From b594188623f2afd0bc61eb69fb3cc26b5c47859d Mon Sep 17 00:00:00 2001
From: Gergely Nagy <forgejo@gergo.csillger.hu>
Date: Sat, 17 Feb 2024 17:36:36 +0100
Subject: [PATCH] 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>
---
.../markup/markdown/callout/github_legacy.go | 60 +++++++++++++++++++
modules/markup/markdown/markdown.go | 1 +
2 files changed, 61 insertions(+)
create mode 100644 modules/markup/markdown/callout/github_legacy.go
diff --git a/modules/markup/markdown/callout/github_legacy.go b/modules/markup/markdown/callout/github_legacy.go
new file mode 100644
index 0000000000..add6b0a847
--- /dev/null
+++ b/modules/markup/markdown/callout/github_legacy.go
@@ -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
+ })
+}
diff --git a/modules/markup/markdown/markdown.go b/modules/markup/markdown/markdown.go
index 92c0e786e9..00d01a2f55 100644
--- a/modules/markup/markdown/markdown.go
+++ b/modules/markup/markdown/markdown.go
@@ -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),
),