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https://codeberg.org/forgejo/forgejo.git
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88c2e24360
This PR adds mathematical rendering with KaTeX. The first step is to add a Goldmark extension that detects the latex (and tex) mathematics delimiters. The second step to make this extension only run if math support is enabled. The second step is to then add KaTeX CSS and JS to the head which will load after the dom is rendered. Fix #3445 Signed-off-by: Andrew Thornton <art27@cantab.net> Signed-off-by: Andrew Thornton <art27@cantab.net> Co-authored-by: silverwind <me@silverwind.io> Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
298 lines
7.7 KiB
Go
298 lines
7.7 KiB
Go
// Copyright 2014 The Gogs Authors. All rights reserved.
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// Copyright 2018 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 markdown
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import (
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"fmt"
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"io"
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"strings"
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"sync"
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"code.gitea.io/gitea/modules/log"
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"code.gitea.io/gitea/modules/markup"
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"code.gitea.io/gitea/modules/markup/common"
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"code.gitea.io/gitea/modules/markup/markdown/math"
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"code.gitea.io/gitea/modules/setting"
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giteautil "code.gitea.io/gitea/modules/util"
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chromahtml "github.com/alecthomas/chroma/formatters/html"
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"github.com/yuin/goldmark"
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highlighting "github.com/yuin/goldmark-highlighting"
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meta "github.com/yuin/goldmark-meta"
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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/util"
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)
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var (
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converter goldmark.Markdown
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once = sync.Once{}
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)
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var (
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urlPrefixKey = parser.NewContextKey()
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isWikiKey = parser.NewContextKey()
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renderMetasKey = parser.NewContextKey()
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renderContextKey = parser.NewContextKey()
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renderConfigKey = parser.NewContextKey()
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)
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type limitWriter struct {
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w io.Writer
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sum int64
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limit int64
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}
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// Write implements the standard Write interface:
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func (l *limitWriter) Write(data []byte) (int, error) {
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leftToWrite := l.limit - l.sum
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if leftToWrite < int64(len(data)) {
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n, err := l.w.Write(data[:leftToWrite])
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l.sum += int64(n)
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if err != nil {
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return n, err
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}
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return n, fmt.Errorf("Rendered content too large - truncating render")
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}
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n, err := l.w.Write(data)
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l.sum += int64(n)
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return n, err
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}
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// newParserContext creates a parser.Context with the render context set
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func newParserContext(ctx *markup.RenderContext) parser.Context {
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pc := parser.NewContext(parser.WithIDs(newPrefixedIDs()))
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pc.Set(urlPrefixKey, ctx.URLPrefix)
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pc.Set(isWikiKey, ctx.IsWiki)
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pc.Set(renderMetasKey, ctx.Metas)
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pc.Set(renderContextKey, ctx)
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return pc
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}
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// actualRender renders Markdown to HTML without handling special links.
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func actualRender(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
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once.Do(func() {
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converter = goldmark.New(
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goldmark.WithExtensions(
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extension.NewTable(
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extension.WithTableCellAlignMethod(extension.TableCellAlignAttribute)),
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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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highlighting.NewHighlighting(
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highlighting.WithFormatOptions(
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chromahtml.WithClasses(true),
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chromahtml.PreventSurroundingPre(true),
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),
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highlighting.WithWrapperRenderer(func(w util.BufWriter, c highlighting.CodeBlockContext, entering bool) {
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if entering {
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language, _ := c.Language()
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if language == nil {
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language = []byte("text")
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}
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languageStr := string(language)
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preClasses := []string{"code-block"}
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if languageStr == "mermaid" || languageStr == "math" {
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preClasses = append(preClasses, "is-loading")
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}
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_, err := w.WriteString(`<pre class="` + strings.Join(preClasses, " ") + `">`)
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if err != nil {
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return
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}
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// include language-x class as part of commonmark spec
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_, err = w.WriteString(`<code class="chroma language-` + string(language) + `">`)
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if err != nil {
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return
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}
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} else {
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_, err := w.WriteString("</code></pre>")
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if err != nil {
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return
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}
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}
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}),
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),
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math.NewExtension(
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math.Enabled(setting.Markdown.EnableMath),
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),
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meta.Meta,
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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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parser.WithASTTransformers(
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util.Prioritized(&ASTTransformer{}, 10000),
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),
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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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// Override the original Tasklist renderer!
