[lexical-markdown] Bug Fix: Replace regex-based format matching with …#8093
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etrepum merged 3 commits intofacebook:mainfrom Jan 27, 2026
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…CommonMark delimiter algorithm Previously, the outer format detection relied on regex patterns to find matched formats. However, regex cannot cover all Markdown specification edge cases. This change implements the CommonMark delimiter algorithm to properly handle emphasis parsing: 1. Scan text to build a delimiter stack with canOpen/canClose properties 2. Process delimiters to find matching pairs using flanking rules and the rule of 3 3. Return the outermost matched emphasis
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etrepum
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I didn't carefully review the algorithm, but this does seem like a positive change! Do you have any thoughts on this before going forward @AlessioGr?
AlessioGr
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Jan 25, 2026
packages/lexical-markdown/src/__tests__/unit/LexicalMarkdown.test.ts
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I think this is a good change! |
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Thank you! I've addressed the feedback in the latest commit. I also fixed the case with Previously, the delimiter stack included delimiters inside code spans, causing incorrect matching. Now, I exclude code span ranges from delimiter scanning to ensure correct behavior. |
etrepum
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ivailop7
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Description
Current Behavior
Currently, Markdown texts are converted into Lexical nodes using regex. In issue #8073, this approach fails to correctly identify nested or complex matching pairs.
For example, with the pattern
*text**text***, the opening tag*should find its corresponding closing tag. But since regex searches for an independently existing closing*, it cannot match correctly.Changes in This PR
To resolve these inconsistencies, I have implemented the CommonMark Delimiter Algorithm for processing emphasis and strong emphasis.
The algorithm proceeds as follows:
Additionally, this PR fixes the issue where formats inside code spans were incorrectly processed. However, there are still some remaining issues. inline elements other than code spans (e.g., links, raw HTML) are handled by text match transformers, making them difficult to address with the current implementation. A new conversion approach may be needed to fully resolve these cases.
As a result, all tests pass. One previously incorrect test was fixed, and 5 new test cases were added.
Closes #8073
Test plan
Before
before.mov
After
after.mov