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// Copyright 2019 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package goldmark
import (
"bytes"
"github.com/gohugoio/hugo/markup/tableofcontents"
"github.com/yuin/goldmark"
"github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/parser"
"github.com/yuin/goldmark/renderer"
"github.com/yuin/goldmark/text"
"github.com/yuin/goldmark/util"
)
var (
tocResultKey = parser.NewContextKey()
tocEnableKey = parser.NewContextKey()
)
type tocTransformer struct {
r renderer.Renderer
}
func (t *tocTransformer) Transform(n *ast.Document, reader text.Reader, pc parser.Context) {
if b, ok := pc.Get(tocEnableKey).(bool); !ok || !b {
return
}
var (
toc tableofcontents.Builder
tocHeading = &tableofcontents.Heading{}
level int
row = -1
inHeading bool
headingText bytes.Buffer
)
ast.Walk(n, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
s := ast.WalkStatus(ast.WalkContinue)
if n.Kind() == ast.KindHeading {
if inHeading && !entering {
tocHeading.Title = headingText.String()
headingText.Reset()
toc.AddAt(tocHeading, row, level-1)
tocHeading = &tableofcontents.Heading{}
inHeading = false
return s, nil
}
inHeading = true
}
if !(inHeading && entering) {
return s, nil
}
switch n.Kind() {
case ast.KindHeading:
heading := n.(*ast.Heading)
level = heading.Level
if level == 1 || row == -1 {
row++
}
id, found := heading.AttributeString("id")
if found {
tocHeading.ID = string(id.([]byte))
tocHeading.Level = level
}
case
ast.KindCodeSpan,
ast.KindLink,
ast.KindImage,
ast.KindEmphasis:
err := t.r.Render(&headingText, reader.Source(), n)
if err != nil {
return s, err
}
return ast.WalkSkipChildren, nil
case
ast.KindAutoLink,
ast.KindRawHTML,
ast.KindText,
ast.KindString:
err := t.r.Render(&headingText, reader.Source(), n)
if err != nil {
return s, err
}
}
return s, nil
})
pc.Set(tocResultKey, toc.Build())
}
type tocExtension struct {
options []renderer.Option
}
func newTocExtension(options []renderer.Option) goldmark.Extender {
return &tocExtension{
options: options,
}
}
func (e *tocExtension) Extend(m goldmark.Markdown) {
r := goldmark.DefaultRenderer()
r.AddOptions(e.options...)
m.Parser().AddOptions(parser.WithASTTransformers(util.Prioritized(&tocTransformer{
r: r,
}, 10)))
}
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