Restore compatibility with the legacy GitHub callout syntax

Although GitHub removed support for the legacy callout syntax, we don't
have to! Restore this support via another AST transformer.

Signed-off-by: Gergely Nagy <forgejo@gergo.csillger.hu>
This commit is contained in:
Gergely Nagy 2024-02-17 17:36:36 +01:00
parent a177a5c4cb
commit b594188623
No known key found for this signature in database
2 changed files with 61 additions and 0 deletions

View file

@ -0,0 +1,60 @@
// Copyright 2019 The Gitea Authors. All rights reserved.
// Copyright 2024 The Forgejo Authors c/o Codeberg e.V.. All rights reserved.
// SPDX-License-Identifier: MIT
package callout
import (
"strings"
"github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/parser"
"github.com/yuin/goldmark/text"
)
// Transformer for GitHub's legacy callout markup.
type GitHubLegacyCalloutTransformer struct{}
func (g *GitHubLegacyCalloutTransformer) Transform(node *ast.Document, reader text.Reader, pc parser.Context) {
supportedCalloutTypes := map[string]bool{"Note": true, "Warning": true}
_ = ast.Walk(node, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkContinue, nil
}
switch v := n.(type) {
case *ast.Blockquote:
// The first paragraph contains the callout type.
firstParagraph := v.FirstChild()
if firstParagraph.ChildCount() < 1 {
return ast.WalkContinue, nil
}
// In the legacy GitHub callout markup, the first node of the first
// paragraph should be an emphasis.
calloutNode, ok := firstParagraph.FirstChild().(*ast.Emphasis)
if !ok {
return ast.WalkContinue, nil
}
calloutText := string(calloutNode.Text(reader.Source()))
calloutType := strings.ToLower(calloutText)
// We only support "Note" and "Warning" callouts in legacy mode,
// match only those.
if _, has := supportedCalloutTypes[calloutText]; !has {
return ast.WalkContinue, nil
}
// Set the attention attribute on the emphasis
calloutNode.SetAttributeString("class", []byte("attention-"+calloutType))
// color the blockquote
v.SetAttributeString("class", []byte("gt-py-3 attention attention-"+calloutType))
// Prepend callout icon before the callout node itself
firstParagraph.InsertBefore(firstParagraph, calloutNode, NewAttention(calloutType))
}
return ast.WalkContinue, nil
})
}

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@ -125,6 +125,7 @@ func SpecializedMarkdown() goldmark.Markdown {
parser.WithAttribute(),
parser.WithAutoHeadingID(),
parser.WithASTTransformers(
util.Prioritized(&callout.GitHubLegacyCalloutTransformer{}, 8000),
util.Prioritized(&callout.GitHubCalloutTransformer{}, 9000),
util.Prioritized(&ASTTransformer{}, 10000),
),