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forgejo/modules/markup/markdown/callout/github_legacy.go
Gergely Nagy b594188623
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>
2024-02-17 18:35:45 +01:00

60 lines
1.8 KiB
Go

// 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
})
}