { // ...
+				node := gast.NewString(s.Substitutions[Ellipsis])
+				node.SetCode(true)
+				block.Advance(3)
+				return node
+			}
+			return nil
+		}
+	}
+	if len(line) > 1 {
+		if c == '<' {
+			if s.Substitutions[LeftAngleQuote] != nil && line[1] == '<' { // <<
+				node := gast.NewString(s.Substitutions[LeftAngleQuote])
+				node.SetCode(true)
+				block.Advance(2)
+				return node
+			}
+			return nil
+		} else if c == '>' {
+			if s.Substitutions[RightAngleQuote] != nil && line[1] == '>' { // >>
+				node := gast.NewString(s.Substitutions[RightAngleQuote])
+				node.SetCode(true)
+				block.Advance(2)
+				return node
+			}
+			return nil
+		} else if s.Substitutions[EnDash] != nil && c == '-' && line[1] == '-' { // --
+			node := gast.NewString(s.Substitutions[EnDash])
+			node.SetCode(true)
+			block.Advance(2)
+			return node
+		}
+	}
+	if c == '\'' || c == '"' {
+		before := block.PrecendingCharacter()
+		d := parser.ScanDelimiter(line, before, 1, defaultTypographerDelimiterProcessor)
+		if d == nil {
+			return nil
+		}
+		counter := getUnclosedCounter(pc)
+		if c == '\'' {
+			if s.Substitutions[Apostrophe] != nil {
+				// Handle decade abbrevations such as '90s
+				if d.CanOpen && !d.CanClose && len(line) > 3 && util.IsNumeric(line[1]) && util.IsNumeric(line[2]) && line[3] == 's' {
+					after := rune(' ')
+					if len(line) > 4 {
+						after = util.ToRune(line, 4)
+					}
+					if len(line) == 3 || util.IsSpaceRune(after) || util.IsPunctRune(after) {
+						node := gast.NewString(s.Substitutions[Apostrophe])
+						node.SetCode(true)
+						block.Advance(1)
+						return node
+					}
+				}
+				// Convert normal apostrophes. This is probably more flexible than necessary but
+				// converts any apostrophe in between two alphanumerics.
+				if len(line) > 1 && (unicode.IsDigit(before) || unicode.IsLetter(before)) && (unicode.IsLetter(util.ToRune(line, 1))) {
+					node := gast.NewString(s.Substitutions[Apostrophe])
+					node.SetCode(true)
+					block.Advance(1)
+					return node
+				}
+			}
+			if s.Substitutions[LeftSingleQuote] != nil && d.CanOpen && !d.CanClose {
+				nt := LeftSingleQuote
+				// special cases: Alice's, I'm ,Don't, You'd
+				if len(line) > 1 && (line[1] == 's' || line[1] == 'm' || line[1] == 't' || line[1] == 'd') && (len(line) < 3 || util.IsPunct(line[2]) || util.IsSpace(line[2])) {
+					nt = RightSingleQuote
+				}
+				// special cases: I've, I'll, You're
+				if len(line) > 2 && ((line[1] == 'v' && line[2] == 'e') || (line[1] == 'l' && line[2] == 'l') || (line[1] == 'r' && line[2] == 'e')) && (len(line) < 4 || util.IsPunct(line[3]) || util.IsSpace(line[3])) {
+					nt = RightSingleQuote
+				}
+				if nt == LeftSingleQuote {
+					counter.Single++
+				}
+
+				node := gast.NewString(s.Substitutions[nt])
+				node.SetCode(true)
+				block.Advance(1)
+				return node
+			}
+			if s.Substitutions[RightSingleQuote] != nil && counter.Single > 0 {
+				isClose := d.CanClose && !d.CanOpen
+				maybeClose := d.CanClose && d.CanOpen && len(line) > 1 && (line[1] == ',' || line[1] == '.' || line[1] == '!' || line[1] == '?') && (len(line) == 2 || (len(line) > 2 && util.IsPunct(line[2]) || util.IsSpace(line[2])))
+				if isClose || maybeClose {
+					node := gast.NewString(s.Substitutions[RightSingleQuote])
+					node.SetCode(true)
+					block.Advance(1)
+					counter.Single--
+					return node
+				}
+			}
+		}
+		if c == '"' {
+			if s.Substitutions[LeftDoubleQuote] != nil && d.CanOpen && !d.CanClose {
+				node := gast.NewString(s.Substitutions[LeftDoubleQuote])
+				node.SetCode(true)
+				block.Advance(1)
+				counter.Double++
+				return node
+			}
+			if s.Substitutions[RightDoubleQuote] != nil && counter.Double > 0 {
+				isClose := d.CanClose && !d.CanOpen
+				maybeClose := d.CanClose && d.CanOpen && len(line) > 1 && (line[1] == ',' || line[1] == '.' || line[1] == '!' || line[1] == '?') && (len(line) == 2 || (len(line) > 2 && util.IsPunct(line[2]) || util.IsSpace(line[2])))
+				if isClose || maybeClose {
+					// special case: "Monitor 21""
+					if len(line) > 1 && line[1] == '"' && unicode.IsDigit(before) {
+						return nil
+					}
+					node := gast.NewString(s.Substitutions[RightDoubleQuote])
+					node.SetCode(true)
+					block.Advance(1)
+					counter.Double--
+					return node
+				}
+			}
+		}
+	}
+	return nil
+}
+
+func (s *typographerParser) CloseBlock(parent gast.Node, pc parser.Context) {
+	getUnclosedCounter(pc).Reset()
+}
+
+type typographer struct {
+	options []TypographerOption
+}
+
+// Typographer is an extension that replaces punctuations with typographic entities.
+var Typographer = &typographer{}
+
+// NewTypographer returns a new Extender that replaces punctuations with typographic entities.
+func NewTypographer(opts ...TypographerOption) goldmark.Extender {
+	return &typographer{
+		options: opts,
+	}
+}
+
+func (e *typographer) Extend(m goldmark.Markdown) {
+	m.Parser().AddOptions(parser.WithInlineParsers(
+		util.Prioritized(NewTypographerParser(e.options...), 9999),
+	))
+}

vendor/github.com/yuin/goldmark/go.mod

@@ -0,0 +1,3 @@
+module github.com/yuin/goldmark
+
+go 1.13

vendor/github.com/yuin/goldmark/markdown.go

@@ -0,0 +1,140 @@
+// Package goldmark implements functions to convert markdown text to a desired format.
+package goldmark
+
+import (
+	"github.com/yuin/goldmark/parser"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/renderer/html"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+	"io"
+)
+
+// DefaultParser returns a new Parser that is configured by default values.
+func DefaultParser() parser.Parser {
+	return parser.NewParser(parser.WithBlockParsers(parser.DefaultBlockParsers()...),
+		parser.WithInlineParsers(parser.DefaultInlineParsers()...),
+		parser.WithParagraphTransformers(parser.DefaultParagraphTransformers()...),
+	)
+}
+
+// DefaultRenderer returns a new Renderer that is configured by default values.
+func DefaultRenderer() renderer.Renderer {
+	return renderer.NewRenderer(renderer.WithNodeRenderers(util.Prioritized(html.NewRenderer(), 1000)))
+}
+
+var defaultMarkdown = New()
+
+// Convert interprets a UTF-8 bytes source in Markdown and
+// write rendered contents to a writer w.
+func Convert(source []byte, w io.Writer, opts ...parser.ParseOption) error {
+	return defaultMarkdown.Convert(source, w, opts...)
+}
+
+// A Markdown interface offers functions to convert Markdown text to
+// a desired format.
+type Markdown interface {
+	// Convert interprets a UTF-8 bytes source in Markdown and write rendered
+	// contents to a writer w.
+	Convert(source []byte, writer io.Writer, opts ...parser.ParseOption) error
+
+	// Parser returns a Parser that will be used for conversion.
+	Parser() parser.Parser
+
+	// SetParser sets a Parser to this object.
+	SetParser(parser.Parser)
+
+	// Parser returns a Renderer that will be used for conversion.
+	Renderer() renderer.Renderer
+
+	// SetRenderer sets a Renderer to this object.
+	SetRenderer(renderer.Renderer)
+}
+
+// Option is a functional option type for Markdown objects.
+type Option func(*markdown)
+
+// WithExtensions adds extensions.
+func WithExtensions(ext ...Extender) Option {
+	return func(m *markdown) {
+		m.extensions = append(m.extensions, ext...)
+	}
+}
+
+// WithParser allows you to override the default parser.
+func WithParser(p parser.Parser) Option {
+	return func(m *markdown) {
+		m.parser = p
+	}
+}
+
+// WithParserOptions applies options for the parser.
+func WithParserOptions(opts ...parser.Option) Option {
+	return func(m *markdown) {
+		m.parser.AddOptions(opts...)
+	}
+}
+
+// WithRenderer allows you to override the default renderer.
+func WithRenderer(r renderer.Renderer) Option {
+	return func(m *markdown) {
+		m.renderer = r
+	}
+}
+
+// WithRendererOptions applies options for the renderer.
+func WithRendererOptions(opts ...renderer.Option) Option {
+	return func(m *markdown) {
+		m.renderer.AddOptions(opts...)
+	}
+}
+
+type markdown struct {
+	parser     parser.Parser
+	renderer   renderer.Renderer
+	extensions []Extender
+}
+
+// New returns a new Markdown with given options.
+func New(options ...Option) Markdown {
+	md := &markdown{
+		parser:     DefaultParser(),
+		renderer:   DefaultRenderer(),
+		extensions: []Extender{},
+	}
+	for _, opt := range options {
+		opt(md)
+	}
+	for _, e := range md.extensions {
+		e.Extend(md)
+	}
+	return md
+}
+
+func (m *markdown) Convert(source []byte, writer io.Writer, opts ...parser.ParseOption) error {
+	reader := text.NewReader(source)
+	doc := m.parser.Parse(reader, opts...)
+	return m.renderer.Render(writer, source, doc)
+}
+
+func (m *markdown) Parser() parser.Parser {
+	return m.parser
+}
+
+func (m *markdown) SetParser(v parser.Parser) {
+	m.parser = v
+}
+
+func (m *markdown) Renderer() renderer.Renderer {
+	return m.renderer
+}
+
+func (m *markdown) SetRenderer(v renderer.Renderer) {
+	m.renderer = v
+}
+
+// An Extender interface is used for extending Markdown.
+type Extender interface {
+	// Extend extends the Markdown.
+	Extend(Markdown)
+}

vendor/github.com/yuin/goldmark/parser/attribute.go

@@ -0,0 +1,319 @@
+package parser
+
+import (
+	"bytes"
+	"io"
+	"strconv"
+
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var attrNameID = []byte("id")
+var attrNameClass = []byte("class")
+
+// An Attribute is an attribute of the markdown elements
+type Attribute struct {
+	Name  []byte
+	Value interface{}
+}
+
+// An Attributes is a collection of attributes.
+type Attributes []Attribute
+
+// Find returns a (value, true) if an attribute correspond with given name is found, otherwise (nil, false).
+func (as Attributes) Find(name []byte) (interface{}, bool) {
+	for _, a := range as {
+		if bytes.Equal(a.Name, name) {
+			return a.Value, true
+		}
+	}
+	return nil, false
+}
+
+func (as Attributes) findUpdate(name []byte, cb func(v interface{}) interface{}) bool {
+	for i, a := range as {
+		if bytes.Equal(a.Name, name) {
+			as[i].Value = cb(a.Value)
+			return true
+		}
+	}
+	return false
+}
+
+// ParseAttributes parses attributes into a map.
+// ParseAttributes returns a parsed attributes and true if could parse
+// attributes, otherwise nil and false.
+func ParseAttributes(reader text.Reader) (Attributes, bool) {
+	savedLine, savedPosition := reader.Position()
+	reader.SkipSpaces()
+	if reader.Peek() != '{' {
+		reader.SetPosition(savedLine, savedPosition)
+		return nil, false
+	}
+	reader.Advance(1)
+	attrs := Attributes{}
+	for {
+		if reader.Peek() == '}' {
+			reader.Advance(1)
+			return attrs, true
+		}
+		attr, ok := parseAttribute(reader)
+		if !ok {
+			reader.SetPosition(savedLine, savedPosition)
+			return nil, false
+		}
+		if bytes.Equal(attr.Name, attrNameClass) {
+			if !attrs.findUpdate(attrNameClass, func(v interface{}) interface{} {
+				ret := make([]byte, 0, len(v.([]byte))+1+len(attr.Value.([]byte)))
+				ret = append(ret, v.([]byte)...)
+				return append(append(ret, ' '), attr.Value.([]byte)...)
+			}) {
+				attrs = append(attrs, attr)
+			}
+		} else {
+			attrs = append(attrs, attr)
+		}
+		reader.SkipSpaces()
+		if reader.Peek() == ',' {
+			reader.Advance(1)
+			reader.SkipSpaces()
+		}
+	}
+}
+
+func parseAttribute(reader text.Reader) (Attribute, bool) {
+	reader.SkipSpaces()
+	c := reader.Peek()
+	if c == '#' || c == '.' {
+		reader.Advance(1)
+		line, _ := reader.PeekLine()
+		i := 0
+		for ; i < len(line) && !util.IsSpace(line[i]) && (!util.IsPunct(line[i]) || line[i] == '_' || line[i] == '-'); i++ {
+		}
+		name := attrNameClass
+		if c == '#' {
+			name = attrNameID
+		}
+		reader.Advance(i)
+		return Attribute{Name: name, Value: line[0:i]}, true
+	}
+	line, _ := reader.PeekLine()
+	if len(line) == 0 {
+		return Attribute{}, false
+	}
+	c = line[0]
+	if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+		c == '_' || c == ':') {
+		return Attribute{}, false
+	}
+	i := 0
+	for ; i < len(line); i++ {
+		c = line[i]
+		if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+			(c >= '0' && c <= '9') ||
+			c == '_' || c == ':' || c == '.' || c == '-') {
+			break
+		}
+	}
+	name := line[:i]
+	reader.Advance(i)
+	reader.SkipSpaces()
+	c = reader.Peek()
+	if c != '=' {
+		return Attribute{}, false
+	}
+	reader.Advance(1)
+	reader.SkipSpaces()
+	value, ok := parseAttributeValue(reader)
+	if !ok {
+		return Attribute{}, false
+	}
+	return Attribute{Name: name, Value: value}, true
+}
+
+func parseAttributeValue(reader text.Reader) (interface{}, bool) {
+	reader.SkipSpaces()
+	c := reader.Peek()
+	var value interface{}
+	ok := false
+	switch c {
+	case text.EOF:
+		return Attribute{}, false
+	case '{':
+		value, ok = ParseAttributes(reader)
+	case '[':
+		value, ok = parseAttributeArray(reader)
+	case '"':
+		value, ok = parseAttributeString(reader)
+	default:
+		if c == '-' || c == '+' || util.IsNumeric(c) {
+			value, ok = parseAttributeNumber(reader)
+		} else {
+			value, ok = parseAttributeOthers(reader)
+		}
+	}
+	if !ok {
+		return nil, false
+	}
+	return value, true
+}
+
+func parseAttributeArray(reader text.Reader) ([]interface{}, bool) {
+	reader.Advance(1) // skip [
+	ret := []interface{}{}
+	for i := 0; ; i++ {
+		c := reader.Peek()
+		comma := false
+		if i != 0 && c == ',' {
+			reader.Advance(1)
+			comma = true
+		}
+		if c == ']' {
+			if !comma {
+				reader.Advance(1)
+				return ret, true
+			}
+			return nil, false
+		}
+		reader.SkipSpaces()
+		value, ok := parseAttributeValue(reader)
+		if !ok {
+			return nil, false
+		}
+		ret = append(ret, value)
+		reader.SkipSpaces()
+	}
+}
+
+func parseAttributeString(reader text.Reader) ([]byte, bool) {
+	reader.Advance(1) // skip "
+	line, _ := reader.PeekLine()
+	i := 0
+	l := len(line)
+	var buf bytes.Buffer
+	for i < l {
+		c := line[i]
+		if c == '\\' && i != l-1 {
+			n := line[i+1]
+			switch n {
+			case '"', '/', '\\':
+				buf.WriteByte(n)
+				i += 2
+			case 'b':
+				buf.WriteString("\b")
+				i += 2
+			case 'f':
+				buf.WriteString("\f")
+				i += 2
+			case 'n':
+				buf.WriteString("\n")
+				i += 2
+			case 'r':
+				buf.WriteString("\r")
+				i += 2
+			case 't':
+				buf.WriteString("\t")
+				i += 2
+			default:
+				buf.WriteByte('\\')
+				i++
+			}
+			continue
+		}
+		if c == '"' {
+			reader.Advance(i + 1)
+			return buf.Bytes(), true
+		}
+		buf.WriteByte(c)
+		i++
+	}
+	return nil, false
+}
+
+func scanAttributeDecimal(reader text.Reader, w io.ByteWriter) {
+	for {
+		c := reader.Peek()
+		if util.IsNumeric(c) {
+			w.WriteByte(c)
+		} else {
+			return
+		}
+		reader.Advance(1)
+	}
+}
+
+func parseAttributeNumber(reader text.Reader) (float64, bool) {
+	sign := 1
+	c := reader.Peek()
+	if c == '-' {
+		sign = -1
+		reader.Advance(1)
+	} else if c == '+' {
+		reader.Advance(1)
+	}
+	var buf bytes.Buffer
+	if !util.IsNumeric(reader.Peek()) {
+		return 0, false
+	}
+	scanAttributeDecimal(reader, &buf)
+	if buf.Len() == 0 {
+		return 0, false
+	}
+	c = reader.Peek()
+	if c == '.' {
+		buf.WriteByte(c)
+		reader.Advance(1)
+		scanAttributeDecimal(reader, &buf)
+	}
+	c = reader.Peek()
+	if c == 'e' || c == 'E' {
+		buf.WriteByte(c)
+		reader.Advance(1)
+		c = reader.Peek()
+		if c == '-' || c == '+' {
+			buf.WriteByte(c)
+			reader.Advance(1)
+		}
+		scanAttributeDecimal(reader, &buf)
+	}
+	f, err := strconv.ParseFloat(buf.String(), 10)
+	if err != nil {
+		return 0, false
+	}
+	return float64(sign) * f, true
+}
+
+var bytesTrue = []byte("true")
+var bytesFalse = []byte("false")
+var bytesNull = []byte("null")
+
+func parseAttributeOthers(reader text.Reader) (interface{}, bool) {
+	line, _ := reader.PeekLine()
+	c := line[0]
+	if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+		c == '_' || c == ':') {
+		return nil, false
+	}
+	i := 0
+	for ; i < len(line); i++ {
+		c := line[i]
+		if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+			(c >= '0' && c <= '9') ||
+			c == '_' || c == ':' || c == '.' || c == '-') {
+			break
+		}
+	}
+	value := line[:i]
+	reader.Advance(i)
+	if bytes.Equal(value, bytesTrue) {
+		return true, true
+	}
+	if bytes.Equal(value, bytesFalse) {
+		return false, true
+	}
+	if bytes.Equal(value, bytesNull) {
+		return nil, true
+	}
+	return value, true
+}

