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/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),
+	))
+}