forgejo/modules/markup/mdstripper/mdstripper.go

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// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package mdstripper
import (
"bytes"
"github.com/russross/blackfriday"
)
// MarkdownStripper extends blackfriday.Renderer
type MarkdownStripper struct {
blackfriday.Renderer
links []string
coallesce bool
}
const (
blackfridayExtensions = 0 |
blackfriday.EXTENSION_NO_INTRA_EMPHASIS |
blackfriday.EXTENSION_TABLES |
blackfriday.EXTENSION_FENCED_CODE |
blackfriday.EXTENSION_STRIKETHROUGH |
blackfriday.EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK |
blackfriday.EXTENSION_DEFINITION_LISTS |
blackfriday.EXTENSION_FOOTNOTES |
blackfriday.EXTENSION_HEADER_IDS |
blackfriday.EXTENSION_AUTO_HEADER_IDS |
// Not included in modules/markup/markdown/markdown.go;
// required here to process inline links
blackfriday.EXTENSION_AUTOLINK
)
//revive:disable:var-naming Implementing the Rendering interface requires breaking some linting rules
// StripMarkdown parses markdown content by removing all markup and code blocks
// in order to extract links and other references
func StripMarkdown(rawBytes []byte) (string, []string) {
stripper := &MarkdownStripper{
links: make([]string, 0, 10),
}
body := blackfriday.Markdown(rawBytes, stripper, blackfridayExtensions)
return string(body), stripper.GetLinks()
}
// StripMarkdownBytes parses markdown content by removing all markup and code blocks
// in order to extract links and other references
func StripMarkdownBytes(rawBytes []byte) ([]byte, []string) {
stripper := &MarkdownStripper{
links: make([]string, 0, 10),
}
body := blackfriday.Markdown(rawBytes, stripper, blackfridayExtensions)
return body, stripper.GetLinks()
}
// block-level callbacks
// BlockCode dummy function to proceed with rendering
func (r *MarkdownStripper) BlockCode(out *bytes.Buffer, text []byte, infoString string) {
// Not rendered
r.coallesce = false
}
// BlockQuote dummy function to proceed with rendering
func (r *MarkdownStripper) BlockQuote(out *bytes.Buffer, text []byte) {
// FIXME: perhaps it's better to leave out block quote for this?
r.processString(out, text, false)
}
// BlockHtml dummy function to proceed with rendering
func (r *MarkdownStripper) BlockHtml(out *bytes.Buffer, text []byte) { //nolint
// Not rendered
r.coallesce = false
}
// Header dummy function to proceed with rendering
func (r *MarkdownStripper) Header(out *bytes.Buffer, text func() bool, level int, id string) {
text()
r.coallesce = false
}
// HRule dummy function to proceed with rendering
func (r *MarkdownStripper) HRule(out *bytes.Buffer) {
// Not rendered
r.coallesce = false
}
// List dummy function to proceed with rendering
func (r *MarkdownStripper) List(out *bytes.Buffer, text func() bool, flags int) {
text()
r.coallesce = false
}
// ListItem dummy function to proceed with rendering
func (r *MarkdownStripper) ListItem(out *bytes.Buffer, text []byte, flags int) {
r.processString(out, text, false)
}
// Paragraph dummy function to proceed with rendering
func (r *MarkdownStripper) Paragraph(out *bytes.Buffer, text func() bool) {
text()
r.coallesce = false
}
// Table dummy function to proceed with rendering
func (r *MarkdownStripper) Table(out *bytes.Buffer, header []byte, body []byte, columnData []int) {
r.processString(out, header, false)
r.processString(out, body, false)
}
// TableRow dummy function to proceed with rendering
func (r *MarkdownStripper) TableRow(out *bytes.Buffer, text []byte) {
r.processString(out, text, false)
}
// TableHeaderCell dummy function to proceed with rendering
func (r *MarkdownStripper) TableHeaderCell(out *bytes.Buffer, text []byte, flags int) {
r.processString(out, text, false)
}
// TableCell dummy function to proceed with rendering
func (r *MarkdownStripper) TableCell(out *bytes.Buffer, text []byte, flags int) {
