Add footnote exteision

README.md

@@ -116,7 +116,9 @@ Parser and Renderer options
   - This extension enables Table, Strikethrough, Linkify and TaskList.
     In addition, this extension sets some tags to `parser.FilterTags` .
 - `extension.DefinitionList`
-  - [PHP Markdown Extra Definition: lists](https://michelf.ca/projects/php-markdown/extra/#def-list)
+  - [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)
 
 Create extensions
 --------------------

extension/ast/footnote.go

@@ -0,0 +1,87 @@
+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 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) {
+	gast.DumpHelper(n, source, level, nil, 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,
+	}
+}
+
+// A FootnoteList struct represents footnotes of Markdown
+// (PHP Markdown Extra) text.
+type FootnoteList struct {
+	gast.BaseBlock
+}
+
+// Dump implements Node.Dump.
+func (n *FootnoteList) Dump(source []byte, level int) {
+	gast.DumpHelper(n, source, level, nil, 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{}
+}

extension/footnote.go

@@ -0,0 +1,284 @@
+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) Open(parent gast.Node, reader text.Reader, pc parser.Context) (gast.Node, parser.State) {
+	line, segment := reader.PeekLine()
+	pos := pc.BlockOffset()
+	if line[pos] != '[' {
+		return nil, parser.NoChildren
+	}
+	pos++
+	if pos > len(line)-1 || line[pos] != '^' {
+		return nil, parser.NoChildren
+	}
+	open := pos + 1
+	closes := -1
+	closure := util.FindClosure(line[pos+1:], '[', ']', false, false)
+	if closure > -1 {
+		closes = pos + 1 + closure
+		next := closes + 1
+		if next >= len(line) || line[next] != ':' {
+			return nil, parser.NoChildren
+		}
+	} else {
+		return nil, parser.NoChildren
+	}
+	label := reader.Value(text.NewSegment(segment.Start+open, segment.Start+closes))
+	if util.IsBlank(label) {
+		return nil, parser.NoChildren
+	}
+	pos = pos + 2 + closes - open + 2
+	childpos, padding := util.IndentPosition(line[pos:], pos, 1)
+	reader.AdvanceAndSetPadding(pos+childpos, padding)
+	item := ast.NewFootnote(label)
+	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)
+		var root gast.Node
+		for n := node; n != nil; n = n.Parent() {
+			root = n
+		}
+		root.AppendChild(root, list)
+	}
+	node.Parent().RemoveChild(node.Parent(), node)
+	n := node.(*ast.Footnote)
+	index := list.ChildCount() + 1
+	n.Index = index
+	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 {
+	return []byte{'['}
+}
+
+func (s *footnoteParser) Parse(parent gast.Node, block text.Reader, pc parser.Context) gast.Node {
+	line, segment := block.PeekLine()
+	pos := 1
+	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) {
+			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)
+		list.Parent().RemoveChild(list.Parent(), list)
+	} else {
+		return
+	}
+	pc.Set(footnoteListKey, nil)
+	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.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) 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">`)
+		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 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().AddOption(
+		parser.WithBlockParsers(
+			util.Prioritized(NewFootnoteBlockParser(), 999),
+		),
+	)
+	m.Parser().AddOption(
+		parser.WithInlineParsers(
+			util.Prioritized(NewFootnoteParser(), 101),
+		),
+	)
+	m.Parser().AddOption(
+		parser.WithASTTransformers(
+			util.Prioritized(NewFootnoteASTTransformer(), 999),
+		),
+	)
+	m.Renderer().AddOption(renderer.WithNodeRenderers(
+		util.Prioritized(NewFootnoteHTMLRenderer(), 500),
+	))
+}

parser/parser.go

@@ -686,7 +686,7 @@ func (p *parser) Parse(reader text.Reader, opts ...ParseOption) ast.Node {
 	for _, at := range p.astTransformers {
 		at.Transform(root, reader, pc)
 	}
-	//root.Dump(reader.Source(), 0)
+	root.Dump(reader.Source(), 0)
 	return root
 }