119 lines
3.4 KiB
Go
119 lines
3.4 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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"io"
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"github.com/russross/blackfriday/v2"
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)
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// MarkdownStripper extends blackfriday.Renderer
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type MarkdownStripper struct {
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links []string
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coallesce bool
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empty bool
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}
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const (
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blackfridayExtensions = 0 |
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blackfriday.NoIntraEmphasis |
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blackfriday.Tables |
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blackfriday.FencedCode |
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blackfriday.Strikethrough |
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blackfriday.NoEmptyLineBeforeBlock |
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blackfriday.DefinitionLists |
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blackfriday.Footnotes |
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blackfriday.HeadingIDs |
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blackfriday.AutoHeadingIDs |
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// Not included in modules/markup/markdown/markdown.go;
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// required here to process inline links
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blackfriday.Autolink
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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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// 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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stripper := &MarkdownStripper{
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links: make([]string, 0, 10),
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empty: true,
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}
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parser := blackfriday.New(blackfriday.WithRenderer(stripper), blackfriday.WithExtensions(blackfridayExtensions))
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ast := parser.Parse(rawBytes)
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var buf bytes.Buffer
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stripper.RenderHeader(&buf, ast)
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ast.Walk(func(node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
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return stripper.RenderNode(&buf, node, entering)
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})
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stripper.RenderFooter(&buf, ast)
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return buf.Bytes(), stripper.GetLinks()
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}
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// RenderNode is the main rendering method. It will be called once for
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// every leaf node and twice for every non-leaf node (first with
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// entering=true, then with entering=false). The method should write its
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// rendition of the node to the supplied writer w.
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func (r *MarkdownStripper) RenderNode(w io.Writer, node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
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if !entering {
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return blackfriday.GoToNext
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}
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switch node.Type {
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case blackfriday.Text:
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r.processString(w, node.Literal, node.Parent == nil)
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return blackfriday.GoToNext
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case blackfriday.Link:
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r.processLink(w, node.LinkData.Destination)
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r.coallesce = false
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return blackfriday.SkipChildren
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}
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r.coallesce = false
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return blackfriday.GoToNext
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}
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// RenderHeader is a method that allows the renderer to produce some
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// content preceding the main body of the output document.
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func (r *MarkdownStripper) RenderHeader(w io.Writer, ast *blackfriday.Node) {
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}
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// RenderFooter is a symmetric counterpart of RenderHeader.
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func (r *MarkdownStripper) RenderFooter(w io.Writer, ast *blackfriday.Node) {
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}
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func (r *MarkdownStripper) 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 *MarkdownStripper) processString(w io.Writer, text []byte, coallesce bool) {
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// Always break-up words
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if !coallesce || !r.coallesce {
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r.doubleSpace(w)
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}
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_, _ = w.Write(text)
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r.coallesce = coallesce
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r.empty = false
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}
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func (r *MarkdownStripper) 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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r.coallesce = false
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}
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// GetLinks returns the list of link data collected while parsing
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func (r *MarkdownStripper) GetLinks() []string {
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return r.links
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}
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