vendor/github.com/yuin/goldmark/parser/atx_heading.go

@@ -0,0 +1,243 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+// A HeadingConfig struct is a data structure that holds configuration of the renderers related to headings.
+type HeadingConfig struct {
+	AutoHeadingID bool
+	Attribute     bool
+}
+
+// SetOption implements SetOptioner.
+func (b *HeadingConfig) SetOption(name OptionName, value interface{}) {
+	switch name {
+	case optAutoHeadingID:
+		b.AutoHeadingID = true
+	case optAttribute:
+		b.Attribute = true
+	}
+}
+
+// A HeadingOption interface sets options for heading parsers.
+type HeadingOption interface {
+	Option
+	SetHeadingOption(*HeadingConfig)
+}
+
+// AutoHeadingID is an option name that enables auto IDs for headings.
+const optAutoHeadingID OptionName = "AutoHeadingID"
+
+type withAutoHeadingID struct {
+}
+
+func (o *withAutoHeadingID) SetParserOption(c *Config) {
+	c.Options[optAutoHeadingID] = true
+}
+
+func (o *withAutoHeadingID) SetHeadingOption(p *HeadingConfig) {
+	p.AutoHeadingID = true
+}
+
+// WithAutoHeadingID is a functional option that enables custom heading ids and
+// auto generated heading ids.
+func WithAutoHeadingID() HeadingOption {
+	return &withAutoHeadingID{}
+}
+
+type withHeadingAttribute struct {
+	Option
+}
+
+func (o *withHeadingAttribute) SetHeadingOption(p *HeadingConfig) {
+	p.Attribute = true
+}
+
+// WithHeadingAttribute is a functional option that enables custom heading attributes.
+func WithHeadingAttribute() HeadingOption {
+	return &withHeadingAttribute{WithAttribute()}
+}
+
+type atxHeadingParser struct {
+	HeadingConfig
+}
+
+// NewATXHeadingParser return a new BlockParser that can parse ATX headings.
+func NewATXHeadingParser(opts ...HeadingOption) BlockParser {
+	p := &atxHeadingParser{}
+	for _, o := range opts {
+		o.SetHeadingOption(&p.HeadingConfig)
+	}
+	return p
+}
+
+func (b *atxHeadingParser) Trigger() []byte {
+	return []byte{'#'}
+}
+
+func (b *atxHeadingParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	line, segment := reader.PeekLine()
+	pos := pc.BlockOffset()
+	if pos < 0 {
+		return nil, NoChildren
+	}
+	i := pos
+	for ; i < len(line) && line[i] == '#'; i++ {
+	}
+	level := i - pos
+	if i == pos || level > 6 {
+		return nil, NoChildren
+	}
+	l := util.TrimLeftSpaceLength(line[i:])
+	if l == 0 {
+		return nil, NoChildren
+	}
+	start := i + l
+	if start >= len(line) {
+		start = len(line) - 1
+	}
+	origstart := start
+	stop := len(line) - util.TrimRightSpaceLength(line)
+
+	node := ast.NewHeading(level)
+	parsed := false
+	if b.Attribute { // handles special case like ### heading ### {#id}
+		start--
+		closureClose := -1
+		closureOpen := -1
+		for j := start; j < stop; {
+			c := line[j]
+			if util.IsEscapedPunctuation(line, j) {
+				j += 2
+			} else if util.IsSpace(c) && j < stop-1 && line[j+1] == '#' {
+				closureOpen = j + 1
+				k := j + 1
+				for ; k < stop && line[k] == '#'; k++ {
+				}
+				closureClose = k
+				break
+			} else {
+				j++
+			}
+		}
+		if closureClose > 0 {
+			reader.Advance(closureClose)
+			attrs, ok := ParseAttributes(reader)
+			rest, _ := reader.PeekLine()
+			parsed = ok && util.IsBlank(rest)
+			if parsed {
+				for _, attr := range attrs {
+					node.SetAttribute(attr.Name, attr.Value)
+				}
+				node.Lines().Append(text.NewSegment(segment.Start+start+1-segment.Padding, segment.Start+closureOpen-segment.Padding))
+			}
+		}
+	}
+	if !parsed {
+		start = origstart
+		stop := len(line) - util.TrimRightSpaceLength(line)
+		if stop <= start { // empty headings like '##[space]'
+			stop = start
+		} else {
+			i = stop - 1
+			for ; line[i] == '#' && i >= start; i-- {
+			}
+			if i != stop-1 && !util.IsSpace(line[i]) {
+				i = stop - 1
+			}
+			i++
+			stop = i
+		}
+
+		if len(util.TrimRight(line[start:stop], []byte{'#'})) != 0 { // empty heading like '### ###'
+			node.Lines().Append(text.NewSegment(segment.Start+start-segment.Padding, segment.Start+stop-segment.Padding))
+		}
+	}
+	return node, NoChildren
+}
+
+func (b *atxHeadingParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	return Close
+}
+
+func (b *atxHeadingParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	if b.Attribute {
+		_, ok := node.AttributeString("id")
+		if !ok {
+			parseLastLineAttributes(node, reader, pc)
+		}
+	}
+
+	if b.AutoHeadingID {
+		id, ok := node.AttributeString("id")
+		if !ok {
+			generateAutoHeadingID(node.(*ast.Heading), reader, pc)
+		} else {
+			pc.IDs().Put(id.([]byte))
+		}
+	}
+}
+
+func (b *atxHeadingParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *atxHeadingParser) CanAcceptIndentedLine() bool {
+	return false
+}
+
+func generateAutoHeadingID(node *ast.Heading, reader text.Reader, pc Context) {
+	var line []byte
+	lastIndex := node.Lines().Len() - 1
+	if lastIndex > -1 {
+		lastLine := node.Lines().At(lastIndex)
+		line = lastLine.Value(reader.Source())
+	}
+	headingID := pc.IDs().Generate(line, ast.KindHeading)
+	node.SetAttribute(attrNameID, headingID)
+}
+
+func parseLastLineAttributes(node ast.Node, reader text.Reader, pc Context) {
+	lastIndex := node.Lines().Len() - 1
+	if lastIndex < 0 { // empty headings
+		return
+	}
+	lastLine := node.Lines().At(lastIndex)
+	line := lastLine.Value(reader.Source())
+	lr := text.NewReader(line)
+	var attrs Attributes
+	var ok bool
+	var start text.Segment
+	var sl int
+	var end text.Segment
+	for {
+		c := lr.Peek()
+		if c == text.EOF {
+			break
+		}
+		if c == '\\' {
+			lr.Advance(1)
+			if lr.Peek() == '{' {
+				lr.Advance(1)
+			}
+			continue
+		}
+		if c == '{' {
+			sl, start = lr.Position()
+			attrs, ok = ParseAttributes(lr)
+			_, end = lr.Position()
+			lr.SetPosition(sl, start)
+		}
+		lr.Advance(1)
+	}
+	if ok && util.IsBlank(line[end.Start:]) {
+		for _, attr := range attrs {
+			node.SetAttribute(attr.Name, attr.Value)
+		}
+		lastLine.Stop = lastLine.Start + start.Start
+		node.Lines().Set(lastIndex, lastLine)
+	}
+}

vendor/github.com/yuin/goldmark/parser/auto_link.go

@@ -0,0 +1,42 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type autoLinkParser struct {
+}
+
+var defaultAutoLinkParser = &autoLinkParser{}
+
+// NewAutoLinkParser returns a new InlineParser that parses autolinks
+// surrounded by '<' and '>' .
+func NewAutoLinkParser() InlineParser {
+	return defaultAutoLinkParser
+}
+
+func (s *autoLinkParser) Trigger() []byte {
+	return []byte{'<'}
+}
+
+func (s *autoLinkParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.Node {
+	line, segment := block.PeekLine()
+	stop := util.FindEmailIndex(line[1:])
+	typ := ast.AutoLinkType(ast.AutoLinkEmail)
+	if stop < 0 {
+		stop = util.FindURLIndex(line[1:])
+		typ = ast.AutoLinkURL
+	}
+	if stop < 0 {
+		return nil
+	}
+	stop++
+	if stop >= len(line) || line[stop] != '>' {
+		return nil
+	}
+	value := ast.NewTextSegment(text.NewSegment(segment.Start+1, segment.Start+stop))
+	block.Advance(stop + 1)
+	return ast.NewAutoLink(typ, value)
+}

vendor/github.com/yuin/goldmark/parser/blockquote.go

@@ -0,0 +1,69 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type blockquoteParser struct {
+}
+
+var defaultBlockquoteParser = &blockquoteParser{}
+
+// NewBlockquoteParser returns a new BlockParser that
+// parses blockquotes.
+func NewBlockquoteParser() BlockParser {
+	return defaultBlockquoteParser
+}
+
+func (b *blockquoteParser) process(reader text.Reader) bool {
+	line, _ := reader.PeekLine()
+	w, pos := util.IndentWidth(line, reader.LineOffset())
+	if w > 3 || pos >= len(line) || line[pos] != '>' {
+		return false
+	}
+	pos++
+	if pos >= len(line) || line[pos] == '\n' {
+		reader.Advance(pos)
+		return true
+	}
+	if line[pos] == ' ' || line[pos] == '\t' {
+		pos++
+	}
+	reader.Advance(pos)
+	if line[pos-1] == '\t' {
+		reader.SetPadding(2)
+	}
+	return true
+}
+
+func (b *blockquoteParser) Trigger() []byte {
+	return []byte{'>'}
+}
+
+func (b *blockquoteParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	if b.process(reader) {
+		return ast.NewBlockquote(), HasChildren
+	}
+	return nil, NoChildren
+}
+
+func (b *blockquoteParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	if b.process(reader) {
+		return Continue | HasChildren
+	}
+	return Close
+}
+
+func (b *blockquoteParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	// nothing to do
+}
+
+func (b *blockquoteParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *blockquoteParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/code_block.go

@@ -0,0 +1,79 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type codeBlockParser struct {
+}
+
+// CodeBlockParser is a BlockParser implementation that parses indented code blocks.
+var defaultCodeBlockParser = &codeBlockParser{}
+
+// NewCodeBlockParser returns a new BlockParser that
+// parses code blocks.
+func NewCodeBlockParser() BlockParser {
+	return defaultCodeBlockParser
+}
+
+func (b *codeBlockParser) Trigger() []byte {
+	return nil
+}
+
+func (b *codeBlockParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	line, segment := reader.PeekLine()
+	pos, padding := util.IndentPosition(line, reader.LineOffset(), 4)
+	if pos < 0 || util.IsBlank(line) {
+		return nil, NoChildren
+	}
+	node := ast.NewCodeBlock()
+	reader.AdvanceAndSetPadding(pos, padding)
+	_, segment = reader.PeekLine()
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return node, NoChildren
+
+}
+
+func (b *codeBlockParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	line, segment := reader.PeekLine()
+	if util.IsBlank(line) {
+		node.Lines().Append(segment.TrimLeftSpaceWidth(4, reader.Source()))
+		return Continue | NoChildren
+	}
+	pos, padding := util.IndentPosition(line, reader.LineOffset(), 4)
+	if pos < 0 {
+		return Close
+	}
+	reader.AdvanceAndSetPadding(pos, padding)
+	_, segment = reader.PeekLine()
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return Continue | NoChildren
+}
+
+func (b *codeBlockParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	// trim trailing blank lines
+	lines := node.Lines()
+	length := lines.Len() - 1
+	source := reader.Source()
+	for length >= 0 {
+		line := lines.At(length)
+		if util.IsBlank(line.Value(source)) {
+			length--
+		} else {
+			break
+		}
+	}
+	lines.SetSliced(0, length+1)
+}
+
+func (b *codeBlockParser) CanInterruptParagraph() bool {
+	return false
+}
+
+func (b *codeBlockParser) CanAcceptIndentedLine() bool {
+	return true
+}

vendor/github.com/yuin/goldmark/parser/code_span.go

@@ -0,0 +1,83 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type codeSpanParser struct {
+}
+
+var defaultCodeSpanParser = &codeSpanParser{}
+
+// NewCodeSpanParser return a new InlineParser that parses inline codes
+// surrounded by '`' .
+func NewCodeSpanParser() InlineParser {
+	return defaultCodeSpanParser
+}
+
+func (s *codeSpanParser) Trigger() []byte {
+	return []byte{'`'}
+}
+
+func (s *codeSpanParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.Node {
+	line, startSegment := block.PeekLine()
+	opener := 0
+	for ; opener < len(line) && line[opener] == '`'; opener++ {
+	}
+	block.Advance(opener)
+	l, pos := block.Position()
+	node := ast.NewCodeSpan()
+	for {
+		line, segment := block.PeekLine()
+		if line == nil {
+			block.SetPosition(l, pos)
+			return ast.NewTextSegment(startSegment.WithStop(startSegment.Start + opener))
+		}
+		for i := 0; i < len(line); i++ {
+			c := line[i]
+			if c == '`' {
+				oldi := i
+				for ; i < len(line) && line[i] == '`'; i++ {
+				}
+				closure := i - oldi
+				if closure == opener && (i >= len(line) || line[i] != '`') {
+					segment = segment.WithStop(segment.Start + i - closure)
+					if !segment.IsEmpty() {
+						node.AppendChild(node, ast.NewRawTextSegment(segment))
+					}
+					block.Advance(i)
+					goto end
+				}
+			}
+		}
+		if !util.IsBlank(line) {
+			node.AppendChild(node, ast.NewRawTextSegment(segment))
+		}
+		block.AdvanceLine()
+	}
+end:
+	if !node.IsBlank(block.Source()) {
+		// trim first halfspace and last halfspace
+		segment := node.FirstChild().(*ast.Text).Segment
+		shouldTrimmed := true
+		if !(!segment.IsEmpty() && block.Source()[segment.Start] == ' ') {
+			shouldTrimmed = false
+		}
+		segment = node.LastChild().(*ast.Text).Segment
+		if !(!segment.IsEmpty() && block.Source()[segment.Stop-1] == ' ') {
+			shouldTrimmed = false
+		}
+		if shouldTrimmed {
+			t := node.FirstChild().(*ast.Text)
+			segment := t.Segment
+			t.Segment = segment.WithStart(segment.Start + 1)
+			t = node.LastChild().(*ast.Text)
+			segment = node.LastChild().(*ast.Text).Segment
+			t.Segment = segment.WithStop(segment.Stop - 1)
+		}
+
+	}
+	return node
+}

vendor/github.com/yuin/goldmark/parser/delimiter.go

@@ -0,0 +1,241 @@
+package parser
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+// A DelimiterProcessor interface provides a set of functions about
+// Delimiter nodes.
+type DelimiterProcessor interface {
+	// IsDelimiter returns true if given character is a delimiter, otherwise false.
+	IsDelimiter(byte) bool
+
+	// CanOpenCloser returns true if given opener can close given closer, otherwise false.
+	CanOpenCloser(opener, closer *Delimiter) bool
+
+	// OnMatch will be called when new matched delimiter found.
+	// OnMatch should return a new Node correspond to the matched delimiter.
+	OnMatch(consumes int) ast.Node
+}
+
+// A Delimiter struct represents a delimiter like '*' of the Markdown text.
+type Delimiter struct {
+	ast.BaseInline
+
+	Segment text.Segment
+
+	// CanOpen is set true if this delimiter can open a span for a new node.
+	// See https://spec.commonmark.org/0.29/#can-open-emphasis for details.
+	CanOpen bool
+
+	// CanClose is set true if this delimiter can close a span for a new node.
+	// See https://spec.commonmark.org/0.29/#can-open-emphasis for details.
+	CanClose bool
+
+	// Length is a remaining length of this delimiter.
+	Length int
+
+	// OriginalLength is a original length of this delimiter.
+	OriginalLength int
+
+	// Char is a character of this delimiter.
+	Char byte
+
+	// PreviousDelimiter is a previous sibling delimiter node of this delimiter.
+	PreviousDelimiter *Delimiter
+
+	// NextDelimiter is a next sibling delimiter node of this delimiter.
+	NextDelimiter *Delimiter
+
+	// Processor is a DelimiterProcessor associated with this delimiter.
+	Processor DelimiterProcessor
+}
+
+// Inline implements Inline.Inline.
+func (d *Delimiter) Inline() {}
+
+// Dump implements Node.Dump.
+func (d *Delimiter) Dump(source []byte, level int) {
+	fmt.Printf("%sDelimiter: \"%s\"\n", strings.Repeat("    ", level), string(d.Text(source)))
+}
+
+var kindDelimiter = ast.NewNodeKind("Delimiter")
+
+// Kind implements Node.Kind
+func (d *Delimiter) Kind() ast.NodeKind {
+	return kindDelimiter
+}
+
+// Text implements Node.Text
+func (d *Delimiter) Text(source []byte) []byte {
+	return d.Segment.Value(source)
+}
+
+// ConsumeCharacters consumes delimiters.
+func (d *Delimiter) ConsumeCharacters(n int) {
+	d.Length -= n
+	d.Segment = d.Segment.WithStop(d.Segment.Start + d.Length)
+}
+
+// CalcComsumption calculates how many characters should be used for opening
+// a new span correspond to given closer.
+func (d *Delimiter) CalcComsumption(closer *Delimiter) int {
+	if (d.CanClose || closer.CanOpen) && (d.OriginalLength+closer.OriginalLength)%3 == 0 && closer.OriginalLength%3 != 0 {
+		return 0
+	}
+	if d.Length >= 2 && closer.Length >= 2 {
+		return 2
+	}
+	return 1
+}
+
+// NewDelimiter returns a new Delimiter node.
+func NewDelimiter(canOpen, canClose bool, length int, char byte, processor DelimiterProcessor) *Delimiter {
+	c := &Delimiter{
+		BaseInline:        ast.BaseInline{},
+		CanOpen:           canOpen,
+		CanClose:          canClose,
+		Length:            length,
+		OriginalLength:    length,
+		Char:              char,
+		PreviousDelimiter: nil,
+		NextDelimiter:     nil,
+		Processor:         processor,
+	}
+	return c
+}
+
+// ScanDelimiter scans a delimiter by given DelimiterProcessor.
+func ScanDelimiter(line []byte, before rune, min int, processor DelimiterProcessor) *Delimiter {
+	i := 0
+	c := line[i]
+	j := i
+	if !processor.IsDelimiter(c) {
+		return nil
+	}
+	for ; j < len(line) && c == line[j]; j++ {
+	}
+	if (j - i) >= min {
+		after := rune(' ')
+		if j != len(line) {
+			after = util.ToRune(line, j)
+		}
+
+		canOpen, canClose := false, false
+		beforeIsPunctuation := util.IsPunctRune(before)
+		beforeIsWhitespace := util.IsSpaceRune(before)
+		afterIsPunctuation := util.IsPunctRune(after)
+		afterIsWhitespace := util.IsSpaceRune(after)
+
+		isLeft := !afterIsWhitespace &&
+			(!afterIsPunctuation || beforeIsWhitespace || beforeIsPunctuation)
+		isRight := !beforeIsWhitespace &&
+			(!beforeIsPunctuation || afterIsWhitespace || afterIsPunctuation)
+
+		if line[i] == '_' {
+			canOpen = isLeft && (!isRight || beforeIsPunctuation)
+			canClose = isRight && (!isLeft || afterIsPunctuation)
+		} else {
+			canOpen = isLeft
+			canClose = isRight
+		}
+		return NewDelimiter(canOpen, canClose, j-i, c, processor)
+	}
+	return nil
+}
+
+// ProcessDelimiters processes the delimiter list in the context.
+// Processing will be stop when reaching the bottom.
+//
+// If you implement an inline parser that can have other inline nodes as
+// children, you should call this function when nesting span has closed.
+func ProcessDelimiters(bottom ast.Node, pc Context) {
+	lastDelimiter := pc.LastDelimiter()
+	if lastDelimiter == nil {
+		return
+	}
+	var closer *Delimiter
+	if bottom != nil {
+		if bottom != lastDelimiter {
+			for c := lastDelimiter.PreviousSibling(); c != nil; {
+				if d, ok := c.(*Delimiter); ok {
+					closer = d
+				}
+				prev := c.PreviousSibling()
+				if prev == bottom {
+					break
+				}
+				c = prev
+			}
+		}
+	} else {
+		closer = pc.FirstDelimiter()
+	}
+	if closer == nil {
+		pc.ClearDelimiters(bottom)
+		return
+	}
+	for closer != nil {
+		if !closer.CanClose {
+			closer = closer.NextDelimiter
+			continue
+		}
+		consume := 0
+		found := false
+		maybeOpener := false
+		var opener *Delimiter
+		for opener = closer.PreviousDelimiter; opener != nil; opener = opener.PreviousDelimiter {
+			if opener.CanOpen && opener.Processor.CanOpenCloser(opener, closer) {
+				maybeOpener = true
+				consume = opener.CalcComsumption(closer)
+				if consume > 0 {
+					found = true
+					break
+				}
+			}
+		}
+		if !found {
+			if !maybeOpener && !closer.CanOpen {
+				pc.RemoveDelimiter(closer)
+			}
+			closer = closer.NextDelimiter
+			continue
+		}
+		opener.ConsumeCharacters(consume)
+		closer.ConsumeCharacters(consume)
+
+		node := opener.Processor.OnMatch(consume)
+
+		parent := opener.Parent()
+		child := opener.NextSibling()
+
+		for child != nil && child != closer {
+			next := child.NextSibling()
+			node.AppendChild(node, child)
+			child = next
+		}
+		parent.InsertAfter(parent, opener, node)
+
+		for c := opener.NextDelimiter; c != nil && c != closer; {
+			next := c.NextDelimiter
+			pc.RemoveDelimiter(c)
+			c = next
+		}
+
+		if opener.Length == 0 {
+			pc.RemoveDelimiter(opener)
+		}
+
+		if closer.Length == 0 {
+			next := closer.NextDelimiter
+			pc.RemoveDelimiter(closer)
+			closer = next
+		}
+	}
+	pc.ClearDelimiters(bottom)
+}

vendor/github.com/yuin/goldmark/parser/emphasis.go

@@ -0,0 +1,50 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+)
+
+type emphasisDelimiterProcessor struct {
+}
+
+func (p *emphasisDelimiterProcessor) IsDelimiter(b byte) bool {
+	return b == '*' || b == '_'
+}
+
+func (p *emphasisDelimiterProcessor) CanOpenCloser(opener, closer *Delimiter) bool {
+	return opener.Char == closer.Char
+}
+
+func (p *emphasisDelimiterProcessor) OnMatch(consumes int) ast.Node {
+	return ast.NewEmphasis(consumes)
+}
+
+var defaultEmphasisDelimiterProcessor = &emphasisDelimiterProcessor{}
+
+type emphasisParser struct {
+}
+
+var defaultEmphasisParser = &emphasisParser{}
+
+// NewEmphasisParser return a new InlineParser that parses emphasises.
+func NewEmphasisParser() InlineParser {
+	return defaultEmphasisParser
+}
+
+func (s *emphasisParser) Trigger() []byte {
+	return []byte{'*', '_'}
+}
+
+func (s *emphasisParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.Node {
+	before := block.PrecendingCharacter()
+	line, segment := block.PeekLine()
+	node := ScanDelimiter(line, before, 1, defaultEmphasisDelimiterProcessor)
+	if node == nil {
+		return nil
+	}
+	node.Segment = segment.WithStop(segment.Start + node.OriginalLength)
+	block.Advance(node.OriginalLength)
+	pc.PushDelimiter(node)
+	return node
+}

