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(``)
}
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(` `)
}
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(`\n")
} else {
_, _ = w.WriteString("\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
\n")
} else {
_, _ = w.WriteString("\n
\n")
}
_, _ = w.WriteString("\n")
} else {
_, _ = w.WriteString("
\n")
_, _ = 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),
))
}