chore: removes the tj/front dependency

Removes the `tj/front` dependency due to licensing concerns. See #490.

internal/frontmatter/frontmatter.go

@@ -0,0 +1,34 @@
+package frontmatter
+
+import (
+	"strings"
+
+	"gopkg.in/yaml.v1"
+)
+
+// Frontmatter encapsulates cheatsheet frontmatter data
+type Frontmatter struct {
+	Tags   []string
+	Syntax string
+}
+
+// Parse parses cheatsheet frontmatter
+func Parse(markdown string) (string, Frontmatter, error) {
+
+	// specify the frontmatter delimiter
+	delim := "---"
+
+	// initialize a frontmatter struct
+	var fm Frontmatter
+
+	// if the markdown does not contain frontmatter, pass it through unmodified
+	if !strings.HasPrefix(markdown, delim) {
+		return strings.TrimSpace(markdown), fm, nil
+	}
+
+	// otherwise, split the frontmatter and cheatsheet text
+	parts := strings.SplitN(markdown, delim, 3)
+	err := yaml.Unmarshal([]byte(parts[1]), &fm)
+
+	return strings.TrimSpace(parts[2]), fm, err
+}

internal/frontmatter/frontmatter_test.go

@@ -0,0 +1,71 @@
+package frontmatter
+
+import (
+	"testing"
+)
+
+// TestHasFrontmatter asserts that markdown is properly parsed when it contains
+// frontmatter
+func TestHasFrontmatter(t *testing.T) {
+
+	// stub our cheatsheet content
+	markdown := `---
+syntax: go
+tags: [ test ]
+---
+To foo the bar: baz`
+
+	// parse the frontmatter
+	text, fm, err := Parse(markdown)
+
+	// assert expectations
+	if err != nil {
+		t.Errorf("failed to parse markdown: %v", err)
+	}
+
+	want := "To foo the bar: baz"
+	if text != want {
+		t.Errorf("failed to parse text: want: %s, got: %s", want, text)
+	}
+
+	want = "go"
+	if fm.Syntax != want {
+		t.Errorf("failed to parse syntax: want: %s, got: %s", want, fm.Syntax)
+	}
+
+	want = "test"
+	if fm.Tags[0] != want {
+		t.Errorf("failed to parse tags: want: %s, got: %s", want, fm.Tags[0])
+	}
+	if len(fm.Tags) != 1 {
+		t.Errorf("failed to parse tags: want: len 0, got: len %d", len(fm.Tags))
+	}
+}
+
+// TestHasFrontmatter asserts that markdown is properly parsed when it does not
+// contain frontmatter
+func TestHasNoFrontmatter(t *testing.T) {
+
+	// stub our cheatsheet content
+	markdown := "To foo the bar: baz"
+
+	// parse the frontmatter
+	text, fm, err := Parse(markdown)
+
+	// assert expectations
+	if err != nil {
+		t.Errorf("failed to parse markdown: %v", err)
+	}
+
+	if text != markdown {
+		t.Errorf("failed to parse text: want: %s, got: %s", markdown, text)
+	}
+
+	if fm.Syntax != "" {
+		t.Errorf("failed to parse syntax: want: '', got: %s", fm.Syntax)
+	}
+
+	if len(fm.Tags) != 0 {
+		t.Errorf("failed to parse tags: want: len 0, got: len %d", len(fm.Tags))
+	}
+}