vendor/github.com/yuin/goldmark/parser/fcode_block.go

@@ -0,0 +1,110 @@
+package parser
+
+import (
+	"bytes"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type fencedCodeBlockParser struct {
+}
+
+var defaultFencedCodeBlockParser = &fencedCodeBlockParser{}
+
+// NewFencedCodeBlockParser returns a new BlockParser that
+// parses fenced code blocks.
+func NewFencedCodeBlockParser() BlockParser {
+	return defaultFencedCodeBlockParser
+}
+
+type fenceData struct {
+	char   byte
+	indent int
+	length int
+	node   ast.Node
+}
+
+var fencedCodeBlockInfoKey = NewContextKey()
+
+func (b *fencedCodeBlockParser) Trigger() []byte {
+	return []byte{'~', '`'}
+}
+
+func (b *fencedCodeBlockParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	line, segment := reader.PeekLine()
+	pos := pc.BlockOffset()
+	if pos < 0 || (line[pos] != '`' && line[pos] != '~') {
+		return nil, NoChildren
+	}
+	findent := pos
+	fenceChar := line[pos]
+	i := pos
+	for ; i < len(line) && line[i] == fenceChar; i++ {
+	}
+	oFenceLength := i - pos
+	if oFenceLength < 3 {
+		return nil, NoChildren
+	}
+	var info *ast.Text
+	if i < len(line)-1 {
+		rest := line[i:]
+		left := util.TrimLeftSpaceLength(rest)
+		right := util.TrimRightSpaceLength(rest)
+		if left < len(rest)-right {
+			infoStart, infoStop := segment.Start-segment.Padding+i+left, segment.Stop-right
+			value := rest[left : len(rest)-right]
+			if fenceChar == '`' && bytes.IndexByte(value, '`') > -1 {
+				return nil, NoChildren
+			} else if infoStart != infoStop {
+				info = ast.NewTextSegment(text.NewSegment(infoStart, infoStop))
+			}
+		}
+	}
+	node := ast.NewFencedCodeBlock(info)
+	pc.Set(fencedCodeBlockInfoKey, &fenceData{fenceChar, findent, oFenceLength, node})
+	return node, NoChildren
+
+}
+
+func (b *fencedCodeBlockParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	line, segment := reader.PeekLine()
+	fdata := pc.Get(fencedCodeBlockInfoKey).(*fenceData)
+	w, pos := util.IndentWidth(line, reader.LineOffset())
+	if w < 4 {
+		i := pos
+		for ; i < len(line) && line[i] == fdata.char; i++ {
+		}
+		length := i - pos
+		if length >= fdata.length && util.IsBlank(line[i:]) {
+			newline := 1
+			if line[len(line)-1] != '\n' {
+				newline = 0
+			}
+			reader.Advance(segment.Stop - segment.Start - newline - segment.Padding)
+			return Close
+		}
+	}
+	pos, padding := util.DedentPositionPadding(line, reader.LineOffset(), segment.Padding, fdata.indent)
+
+	seg := text.NewSegmentPadding(segment.Start+pos, segment.Stop, padding)
+	node.Lines().Append(seg)
+	reader.AdvanceAndSetPadding(segment.Stop-segment.Start-pos-1, padding)
+	return Continue | NoChildren
+}
+
+func (b *fencedCodeBlockParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	fdata := pc.Get(fencedCodeBlockInfoKey).(*fenceData)
+	if fdata.node == node {
+		pc.Set(fencedCodeBlockInfoKey, nil)
+	}
+}
+
+func (b *fencedCodeBlockParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *fencedCodeBlockParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/html_block.go

@@ -0,0 +1,228 @@
+package parser
+
+import (
+	"bytes"
+	"regexp"
+	"strings"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var allowedBlockTags = map[string]bool{
+	"address":    true,
+	"article":    true,
+	"aside":      true,
+	"base":       true,
+	"basefont":   true,
+	"blockquote": true,
+	"body":       true,
+	"caption":    true,
+	"center":     true,
+	"col":        true,
+	"colgroup":   true,
+	"dd":         true,
+	"details":    true,
+	"dialog":     true,
+	"dir":        true,
+	"div":        true,
+	"dl":         true,
+	"dt":         true,
+	"fieldset":   true,
+	"figcaption": true,
+	"figure":     true,
+	"footer":     true,
+	"form":       true,
+	"frame":      true,
+	"frameset":   true,
+	"h1":         true,
+	"h2":         true,
+	"h3":         true,
+	"h4":         true,
+	"h5":         true,
+	"h6":         true,
+	"head":       true,
+	"header":     true,
+	"hr":         true,
+	"html":       true,
+	"iframe":     true,
+	"legend":     true,
+	"li":         true,
+	"link":       true,
+	"main":       true,
+	"menu":       true,
+	"menuitem":   true,
+	"meta":       true,
+	"nav":        true,
+	"noframes":   true,
+	"ol":         true,
+	"optgroup":   true,
+	"option":     true,
+	"p":          true,
+	"param":      true,
+	"section":    true,
+	"source":     true,
+	"summary":    true,
+	"table":      true,
+	"tbody":      true,
+	"td":         true,
+	"tfoot":      true,
+	"th":         true,
+	"thead":      true,
+	"title":      true,
+	"tr":         true,
+	"track":      true,
+	"ul":         true,
+}
+
+var htmlBlockType1OpenRegexp = regexp.MustCompile(`(?i)^[ ]{0,3}<(script|pre|style)(?:\s.*|>.*|/>.*|)\n?$`)
+var htmlBlockType1CloseRegexp = regexp.MustCompile(`(?i)^.*</(?:script|pre|style)>.*`)
+
+var htmlBlockType2OpenRegexp = regexp.MustCompile(`^[ ]{0,3}<!\-\-`)
+var htmlBlockType2Close = []byte{'-', '-', '>'}
+
+var htmlBlockType3OpenRegexp = regexp.MustCompile(`^[ ]{0,3}<\?`)
+var htmlBlockType3Close = []byte{'?', '>'}
+
+var htmlBlockType4OpenRegexp = regexp.MustCompile(`^[ ]{0,3}<![A-Z]+.*\n?$`)
+var htmlBlockType4Close = []byte{'>'}
+
+var htmlBlockType5OpenRegexp = regexp.MustCompile(`^[ ]{0,3}<\!\[CDATA\[`)
+var htmlBlockType5Close = []byte{']', ']', '>'}
+
+var htmlBlockType6Regexp = regexp.MustCompile(`^[ ]{0,3}</?([a-zA-Z0-9]+)(?:\s.*|>.*|/>.*|)\n?$`)
+
+var htmlBlockType7Regexp = regexp.MustCompile(`^[ ]{0,3}<(/)?([a-zA-Z0-9\-]+)(` + attributePattern + `*)(:?>|/>)\s*\n?$`)
+
+type htmlBlockParser struct {
+}
+
+var defaultHTMLBlockParser = &htmlBlockParser{}
+
+// NewHTMLBlockParser return a new BlockParser that can parse html
+// blocks.
+func NewHTMLBlockParser() BlockParser {
+	return defaultHTMLBlockParser
+}
+
+func (b *htmlBlockParser) Trigger() []byte {
+	return []byte{'<'}
+}
+
+func (b *htmlBlockParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	var node *ast.HTMLBlock
+	line, segment := reader.PeekLine()
+	last := pc.LastOpenedBlock().Node
+	if pos := pc.BlockOffset(); pos < 0 || line[pos] != '<' {
+		return nil, NoChildren
+	}
+
+	if m := htmlBlockType1OpenRegexp.FindSubmatchIndex(line); m != nil {
+		node = ast.NewHTMLBlock(ast.HTMLBlockType1)
+	} else if htmlBlockType2OpenRegexp.Match(line) {
+		node = ast.NewHTMLBlock(ast.HTMLBlockType2)
+	} else if htmlBlockType3OpenRegexp.Match(line) {
+		node = ast.NewHTMLBlock(ast.HTMLBlockType3)
+	} else if htmlBlockType4OpenRegexp.Match(line) {
+		node = ast.NewHTMLBlock(ast.HTMLBlockType4)
+	} else if htmlBlockType5OpenRegexp.Match(line) {
+		node = ast.NewHTMLBlock(ast.HTMLBlockType5)
+	} else if match := htmlBlockType7Regexp.FindSubmatchIndex(line); match != nil {
+		isCloseTag := match[2] > -1 && bytes.Equal(line[match[2]:match[3]], []byte("/"))
+		hasAttr := match[6] != match[7]
+		tagName := strings.ToLower(string(line[match[4]:match[5]]))
+		_, ok := allowedBlockTags[tagName]
+		if ok {
+			node = ast.NewHTMLBlock(ast.HTMLBlockType6)
+		} else if tagName != "script" && tagName != "style" && tagName != "pre" && !ast.IsParagraph(last) && !(isCloseTag && hasAttr) { // type 7 can not interrupt paragraph
+			node = ast.NewHTMLBlock(ast.HTMLBlockType7)
+		}
+	}
+	if node == nil {
+		if match := htmlBlockType6Regexp.FindSubmatchIndex(line); match != nil {
+			tagName := string(line[match[2]:match[3]])
+			_, ok := allowedBlockTags[strings.ToLower(tagName)]
+			if ok {
+				node = ast.NewHTMLBlock(ast.HTMLBlockType6)
+			}
+		}
+	}
+	if node != nil {
+		reader.Advance(segment.Len() - 1)
+		node.Lines().Append(segment)
+		return node, NoChildren
+	}
+	return nil, NoChildren
+}
+
+func (b *htmlBlockParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	htmlBlock := node.(*ast.HTMLBlock)
+	lines := htmlBlock.Lines()
+	line, segment := reader.PeekLine()
+	var closurePattern []byte
+
+	switch htmlBlock.HTMLBlockType {
+	case ast.HTMLBlockType1:
+		if lines.Len() == 1 {
+			firstLine := lines.At(0)
+			if htmlBlockType1CloseRegexp.Match(firstLine.Value(reader.Source())) {
+				return Close
+			}
+		}
+		if htmlBlockType1CloseRegexp.Match(line) {
+			htmlBlock.ClosureLine = segment
+			reader.Advance(segment.Len() - 1)
+			return Close
+		}
+	case ast.HTMLBlockType2:
+		closurePattern = htmlBlockType2Close
+		fallthrough
+	case ast.HTMLBlockType3:
+		if closurePattern == nil {
+			closurePattern = htmlBlockType3Close
+		}
+		fallthrough
+	case ast.HTMLBlockType4:
+		if closurePattern == nil {
+			closurePattern = htmlBlockType4Close
+		}
+		fallthrough
+	case ast.HTMLBlockType5:
+		if closurePattern == nil {
+			closurePattern = htmlBlockType5Close
+		}
+
+		if lines.Len() == 1 {
+			firstLine := lines.At(0)
+			if bytes.Contains(firstLine.Value(reader.Source()), closurePattern) {
+				return Close
+			}
+		}
+		if bytes.Contains(line, closurePattern) {
+			htmlBlock.ClosureLine = segment
+			reader.Advance(segment.Len() - 1)
+			return Close
+		}
+
+	case ast.HTMLBlockType6, ast.HTMLBlockType7:
+		if util.IsBlank(line) {
+			return Close
+		}
+	}
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return Continue | NoChildren
+}
+
+func (b *htmlBlockParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	// nothing to do
+}
+
+func (b *htmlBlockParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *htmlBlockParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/link.go

@@ -0,0 +1,387 @@
+package parser
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var linkLabelStateKey = NewContextKey()
+
+type linkLabelState struct {
+	ast.BaseInline
+
+	Segment text.Segment
+
+	IsImage bool
+
+	Prev *linkLabelState
+
+	Next *linkLabelState
+
+	First *linkLabelState
+
+	Last *linkLabelState
+}
+
+func newLinkLabelState(segment text.Segment, isImage bool) *linkLabelState {
+	return &linkLabelState{
+		Segment: segment,
+		IsImage: isImage,
+	}
+}
+
+func (s *linkLabelState) Text(source []byte) []byte {
+	return s.Segment.Value(source)
+}
+
+func (s *linkLabelState) Dump(source []byte, level int) {
+	fmt.Printf("%slinkLabelState: \"%s\"\n", strings.Repeat("    ", level), s.Text(source))
+}
+
+var kindLinkLabelState = ast.NewNodeKind("LinkLabelState")
+
+func (s *linkLabelState) Kind() ast.NodeKind {
+	return kindLinkLabelState
+}
+
+func pushLinkLabelState(pc Context, v *linkLabelState) {
+	tlist := pc.Get(linkLabelStateKey)
+	var list *linkLabelState
+	if tlist == nil {
+		list = v
+		v.First = v
+		v.Last = v
+		pc.Set(linkLabelStateKey, list)
+	} else {
+		list = tlist.(*linkLabelState)
+		l := list.Last
+		list.Last = v
+		l.Next = v
+		v.Prev = l
+	}
+}
+
+func removeLinkLabelState(pc Context, d *linkLabelState) {
+	tlist := pc.Get(linkLabelStateKey)
+	var list *linkLabelState
+	if tlist == nil {
+		return
+	}
+	list = tlist.(*linkLabelState)
+
+	if d.Prev == nil {
+		list = d.Next
+		if list != nil {
+			list.First = d
+			list.Last = d.Last
+			list.Prev = nil
+			pc.Set(linkLabelStateKey, list)
+		} else {
+			pc.Set(linkLabelStateKey, nil)
+		}
+	} else {
+		d.Prev.Next = d.Next
+		if d.Next != nil {
+			d.Next.Prev = d.Prev
+		}
+	}
+	if list != nil && d.Next == nil {
+		list.Last = d.Prev
+	}
+	d.Next = nil
+	d.Prev = nil
+	d.First = nil
+	d.Last = nil
+}
+
+type linkParser struct {
+}
+
+var defaultLinkParser = &linkParser{}
+
+// NewLinkParser return a new InlineParser that parses links.
+func NewLinkParser() InlineParser {
+	return defaultLinkParser
+}
+
+func (s *linkParser) Trigger() []byte {
+	return []byte{'!', '[', ']'}
+}
+
+var linkDestinationRegexp = regexp.MustCompile(`\s*([^\s].+)`)
+var linkTitleRegexp = regexp.MustCompile(`\s+(\)|["'\(].+)`)
+var linkBottom = NewContextKey()
+
+func (s *linkParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.Node {
+	line, segment := block.PeekLine()
+	if line[0] == '!' {
+		if len(line) > 1 && line[1] == '[' {
+			block.Advance(1)
+			pc.Set(linkBottom, pc.LastDelimiter())
+			return processLinkLabelOpen(block, segment.Start+1, true, pc)
+		}
+		return nil
+	}
+	if line[0] == '[' {
+		pc.Set(linkBottom, pc.LastDelimiter())
+		return processLinkLabelOpen(block, segment.Start, false, pc)
+	}
+
+	// line[0] == ']'
+	tlist := pc.Get(linkLabelStateKey)
+	if tlist == nil {
+		return nil
+	}
+	last := tlist.(*linkLabelState).Last
+	if last == nil {
+		return nil
+	}
+	block.Advance(1)
+	removeLinkLabelState(pc, last)
+	if s.containsLink(last) { // a link in a link text is not allowed
+		ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
+		return nil
+	}
+
+	c := block.Peek()
+	l, pos := block.Position()
+	var link *ast.Link
+	var hasValue bool
+	if c == '(' { // normal link
+		link = s.parseLink(parent, last, block, pc)
+	} else if c == '[' { // reference link
+		link, hasValue = s.parseReferenceLink(parent, last, block, pc)
+		if link == nil && hasValue {
+			ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
+			return nil
+		}
+	}
+
+	if link == nil {
+		// maybe shortcut reference link
+		block.SetPosition(l, pos)
+		ssegment := text.NewSegment(last.Segment.Stop, segment.Start)
+		maybeReference := block.Value(ssegment)
+		ref, ok := pc.Reference(util.ToLinkReference(maybeReference))
+		if !ok {
+			ast.MergeOrReplaceTextSegment(last.Parent(), last, last.Segment)
+			return nil
+		}
+		link = ast.NewLink()
+		s.processLinkLabel(parent, link, last, pc)
+		link.Title = ref.Title()
+		link.Destination = ref.Destination()
+	}
+	if last.IsImage {
+		last.Parent().RemoveChild(last.Parent(), last)
+		return ast.NewImage(link)
+	}
+	last.Parent().RemoveChild(last.Parent(), last)
+	return link
+}
+
+func (s *linkParser) containsLink(last *linkLabelState) bool {
+	if last.IsImage {
+		return false
+	}
+	var c ast.Node
+	for c = last; c != nil; c = c.NextSibling() {
+		if _, ok := c.(*ast.Link); ok {
+			return true
+		}
+	}
+	return false
+}
+
+func processLinkLabelOpen(block text.Reader, pos int, isImage bool, pc Context) *linkLabelState {
+	start := pos
+	if isImage {
+		start--
+	}
+	state := newLinkLabelState(text.NewSegment(start, pos+1), isImage)
+	pushLinkLabelState(pc, state)
+	block.Advance(1)
+	return state
+}
+
+func (s *linkParser) processLinkLabel(parent ast.Node, link *ast.Link, last *linkLabelState, pc Context) {
+	var bottom ast.Node
+	if v := pc.Get(linkBottom); v != nil {
+		bottom = v.(ast.Node)
+	}
+	pc.Set(linkBottom, nil)
+	ProcessDelimiters(bottom, pc)
+	for c := last.NextSibling(); c != nil; {
+		next := c.NextSibling()
+		parent.RemoveChild(parent, c)
+		link.AppendChild(link, c)
+		c = next
+	}
+}
+
+func (s *linkParser) parseReferenceLink(parent ast.Node, last *linkLabelState, block text.Reader, pc Context) (*ast.Link, bool) {
+	_, orgpos := block.Position()
+	block.Advance(1) // skip '['
+	line, segment := block.PeekLine()
+	endIndex := util.FindClosure(line, '[', ']', false, true)
+	if endIndex < 0 {
+		return nil, false
+	}
+
+	block.Advance(endIndex + 1)
+	ssegment := segment.WithStop(segment.Start + endIndex)
+	maybeReference := block.Value(ssegment)
+	if util.IsBlank(maybeReference) { // collapsed reference link
+		ssegment = text.NewSegment(last.Segment.Stop, orgpos.Start-1)
+		maybeReference = block.Value(ssegment)
+	}
+
+	ref, ok := pc.Reference(util.ToLinkReference(maybeReference))
+	if !ok {
+		return nil, true
+	}
+
+	link := ast.NewLink()
+	s.processLinkLabel(parent, link, last, pc)
+	link.Title = ref.Title()
+	link.Destination = ref.Destination()
+	return link, true
+}
+
+func (s *linkParser) parseLink(parent ast.Node, last *linkLabelState, block text.Reader, pc Context) *ast.Link {
+	block.Advance(1) // skip '('
+	block.SkipSpaces()
+	var title []byte
+	var destination []byte
+	var ok bool
+	if block.Peek() == ')' { // empty link like '[link]()'
+		block.Advance(1)
+	} else {
+		destination, ok = parseLinkDestination(block)
+		if !ok {
+			return nil
+		}
+		block.SkipSpaces()
+		if block.Peek() == ')' {
+			block.Advance(1)
+		} else {
+			title, ok = parseLinkTitle(block)
+			if !ok {
+				return nil
+			}
+			block.SkipSpaces()
+			if block.Peek() == ')' {
+				block.Advance(1)
+			} else {
+				return nil
+			}
+		}
+	}
+
+	link := ast.NewLink()
+	s.processLinkLabel(parent, link, last, pc)
+	link.Destination = destination
+	link.Title = title
+	return link
+}
+
+func parseLinkDestination(block text.Reader) ([]byte, bool) {
+	block.SkipSpaces()
+	line, _ := block.PeekLine()
+	buf := []byte{}
+	if block.Peek() == '<' {
+		i := 1
+		for i < len(line) {
+			c := line[i]
+			if c == '\\' && i < len(line)-1 && util.IsPunct(line[i+1]) {
+				buf = append(buf, '\\', line[i+1])
+				i += 2
+				continue
+			} else if c == '>' {
+				block.Advance(i + 1)
+				return line[1:i], true
+			}
+			buf = append(buf, c)
+			i++
+		}
+		return nil, false
+	}
+	opened := 0
+	i := 0
+	for i < len(line) {
+		c := line[i]
+		if c == '\\' && i < len(line)-1 && util.IsPunct(line[i+1]) {
+			buf = append(buf, '\\', line[i+1])
+			i += 2
+			continue
+		} else if c == '(' {
+			opened++
+		} else if c == ')' {
+			opened--
+			if opened < 0 {
+				break
+			}
+		} else if util.IsSpace(c) {
+			break
+		}
+		buf = append(buf, c)
+		i++
+	}
+	block.Advance(i)
+	return line[:i], len(line[:i]) != 0
+}
+
+func parseLinkTitle(block text.Reader) ([]byte, bool) {
+	block.SkipSpaces()
+	opener := block.Peek()
+	if opener != '"' && opener != '\'' && opener != '(' {
+		return nil, false
+	}
+	closer := opener
+	if opener == '(' {
+		closer = ')'
+	}
+	savedLine, savedPosition := block.Position()
+	var title []byte
+	for i := 0; ; i++ {
+		line, _ := block.PeekLine()
+		if line == nil {
+			block.SetPosition(savedLine, savedPosition)
+			return nil, false
+		}
+		offset := 0
+		if i == 0 {
+			offset = 1
+		}
+		pos := util.FindClosure(line[offset:], opener, closer, false, true)
+		if pos < 0 {
+			title = append(title, line[offset:]...)
+			block.AdvanceLine()
+			continue
+		}
+		pos += offset + 1 // 1: closer
+		block.Advance(pos)
+		if i == 0 { // avoid allocating new slice
+			return line[offset : pos-1], true
+		}
+		return append(title, line[offset:pos-1]...), true
+	}
+}
+
+func (s *linkParser) CloseBlock(parent ast.Node, block text.Reader, pc Context) {
+	tlist := pc.Get(linkLabelStateKey)
+	if tlist == nil {
+		return
+	}
+	for s := tlist.(*linkLabelState); s != nil; {
+		next := s.Next
+		removeLinkLabelState(pc, s)
+		s.Parent().ReplaceChild(s.Parent(), s, ast.NewTextSegment(s.Segment))
+		s = next
+	}
+}

