* perf: pre-compile KaTeX Unicode regex at module load time
The katexStart() function was creating a new RegExp with Unicode
property escapes (\p{Script=Han}, \p{Script=Hiragana}, etc.) on
every invocation. Unicode property escapes are extremely expensive
to compile as the regex engine must build character class tables
covering tens of thousands of code points.
Since marked calls the start() function at every character position
while scanning source text, this meant hundreds of regex compilations
per marked.lexer() call, and lexer runs ~60 times/sec during streaming.
Profiling showed KaTeX regex consuming 87% (320ms/365ms) of total
markdown rendering time.
Changes:
- Pre-compile SURROUNDING_CHARS_REGEX once at module load time
- Use .test() instead of .match() to avoid array allocations
- Fix delimiter search to find earliest match, not last match
* perf: replace katexStart with single-pass character scan
The katexStart() function was the dominant cost in marked's lexer,
consuming 55-58% of total markdown rendering time per profiling.
It was called at every character position by marked and each call:
- Looped through 3-5 delimiters, each doing indexOf() on the full
remaining source (3-5 x O(n) string scans per call)
- Ran the complex ruleReg regex with Unicode lookaheads for validation
- On failed validation, created substrings and looped again
Replace with a single linear character scan using charCodeAt that:
- Checks only for $ (charCode 36) or backslash (charCode 92)
- Filters backslash hits by next character to avoid false positives
- Preserves the surrounding-character validation
- Returns immediately on first valid candidate
- Lets the tokenizer handle full validation (it already does this)
This reduces start() from O(n * delimiters * retries) to O(n) with
a very small constant factor per call.
* Update katex-extension.ts
Fixes an issue where `ue.getWordAtDocPos is not a function` would be thrown in `MessageInput.svelte`.
The error was caused by a timing issue where the `getWordAtDocPos` method on the `RichTextInput` component was not available when called from an event handler within the same component.
This change refactors the code to pass the `getWordAtDocPos` function as a callback prop from `RichTextInput` to `MessageInput`, ensuring it's available when needed.
Timothy Jaeryang Baek