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converter.Renderer().AddOptions(
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renderer.WithNodeRenderers(
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util.Prioritized(NewHTMLRenderer(), 10),
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),
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)
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})
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lw := &limitWriter{
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w: output,
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limit: setting.UI.MaxDisplayFileSize * 3,
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}
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// FIXME: should we include a timeout to abort the renderer if it takes too long?
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defer func() {
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err := recover()
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if err == nil {
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return
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}
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log.Warn("Unable to render markdown due to panic in goldmark: %v", err)
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if log.IsDebug() {
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log.Debug("Panic in markdown: %v\n%s", err, log.Stack(2))
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}
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}()
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// FIXME: Don't read all to memory, but goldmark doesn't support
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pc := newParserContext(ctx)
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buf, err := io.ReadAll(input)
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if err != nil {
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log.Error("Unable to ReadAll: %v", err)
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return err
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}
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buf = giteautil.NormalizeEOL(buf)
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rc := &RenderConfig{
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Meta: "table",
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Icon: "table",
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Lang: "",
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}
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buf, _ = ExtractMetadataBytes(buf, rc)
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pc.Set(renderConfigKey, rc)
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if err := converter.Convert(buf, lw, parser.WithContext(pc)); err != nil {
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log.Error("Unable to render: %v", err)
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return err
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}
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return nil
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}
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// Note: The output of this method must get sanitized.
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func render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
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defer func() {
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err := recover()
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if err == nil {
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return
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}
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log.Warn("Unable to render markdown due to panic in goldmark - will return raw bytes")
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if log.IsDebug() {
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log.Debug("Panic in markdown: %v\n%s", err, log.Stack(2))
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}
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_, err = io.Copy(output, input)
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if err != nil {
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log.Error("io.Copy failed: %v", err)
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}
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}()
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return actualRender(ctx, input, output)
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}
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// MarkupName describes markup's name
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var MarkupName = "markdown"
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func init() {
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markup.RegisterRenderer(Renderer{})
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}
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// Renderer implements markup.Renderer
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type Renderer struct{}
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var _ markup.PostProcessRenderer = (*Renderer)(nil)
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// Name implements markup.Renderer
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func (Renderer) Name() string {
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return MarkupName
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}
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// NeedPostProcess implements markup.PostProcessRenderer
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func (Renderer) NeedPostProcess() bool { return true }
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// Extensions implements markup.Renderer
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func (Renderer) Extensions() []string {
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return setting.Markdown.FileExtensions
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}
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// SanitizerRules implements markup.Renderer
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func (Renderer) SanitizerRules() []setting.MarkupSanitizerRule {
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return []setting.MarkupSanitizerRule{}
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}
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// Render implements markup.Renderer
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func (Renderer) Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
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return render(ctx, input, output)
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}
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// Render renders Markdown to HTML with all specific handling stuff.
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func Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
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if ctx.Type == "" {
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ctx.Type = MarkupName
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}
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return markup.Render(ctx, input, output)
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}
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// RenderString renders Markdown string to HTML with all specific handling stuff and return string
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func RenderString(ctx *markup.RenderContext, content string) (string, error) {
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var buf strings.Builder
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if err := Render(ctx, strings.NewReader(content), &buf); err != nil {
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return "", err
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}
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return buf.String(), nil
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}
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// RenderRaw renders Markdown to HTML without handling special links.
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func RenderRaw(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
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rd, wr := io.Pipe()
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defer func() {
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_ = rd.Close()
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_ = wr.Close()
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}()
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go func() {
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if err := render(ctx, input, wr); err != nil {
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_ = wr.CloseWithError(err)
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return
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}
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_ = wr.Close()
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}()
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return markup.SanitizeReader(rd, "", output)
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}
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// RenderRawString renders Markdown to HTML without handling special links and return string
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func RenderRawString(ctx *markup.RenderContext, content string) (string, error) {
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var buf strings.Builder
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if err := RenderRaw(ctx, strings.NewReader(content), &buf); err != nil {
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return "", err
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}
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return buf.String(), nil
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}
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// IsMarkdownFile reports whether name looks like a Markdown file
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// based on its extension.
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func IsMarkdownFile(name string) bool {
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return markup.IsMarkupFile(name, MarkupName)
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}
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