vendor/github.com/yuin/goldmark/parser/link_ref.go

@@ -0,0 +1,163 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type linkReferenceParagraphTransformer struct {
+}
+
+// LinkReferenceParagraphTransformer is a ParagraphTransformer implementation
+// that parses and extracts link reference from paragraphs.
+var LinkReferenceParagraphTransformer = &linkReferenceParagraphTransformer{}
+
+func (p *linkReferenceParagraphTransformer) Transform(node *ast.Paragraph, reader text.Reader, pc Context) {
+	lines := node.Lines()
+	block := text.NewBlockReader(reader.Source(), lines)
+	removes := [][2]int{}
+	for {
+		start, end := parseLinkReferenceDefinition(block, pc)
+		if start > -1 {
+			if start == end {
+				end++
+			}
+			removes = append(removes, [2]int{start, end})
+			continue
+		}
+		break
+	}
+
+	offset := 0
+	for _, remove := range removes {
+		if lines.Len() == 0 {
+			break
+		}
+		s := lines.Sliced(remove[1]-offset, lines.Len())
+		lines.SetSliced(0, remove[0]-offset)
+		lines.AppendAll(s)
+		offset = remove[1]
+	}
+
+	if lines.Len() == 0 {
+		t := ast.NewTextBlock()
+		t.SetBlankPreviousLines(node.HasBlankPreviousLines())
+		node.Parent().ReplaceChild(node.Parent(), node, t)
+		return
+	}
+
+	node.SetLines(lines)
+}
+
+func parseLinkReferenceDefinition(block text.Reader, pc Context) (int, int) {
+	block.SkipSpaces()
+	line, segment := block.PeekLine()
+	if line == nil {
+		return -1, -1
+	}
+	startLine, _ := block.Position()
+	width, pos := util.IndentWidth(line, 0)
+	if width > 3 {
+		return -1, -1
+	}
+	if width != 0 {
+		pos++
+	}
+	if line[pos] != '[' {
+		return -1, -1
+	}
+	open := segment.Start + pos + 1
+	closes := -1
+	block.Advance(pos + 1)
+	for {
+		line, segment = block.PeekLine()
+		if line == nil {
+			return -1, -1
+		}
+		closure := util.FindClosure(line, '[', ']', false, false)
+		if closure > -1 {
+			closes = segment.Start + closure
+			next := closure + 1
+			if next >= len(line) || line[next] != ':' {
+				return -1, -1
+			}
+			block.Advance(next + 1)
+			break
+		}
+		block.AdvanceLine()
+	}
+	if closes < 0 {
+		return -1, -1
+	}
+	label := block.Value(text.NewSegment(open, closes))
+	if util.IsBlank(label) {
+		return -1, -1
+	}
+	block.SkipSpaces()
+	destination, ok := parseLinkDestination(block)
+	if !ok {
+		return -1, -1
+	}
+	line, segment = block.PeekLine()
+	isNewLine := line == nil || util.IsBlank(line)
+
+	endLine, _ := block.Position()
+	_, spaces, _ := block.SkipSpaces()
+	opener := block.Peek()
+	if opener != '"' && opener != '\'' && opener != '(' {
+		if !isNewLine {
+			return -1, -1
+		}
+		ref := NewReference(label, destination, nil)
+		pc.AddReference(ref)
+		return startLine, endLine + 1
+	}
+	if spaces == 0 {
+		return -1, -1
+	}
+	block.Advance(1)
+	open = -1
+	closes = -1
+	closer := opener
+	if opener == '(' {
+		closer = ')'
+	}
+	for {
+		line, segment = block.PeekLine()
+		if line == nil {
+			return -1, -1
+		}
+		if open < 0 {
+			open = segment.Start
+		}
+		closure := util.FindClosure(line, opener, closer, false, true)
+		if closure > -1 {
+			closes = segment.Start + closure
+			block.Advance(closure + 1)
+			break
+		}
+		block.AdvanceLine()
+	}
+	if closes < 0 {
+		return -1, -1
+	}
+
+	line, segment = block.PeekLine()
+	if line != nil && !util.IsBlank(line) {
+		if !isNewLine {
+			return -1, -1
+		}
+		title := block.Value(text.NewSegment(open, closes))
+		ref := NewReference(label, destination, title)
+		pc.AddReference(ref)
+		return startLine, endLine
+	}
+
+	title := block.Value(text.NewSegment(open, closes))
+
+	endLine, _ = block.Position()
+	ref := NewReference(label, destination, title)
+	pc.AddReference(ref)
+	return startLine, endLine + 1
+}

vendor/github.com/yuin/goldmark/parser/list.go

@@ -0,0 +1,251 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+	"strconv"
+)
+
+type listItemType int
+
+const (
+	notList listItemType = iota
+	bulletList
+	orderedList
+)
+
+// Same as
+// `^(([ ]*)([\-\*\+]))(\s+.*)?\n?$`.FindSubmatchIndex or
+// `^(([ ]*)(\d{1,9}[\.\)]))(\s+.*)?\n?$`.FindSubmatchIndex
+func parseListItem(line []byte) ([6]int, listItemType) {
+	i := 0
+	l := len(line)
+	ret := [6]int{}
+	for ; i < l && line[i] == ' '; i++ {
+		c := line[i]
+		if c == '\t' {
+			return ret, notList
+		}
+	}
+	if i > 3 {
+		return ret, notList
+	}
+	ret[0] = 0
+	ret[1] = i
+	ret[2] = i
+	var typ listItemType
+	if i < l && (line[i] == '-' || line[i] == '*' || line[i] == '+') {
+		i++
+		ret[3] = i
+		typ = bulletList
+	} else if i < l {
+		for ; i < l && util.IsNumeric(line[i]); i++ {
+		}
+		ret[3] = i
+		if ret[3] == ret[2] || ret[3]-ret[2] > 9 {
+			return ret, notList
+		}
+		if i < l && (line[i] == '.' || line[i] == ')') {
+			i++
+			ret[3] = i
+		} else {
+			return ret, notList
+		}
+		typ = orderedList
+	} else {
+		return ret, notList
+	}
+	if i < l && line[i] != '\n' {
+		w, _ := util.IndentWidth(line[i:], 0)
+		if w == 0 {
+			return ret, notList
+		}
+	}
+	if i >= l {
+		ret[4] = -1
+		ret[5] = -1
+		return ret, typ
+	}
+	ret[4] = i
+	ret[5] = len(line)
+	if line[ret[5]-1] == '\n' && line[i] != '\n' {
+		ret[5]--
+	}
+	return ret, typ
+}
+
+func matchesListItem(source []byte, strict bool) ([6]int, listItemType) {
+	m, typ := parseListItem(source)
+	if typ != notList && (!strict || strict && m[1] < 4) {
+		return m, typ
+	}
+	return m, notList
+}
+
+func calcListOffset(source []byte, match [6]int) int {
+	offset := 0
+	if match[4] < 0 || util.IsBlank(source[match[4]:]) { // list item starts with a blank line
+		offset = 1
+	} else {
+		offset, _ = util.IndentWidth(source[match[4]:], match[4])
+		if offset > 4 { // offseted codeblock
+			offset = 1
+		}
+	}
+	return offset
+}
+
+func lastOffset(node ast.Node) int {
+	lastChild := node.LastChild()
+	if lastChild != nil {
+		return lastChild.(*ast.ListItem).Offset
+	}
+	return 0
+}
+
+type listParser struct {
+}
+
+var defaultListParser = &listParser{}
+
+// NewListParser returns a new BlockParser that
+// parses lists.
+// This parser must take precedence over the ListItemParser.
+func NewListParser() BlockParser {
+	return defaultListParser
+}
+
+func (b *listParser) Trigger() []byte {
+	return []byte{'-', '+', '*', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'}
+}
+
+func (b *listParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	last := pc.LastOpenedBlock().Node
+	if _, lok := last.(*ast.List); lok || pc.Get(skipListParser) != nil {
+		pc.Set(skipListParser, nil)
+		return nil, NoChildren
+	}
+	line, _ := reader.PeekLine()
+	match, typ := matchesListItem(line, true)
+	if typ == notList {
+		return nil, NoChildren
+	}
+	start := -1
+	if typ == orderedList {
+		number := line[match[2] : match[3]-1]
+		start, _ = strconv.Atoi(string(number))
+	}
+
+	if ast.IsParagraph(last) && last.Parent() == parent {
+		// we allow only lists starting with 1 to interrupt paragraphs.
+		if typ == orderedList && start != 1 {
+			return nil, NoChildren
+		}
+		//an empty list item cannot interrupt a paragraph:
+		if match[5]-match[4] == 1 {
+			return nil, NoChildren
+		}
+	}
+
+	marker := line[match[3]-1]
+	node := ast.NewList(marker)
+	if start > -1 {
+		node.Start = start
+	}
+	return node, HasChildren
+}
+
+func (b *listParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	list := node.(*ast.List)
+	line, _ := reader.PeekLine()
+	if util.IsBlank(line) {
+		// A list item can begin with at most one blank line
+		if node.ChildCount() == 1 && node.LastChild().ChildCount() == 0 {
+			return Close
+		}
+		return Continue | HasChildren
+	}
+
+	// "offset" means a width that bar indicates.
+	//    -  aaaaaaaa
+	// |----|
+	//
+	// If the indent is less than the last offset like
+	// - a
+	//  - b          <--- current line
+	// it maybe a new child of the list.
+	offset := lastOffset(node)
+	indent, _ := util.IndentWidth(line, reader.LineOffset())
+
+	if indent < offset {
+		if indent < 4 {
+			match, typ := matchesListItem(line, false) // may have a leading spaces more than 3
+			if typ != notList && match[1]-offset < 4 {
+				marker := line[match[3]-1]
+				if !list.CanContinue(marker, typ == orderedList) {
+					return Close
+				}
+				// Thematic Breaks take precedence over lists
+				if isThematicBreak(line[match[3]-1:], 0) {
+					isHeading := false
+					last := pc.LastOpenedBlock().Node
+					if ast.IsParagraph(last) {
+						c, ok := matchesSetextHeadingBar(line[match[3]-1:])
+						if ok && c == '-' {
+							isHeading = true
+						}
+					}
+					if !isHeading {
+						return Close
+					}
+				}
+
+				return Continue | HasChildren
+			}
+		}
+		return Close
+	}
+	return Continue | HasChildren
+}
+
+func (b *listParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	list := node.(*ast.List)
+
+	for c := node.FirstChild(); c != nil && list.IsTight; c = c.NextSibling() {
+		if c.FirstChild() != nil && c.FirstChild() != c.LastChild() {
+			for c1 := c.FirstChild().NextSibling(); c1 != nil; c1 = c1.NextSibling() {
+				if bl, ok := c1.(ast.Node); ok && bl.HasBlankPreviousLines() {
+					list.IsTight = false
+					break
+				}
+			}
+		}
+		if c != node.FirstChild() {
+			if bl, ok := c.(ast.Node); ok && bl.HasBlankPreviousLines() {
+				list.IsTight = false
+			}
+		}
+	}
+
+	if list.IsTight {
+		for child := node.FirstChild(); child != nil; child = child.NextSibling() {
+			for gc := child.FirstChild(); gc != nil; gc = gc.NextSibling() {
+				paragraph, ok := gc.(*ast.Paragraph)
+				if ok {
+					textBlock := ast.NewTextBlock()
+					textBlock.SetLines(paragraph.Lines())
+					child.ReplaceChild(child, paragraph, textBlock)
+				}
+			}
+		}
+	}
+}
+
+func (b *listParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *listParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/list_item.go

@@ -0,0 +1,85 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type listItemParser struct {
+}
+
+var defaultListItemParser = &listItemParser{}
+
+// NewListItemParser returns a new BlockParser that
+// parses list items.
+func NewListItemParser() BlockParser {
+	return defaultListItemParser
+}
+
+var skipListParser = NewContextKey()
+var skipListParserValue interface{} = true
+
+func (b *listItemParser) Trigger() []byte {
+	return []byte{'-', '+', '*', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'}
+}
+
+func (b *listItemParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	list, lok := parent.(*ast.List)
+	if !lok { // list item must be a child of a list
+		return nil, NoChildren
+	}
+	offset := lastOffset(list)
+	line, _ := reader.PeekLine()
+	match, typ := matchesListItem(line, false)
+	if typ == notList {
+		return nil, NoChildren
+	}
+	if match[1]-offset > 3 {
+		return nil, NoChildren
+	}
+	itemOffset := calcListOffset(line, match)
+	node := ast.NewListItem(match[3] + itemOffset)
+	if match[4] < 0 || match[5]-match[4] == 1 {
+		return node, NoChildren
+	}
+
+	pos, padding := util.IndentPosition(line[match[4]:], match[4], itemOffset)
+	child := match[3] + pos
+	reader.AdvanceAndSetPadding(child, padding)
+	return node, HasChildren
+}
+
+func (b *listItemParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	line, _ := reader.PeekLine()
+	if util.IsBlank(line) {
+		return Continue | HasChildren
+	}
+
+	indent, _ := util.IndentWidth(line, reader.LineOffset())
+	offset := lastOffset(node.Parent())
+	if indent < offset && indent < 4 {
+		_, typ := matchesListItem(line, true)
+		// new list item found
+		if typ != notList {
+			pc.Set(skipListParser, skipListParserValue)
+		}
+		return Close
+	}
+	pos, padding := util.IndentPosition(line, reader.LineOffset(), offset)
+	reader.AdvanceAndSetPadding(pos, padding)
+
+	return Continue | HasChildren
+}
+
+func (b *listItemParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	// nothing to do
+}
+
+func (b *listItemParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *listItemParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/paragraph.go

@@ -0,0 +1,71 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+)
+
+type paragraphParser struct {
+}
+
+var defaultParagraphParser = &paragraphParser{}
+
+// NewParagraphParser returns a new BlockParser that
+// parses paragraphs.
+func NewParagraphParser() BlockParser {
+	return defaultParagraphParser
+}
+
+func (b *paragraphParser) Trigger() []byte {
+	return nil
+}
+
+func (b *paragraphParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	_, segment := reader.PeekLine()
+	segment = segment.TrimLeftSpace(reader.Source())
+	if segment.IsEmpty() {
+		return nil, NoChildren
+	}
+	node := ast.NewParagraph()
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return node, NoChildren
+}
+
+func (b *paragraphParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	_, segment := reader.PeekLine()
+	segment = segment.TrimLeftSpace(reader.Source())
+	if segment.IsEmpty() {
+		return Close
+	}
+	node.Lines().Append(segment)
+	reader.Advance(segment.Len() - 1)
+	return Continue | NoChildren
+}
+
+func (b *paragraphParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	parent := node.Parent()
+	if parent == nil {
+		// paragraph has been transformed
+		return
+	}
+	lines := node.Lines()
+	if lines.Len() != 0 {
+		// trim trailing spaces
+		length := lines.Len()
+		lastLine := node.Lines().At(length - 1)
+		node.Lines().Set(length-1, lastLine.TrimRightSpace(reader.Source()))
+	}
+	if lines.Len() == 0 {
+		node.Parent().RemoveChild(node.Parent(), node)
+		return
+	}
+}
+
+func (b *paragraphParser) CanInterruptParagraph() bool {
+	return false
+}
+
+func (b *paragraphParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/raw_html.go

@@ -0,0 +1,108 @@
+package parser
+
+import (
+	"bytes"
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+	"regexp"
+)
+
+type rawHTMLParser struct {
+}
+
+var defaultRawHTMLParser = &rawHTMLParser{}
+
+// NewRawHTMLParser return a new InlineParser that can parse
+// inline htmls
+func NewRawHTMLParser() InlineParser {
+	return defaultRawHTMLParser
+}
+
+func (s *rawHTMLParser) Trigger() []byte {
+	return []byte{'<'}
+}
+
+func (s *rawHTMLParser) Parse(parent ast.Node, block text.Reader, pc Context) ast.Node {
+	line, _ := block.PeekLine()
+	if len(line) > 1 && util.IsAlphaNumeric(line[1]) {
+		return s.parseMultiLineRegexp(openTagRegexp, block, pc)
+	}
+	if len(line) > 2 && line[1] == '/' && util.IsAlphaNumeric(line[2]) {
+		return s.parseMultiLineRegexp(closeTagRegexp, block, pc)
+	}
+	if bytes.HasPrefix(line, []byte("<!--")) {
+		return s.parseMultiLineRegexp(commentRegexp, block, pc)
+	}
+	if bytes.HasPrefix(line, []byte("<?")) {
+		return s.parseSingleLineRegexp(processingInstructionRegexp, block, pc)
+	}
+	if len(line) > 2 && line[1] == '!' && line[2] >= 'A' && line[2] <= 'Z' {
+		return s.parseSingleLineRegexp(declRegexp, block, pc)
+	}
+	if bytes.HasPrefix(line, []byte("<![CDATA[")) {
+		return s.parseMultiLineRegexp(cdataRegexp, block, pc)
+	}
+	return nil
+}
+
+var tagnamePattern = `([A-Za-z][A-Za-z0-9-]*)`
+var attributePattern = `(?:\s+[a-zA-Z_:][a-zA-Z0-9:._-]*(?:\s*=\s*(?:[^\"'=<>` + "`" + `\x00-\x20]+|'[^']*'|"[^"]*"))?)`
+var openTagRegexp = regexp.MustCompile("^<" + tagnamePattern + attributePattern + `*\s*/?>`)
+var closeTagRegexp = regexp.MustCompile("^</" + tagnamePattern + `\s*>`)
+var commentRegexp = regexp.MustCompile(`^<!---->|<!--(?:-?[^>-])(?:-?[^-])*-->`)
+var processingInstructionRegexp = regexp.MustCompile(`^(?:<\?).*?(?:\?>)`)
+var declRegexp = regexp.MustCompile(`^<![A-Z]+\s+[^>]*>`)
+var cdataRegexp = regexp.MustCompile(`<!\[CDATA\[[\s\S]*?\]\]>`)
+
+func (s *rawHTMLParser) parseSingleLineRegexp(reg *regexp.Regexp, block text.Reader, pc Context) ast.Node {
+	line, segment := block.PeekLine()
+	match := reg.FindSubmatchIndex(line)
+	if match == nil {
+		return nil
+	}
+	node := ast.NewRawHTML()
+	node.Segments.Append(segment.WithStop(segment.Start + match[1]))
+	block.Advance(match[1])
+	return node
+}
+
+var dummyMatch = [][]byte{}
+
+func (s *rawHTMLParser) parseMultiLineRegexp(reg *regexp.Regexp, block text.Reader, pc Context) ast.Node {
+	sline, ssegment := block.Position()
+	if block.Match(reg) {
+		node := ast.NewRawHTML()
+		eline, esegment := block.Position()
+		block.SetPosition(sline, ssegment)
+		for {
+			line, segment := block.PeekLine()
+			if line == nil {
+				break
+			}
+			l, _ := block.Position()
+			start := segment.Start
+			if l == sline {
+				start = ssegment.Start
+			}
+			end := segment.Stop
+			if l == eline {
+				end = esegment.Start
+			}
+
+			node.Segments.Append(text.NewSegment(start, end))
+			if l == eline {
+				block.Advance(end - start)
+				break
+			} else {
+				block.AdvanceLine()
+			}
+		}
+		return node
+	}
+	return nil
+}
+
+func (s *rawHTMLParser) CloseBlock(parent ast.Node, pc Context) {
+	// nothing to do
+}

vendor/github.com/yuin/goldmark/parser/setext_headings.go

@@ -0,0 +1,126 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+var temporaryParagraphKey = NewContextKey()
+
+type setextHeadingParser struct {
+	HeadingConfig
+}
+
+func matchesSetextHeadingBar(line []byte) (byte, bool) {
+	start := 0
+	end := len(line)
+	space := util.TrimLeftLength(line, []byte{' '})
+	if space > 3 {
+		return 0, false
+	}
+	start += space
+	level1 := util.TrimLeftLength(line[start:end], []byte{'='})
+	c := byte('=')
+	var level2 int
+	if level1 == 0 {
+		level2 = util.TrimLeftLength(line[start:end], []byte{'-'})
+		c = '-'
+	}
+	if util.IsSpace(line[end-1]) {
+		end -= util.TrimRightSpaceLength(line[start:end])
+	}
+	if !((level1 > 0 && start+level1 == end) || (level2 > 0 && start+level2 == end)) {
+		return 0, false
+	}
+	return c, true
+}
+
+// NewSetextHeadingParser return a new BlockParser that can parse Setext headings.
+func NewSetextHeadingParser(opts ...HeadingOption) BlockParser {
+	p := &setextHeadingParser{}
+	for _, o := range opts {
+		o.SetHeadingOption(&p.HeadingConfig)
+	}
+	return p
+}
+
+func (b *setextHeadingParser) Trigger() []byte {
+	return []byte{'-', '='}
+}
+
+func (b *setextHeadingParser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	last := pc.LastOpenedBlock().Node
+	if last == nil {
+		return nil, NoChildren
+	}
+	paragraph, ok := last.(*ast.Paragraph)
+	if !ok || paragraph.Parent() != parent {
+		return nil, NoChildren
+	}
+	line, segment := reader.PeekLine()
+	c, ok := matchesSetextHeadingBar(line)
+	if !ok {
+		return nil, NoChildren
+	}
+	level := 1
+	if c == '-' {
+		level = 2
+	}
+	node := ast.NewHeading(level)
+	node.Lines().Append(segment)
+	pc.Set(temporaryParagraphKey, last)
+	return node, NoChildren | RequireParagraph
+}
+
+func (b *setextHeadingParser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	return Close
+}
+
+func (b *setextHeadingParser) Close(node ast.Node, reader text.Reader, pc Context) {
+	heading := node.(*ast.Heading)
+	segment := node.Lines().At(0)
+	heading.Lines().Clear()
+	tmp := pc.Get(temporaryParagraphKey).(*ast.Paragraph)
+	pc.Set(temporaryParagraphKey, nil)
+	if tmp.Lines().Len() == 0 {
+		next := heading.NextSibling()
+		segment = segment.TrimLeftSpace(reader.Source())
+		if next == nil || !ast.IsParagraph(next) {
+			para := ast.NewParagraph()
+			para.Lines().Append(segment)
+			heading.Parent().InsertAfter(heading.Parent(), heading, para)
+		} else {
+			next.(ast.Node).Lines().Unshift(segment)
+		}
+		heading.Parent().RemoveChild(heading.Parent(), heading)
+	} else {
+		heading.SetLines(tmp.Lines())
+		heading.SetBlankPreviousLines(tmp.HasBlankPreviousLines())
+		tp := tmp.Parent()
+		if tp != nil {
+			tp.RemoveChild(tp, tmp)
+		}
+	}
+
+	if b.Attribute {
+		parseLastLineAttributes(node, reader, pc)
+	}
+
+	if b.AutoHeadingID {
+		id, ok := node.AttributeString("id")
+		if !ok {
+			generateAutoHeadingID(heading, reader, pc)
+		} else {
+			pc.IDs().Put(id.([]byte))
+		}
+	}
+}
+
+func (b *setextHeadingParser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *setextHeadingParser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/parser/thematic_break.go