r.processString(out, text, false)
}
// Footnotes dummy function to proceed with rendering
func (r *MarkdownStripper) Footnotes(out *bytes.Buffer, text func() bool) {
text()
}
// FootnoteItem dummy function to proceed with rendering
func (r *MarkdownStripper) FootnoteItem(out *bytes.Buffer, name, text []byte, flags int) {
r.processString(out, text, false)
}
// TitleBlock dummy function to proceed with rendering
func (r *MarkdownStripper) TitleBlock(out *bytes.Buffer, text []byte) {
r.processString(out, text, false)
}
// Span-level callbacks
// AutoLink dummy function to proceed with rendering
func (r *MarkdownStripper) AutoLink(out *bytes.Buffer, link []byte, kind int) {
r.processLink(out, link, []byte{})
}
// CodeSpan dummy function to proceed with rendering
func (r *MarkdownStripper) CodeSpan(out *bytes.Buffer, text []byte) {
// Not rendered
r.coallesce = false
}
// DoubleEmphasis dummy function to proceed with rendering
func (r *MarkdownStripper) DoubleEmphasis(out *bytes.Buffer, text []byte) {
r.processString(out, text, false)
}
// Emphasis dummy function to proceed with rendering
func (r *MarkdownStripper) Emphasis(out *bytes.Buffer, text []byte) {
r.processString(out, text, false)
}
// Image dummy function to proceed with rendering
func (r *MarkdownStripper) Image(out *bytes.Buffer, link []byte, title []byte, alt []byte) {
// Not rendered
r.coallesce = false
}
// LineBreak dummy function to proceed with rendering
func (r *MarkdownStripper) LineBreak(out *bytes.Buffer) {
// Not rendered
r.coallesce = false
}
// Link dummy function to proceed with rendering
func (r *MarkdownStripper) Link(out *bytes.Buffer, link []byte, title []byte, content []byte) {
r.processLink(out, link, content)
}
// RawHtmlTag dummy function to proceed with rendering
func (r *MarkdownStripper) RawHtmlTag(out *bytes.Buffer, tag []byte) { //nolint
// Not rendered
r.coallesce = false
}
// TripleEmphasis dummy function to proceed with rendering
func (r *MarkdownStripper) TripleEmphasis(out *bytes.Buffer, text []byte) {
r.processString(out, text, false)
}
// StrikeThrough dummy function to proceed with rendering
func (r *MarkdownStripper) StrikeThrough(out *bytes.Buffer, text []byte) {
r.processString(out, text, false)
}
// FootnoteRef dummy function to proceed with rendering
func (r *MarkdownStripper) FootnoteRef(out *bytes.Buffer, ref []byte, id int) {
// Not rendered
r.coallesce = false
}
// Low-level callbacks
// Entity dummy function to proceed with rendering
func (r *MarkdownStripper) Entity(out *bytes.Buffer, entity []byte) {
// FIXME: literal entities are not parsed; perhaps they should
r.coallesce = false
}
// NormalText dummy function to proceed with rendering
func (r *MarkdownStripper) NormalText(out *bytes.Buffer, text []byte) {
r.processString(out, text, true)
}
// Header and footer
// DocumentHeader dummy function to proceed with rendering
func (r *MarkdownStripper) DocumentHeader(out *bytes.Buffer) {
r.coallesce = false
}
// DocumentFooter dummy function to proceed with rendering
func (r *MarkdownStripper) DocumentFooter(out *bytes.Buffer) {
r.coallesce = false
}
// GetFlags returns rendering flags
func (r *MarkdownStripper) GetFlags() int {
return 0
}
//revive:enable:var-naming
func doubleSpace(out *bytes.Buffer) {
if out.Len() > 0 {
out.WriteByte('\n')
}
}
func (r *MarkdownStripper) processString(out *bytes.Buffer, text []byte, coallesce bool) {
// Always break-up words
if !coallesce || !r.coallesce {
doubleSpace(out)
}
out.Write(text)
r.coallesce = coallesce
}
func (r *MarkdownStripper) processLink(out *bytes.Buffer, link []byte, content []byte) {
// Links are processed out of band
r.links = append(r.links, string(link))
r.coallesce = false
}
// GetLinks returns the list of link data collected while parsing
func (r *MarkdownStripper) GetLinks() []string {
return r.links
}