Sergey Filkin
124 lines
2.8 KiB
Go
124 lines
2.8 KiB
Go
package converter
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import (
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"strings"
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"github.com/yuin/goldmark"
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emojiast "github.com/yuin/goldmark-emoji/ast"
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"github.com/yuin/goldmark/ast"
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"github.com/yuin/goldmark/parser"
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"github.com/yuin/goldmark/text"
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"github.com/yuin/goldmark/util"
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)
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type anchorExtension struct{}
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func (e *anchorExtension) Extend(m goldmark.Markdown) {
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m.Parser().AddOptions(parser.WithASTTransformers(
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util.Prioritized(&anchorTransformer{}, 900),
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))
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}
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type anchorTransformer struct{}
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func (t *anchorTransformer) Transform(doc *ast.Document, reader text.Reader, pc parser.Context) {
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src := reader.Source()
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used := map[string]int{}
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_ = pc
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_ = ast.Walk(doc, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
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if !entering {
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return ast.WalkContinue, nil
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}
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h, ok := n.(*ast.Heading)
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if !ok {
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return ast.WalkContinue, nil
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}
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slug := translitSlug(extractHeadingText(h, src), used)
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h.SetAttributeString("id", []byte(slug))
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link := ast.NewLink()
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link.Destination = []byte("#" + slug)
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link.SetAttributeString("class", []byte("heading-anchor"))
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link.SetAttributeString("aria-hidden", []byte("true"))
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link.AppendChild(link, ast.NewString([]byte("#")))
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if first := h.FirstChild(); first != nil {
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h.InsertBefore(h, first, link)
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} else {
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h.AppendChild(h, link)
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}
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return ast.WalkSkipChildren, nil
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})
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}
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func extractHeadingText(h *ast.Heading, src []byte) string {
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var b strings.Builder
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_ = ast.Walk(h, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
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if !entering {
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return ast.WalkContinue, nil
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}
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switch v := n.(type) {
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case *ast.Link:
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if isHeadingAnchor(v) {
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return ast.WalkSkipChildren, nil
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}
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case *ast.Text:
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b.Write(v.Segment.Value(src))
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if v.HardLineBreak() || v.SoftLineBreak() {
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b.WriteByte(' ')
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}
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case *ast.String:
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b.Write(v.Value)
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case *ast.CodeSpan:
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for child := v.FirstChild(); child != nil; child = child.NextSibling() {
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switch c := child.(type) {
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case *ast.Text:
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b.Write(c.Segment.Value(src))
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case *ast.String:
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b.Write(c.Value)
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}
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}
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return ast.WalkSkipChildren, nil
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case *ast.AutoLink:
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b.Write(v.Label(src))
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return ast.WalkSkipChildren, nil
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case *emojiast.Emoji:
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if v.Value != nil && len(v.Value.Unicode) > 0 {
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b.WriteString(string(v.Value.Unicode))
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} else if len(v.ShortName) > 0 {
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b.WriteByte(':')
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b.Write(v.ShortName)
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b.WriteByte(':')
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}
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return ast.WalkSkipChildren, nil
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}
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return ast.WalkContinue, nil
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})
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return strings.TrimSpace(b.String())
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}
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func isHeadingAnchor(link *ast.Link) bool {
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attr, ok := link.AttributeString("class")
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if !ok {
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return false
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}
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switch value := attr.(type) {
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case []byte:
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return string(value) == "heading-anchor"
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case string:
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return value == "heading-anchor"
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default:
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return false
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}
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}
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