@@ -0,0 +1,75 @@
+package parser
+
+import (
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/text"
+	"github.com/yuin/goldmark/util"
+)
+
+type thematicBreakPraser struct {
+}
+
+var defaultThematicBreakPraser = &thematicBreakPraser{}
+
+// NewThematicBreakParser returns a new BlockParser that
+// parses thematic breaks.
+func NewThematicBreakParser() BlockParser {
+	return defaultThematicBreakPraser
+}
+
+func isThematicBreak(line []byte, offset int) bool {
+	w, pos := util.IndentWidth(line, offset)
+	if w > 3 {
+		return false
+	}
+	mark := byte(0)
+	count := 0
+	for i := pos; i < len(line); i++ {
+		c := line[i]
+		if util.IsSpace(c) {
+			continue
+		}
+		if mark == 0 {
+			mark = c
+			count = 1
+			if mark == '*' || mark == '-' || mark == '_' {
+				continue
+			}
+			return false
+		}
+		if c != mark {
+			return false
+		}
+		count++
+	}
+	return count > 2
+}
+
+func (b *thematicBreakPraser) Trigger() []byte {
+	return []byte{'-', '*', '_'}
+}
+
+func (b *thematicBreakPraser) Open(parent ast.Node, reader text.Reader, pc Context) (ast.Node, State) {
+	line, segment := reader.PeekLine()
+	if isThematicBreak(line, reader.LineOffset()) {
+		reader.Advance(segment.Len() - 1)
+		return ast.NewThematicBreak(), NoChildren
+	}
+	return nil, NoChildren
+}
+
+func (b *thematicBreakPraser) Continue(node ast.Node, reader text.Reader, pc Context) State {
+	return Close
+}
+
+func (b *thematicBreakPraser) Close(node ast.Node, reader text.Reader, pc Context) {
+	// nothing to do
+}
+
+func (b *thematicBreakPraser) CanInterruptParagraph() bool {
+	return true
+}
+
+func (b *thematicBreakPraser) CanAcceptIndentedLine() bool {
+	return false
+}

vendor/github.com/yuin/goldmark/renderer/html/html.go

@@ -0,0 +1,804 @@
+package html
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/renderer"
+	"github.com/yuin/goldmark/util"
+)
+
+// A Config struct has configurations for the HTML based renderers.
+type Config struct {
+	Writer    Writer
+	HardWraps bool
+	XHTML     bool
+	Unsafe    bool
+}
+
+// NewConfig returns a new Config with defaults.
+func NewConfig() Config {
+	return Config{
+		Writer:    DefaultWriter,
+		HardWraps: false,
+		XHTML:     false,
+		Unsafe:    false,
+	}
+}
+
+// SetOption implements renderer.NodeRenderer.SetOption.
+func (c *Config) SetOption(name renderer.OptionName, value interface{}) {
+	switch name {
+	case optHardWraps:
+		c.HardWraps = value.(bool)
+	case optXHTML:
+		c.XHTML = value.(bool)
+	case optUnsafe:
+		c.Unsafe = value.(bool)
+	case optTextWriter:
+		c.Writer = value.(Writer)
+	}
+}
+
+// An Option interface sets options for HTML based renderers.
+type Option interface {
+	SetHTMLOption(*Config)
+}
+
+// TextWriter is an option name used in WithWriter.
+const optTextWriter renderer.OptionName = "Writer"
+
+type withWriter struct {
+	value Writer
+}
+
+func (o *withWriter) SetConfig(c *renderer.Config) {
+	c.Options[optTextWriter] = o.value
+}
+
+func (o *withWriter) SetHTMLOption(c *Config) {
+	c.Writer = o.value
+}
+
+// WithWriter is a functional option that allow you to set the given writer to
+// the renderer.
+func WithWriter(writer Writer) interface {
+	renderer.Option
+	Option
+} {
+	return &withWriter{writer}
+}
+
+// HardWraps is an option name used in WithHardWraps.
+const optHardWraps renderer.OptionName = "HardWraps"
+
+type withHardWraps struct {
+}
+
+func (o *withHardWraps) SetConfig(c *renderer.Config) {
+	c.Options[optHardWraps] = true
+}
+
+func (o *withHardWraps) SetHTMLOption(c *Config) {
+	c.HardWraps = true
+}
+
+// WithHardWraps is a functional option that indicates whether softline breaks
+// should be rendered as '<br>'.
+func WithHardWraps() interface {
+	renderer.Option
+	Option
+} {
+	return &withHardWraps{}
+}
+
+// XHTML is an option name used in WithXHTML.
+const optXHTML renderer.OptionName = "XHTML"
+
+type withXHTML struct {
+}
+
+func (o *withXHTML) SetConfig(c *renderer.Config) {
+	c.Options[optXHTML] = true
+}
+
+func (o *withXHTML) SetHTMLOption(c *Config) {
+	c.XHTML = true
+}
+
+// WithXHTML is a functional option indicates that nodes should be rendered in
+// xhtml instead of HTML5.
+func WithXHTML() interface {
+	Option
+	renderer.Option
+} {
+	return &withXHTML{}
+}
+
+// Unsafe is an option name used in WithUnsafe.
+const optUnsafe renderer.OptionName = "Unsafe"
+
+type withUnsafe struct {
+}
+
+func (o *withUnsafe) SetConfig(c *renderer.Config) {
+	c.Options[optUnsafe] = true
+}
+
+func (o *withUnsafe) SetHTMLOption(c *Config) {
+	c.Unsafe = true
+}
+
+// WithUnsafe is a functional option that renders dangerous contents
+// (raw htmls and potentially dangerous links) as it is.
+func WithUnsafe() interface {
+	renderer.Option
+	Option
+} {
+	return &withUnsafe{}
+}
+
+// A Renderer struct is an implementation of renderer.NodeRenderer that renders
+// nodes as (X)HTML.
+type Renderer struct {
+	Config
+}
+
+// NewRenderer returns a new Renderer with given options.
+func NewRenderer(opts ...Option) renderer.NodeRenderer {
+	r := &Renderer{
+		Config: NewConfig(),
+	}
+
+	for _, opt := range opts {
+		opt.SetHTMLOption(&r.Config)
+	}
+	return r
+}
+
+// RegisterFuncs implements NodeRenderer.RegisterFuncs .
+func (r *Renderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
+	// blocks
+
+	reg.Register(ast.KindDocument, r.renderDocument)
+	reg.Register(ast.KindHeading, r.renderHeading)
+	reg.Register(ast.KindBlockquote, r.renderBlockquote)
+	reg.Register(ast.KindCodeBlock, r.renderCodeBlock)
+	reg.Register(ast.KindFencedCodeBlock, r.renderFencedCodeBlock)
+	reg.Register(ast.KindHTMLBlock, r.renderHTMLBlock)
+	reg.Register(ast.KindList, r.renderList)
+	reg.Register(ast.KindListItem, r.renderListItem)
+	reg.Register(ast.KindParagraph, r.renderParagraph)
+	reg.Register(ast.KindTextBlock, r.renderTextBlock)
+	reg.Register(ast.KindThematicBreak, r.renderThematicBreak)
+
+	// inlines
+
+	reg.Register(ast.KindAutoLink, r.renderAutoLink)
+	reg.Register(ast.KindCodeSpan, r.renderCodeSpan)
+	reg.Register(ast.KindEmphasis, r.renderEmphasis)
+	reg.Register(ast.KindImage, r.renderImage)
+	reg.Register(ast.KindLink, r.renderLink)
+	reg.Register(ast.KindRawHTML, r.renderRawHTML)
+	reg.Register(ast.KindText, r.renderText)
+	reg.Register(ast.KindString, r.renderString)
+}
+
+func (r *Renderer) writeLines(w util.BufWriter, source []byte, n ast.Node) {
+	l := n.Lines().Len()
+	for i := 0; i < l; i++ {
+		line := n.Lines().At(i)
+		r.Writer.RawWrite(w, line.Value(source))
+	}
+}
+
+// GlobalAttributeFilter defines attribute names which any elements can have.
+var GlobalAttributeFilter = util.NewBytesFilter(
+	[]byte("accesskey"),
+	[]byte("autocapitalize"),
+	[]byte("class"),
+	[]byte("contenteditable"),
+	[]byte("contextmenu"),
+	[]byte("dir"),
+	[]byte("draggable"),
+	[]byte("dropzone"),
+	[]byte("hidden"),
+	[]byte("id"),
+	[]byte("itemprop"),
+	[]byte("lang"),
+	[]byte("slot"),
+	[]byte("spellcheck"),
+	[]byte("style"),
+	[]byte("tabindex"),
+	[]byte("title"),
+	[]byte("translate"),
+)
+
+func (r *Renderer) renderDocument(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	// nothing to do
+	return ast.WalkContinue, nil
+}
+
+// HeadingAttributeFilter defines attribute names which heading elements can have
+var HeadingAttributeFilter = GlobalAttributeFilter
+
+func (r *Renderer) renderHeading(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.Heading)
+	if entering {
+		_, _ = w.WriteString("<h")
+		_ = w.WriteByte("0123456"[n.Level])
+		if n.Attributes() != nil {
+			RenderAttributes(w, node, HeadingAttributeFilter)
+		}
+		_ = w.WriteByte('>')
+	} else {
+		_, _ = w.WriteString("</h")
+		_ = w.WriteByte("0123456"[n.Level])
+		_, _ = w.WriteString(">\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+// BlockquoteAttributeFilter defines attribute names which blockquote elements can have
+var BlockquoteAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("cite"),
+)
+
+func (r *Renderer) renderBlockquote(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<blockquote")
+			RenderAttributes(w, n, BlockquoteAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<blockquote>\n")
+		}
+	} else {
+		_, _ = w.WriteString("</blockquote>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderCodeBlock(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if entering {
+		_, _ = w.WriteString("<pre><code>")
+		r.writeLines(w, source, n)
+	} else {
+		_, _ = w.WriteString("</code></pre>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderFencedCodeBlock(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.FencedCodeBlock)
+	if entering {
+		_, _ = w.WriteString("<pre><code")
+		language := n.Language(source)
+		if language != nil {
+			_, _ = w.WriteString(" class=\"language-")
+			r.Writer.Write(w, language)
+			_, _ = w.WriteString("\"")
+		}
+		_ = w.WriteByte('>')
+		r.writeLines(w, source, n)
+	} else {
+		_, _ = w.WriteString("</code></pre>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderHTMLBlock(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.HTMLBlock)
+	if entering {
+		if r.Unsafe {
+			l := n.Lines().Len()
+			for i := 0; i < l; i++ {
+				line := n.Lines().At(i)
+				_, _ = w.Write(line.Value(source))
+			}
+		} else {
+			_, _ = w.WriteString("<!-- raw HTML omitted -->\n")
+		}
+	} else {
+		if n.HasClosure() {
+			if r.Unsafe {
+				closure := n.ClosureLine
+				_, _ = w.Write(closure.Value(source))
+			} else {
+				_, _ = w.WriteString("<!-- raw HTML omitted -->\n")
+			}
+		}
+	}
+	return ast.WalkContinue, nil
+}
+
+// ListAttributeFilter defines attribute names which list elements can have.
+var ListAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("start"),
+	[]byte("reversed"),
+)
+
+func (r *Renderer) renderList(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.List)
+	tag := "ul"
+	if n.IsOrdered() {
+		tag = "ol"
+	}
+	if entering {
+		_ = w.WriteByte('<')
+		_, _ = w.WriteString(tag)
+		if n.IsOrdered() && n.Start != 1 {
+			fmt.Fprintf(w, " start=\"%d\"", n.Start)
+		}
+		if n.Attributes() != nil {
+			RenderAttributes(w, n, ListAttributeFilter)
+		}
+		_, _ = w.WriteString(">\n")
+	} else {
+		_, _ = w.WriteString("</")
+		_, _ = w.WriteString(tag)
+		_, _ = w.WriteString(">\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+// ListItemAttributeFilter defines attribute names which list item elements can have.
+var ListItemAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("value"),
+)
+
+func (r *Renderer) renderListItem(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<li")
+			RenderAttributes(w, n, ListItemAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<li>")
+		}
+		fc := n.FirstChild()
+		if fc != nil {
+			if _, ok := fc.(*ast.TextBlock); !ok {
+				_ = w.WriteByte('\n')
+			}
+		}
+	} else {
+		_, _ = w.WriteString("</li>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+// ParagraphAttributeFilter defines attribute names which paragraph elements can have.
+var ParagraphAttributeFilter = GlobalAttributeFilter
+
+func (r *Renderer) renderParagraph(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<p")
+			RenderAttributes(w, n, ParagraphAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<p>")
+		}
+	} else {
+		_, _ = w.WriteString("</p>\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderTextBlock(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		if _, ok := n.NextSibling().(ast.Node); ok && n.FirstChild() != nil {
+			_ = w.WriteByte('\n')
+		}
+	}
+	return ast.WalkContinue, nil
+}
+
+// ThematicAttributeFilter defines attribute names which hr elements can have.
+var ThematicAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("align"),   // [Deprecated]
+	[]byte("color"),   // [Not Standardized]
+	[]byte("noshade"), // [Deprecated]
+	[]byte("size"),    // [Deprecated]
+	[]byte("width"),   // [Deprecated]
+)
+
+func (r *Renderer) renderThematicBreak(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+	_, _ = w.WriteString("<hr")
+	if n.Attributes() != nil {
+		RenderAttributes(w, n, ThematicAttributeFilter)
+	}
+	if r.XHTML {
+		_, _ = w.WriteString(" />\n")
+	} else {
+		_, _ = w.WriteString(">\n")
+	}
+	return ast.WalkContinue, nil
+}
+
+// LinkAttributeFilter defines attribute names which link elements can have.
+var LinkAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("download"),
+	// []byte("href"),
+	[]byte("hreflang"),
+	[]byte("media"),
+	[]byte("ping"),
+	[]byte("referrerpolicy"),
+	[]byte("rel"),
+	[]byte("shape"),
+	[]byte("target"),
+)
+
+func (r *Renderer) renderAutoLink(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.AutoLink)
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+	_, _ = w.WriteString(`<a href="`)
+	url := n.URL(source)
+	label := n.Label(source)
+	if n.AutoLinkType == ast.AutoLinkEmail && !bytes.HasPrefix(bytes.ToLower(url), []byte("mailto:")) {
+		_, _ = w.WriteString("mailto:")
+	}
+	_, _ = w.Write(util.EscapeHTML(util.URLEscape(url, false)))
+	if n.Attributes() != nil {
+		_ = w.WriteByte('"')
+		RenderAttributes(w, n, LinkAttributeFilter)
+		_ = w.WriteByte('>')
+	} else {
+		_, _ = w.WriteString(`">`)
+	}
+	_, _ = w.Write(util.EscapeHTML(label))
+	_, _ = w.WriteString(`</a>`)
+	return ast.WalkContinue, nil
+}
+
+// CodeAttributeFilter defines attribute names which code elements can have.
+var CodeAttributeFilter = GlobalAttributeFilter
+
+func (r *Renderer) renderCodeSpan(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
+	if entering {
+		if n.Attributes() != nil {
+			_, _ = w.WriteString("<code")
+			RenderAttributes(w, n, CodeAttributeFilter)
+			_ = w.WriteByte('>')
+		} else {
+			_, _ = w.WriteString("<code>")
+		}
+		for c := n.FirstChild(); c != nil; c = c.NextSibling() {
+			segment := c.(*ast.Text).Segment
+			value := segment.Value(source)
+			if bytes.HasSuffix(value, []byte("\n")) {
+				r.Writer.RawWrite(w, value[:len(value)-1])
+				if c != n.LastChild() {
+					r.Writer.RawWrite(w, []byte(" "))
+				}
+			} else {
+				r.Writer.RawWrite(w, value)
+			}
+		}
+		return ast.WalkSkipChildren, nil
+	}
+	_, _ = w.WriteString("</code>")
+	return ast.WalkContinue, nil
+}
+
+// EmphasisAttributeFilter defines attribute names which emphasis elements can have.
+var EmphasisAttributeFilter = GlobalAttributeFilter
+
+func (r *Renderer) renderEmphasis(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.Emphasis)
+	tag := "em"
+	if n.Level == 2 {
+		tag = "strong"
+	}
+	if entering {
+		_ = w.WriteByte('<')
+		_, _ = w.WriteString(tag)
+		if n.Attributes() != nil {
+			RenderAttributes(w, n, EmphasisAttributeFilter)
+		}
+		_ = w.WriteByte('>')
+	} else {
+		_, _ = w.WriteString("</")
+		_, _ = w.WriteString(tag)
+		_ = w.WriteByte('>')
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderLink(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	n := node.(*ast.Link)
+	if entering {
+		_, _ = w.WriteString("<a href=\"")
+		if r.Unsafe || !IsDangerousURL(n.Destination) {
+			_, _ = w.Write(util.EscapeHTML(util.URLEscape(n.Destination, true)))
+		}
+		_ = w.WriteByte('"')
+		if n.Title != nil {
+			_, _ = w.WriteString(` title="`)
+			r.Writer.Write(w, n.Title)
+			_ = w.WriteByte('"')
+		}
+		if n.Attributes() != nil {
+			RenderAttributes(w, n, LinkAttributeFilter)
+		}
+		_ = w.WriteByte('>')
+	} else {
+		_, _ = w.WriteString("</a>")
+	}
+	return ast.WalkContinue, nil
+}
+
+// ImageAttributeFilter defines attribute names which image elements can have.
+var ImageAttributeFilter = GlobalAttributeFilter.Extend(
+	[]byte("align"),
+	[]byte("border"),
+	[]byte("crossorigin"),
+	[]byte("decoding"),
+	[]byte("height"),
+	[]byte("importance"),
+	[]byte("intrinsicsize"),
+	[]byte("ismap"),
+	[]byte("loading"),
+	[]byte("referrerpolicy"),
+	[]byte("sizes"),
+	[]byte("srcset"),
+	[]byte("usemap"),
+	[]byte("width"),
+)
+
+func (r *Renderer) renderImage(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+	n := node.(*ast.Image)
+	_, _ = w.WriteString("<img src=\"")
+	if r.Unsafe || !IsDangerousURL(n.Destination) {
+		_, _ = w.Write(util.EscapeHTML(util.URLEscape(n.Destination, true)))
+	}
+	_, _ = w.WriteString(`" alt="`)
+	_, _ = w.Write(util.EscapeHTML(n.Text(source)))
+	_ = w.WriteByte('"')
+	if n.Title != nil {
+		_, _ = w.WriteString(` title="`)
+		r.Writer.Write(w, n.Title)
+		_ = w.WriteByte('"')
+	}
+	if n.Attributes() != nil {
+		RenderAttributes(w, n, ImageAttributeFilter)
+	}
+	if r.XHTML {
+		_, _ = w.WriteString(" />")
+	} else {
+		_, _ = w.WriteString(">")
+	}
+	return ast.WalkSkipChildren, nil
+}
+
+func (r *Renderer) renderRawHTML(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkSkipChildren, nil
+	}
+	if r.Unsafe {
+		n := node.(*ast.RawHTML)
+		l := n.Segments.Len()
+		for i := 0; i < l; i++ {
+			segment := n.Segments.At(i)
+			_, _ = w.Write(segment.Value(source))
+		}
+		return ast.WalkSkipChildren, nil
+	}
+	_, _ = w.WriteString("<!-- raw HTML omitted -->")
+	return ast.WalkSkipChildren, nil
+}
+
+func (r *Renderer) renderText(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+	n := node.(*ast.Text)
+	segment := n.Segment
+	if n.IsRaw() {
+		r.Writer.RawWrite(w, segment.Value(source))
+	} else {
+		r.Writer.Write(w, segment.Value(source))
+		if n.HardLineBreak() || (n.SoftLineBreak() && r.HardWraps) {
+			if r.XHTML {
+				_, _ = w.WriteString("<br />\n")
+			} else {
+				_, _ = w.WriteString("<br>\n")
+			}
+		} else if n.SoftLineBreak() {
+			_ = w.WriteByte('\n')
+		}
+	}
+	return ast.WalkContinue, nil
+}
+
+func (r *Renderer) renderString(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
+	if !entering {
+		return ast.WalkContinue, nil
+	}
+	n := node.(*ast.String)
+	if n.IsCode() {
+		_, _ = w.Write(n.Value)
+	} else {
+		if n.IsRaw() {
+			r.Writer.RawWrite(w, n.Value)
+		} else {
+			r.Writer.Write(w, n.Value)
+		}
+	}
+	return ast.WalkContinue, nil
+}
+
+var dataPrefix = []byte("data-")
+
+// RenderAttributes renders given node's attributes.
+// You can specify attribute names to render by the filter.
+// If filter is nil, RenderAttributes renders all attributes.
+func RenderAttributes(w util.BufWriter, node ast.Node, filter util.BytesFilter) {
+	for _, attr := range node.Attributes() {
+		if filter != nil && !filter.Contains(attr.Name) {
+			if !bytes.HasPrefix(attr.Name, dataPrefix) {
+				continue
+			}
+		}
+		_, _ = w.WriteString(" ")
+		_, _ = w.Write(attr.Name)
+		_, _ = w.WriteString(`="`)
+		// TODO: convert numeric values to strings
+		_, _ = w.Write(util.EscapeHTML(attr.Value.([]byte)))
+		_ = w.WriteByte('"')
+	}
+}
+
+// A Writer interface writes textual contents to a writer.
+type Writer interface {
+	// Write writes the given source to writer with resolving references and unescaping
+	// backslash escaped characters.
+	Write(writer util.BufWriter, source []byte)
+
+	// RawWrite writes the given source to writer without resolving references and
+	// unescaping backslash escaped characters.
+	RawWrite(writer util.BufWriter, source []byte)
+}
+
+type defaultWriter struct {
+}
+
+func escapeRune(writer util.BufWriter, r rune) {
+	if r < 256 {
+		v := util.EscapeHTMLByte(byte(r))
+		if v != nil {
+			_, _ = writer.Write(v)
+			return
+		}
+	}
+	_, _ = writer.WriteRune(util.ToValidRune(r))
+}
+
+func (d *defaultWriter) RawWrite(writer util.BufWriter, source []byte) {
+	n := 0
+	l := len(source)
+	for i := 0; i < l; i++ {
+		v := util.EscapeHTMLByte(source[i])
+		if v != nil {
+			_, _ = writer.Write(source[i-n : i])
+			n = 0
+			_, _ = writer.Write(v)
+			continue
+		}
+		n++
+	}
+	if n != 0 {
+		_, _ = writer.Write(source[l-n:])
+	}
+}
+
+func (d *defaultWriter) Write(writer util.BufWriter, source []byte) {
+	escaped := false
+	var ok bool
+	limit := len(source)
+	n := 0
+	for i := 0; i < limit; i++ {
+		c := source[i]
+		if escaped {
+			if util.IsPunct(c) {
+				d.RawWrite(writer, source[n:i-1])
+				n = i
+				escaped = false
+				continue
+			}
+		}
+		if c == '&' {
+			pos := i
+			next := i + 1
+			if next < limit && source[next] == '#' {
+				nnext := next + 1
+				if nnext < limit {
+					nc := source[nnext]
+					// code point like #x22;
+					if nnext < limit && nc == 'x' || nc == 'X' {
+						start := nnext + 1
+						i, ok = util.ReadWhile(source, [2]int{start, limit}, util.IsHexDecimal)
+						if ok && i < limit && source[i] == ';' {
+							v, _ := strconv.ParseUint(util.BytesToReadOnlyString(source[start:i]), 16, 32)
+							d.RawWrite(writer, source[n:pos])
+							n = i + 1
+							escapeRune(writer, rune(v))
+							continue
+						}
+						// code point like #1234;
+					} else if nc >= '0' && nc <= '9' {
+						start := nnext
+						i, ok = util.ReadWhile(source, [2]int{start, limit}, util.IsNumeric)
+						if ok && i < limit && i-start < 8 && source[i] == ';' {
+							v, _ := strconv.ParseUint(util.BytesToReadOnlyString(source[start:i]), 0, 32)
+							d.RawWrite(writer, source[n:pos])
+							n = i + 1
+							escapeRune(writer, rune(v))
+							continue
+						}
+					}
+				}
+			} else {
+				start := next
+				i, ok = util.ReadWhile(source, [2]int{start, limit}, util.IsAlphaNumeric)
+				// entity reference
+				if ok && i < limit && source[i] == ';' {
+					name := util.BytesToReadOnlyString(source[start:i])
+					entity, ok := util.LookUpHTML5EntityByName(name)
+					if ok {
+						d.RawWrite(writer, source[n:pos])
+						n = i + 1
+						d.RawWrite(writer, entity.Characters)
+						continue
+					}
+				}
+			}
+			i = next - 1
+		}
+		if c == '\\' {
+			escaped = true
+			continue
+		}
+		escaped = false
+	}
+	d.RawWrite(writer, source[n:])
+}
+
+// DefaultWriter is a default implementation of the Writer.
+var DefaultWriter = &defaultWriter{}
+
+var bDataImage = []byte("data:image/")
+var bPng = []byte("png;")
+var bGif = []byte("gif;")
+var bJpeg = []byte("jpeg;")
+var bWebp = []byte("webp;")
+var bJs = []byte("javascript:")
+var bVb = []byte("vbscript:")
+var bFile = []byte("file:")
+var bData = []byte("data:")
+
+// IsDangerousURL returns true if the given url seems a potentially dangerous url,
+// otherwise false.
+func IsDangerousURL(url []byte) bool {
+	if bytes.HasPrefix(url, bDataImage) && len(url) >= 11 {
+		v := url[11:]
+		if bytes.HasPrefix(v, bPng) || bytes.HasPrefix(v, bGif) ||
+			bytes.HasPrefix(v, bJpeg) || bytes.HasPrefix(v, bWebp) {
+			return false
+		}
+		return true
+	}
+	return bytes.HasPrefix(url, bJs) || bytes.HasPrefix(url, bVb) ||
+		bytes.HasPrefix(url, bFile) || bytes.HasPrefix(url, bData)
+}

