#6768 fix to avoid infinite markdown shortcut matchers run

[fantactuka]

Issue #6768 happens because of emoji markdown shortcut. It has conditional replacement which was not really supported for shortcuts:

lexical/packages/lexical-playground/src/plugins/MarkdownTransformers/index.ts

Lines 105 to 108 in 07ca5c8

	const emoji = emojiList.find((e) => e.aliases.includes(name))?.emoji;
	if (emoji) {
	textNode.replace($createTextNode(emoji));
	}

1. Quick option is to disable it from list of shortcut transformers:

lexical/packages/lexical-playground/src/plugins/MarkdownShortcutPlugin/index.tsx

Line 15 in 07ca5c8

return <MarkdownShortcutPlugin transformers={PLAYGROUND_TRANSFORMERS} />;

2. Another alternative would be to update emoji RegExp to match exact emoji names and instead of having :([a-Z0-9]): it'd be :(smile|sad|happy|...|joy):. The problem is that with current emoji-list that regex is 23kb long.

3. Enable conditional replacement (this PR). The reason it ran infinitely is because once we find match we call textNode.splitText(matchOffset) to extract text node that should be replaced:

lexical/packages/lexical-markdown/src/MarkdownShortcuts.ts

Lines 174 to 181 in 07ca5c8

	if (startIndex === 0) {
	[replaceNode] = anchorNode.splitText(endIndex);
	} else {
	[, replaceNode] = anchorNode.splitText(startIndex, endIndex);
	}
	replaceNode.selectNext(0, 0);
	transformer.replace(replaceNode, match);

Even if we don't replace anything, it still causes full update cycle which triggers another transformers run. One thing is whether we should even call update cycle for unused result of .splitText (cc @zurfyx) given split nodes will reconcile back to a single text node. But on top of it, we don't really need to run any shortcuts logic if selection itself hasn't changed as we only suppose to do it when user types (i.e. selection moves).

Another (more minor) issue was in emoji regex that should ensure we only attempt to run matcher against end of node's text

Test plan

Tests + sanity check

npm run test-e2e-chromium -- Markdown
✓ 52 passed (28.5s)

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Name	Status	Preview	Comments	Updated (UTC)
lexical	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Oct 30, 2024 3:34am
lexical-playground	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Oct 30, 2024 3:34am

[github-actions]

size-limit report 📦

Path	Size
lexical - cjs	29.94 KB (0%)
lexical - esm	29.78 KB (0%)
@lexical/rich-text - cjs	38.59 KB (0%)
@lexical/rich-text - esm	31.65 KB (0%)
@lexical/plain-text - cjs	37.25 KB (0%)
@lexical/plain-text - esm	28.94 KB (0%)
@lexical/react - cjs	40.32 KB (0%)
@lexical/react - esm	33.01 KB (0%)

[potatowagon]

thanks for the quick fix!

[potatowagon]

closes: #6768