134 lines
3.2 KiB
Go
134 lines
3.2 KiB
Go
// Copyright 2019 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package mdstripper
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import (
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"bytes"
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"sync"
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"io"
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"code.gitea.io/gitea/modules/log"
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"code.gitea.io/gitea/modules/markup/common"
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"github.com/yuin/goldmark"
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"github.com/yuin/goldmark/ast"
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"github.com/yuin/goldmark/extension"
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"github.com/yuin/goldmark/parser"
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"github.com/yuin/goldmark/renderer"
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"github.com/yuin/goldmark/renderer/html"
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"github.com/yuin/goldmark/text"
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)
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type stripRenderer struct {
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links []string
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empty bool
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}
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func (r *stripRenderer) Render(w io.Writer, source []byte, doc ast.Node) error {
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return 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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switch v := n.(type) {
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case *ast.Text:
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if !v.IsRaw() {
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_, prevSibIsText := n.PreviousSibling().(*ast.Text)
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coalesce := prevSibIsText
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r.processString(
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w,
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v.Text(source),
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coalesce)
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if v.SoftLineBreak() {
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r.doubleSpace(w)
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}
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}
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return ast.WalkContinue, nil
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case *ast.Link:
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r.processLink(w, v.Destination)
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return ast.WalkSkipChildren, nil
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case *ast.AutoLink:
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r.processLink(w, v.URL(source))
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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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}
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func (r *stripRenderer) doubleSpace(w io.Writer) {
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if !r.empty {
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_, _ = w.Write([]byte{'\n'})
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}
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}
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func (r *stripRenderer) processString(w io.Writer, text []byte, coalesce bool) {
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// Always break-up words
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if !coalesce {
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r.doubleSpace(w)
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}
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_, _ = w.Write(text)
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r.empty = false
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}
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func (r *stripRenderer) processLink(w io.Writer, link []byte) {
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// Links are processed out of band
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r.links = append(r.links, string(link))
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}
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// GetLinks returns the list of link data collected while parsing
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func (r *stripRenderer) GetLinks() []string {
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return r.links
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}
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// AddOptions adds given option to this renderer.
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func (r *stripRenderer) AddOptions(...renderer.Option) {
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// no-op
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}
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// StripMarkdown parses markdown content by removing all markup and code blocks
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// in order to extract links and other references
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func StripMarkdown(rawBytes []byte) (string, []string) {
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buf, links := StripMarkdownBytes(rawBytes)
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return string(buf), links
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}
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var stripParser parser.Parser
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var once = sync.Once{}
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// StripMarkdownBytes parses markdown content by removing all markup and code blocks
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// in order to extract links and other references
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func StripMarkdownBytes(rawBytes []byte) ([]byte, []string) {
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once.Do(func() {
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gdMarkdown := goldmark.New(
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goldmark.WithExtensions(extension.Table,
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extension.Strikethrough,
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extension.TaskList,
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extension.DefinitionList,
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common.FootnoteExtension,
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common.Linkify,
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),
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goldmark.WithParserOptions(
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parser.WithAttribute(),
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parser.WithAutoHeadingID(),
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),
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goldmark.WithRendererOptions(
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html.WithUnsafe(),
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),
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)
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stripParser = gdMarkdown.Parser()
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})
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stripper := &stripRenderer{
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links: make([]string, 0, 10),
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empty: true,
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}
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reader := text.NewReader(rawBytes)
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doc := stripParser.Parse(reader)
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var buf bytes.Buffer
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if err := stripper.Render(&buf, rawBytes, doc); err != nil {
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log.Error("Unable to strip: %v", err)
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}
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return buf.Bytes(), stripper.GetLinks()
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}
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