vendor/github.com/yuin/goldmark/renderer/renderer.go

@@ -0,0 +1,174 @@
+// Package renderer renders the given AST to certain formats.
+package renderer
+
+import (
+	"bufio"
+	"io"
+	"sync"
+
+	"github.com/yuin/goldmark/ast"
+	"github.com/yuin/goldmark/util"
+)
+
+// A Config struct is a data structure that holds configuration of the Renderer.
+type Config struct {
+	Options       map[OptionName]interface{}
+	NodeRenderers util.PrioritizedSlice
+}
+
+// NewConfig returns a new Config
+func NewConfig() *Config {
+	return &Config{
+		Options:       map[OptionName]interface{}{},
+		NodeRenderers: util.PrioritizedSlice{},
+	}
+}
+
+// An OptionName is a name of the option.
+type OptionName string
+
+// An Option interface is a functional option type for the Renderer.
+type Option interface {
+	SetConfig(*Config)
+}
+
+type withNodeRenderers struct {
+	value []util.PrioritizedValue
+}
+
+func (o *withNodeRenderers) SetConfig(c *Config) {
+	c.NodeRenderers = append(c.NodeRenderers, o.value...)
+}
+
+// WithNodeRenderers is a functional option that allow you to add
+// NodeRenderers to the renderer.
+func WithNodeRenderers(ps ...util.PrioritizedValue) Option {
+	return &withNodeRenderers{ps}
+}
+
+type withOption struct {
+	name  OptionName
+	value interface{}
+}
+
+func (o *withOption) SetConfig(c *Config) {
+	c.Options[o.name] = o.value
+}
+
+// WithOption is a functional option that allow you to set
+// an arbitrary option to the parser.
+func WithOption(name OptionName, value interface{}) Option {
+	return &withOption{name, value}
+}
+
+// A SetOptioner interface sets given option to the object.
+type SetOptioner interface {
+	// SetOption sets given option to the object.
+	// Unacceptable options may be passed.
+	// Thus implementations must ignore unacceptable options.
+	SetOption(name OptionName, value interface{})
+}
+
+// NodeRendererFunc is a function that renders a given node.
+type NodeRendererFunc func(writer util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error)
+
+// A NodeRenderer interface offers NodeRendererFuncs.
+type NodeRenderer interface {
+	// RendererFuncs registers NodeRendererFuncs to given NodeRendererFuncRegisterer.
+	RegisterFuncs(NodeRendererFuncRegisterer)
+}
+
+// A NodeRendererFuncRegisterer registers
+type NodeRendererFuncRegisterer interface {
+	// Register registers given NodeRendererFunc to this object.
+	Register(ast.NodeKind, NodeRendererFunc)
+}
+
+// A Renderer interface renders given AST node to given
+// writer with given Renderer.
+type Renderer interface {
+	Render(w io.Writer, source []byte, n ast.Node) error
+
+	// AddOptions adds given option to this renderer.
+	AddOptions(...Option)
+}
+
+type renderer struct {
+	config               *Config
+	options              map[OptionName]interface{}
+	nodeRendererFuncsTmp map[ast.NodeKind]NodeRendererFunc
+	maxKind              int
+	nodeRendererFuncs    []NodeRendererFunc
+	initSync             sync.Once
+}
+
+// NewRenderer returns a new Renderer with given options.
+func NewRenderer(options ...Option) Renderer {
+	config := NewConfig()
+	for _, opt := range options {
+		opt.SetConfig(config)
+	}
+
+	r := &renderer{
+		options:              map[OptionName]interface{}{},
+		config:               config,
+		nodeRendererFuncsTmp: map[ast.NodeKind]NodeRendererFunc{},
+	}
+
+	return r
+}
+
+func (r *renderer) AddOptions(opts ...Option) {
+	for _, opt := range opts {
+		opt.SetConfig(r.config)
+	}
+}
+
+func (r *renderer) Register(kind ast.NodeKind, v NodeRendererFunc) {
+	r.nodeRendererFuncsTmp[kind] = v
+	if int(kind) > r.maxKind {
+		r.maxKind = int(kind)
+	}
+}
+
+// Render renders the given AST node to the given writer with the given Renderer.
+func (r *renderer) Render(w io.Writer, source []byte, n ast.Node) error {
+	r.initSync.Do(func() {
+		r.options = r.config.Options
+		r.config.NodeRenderers.Sort()
+		l := len(r.config.NodeRenderers)
+		for i := l - 1; i >= 0; i-- {
+			v := r.config.NodeRenderers[i]
+			nr, _ := v.Value.(NodeRenderer)
+			if se, ok := v.Value.(SetOptioner); ok {
+				for oname, ovalue := range r.options {
+					se.SetOption(oname, ovalue)
+				}
+			}
+			nr.RegisterFuncs(r)
+		}
+		r.nodeRendererFuncs = make([]NodeRendererFunc, r.maxKind+1)
+		for kind, nr := range r.nodeRendererFuncsTmp {
+			r.nodeRendererFuncs[kind] = nr
+		}
+		r.config = nil
+		r.nodeRendererFuncsTmp = nil
+	})
+	writer, ok := w.(util.BufWriter)
+	if !ok {
+		writer = bufio.NewWriter(w)
+	}
+	err := ast.Walk(n, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
+		s := ast.WalkStatus(ast.WalkContinue)
+		var err error
+		f := r.nodeRendererFuncs[n.Kind()]
+		if f != nil {
+			s, err = f(writer, source, n, entering)
+		}
+		return s, err
+	})
+	if err != nil {
+		return err
+	}
+	return writer.Flush()
+}

vendor/github.com/yuin/goldmark/text/reader.go

@@ -0,0 +1,543 @@
+package text
+
+import (
+	"io"
+	"regexp"
+	"unicode/utf8"
+
+	"github.com/yuin/goldmark/util"
+)
+
+const invalidValue = -1
+
+// EOF indicates the end of file.
+const EOF = byte(0xff)
+
+// A Reader interface provides abstracted method for reading text.
+type Reader interface {
+	io.RuneReader
+
+	// Source returns a source of the reader.
+	Source() []byte
+
+	// ResetPosition resets positions.
+	ResetPosition()
+
+	// Peek returns a byte at current position without advancing the internal pointer.
+	Peek() byte
+
+	// PeekLine returns the current line without advancing the internal pointer.
+	PeekLine() ([]byte, Segment)
+
+	// PrecendingCharacter returns a character just before current internal pointer.
+	PrecendingCharacter() rune
+
+	// Value returns a value of the given segment.
+	Value(Segment) []byte
+
+	// LineOffset returns a distance from the line head to current position.
+	LineOffset() int
+
+	// Position returns current line number and position.
+	Position() (int, Segment)
+
+	// SetPosition sets current line number and position.
+	SetPosition(int, Segment)
+
+	// SetPadding sets padding to the reader.
+	SetPadding(int)
+
+	// Advance advances the internal pointer.
+	Advance(int)
+
+	// AdvanceAndSetPadding advances the internal pointer and add padding to the
+	// reader.
+	AdvanceAndSetPadding(int, int)
+
+	// AdvanceLine advances the internal pointer to the next line head.
+	AdvanceLine()
+
+	// SkipSpaces skips space characters and returns a non-blank line.
+	// If it reaches EOF, returns false.
+	SkipSpaces() (Segment, int, bool)
+
+	// SkipSpaces skips blank lines and returns a non-blank line.
+	// If it reaches EOF, returns false.
+	SkipBlankLines() (Segment, int, bool)
+
+	// Match performs regular expression matching to current line.
+	Match(reg *regexp.Regexp) bool
+
+	// Match performs regular expression searching to current line.
+	FindSubMatch(reg *regexp.Regexp) [][]byte
+}
+
+type reader struct {
+	source       []byte
+	sourceLength int
+	line         int
+	peekedLine   []byte
+	pos          Segment
+	head         int
+	lineOffset   int
+}
+
+// NewReader return a new Reader that can read UTF-8 bytes .
+func NewReader(source []byte) Reader {
+	r := &reader{
+		source:       source,
+		sourceLength: len(source),
+	}
+	r.ResetPosition()
+	return r
+}
+
+func (r *reader) ResetPosition() {
+	r.line = -1
+	r.head = 0
+	r.lineOffset = -1
+	r.AdvanceLine()
+}
+
+func (r *reader) Source() []byte {
+	return r.source
+}
+
+func (r *reader) Value(seg Segment) []byte {
+	return seg.Value(r.source)
+}
+
+func (r *reader) Peek() byte {
+	if r.pos.Start >= 0 && r.pos.Start < r.sourceLength {
+		if r.pos.Padding != 0 {
+			return space[0]
+		}
+		return r.source[r.pos.Start]
+	}
+	return EOF
+}
+
+func (r *reader) PeekLine() ([]byte, Segment) {
+	if r.pos.Start >= 0 && r.pos.Start < r.sourceLength {
+		if r.peekedLine == nil {
+			r.peekedLine = r.pos.Value(r.Source())
+		}
+		return r.peekedLine, r.pos
+	}
+	return nil, r.pos
+}
+
+// io.RuneReader interface
+func (r *reader) ReadRune() (rune, int, error) {
+	return readRuneReader(r)
+}
+
+func (r *reader) LineOffset() int {
+	if r.lineOffset < 0 {
+		v := 0
+		for i := r.head; i < r.pos.Start; i++ {
+			if r.source[i] == '\t' {
+				v += util.TabWidth(v)
+			} else {
+				v++
+			}
+		}
+		r.lineOffset = v - r.pos.Padding
+	}
+	return r.lineOffset
+}
+
+func (r *reader) PrecendingCharacter() rune {
+	if r.pos.Start <= 0 {
+		if r.pos.Padding != 0 {
+			return rune(' ')
+		}
+		return rune('\n')
+	}
+	i := r.pos.Start - 1
+	for ; i >= 0; i-- {
+		if utf8.RuneStart(r.source[i]) {
+			break
+		}
+	}
+	rn, _ := utf8.DecodeRune(r.source[i:])
+	return rn
+}
+
+func (r *reader) Advance(n int) {
+	r.lineOffset = -1
+	if n < len(r.peekedLine) && r.pos.Padding == 0 {
+		r.pos.Start += n
+		r.peekedLine = nil
+		return
+	}
+	r.peekedLine = nil
+	l := r.sourceLength
+	for ; n > 0 && r.pos.Start < l; n-- {
+		if r.pos.Padding != 0 {
+			r.pos.Padding--
+			continue
+		}
+		if r.source[r.pos.Start] == '\n' {
+			r.AdvanceLine()
+			continue
+		}
+		r.pos.Start++
+	}
+}
+
+func (r *reader) AdvanceAndSetPadding(n, padding int) {
+	r.Advance(n)
+	if padding > r.pos.Padding {
+		r.SetPadding(padding)
+	}
+}
+
+func (r *reader) AdvanceLine() {
+	r.lineOffset = -1
+	r.peekedLine = nil
+	r.pos.Start = r.pos.Stop
+	r.head = r.pos.Start
+	if r.pos.Start < 0 {
+		return
+	}
+	r.pos.Stop = r.sourceLength
+	for i := r.pos.Start; i < r.sourceLength; i++ {
+		c := r.source[i]
+		if c == '\n' {
+			r.pos.Stop = i + 1
+			break
+		}
+	}
+	r.line++
+	r.pos.Padding = 0
+}
+
+func (r *reader) Position() (int, Segment) {
+	return r.line, r.pos
+}
+
+func (r *reader) SetPosition(line int, pos Segment) {
+	r.lineOffset = -1
+	r.line = line
+	r.pos = pos
+}
+
+func (r *reader) SetPadding(v int) {
+	r.pos.Padding = v
+}
+
+func (r *reader) SkipSpaces() (Segment, int, bool) {
+	return skipSpacesReader(r)
+}
+
+func (r *reader) SkipBlankLines() (Segment, int, bool) {
+	return skipBlankLinesReader(r)
+}
+
+func (r *reader) Match(reg *regexp.Regexp) bool {
+	return matchReader(r, reg)
+}
+
+func (r *reader) FindSubMatch(reg *regexp.Regexp) [][]byte {
+	return findSubMatchReader(r, reg)
+}
+
+// A BlockReader interface is a reader that is optimized for Blocks.
+type BlockReader interface {
+	Reader
+	// Reset resets current state and sets new segments to the reader.
+	Reset(segment *Segments)
+}
+
+type blockReader struct {
+	source         []byte
+	segments       *Segments
+	segmentsLength int
+	line           int
+	pos            Segment
+	head           int
+	last           int
+	lineOffset     int
+}
+
+// NewBlockReader returns a new BlockReader.
+func NewBlockReader(source []byte, segments *Segments) BlockReader {
+	r := &blockReader{
+		source: source,
+	}
+	if segments != nil {
+		r.Reset(segments)
+	}
+	return r
+}
+
+func (r *blockReader) ResetPosition() {
+	r.line = -1
+	r.head = 0
+	r.last = 0
+	r.lineOffset = -1
+	r.pos.Start = -1
+	r.pos.Stop = -1
+	r.pos.Padding = 0
+	if r.segmentsLength > 0 {
+		last := r.segments.At(r.segmentsLength - 1)
+		r.last = last.Stop
+	}
+	r.AdvanceLine()
+}
+
+func (r *blockReader) Reset(segments *Segments) {
+	r.segments = segments
+	r.segmentsLength = segments.Len()
+	r.ResetPosition()
+}
+
+func (r *blockReader) Source() []byte {
+	return r.source
+}
+
+func (r *blockReader) Value(seg Segment) []byte {
+	line := r.segmentsLength - 1
+	ret := make([]byte, 0, seg.Stop-seg.Start+1)
+	for ; line >= 0; line-- {
+		if seg.Start >= r.segments.At(line).Start {
+			break
+		}
+	}
+	i := seg.Start
+	for ; line < r.segmentsLength; line++ {
+		s := r.segments.At(line)
+		if i < 0 {
+			i = s.Start
+		}
+		ret = s.ConcatPadding(ret)
+		for ; i < seg.Stop && i < s.Stop; i++ {
+			ret = append(ret, r.source[i])
+		}
+		i = -1
+		if s.Stop > seg.Stop {
+			break
+		}
+	}
+	return ret
+}
+
+// io.RuneReader interface
+func (r *blockReader) ReadRune() (rune, int, error) {
+	return readRuneReader(r)
+}
+
+func (r *blockReader) PrecendingCharacter() rune {
+	if r.pos.Padding != 0 {
+		return rune(' ')
+	}
+	if r.segments.Len() < 1 {
+		return rune('\n')
+	}
+	firstSegment := r.segments.At(0)
+	if r.line == 0 && r.pos.Start <= firstSegment.Start {
+		return rune('\n')
+	}
+	l := len(r.source)
+	i := r.pos.Start - 1
+	for ; i < l && i >= 0; i-- {
+		if utf8.RuneStart(r.source[i]) {
+			break
+		}
+	}
+	if i < 0 || i >= l {
+		return rune('\n')
+	}
+	rn, _ := utf8.DecodeRune(r.source[i:])
+	return rn
+}
+
+func (r *blockReader) LineOffset() int {
+	if r.lineOffset < 0 {
+		v := 0
+		for i := r.head; i < r.pos.Start; i++ {
+			if r.source[i] == '\t' {
+				v += util.TabWidth(v)
+			} else {
+				v++
+			}
+		}
+		r.lineOffset = v - r.pos.Padding
+	}
+	return r.lineOffset
+}
+
+func (r *blockReader) Peek() byte {
+	if r.line < r.segmentsLength && r.pos.Start >= 0 && r.pos.Start < r.last {
+		if r.pos.Padding != 0 {
+			return space[0]
+		}
+		return r.source[r.pos.Start]
+	}
+	return EOF
+}
+
+func (r *blockReader) PeekLine() ([]byte, Segment) {
+	if r.line < r.segmentsLength && r.pos.Start >= 0 && r.pos.Start < r.last {
+		return r.pos.Value(r.source), r.pos
+	}
+	return nil, r.pos
+}
+
+func (r *blockReader) Advance(n int) {
+	r.lineOffset = -1
+
+	if n < r.pos.Stop-r.pos.Start && r.pos.Padding == 0 {
+		r.pos.Start += n
+		return
+	}
+
+	for ; n > 0; n-- {
+		if r.pos.Padding != 0 {
+			r.pos.Padding--
+			continue
+		}
+		if r.pos.Start >= r.pos.Stop-1 && r.pos.Stop < r.last {
+			r.AdvanceLine()
+			continue
+		}
+		r.pos.Start++
+	}
+}
+
+func (r *blockReader) AdvanceAndSetPadding(n, padding int) {
+	r.Advance(n)
+	if padding > r.pos.Padding {
+		r.SetPadding(padding)
+	}
+}
+
+func (r *blockReader) AdvanceLine() {
+	r.SetPosition(r.line+1, NewSegment(invalidValue, invalidValue))
+	r.head = r.pos.Start
+}
+
+func (r *blockReader) Position() (int, Segment) {
+	return r.line, r.pos
+}
+
+func (r *blockReader) SetPosition(line int, pos Segment) {
+	r.lineOffset = -1
+	r.line = line
+	if pos.Start == invalidValue {
+		if r.line < r.segmentsLength {
+			s := r.segments.At(line)
+			r.head = s.Start
+			r.pos = s
+		}
+	} else {
+		r.pos = pos
+		if r.line < r.segmentsLength {
+			s := r.segments.At(line)
+			r.head = s.Start
+		}
+	}
+}
+
+func (r *blockReader) SetPadding(v int) {
+	r.lineOffset = -1
+	r.pos.Padding = v
+}
+
+func (r *blockReader) SkipSpaces() (Segment, int, bool) {
+	return skipSpacesReader(r)
+}
+
+func (r *blockReader) SkipBlankLines() (Segment, int, bool) {
+	return skipBlankLinesReader(r)
+}
+
+func (r *blockReader) Match(reg *regexp.Regexp) bool {
+	return matchReader(r, reg)
+}
+
+func (r *blockReader) FindSubMatch(reg *regexp.Regexp) [][]byte {
+	return findSubMatchReader(r, reg)
+}
+
+func skipBlankLinesReader(r Reader) (Segment, int, bool) {
+	lines := 0
+	for {
+		line, seg := r.PeekLine()
+		if line == nil {
+			return seg, lines, false
+		}
+		if util.IsBlank(line) {
+			lines++
+			r.AdvanceLine()
+		} else {
+			return seg, lines, true
+		}
+	}
+}
+
+func skipSpacesReader(r Reader) (Segment, int, bool) {
+	chars := 0
+	for {
+		line, segment := r.PeekLine()
+		if line == nil {
+			return segment, chars, false
+		}
+		for i, c := range line {
+			if util.IsSpace(c) {
+				chars++
+				r.Advance(1)
+				continue
+			}
+			return segment.WithStart(segment.Start + i + 1), chars, true
+		}
+	}
+}
+
+func matchReader(r Reader, reg *regexp.Regexp) bool {
+	oldline, oldseg := r.Position()
+	match := reg.FindReaderSubmatchIndex(r)
+	r.SetPosition(oldline, oldseg)
+	if match == nil {
+		return false
+	}
+	r.Advance(match[1] - match[0])
+	return true
+}
+
+func findSubMatchReader(r Reader, reg *regexp.Regexp) [][]byte {
+	oldline, oldseg := r.Position()
+	match := reg.FindReaderSubmatchIndex(r)
+	r.SetPosition(oldline, oldseg)
+	if match == nil {
+		return nil
+	}
+	runes := make([]rune, 0, match[1]-match[0])
+	for i := 0; i < match[1]; {
+		r, size, _ := readRuneReader(r)
+		i += size
+		runes = append(runes, r)
+	}
+	result := [][]byte{}
+	for i := 0; i < len(match); i += 2 {
+		result = append(result, []byte(string(runes[match[i]:match[i+1]])))
+	}
+
+	r.SetPosition(oldline, oldseg)
+	r.Advance(match[1] - match[0])
+	return result
+}
+
+func readRuneReader(r Reader) (rune, int, error) {
+	line, _ := r.PeekLine()
+	if line == nil {
+		return 0, 0, io.EOF
+	}
+	rn, size := utf8.DecodeRune(line)
+	if rn == utf8.RuneError {
+		return 0, 0, io.EOF
+	}
+	r.Advance(size)
+	return rn, size, nil
+}

vendor/github.com/yuin/goldmark/text/segment.go

@@ -0,0 +1,209 @@
+package text
+
+import (
+	"bytes"
+	"github.com/yuin/goldmark/util"
+)
+
+var space = []byte(" ")
+
+// A Segment struct holds information about source positions.
+type Segment struct {
+	// Start is a start position of the segment.
+	Start int
+
+	// Stop is a stop position of the segment.
+	// This value should be excluded.
+	Stop int
+
+	// Padding is a padding length of the segment.
+	Padding int
+}
+
+// NewSegment return a new Segment.
+func NewSegment(start, stop int) Segment {
+	return Segment{
+		Start:   start,
+		Stop:    stop,
+		Padding: 0,
+	}
+}
+
+// NewSegmentPadding returns a new Segment with the given padding.
+func NewSegmentPadding(start, stop, n int) Segment {
+	return Segment{
+		Start:   start,
+		Stop:    stop,
+		Padding: n,
+	}
+}
+
+// Value returns a value of the segment.
+func (t *Segment) Value(buffer []byte) []byte {
+	if t.Padding == 0 {
+		return buffer[t.Start:t.Stop]
+	}
+	result := make([]byte, 0, t.Padding+t.Stop-t.Start+1)
+	result = append(result, bytes.Repeat(space, t.Padding)...)
+	return append(result, buffer[t.Start:t.Stop]...)
+}
+
+// Len returns a length of the segment.
+func (t *Segment) Len() int {
+	return t.Stop - t.Start + t.Padding
+}
+
+// Between returns a segment between this segment and the given segment.
+func (t *Segment) Between(other Segment) Segment {
+	if t.Stop != other.Stop {
+		panic("invalid state")
+	}
+	return NewSegmentPadding(
+		t.Start,
+		other.Start,
+		t.Padding-other.Padding,
+	)
+}
+
+// IsEmpty returns true if this segment is empty, otherwise false.
+func (t *Segment) IsEmpty() bool {
+	return t.Start >= t.Stop && t.Padding == 0
+}
+
+// TrimRightSpace returns a new segment by slicing off all trailing
+// space characters.
+func (t *Segment) TrimRightSpace(buffer []byte) Segment {
+	v := buffer[t.Start:t.Stop]
+	l := util.TrimRightSpaceLength(v)
+	if l == len(v) {
+		return NewSegment(t.Start, t.Start)
+	}
+	return NewSegmentPadding(t.Start, t.Stop-l, t.Padding)
+}
+
+// TrimLeftSpace returns a new segment by slicing off all leading
+// space characters including padding.
+func (t *Segment) TrimLeftSpace(buffer []byte) Segment {
+	v := buffer[t.Start:t.Stop]
+	l := util.TrimLeftSpaceLength(v)
+	return NewSegment(t.Start+l, t.Stop)
+}
+
+// TrimLeftSpaceWidth returns a new segment by slicing off leading space
+// characters until the given width.
+func (t *Segment) TrimLeftSpaceWidth(width int, buffer []byte) Segment {
+	padding := t.Padding
+	for ; width > 0; width-- {
+		if padding == 0 {
+			break
+		}
+		padding--
+	}
+	if width == 0 {
+		return NewSegmentPadding(t.Start, t.Stop, padding)
+	}
+	text := buffer[t.Start:t.Stop]
+	start := t.Start
+	for _, c := range text {
+		if start >= t.Stop-1 || width <= 0 {
+			break
+		}
+		if c == ' ' {
+			width--
+		} else if c == '\t' {
+			width -= 4
+		} else {
+			break
+		}
+		start++
+	}
+	if width < 0 {
+		padding = width * -1
+	}
+	return NewSegmentPadding(start, t.Stop, padding)
+}
+
+// WithStart returns a new Segment with same value except Start.
+func (t *Segment) WithStart(v int) Segment {
+	return NewSegmentPadding(v, t.Stop, t.Padding)
+}
+
+// WithStop returns a new Segment with same value except Stop.
+func (t *Segment) WithStop(v int) Segment {
+	return NewSegmentPadding(t.Start, v, t.Padding)
+}
+
+// ConcatPadding concats the padding to the given slice.
+func (t *Segment) ConcatPadding(v []byte) []byte {
+	if t.Padding > 0 {
+		return append(v, bytes.Repeat(space, t.Padding)...)
+	}
+	return v
+}
+
+// Segments is a collection of the Segment.
+type Segments struct {
+	values []Segment
+}
+
+// NewSegments return a new Segments.
+func NewSegments() *Segments {
+	return &Segments{
+		values: nil,
+	}
+}
+
+// Append appends the given segment after the tail of the collection.
+func (s *Segments) Append(t Segment) {
+	if s.values == nil {
+		s.values = make([]Segment, 0, 20)
+	}
+	s.values = append(s.values, t)
+}
+
+// AppendAll appends all elements of given segments after the tail of the collection.
+func (s *Segments) AppendAll(t []Segment) {
+	if s.values == nil {
+		s.values = make([]Segment, 0, 20)
+	}
+	s.values = append(s.values, t...)
+}
+
+// Len returns the length of the collection.
+func (s *Segments) Len() int {
+	if s.values == nil {
+		return 0
+	}
+	return len(s.values)
+}
+
+// At returns a segment at the given index.
+func (s *Segments) At(i int) Segment {
+	return s.values[i]
+}
+
+// Set sets the given Segment.
+func (s *Segments) Set(i int, v Segment) {
+	s.values[i] = v
+}
+
+// SetSliced replace the collection with a subsliced value.
+func (s *Segments) SetSliced(lo, hi int) {
+	s.values = s.values[lo:hi]
+}
+
+// Sliced returns a subslice of the collection.
+func (s *Segments) Sliced(lo, hi int) []Segment {
+	return s.values[lo:hi]
+}
+
+// Clear delete all element of the collection.
+func (s *Segments) Clear() {
+	s.values = nil
+}
+
+// Unshift insert the given Segment to head of the collection.
+func (s *Segments) Unshift(v Segment) {
+	s.values = append(s.values[0:1], s.values[0:]...)
+	s.values[0] = v
+}

vendor/github.com/yuin/goldmark/util/util.go

@@ -0,0 +1,980 @@
+// Package util provides utility functions for the goldmark.
+package util
+
+import (
+	"bytes"
+	"io"
+	"net/url"
+	"regexp"
+	"sort"
+	"strconv"
+	"unicode"
+	"unicode/utf8"
+)
+
+// A CopyOnWriteBuffer is a byte buffer that copies buffer when
+// it need to be changed.
+type CopyOnWriteBuffer struct {
+	buffer []byte
+	copied bool
+}
+
+// NewCopyOnWriteBuffer returns a new CopyOnWriteBuffer.
+func NewCopyOnWriteBuffer(buffer []byte) CopyOnWriteBuffer {
+	return CopyOnWriteBuffer{
+		buffer: buffer,
+		copied: false,
+	}
+}
+
+// Write writes given bytes to the buffer.
+// Write allocate new buffer and clears it at the first time.
+func (b *CopyOnWriteBuffer) Write(value []byte) {
+	if !b.copied {
+		b.buffer = make([]byte, 0, len(b.buffer)+20)
+		b.copied = true
+	}
+	b.buffer = append(b.buffer, value...)
+}
+
+// Append appends given bytes to the buffer.
+// Append copy buffer at the first time.
+func (b *CopyOnWriteBuffer) Append(value []byte) {
+	if !b.copied {
+		tmp := make([]byte, len(b.buffer), len(b.buffer)+20)
+		copy(tmp, b.buffer)
+		b.buffer = tmp
+		b.copied = true
+	}
+	b.buffer = append(b.buffer, value...)
+}
+
+// WriteByte writes the given byte to the buffer.
+// WriteByte allocate new buffer and clears it at the first time.
+func (b *CopyOnWriteBuffer) WriteByte(c byte) {
+	if !b.copied {
+		b.buffer = make([]byte, 0, len(b.buffer)+20)
+		b.copied = true
+	}
+	b.buffer = append(b.buffer, c)
+}
+
+// AppendByte appends given bytes to the buffer.
+// AppendByte copy buffer at the first time.
+func (b *CopyOnWriteBuffer) AppendByte(c byte) {
+	if !b.copied {
+		tmp := make([]byte, len(b.buffer), len(b.buffer)+20)
+		copy(tmp, b.buffer)
+		b.buffer = tmp
+		b.copied = true
+	}
+	b.buffer = append(b.buffer, c)
+}
+
+// Bytes returns bytes of this buffer.
+func (b *CopyOnWriteBuffer) Bytes() []byte {
+	return b.buffer
+}
+
+// IsCopied returns true if buffer has been copied, otherwise false.
+func (b *CopyOnWriteBuffer) IsCopied() bool {
+	return b.copied
+}
+
+// IsEscapedPunctuation returns true if character at a given index i
+// is an escaped punctuation, otherwise false.
+func IsEscapedPunctuation(source []byte, i int) bool {
+	return source[i] == '\\' && i < len(source)-1 && IsPunct(source[i+1])
+}
+
+// ReadWhile read the given source while pred is true.
+func ReadWhile(source []byte, index [2]int, pred func(byte) bool) (int, bool) {
+	j := index[0]
+	ok := false
+	for ; j < index[1]; j++ {
+		c1 := source[j]
+		if pred(c1) {
+			ok = true
+			continue
+		}
+		break
+	}
+	return j, ok
+}
+
+// IsBlank returns true if the given string is all space characters.
+func IsBlank(bs []byte) bool {
+	for _, b := range bs {
+		if !IsSpace(b) {
+			return false
+		}
+	}
+	return true
+}
+
+// VisualizeSpaces visualize invisible space characters.
+func VisualizeSpaces(bs []byte) []byte {
+	bs = bytes.Replace(bs, []byte(" "), []byte("[SPACE]"), -1)
+	bs = bytes.Replace(bs, []byte("\t"), []byte("[TAB]"), -1)
+	bs = bytes.Replace(bs, []byte("\n"), []byte("[NEWLINE]\n"), -1)
+	bs = bytes.Replace(bs, []byte("\r"), []byte("[CR]"), -1)
+	return bs
+}
+
+// TabWidth calculates actual width of a tab at the given position.
+func TabWidth(currentPos int) int {
+	return 4 - currentPos%4
+}
+
+// IndentPosition searches an indent position with the given width for the given line.
+// If the line contains tab characters, paddings may be not zero.
+// currentPos==0 and width==2:
+//
+//     position: 0    1
+//               [TAB]aaaa
+//     width:    1234 5678
+//
+// width=2 is in the tab character. In this case, IndentPosition returns
+// (pos=1, padding=2)
+func IndentPosition(bs []byte, currentPos, width int) (pos, padding int) {
+	if width == 0 {
+		return 0, 0
+	}
+	w := 0
+	l := len(bs)
+	i := 0
+	hasTab := false
+	for ; i < l; i++ {
+		if bs[i] == '\t' {
+			w += TabWidth(currentPos + w)
+			hasTab = true
+		} else if bs[i] == ' ' {
+			w++
+		} else {
+			break
+		}
+	}
+	if w >= width {
+		if !hasTab {
+			return width, 0
+		}
+		return i, w - width
+	}
+	return -1, -1
+}
+
+// IndentPositionPadding searches an indent position with the given width for the given line.
+// This function is mostly same as IndentPosition except this function
+// takes account into additional paddings.
+func IndentPositionPadding(bs []byte, currentPos, paddingv, width int) (pos, padding int) {
+	if width == 0 {
+		return 0, paddingv
+	}
+	w := 0
+	i := 0
+	l := len(bs)
+	for ; i < l; i++ {
+		if bs[i] == '\t' {
+			w += TabWidth(currentPos + w)
+		} else if bs[i] == ' ' {
+			w++
+		} else {
+			break
+		}
+	}
+	if w >= width {
+		return i - paddingv, w - width
+	}
+	return -1, -1
+}
+
+// DedentPosition dedents lines by the given width.
+func DedentPosition(bs []byte, currentPos, width int) (pos, padding int) {
+	if width == 0 {
+		return 0, 0
+	}
+	w := 0
+	l := len(bs)
+	i := 0
+	for ; i < l; i++ {
+		if bs[i] == '\t' {
+			w += TabWidth(currentPos + w)
+		} else if bs[i] == ' ' {
+			w++
+		} else {
+			break
+		}
+	}
+	if w >= width {
+		return i, w - width
+	}
+	return i, 0
+}
+
+// DedentPositionPadding dedents lines by the given width.
+// This function is mostly same as DedentPosition except this function
+// takes account into additional paddings.
+func DedentPositionPadding(bs []byte, currentPos, paddingv, width int) (pos, padding int) {
+	if width == 0 {
+		return 0, paddingv
+	}
+
+	w := 0
+	i := 0
+	l := len(bs)
+	for ; i < l; i++ {
+		if bs[i] == '\t' {
+			w += TabWidth(currentPos + w)
+		} else if bs[i] == ' ' {
+			w++
+		} else {
+			break
+		}
+	}
+	if w >= width {
+		return i - paddingv, w - width
+	}
+	return i - paddingv, 0
+}
+
+// IndentWidth calculate an indent width for the given line.
+func IndentWidth(bs []byte, currentPos int) (width, pos int) {
+	l := len(bs)
+	for i := 0; i < l; i++ {
+		b := bs[i]
+		if b == ' ' {
+			width++
+			pos++
+		} else if b == '\t' {
+			width += TabWidth(currentPos + width)
+			pos++
+		} else {
+			break
+		}
+	}
+	return
+}
+
+// FirstNonSpacePosition returns a position line that is a first nonspace
+// character.
+func FirstNonSpacePosition(bs []byte) int {
+	i := 0
+	for ; i < len(bs); i++ {
+		c := bs[i]
+		if c == ' ' || c == '\t' {
+			continue
+		}
+		if c == '\n' {
+			return -1
+		}
+		return i
+	}
+	return -1
+}
+
+// FindClosure returns a position that closes the given opener.
+// If codeSpan is set true, it ignores characters in code spans.
+// If allowNesting is set true, closures correspond to nested opener will be
+// ignored.
+func FindClosure(bs []byte, opener, closure byte, codeSpan, allowNesting bool) int {
+	i := 0
+	opened := 1
+	codeSpanOpener := 0
+	for i < len(bs) {
+		c := bs[i]
+		if codeSpan && codeSpanOpener != 0 && c == '`' {
+			codeSpanCloser := 0
+			for ; i < len(bs); i++ {
+				if bs[i] == '`' {
+					codeSpanCloser++
+				} else {
+					i--
+					break
+				}
+			}
+			if codeSpanCloser == codeSpanOpener {
+				codeSpanOpener = 0
+			}
+		} else if codeSpanOpener == 0 && c == '\\' && i < len(bs)-1 && IsPunct(bs[i+1]) {
+			i += 2
+			continue
+		} else if codeSpan && codeSpanOpener == 0 && c == '`' {
+			for ; i < len(bs); i++ {
+				if bs[i] == '`' {
+					codeSpanOpener++
+				} else {
+					i--
+					break
+				}
+			}
+		} else if (codeSpan && codeSpanOpener == 0) || !codeSpan {
+			if c == closure {
+				opened--
+				if opened == 0 {
+					return i
+				}
+			} else if c == opener {
+				if !allowNesting {
+					return -1
+				}
+				opened++
+			}
+		}
+		i++
+	}
+	return -1
+}
+
+// TrimLeft trims characters in the given s from head of the source.
+// bytes.TrimLeft offers same functionalities, but bytes.TrimLeft
+// allocates new buffer for the result.
+func TrimLeft(source, b []byte) []byte {
+	i := 0
+	for ; i < len(source); i++ {
+		c := source[i]
+		found := false
+		for j := 0; j < len(b); j++ {
+			if c == b[j] {
+				found = true
+				break
+			}
+		}
+		if !found {
+			break
+		}
+	}
+	return source[i:]
+}
+
+// TrimRight trims characters in the given s from tail of the source.
+func TrimRight(source, b []byte) []byte {
+	i := len(source) - 1
+	for ; i >= 0; i-- {
+		c := source[i]
+		found := false
+		for j := 0; j < len(b); j++ {
+			if c == b[j] {
+				found = true
+				break
+			}
+		}
+		if !found {
+			break
+		}
+	}
+	return source[:i+1]
+}
+
+// TrimLeftLength returns a length of leading specified characters.
+func TrimLeftLength(source, s []byte) int {
+	return len(source) - len(TrimLeft(source, s))
+}
+
+// TrimRightLength returns a length of trailing specified characters.
+func TrimRightLength(source, s []byte) int {
+	return len(source) - len(TrimRight(source, s))
+}
+
+// TrimLeftSpaceLength returns a length of leading space characters.
+func TrimLeftSpaceLength(source []byte) int {
+	i := 0
+	for ; i < len(source); i++ {
+		if !IsSpace(source[i]) {
+			break
+		}
+	}
+	return i
+}
+
+// TrimRightSpaceLength returns a length of trailing space characters.
+func TrimRightSpaceLength(source []byte) int {
+	l := len(source)
+	i := l - 1
+	for ; i >= 0; i-- {
+		if !IsSpace(source[i]) {
+			break
+		}
+	}
+	if i < 0 {
+		return l
+	}
+	return l - 1 - i
+}
+
+// TrimLeftSpace returns a subslice of the given string by slicing off all leading
+// space characters.
+func TrimLeftSpace(source []byte) []byte {
+	return TrimLeft(source, spaces)
+}
+
+// TrimRightSpace returns a subslice of the given string by slicing off all trailing
+// space characters.
+func TrimRightSpace(source []byte) []byte {
+	return TrimRight(source, spaces)
+}
+
+// DoFullUnicodeCaseFolding performs full unicode case folding to given bytes.
+func DoFullUnicodeCaseFolding(v []byte) []byte {
+	var rbuf []byte
+	cob := NewCopyOnWriteBuffer(v)
+	n := 0
+	for i := 0; i < len(v); i++ {
+		c := v[i]
+		if c < 0xb5 {
+			if c >= 0x41 && c <= 0x5a {
+				// A-Z to a-z
+				cob.Write(v[n:i])
+				cob.WriteByte(c + 32)
+				n = i + 1
+			}
+			continue
+		}
+
+		if !utf8.RuneStart(c) {
+			continue
+		}
+		r, length := utf8.DecodeRune(v[i:])
+		if r == utf8.RuneError {
+			continue
+		}
+		folded, ok := unicodeCaseFoldings[r]
+		if !ok {
+			continue
+		}
+
+		cob.Write(v[n:i])
+		if rbuf == nil {
+			rbuf = make([]byte, 4)
+		}
+		for _, f := range folded {
+			l := utf8.EncodeRune(rbuf, f)
+			cob.Write(rbuf[:l])
+		}
+		i += length - 1
+		n = i + 1
+	}
+	if cob.IsCopied() {
+		cob.Write(v[n:])
+	}
+	return cob.Bytes()
+}
+
+// ReplaceSpaces replaces sequence of spaces with the given repl.
+func ReplaceSpaces(source []byte, repl byte) []byte {
+	var ret []byte
+	start := -1
+	for i, c := range source {
+		iss := IsSpace(c)
+		if start < 0 && iss {
+			start = i
+			continue
+		} else if start >= 0 && iss {
+			continue
+		} else if start >= 0 {
+			if ret == nil {
+				ret = make([]byte, 0, len(source))
+				ret = append(ret, source[:start]...)
+			}
+			ret = append(ret, repl)
+			start = -1
+		}
+		if ret != nil {
+			ret = append(ret, c)
+		}
+	}
+	if start >= 0 && ret != nil {
+		ret = append(ret, repl)
+	}
+	if ret == nil {
+		return source
+	}
+	return ret
+}
+
+// ToRune decode given bytes start at pos and returns a rune.
+func ToRune(source []byte, pos int) rune {
+	i := pos
+	for ; i >= 0; i-- {
+		if utf8.RuneStart(source[i]) {
+			break
+		}
+	}
+	r, _ := utf8.DecodeRune(source[i:])
+	return r
+}
+
+// ToValidRune returns 0xFFFD if the given rune is invalid, otherwise v.
+func ToValidRune(v rune) rune {
+	if v == 0 || !utf8.ValidRune(v) {
+		return rune(0xFFFD)
+	}
+	return v
+}
+
+// ToLinkReference converts given bytes into a valid link reference string.
+// ToLinkReference performs unicode case folding, trims leading and trailing spaces,  converts into lower
+// case and replace spaces with a single space character.
+func ToLinkReference(v []byte) string {
+	v = TrimLeftSpace(v)
+	v = TrimRightSpace(v)
+	v = DoFullUnicodeCaseFolding(v)
+	return string(ReplaceSpaces(v, ' '))
+}
+
+var htmlEscapeTable = [256][]byte{nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, []byte("&quot;"), nil, nil, nil, []byte("&amp;"), nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, []byte("&lt;"), nil, []byte("&gt;"), nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil}
+
+// EscapeHTMLByte returns HTML escaped bytes if the given byte should be escaped,
+// otherwise nil.
+func EscapeHTMLByte(b byte) []byte {
+	return htmlEscapeTable[b]
+}
+
+// EscapeHTML escapes characters that should be escaped in HTML text.
+func EscapeHTML(v []byte) []byte {
+	cob := NewCopyOnWriteBuffer(v)
+	n := 0
+	for i := 0; i < len(v); i++ {
+		c := v[i]
+		escaped := htmlEscapeTable[c]
+		if escaped != nil {
+			cob.Write(v[n:i])
+			cob.Write(escaped)
+			n = i + 1
+		}
+	}
+	if cob.IsCopied() {
+		cob.Write(v[n:])
+	}
+	return cob.Bytes()
+}
+
+// UnescapePunctuations unescapes blackslash escaped punctuations.
+func UnescapePunctuations(source []byte) []byte {
+	cob := NewCopyOnWriteBuffer(source)
+	limit := len(source)
+	n := 0
+	for i := 0; i < limit; {
+		c := source[i]
+		if i < limit-1 && c == '\\' && IsPunct(source[i+1]) {
+			cob.Write(source[n:i])
+			cob.WriteByte(source[i+1])
+			i += 2
+			n = i
+			continue
+		}
+		i++
+	}
+	if cob.IsCopied() {
+		cob.Write(source[n:])
+	}
+	return cob.Bytes()
+}
+
+// ResolveNumericReferences resolve numeric references like '&#1234;" .
+func ResolveNumericReferences(source []byte) []byte {
+	cob := NewCopyOnWriteBuffer(source)
+	buf := make([]byte, 6, 6)
+	limit := len(source)
+	ok := false
+	n := 0
+	for i := 0; i < limit; i++ {
+		if source[i] == '&' {
+			pos := i
+			next := i + 1
+			if next < limit && source[next] == '#' {
+				nnext := next + 1
+				if nnext < limit {
+					nc := source[nnext]
+					// code point like #x22;
+					if nnext < limit && nc == 'x' || nc == 'X' {
+						start := nnext + 1
+						i, ok = ReadWhile(source, [2]int{start, limit}, IsHexDecimal)
+						if ok && i < limit && source[i] == ';' {
+							v, _ := strconv.ParseUint(BytesToReadOnlyString(source[start:i]), 16, 32)
+							cob.Write(source[n:pos])
+							n = i + 1
+							runeSize := utf8.EncodeRune(buf, ToValidRune(rune(v)))
+							cob.Write(buf[:runeSize])
+							continue
+						}
+						// code point like #1234;
+					} else if nc >= '0' && nc <= '9' {
+						start := nnext
+						i, ok = ReadWhile(source, [2]int{start, limit}, IsNumeric)
+						if ok && i < limit && i-start < 8 && source[i] == ';' {
+							v, _ := strconv.ParseUint(BytesToReadOnlyString(source[start:i]), 0, 32)
+							cob.Write(source[n:pos])
+							n = i + 1
+							runeSize := utf8.EncodeRune(buf, ToValidRune(rune(v)))
+							cob.Write(buf[:runeSize])
+							continue
+						}
+					}
+				}
+			}
+			i = next - 1
+		}
+	}
+	if cob.IsCopied() {
+		cob.Write(source[n:])
+	}
+	return cob.Bytes()
+}
+
+// ResolveEntityNames resolve entity references like '&ouml;" .
+func ResolveEntityNames(source []byte) []byte {
+	cob := NewCopyOnWriteBuffer(source)
+	limit := len(source)
+	ok := false
+	n := 0
+	for i := 0; i < limit; i++ {
+		if source[i] == '&' {
+			pos := i
+			next := i + 1
+			if !(next < limit && source[next] == '#') {
+				start := next
+				i, ok = ReadWhile(source, [2]int{start, limit}, IsAlphaNumeric)
+				if ok && i < limit && source[i] == ';' {
+					name := BytesToReadOnlyString(source[start:i])
+					entity, ok := LookUpHTML5EntityByName(name)
+					if ok {
+						cob.Write(source[n:pos])
+						n = i + 1
+						cob.Write(entity.Characters)
+						continue
+					}
+				}
+			}
+			i = next - 1
+		}
+	}
+	if cob.IsCopied() {
+		cob.Write(source[n:])
+	}
+	return cob.Bytes()
+}
+
+var htmlSpace = []byte("%20")
+
+// URLEscape escape the given URL.
+// If resolveReference is set true:
+//   1. unescape punctuations
+//   2. resolve numeric references
+//   3. resolve entity references
+//
+// URL encoded values (%xx) are kept as is.
+func URLEscape(v []byte, resolveReference bool) []byte {
+	if resolveReference {
+		v = UnescapePunctuations(v)
+		v = ResolveNumericReferences(v)
+		v = ResolveEntityNames(v)
+	}
+	cob := NewCopyOnWriteBuffer(v)
+	limit := len(v)
+	n := 0
+
+	for i := 0; i < limit; {
+		c := v[i]
+		if urlEscapeTable[c] == 1 {
+			i++
+			continue
+		}
+		if c == '%' && i+2 < limit && IsHexDecimal(v[i+1]) && IsHexDecimal(v[i+1]) {
+			i += 3
+			continue
+		}
+		u8len := utf8lenTable[c]
+		if u8len == 99 { // invalid utf8 leading byte, skip it
+			i++
+			continue
+		}
+		if c == ' ' {
+			cob.Write(v[n:i])
+			cob.Write(htmlSpace)
+			i++
+			n = i
+			continue
+		}
+		if int(u8len) >= len(v) {
+			u8len = int8(len(v) - 1)
+		}
+		if u8len == 0 {
+			i++
+			n = i
+			continue
+		}
+		cob.Write(v[n:i])
+		stop := i + int(u8len)
+		if stop > len(v) {
+			i++
+			n = i
+			continue
+		}
+		cob.Write(StringToReadOnlyBytes(url.QueryEscape(string(v[i:stop]))))
+		i += int(u8len)
+		n = i
+	}
+	if cob.IsCopied() && n < limit {
+		cob.Write(v[n:])
+	}
+	return cob.Bytes()
+}
+
+// FindURLIndex returns a stop index value if the given bytes seem an URL.
+// This function is equivalent to [A-Za-z][A-Za-z0-9.+-]{1,31}:[^<>\x00-\x20]* .
+func FindURLIndex(b []byte) int {
+	i := 0
+	if !(len(b) > 0 && urlTable[b[i]]&7 == 7) {
+		return -1
+	}
+	i++
+	for ; i < len(b); i++ {
+		c := b[i]
+		if urlTable[c]&4 != 4 {
+			break
+		}
+	}
+	if i == 1 || i > 33 || i >= len(b) {
+		return -1
+	}
+	if b[i] != ':' {
+		return -1
+	}
+	i++
+	for ; i < len(b); i++ {
+		c := b[i]
+		if urlTable[c]&1 != 1 {
+			break
+		}
+	}
+	return i
+}
+
+var emailDomainRegexp = regexp.MustCompile(`^[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*`)
+
+// FindEmailIndex returns a stop index value if the given bytes seem an email address.
+func FindEmailIndex(b []byte) int {
+	// TODO: eliminate regexps
+	i := 0
+	for ; i < len(b); i++ {
+		c := b[i]
+		if emailTable[c]&1 != 1 {
+			break
+		}
+	}
+	if i == 0 {
+		return -1
+	}
+	if i >= len(b) || b[i] != '@' {
+		return -1
+	}
+	i++
+	if i >= len(b) {
+		return -1
+	}
+	match := emailDomainRegexp.FindSubmatchIndex(b[i:])
+	if match == nil {
+		return -1
+	}
+	return i + match[1]
+}
+
+var spaces = []byte(" \t\n\x0b\x0c\x0d")
+
+var spaceTable = [256]int8{0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+var punctTable = [256]int8{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+// a-zA-Z0-9, ;/?:@&=+$,-_.!~*'()#
+var urlEscapeTable = [256]int8{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+var utf8lenTable = [256]int8{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 99, 99, 99, 99, 99, 99, 99, 99}
+
+var urlTable = [256]uint8{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 5, 5, 1, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 1, 1, 0, 1, 0, 1, 1, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 1, 1, 1, 1, 1, 1, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}
+
+var emailTable = [256]uint8{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+// UTF8Len returns a byte length of the utf-8 character.
+func UTF8Len(b byte) int8 {
+	return utf8lenTable[b]
+}
+
+// IsPunct returns true if the given character is a punctuation, otherwise false.
+func IsPunct(c byte) bool {
+	return punctTable[c] == 1
+}
+
+// IsPunct returns true if the given rune is a punctuation, otherwise false.
+func IsPunctRune(r rune) bool {
+	return int32(r) <= 256 && IsPunct(byte(r)) || unicode.IsPunct(r)
+}
+
+// IsSpace returns true if the given character is a space, otherwise false.
+func IsSpace(c byte) bool {
+	return spaceTable[c] == 1
+}
+
+// IsSpace returns true if the given rune is a space, otherwise false.
+func IsSpaceRune(r rune) bool {
+	return int32(r) <= 256 && IsSpace(byte(r)) || unicode.IsSpace(r)
+}
+
+// IsNumeric returns true if the given character is a numeric, otherwise false.
+func IsNumeric(c byte) bool {
+	return c >= '0' && c <= '9'
+}
+
+// IsHexDecimal returns true if the given character is a hexdecimal, otherwise false.
+func IsHexDecimal(c byte) bool {
+	return c >= '0' && c <= '9' || c >= 'a' && c <= 'f' || c >= 'A' && c <= 'F'
+}
+
+// IsAlphaNumeric returns true if the given character is a alphabet or a numeric, otherwise false.
+func IsAlphaNumeric(c byte) bool {
+	return c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9'
+}
+
+// A BufWriter is a subset of the bufio.Writer .
+type BufWriter interface {
+	io.Writer
+	Available() int
+	Buffered() int
+	Flush() error
+	WriteByte(c byte) error
+	WriteRune(r rune) (size int, err error)
+	WriteString(s string) (int, error)
+}
+
+// A PrioritizedValue struct holds pair of an arbitrary value and a priority.
+type PrioritizedValue struct {
+	// Value is an arbitrary value that you want to prioritize.
+	Value interface{}
+	// Priority is a priority of the value.
+	Priority int
+}
+
+// PrioritizedSlice is a slice of the PrioritizedValues
+type PrioritizedSlice []PrioritizedValue
+
+// Sort sorts the PrioritizedSlice in ascending order.
+func (s PrioritizedSlice) Sort() {
+	sort.Slice(s, func(i, j int) bool {
+		return s[i].Priority < s[j].Priority
+	})
+}
+
+// Remove removes the given value from this slice.
+func (s PrioritizedSlice) Remove(v interface{}) PrioritizedSlice {
+	i := 0
+	found := false
+	for ; i < len(s); i++ {
+		if s[i].Value == v {
+			found = true
+			break
+		}
+	}
+	if !found {
+		return s
+	}
+	return append(s[:i], s[i+1:]...)
+}
+
+// Prioritized returns a new PrioritizedValue.
+func Prioritized(v interface{}, priority int) PrioritizedValue {
+	return PrioritizedValue{v, priority}
+}
+
+func bytesHash(b []byte) uint64 {
+	var hash uint64 = 5381
+	for _, c := range b {
+		hash = ((hash << 5) + hash) + uint64(c)
+	}
+	return hash
+}
+
+// BytesFilter is a efficient data structure for checking whether bytes exist or not.
+// BytesFilter is thread-safe.
+type BytesFilter interface {
+	// Add adds given bytes to this set.
+	Add([]byte)
+
+	// Contains return true if this set contains given bytes, otherwise false.
+	Contains([]byte) bool
+
+	// Extend copies this filter and adds given bytes to new filter.
+	Extend(...[]byte) BytesFilter
+}
+
+type bytesFilter struct {
+	chars     [256]uint8
+	threshold int
+	slots     [][][]byte
+}
+
+// NewBytesFilter returns a new BytesFilter.
+func NewBytesFilter(elements ...[]byte) BytesFilter {
+	s := &bytesFilter{
+		threshold: 3,
+		slots:     make([][][]byte, 64),
+	}
+	for _, element := range elements {
+		s.Add(element)
+	}
+	return s
+}
+
+func (s *bytesFilter) Add(b []byte) {
+	l := len(b)
+	m := s.threshold
+	if l < s.threshold {
+		m = l
+	}
+	for i := 0; i < m; i++ {
+		s.chars[b[i]] |= 1 << uint8(i)
+	}
+	h := bytesHash(b) % uint64(len(s.slots))
+	slot := s.slots[h]
+	if slot == nil {
+		slot = [][]byte{}
+	}
+	s.slots[h] = append(slot, b)
+}
+
+func (s *bytesFilter) Extend(bs ...[]byte) BytesFilter {
+	newFilter := NewBytesFilter().(*bytesFilter)
+	newFilter.chars = s.chars
+	newFilter.threshold = s.threshold
+	for k, v := range s.slots {
+		newSlot := make([][]byte, len(v))
+		copy(newSlot, v)
+		newFilter.slots[k] = v
+	}
+	for _, b := range bs {
+		newFilter.Add(b)
+	}
+	return newFilter
+}
+
+func (s *bytesFilter) Contains(b []byte) bool {
+	l := len(b)
+	m := s.threshold
+	if l < s.threshold {
+		m = l
+	}
+	for i := 0; i < m; i++ {
+		if (s.chars[b[i]] & (1 << uint8(i))) == 0 {
+			return false
+		}
+	}
+	h := bytesHash(b) % uint64(len(s.slots))
+	slot := s.slots[h]
+	if slot == nil || len(slot) == 0 {
+		return false
+	}
+	for _, element := range slot {
+		if bytes.Equal(element, b) {
+			return true
+		}
+	}
+	return false
+}

vendor/github.com/yuin/goldmark/util/util_safe.go

@@ -0,0 +1,13 @@
+// +build appengine js
+
+package util
+
+// BytesToReadOnlyString returns a string converted from given bytes.
+func BytesToReadOnlyString(b []byte) string {
+	return string(b)
+}
+
+// StringToReadOnlyBytes returns bytes converted from given string.
+func StringToReadOnlyBytes(s string) []byte {
+	return []byte(s)
+}

vendor/github.com/yuin/goldmark/util/util_unsafe.go

@@ -0,0 +1,23 @@
+// +build !appengine,!js
+
+package util
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+// BytesToReadOnlyString returns a string converted from given bytes.
+func BytesToReadOnlyString(b []byte) string {
+	return *(*string)(unsafe.Pointer(&b))
+}
+
+// StringToReadOnlyBytes returns bytes converted from given string.
+func StringToReadOnlyBytes(s string) (bs []byte) {
+	sh := (*reflect.StringHeader)(unsafe.Pointer(&s))
+	bh := (*reflect.SliceHeader)(unsafe.Pointer(&bs))
+	bh.Data = sh.Data
+	bh.Cap = sh.Len
+	bh.Len = sh.Len
+	return
+}