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[codex] Cache list indentation regexes #3969

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[codex] Cache list indentation regexes #3969

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012f1de
Cache list indentation regexes
astelmach01 May 8, 2026
2cb28e9
Handle zero indent in cached regexes
astelmach01 May 9, 2026
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26 changes: 20 additions & 6 deletions src/rules.ts
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Original file line number Diff line number Diff line change
@@ -1,5 +1,19 @@
const noopTest = { exec: () => null } as unknown as RegExp;

function cachedIndentRegex(createRegex: (indent: number) => RegExp) {
const cache: RegExp[] = [];
return (indent: number) => {
const cappedIndent = Math.max(0, Math.min(3, indent - 1));
const cacheIndex = cappedIndent;
let regex = cache[cacheIndex];
if (!regex) {
regex = createRegex(cappedIndent);
cache[cacheIndex] = regex;
}
return regex;
Comment on lines +6 to +13
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@styfle styfle May 12, 2026

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Suggested change
const cappedIndent = Math.max(0, Math.min(3, indent - 1));
const cacheIndex = cappedIndent;
let regex = cache[cacheIndex];
if (!regex) {
regex = createRegex(cappedIndent);
cache[cacheIndex] = regex;
}
return regex;
const cacheIndex = Math.max(0, Math.min(3, indent - 1));
let regex = cache[cacheIndex];
if (!regex) {
regex = createRegex(cacheIndex);
cache[cacheIndex] = regex;
}
return regex;

Seems like you could eliminate one of these variables since the indent and index are the same value.

};
}

function edit(regex: string | RegExp, opt = '') {
let source = typeof regex === 'string' ? regex : regex.source;
const obj = {
Expand Down Expand Up @@ -78,12 +92,12 @@ export const other = {
notSpaceStart: /^\S*/,
endingNewline: /\n$/,
listItemRegex: (bull: string) => new RegExp(`^( {0,3}${bull})((?:[\t ][^\\n]*)?(?:\\n|$))`),
nextBulletRegex: (indent: number) => new RegExp(`^ {0,${Math.min(3, indent - 1)}}(?:[*+-]|\\d{1,9}[.)])((?:[ \t][^\\n]*)?(?:\\n|$))`),
hrRegex: (indent: number) => new RegExp(`^ {0,${Math.min(3, indent - 1)}}((?:- *){3,}|(?:_ *){3,}|(?:\\* *){3,})(?:\\n+|$)`),
fencesBeginRegex: (indent: number) => new RegExp(`^ {0,${Math.min(3, indent - 1)}}(?:\`\`\`|~~~)`),
headingBeginRegex: (indent: number) => new RegExp(`^ {0,${Math.min(3, indent - 1)}}#`),
htmlBeginRegex: (indent: number) => new RegExp(`^ {0,${Math.min(3, indent - 1)}}<(?:[a-z].*>|!--)`, 'i'),
blockquoteBeginRegex: (indent: number) => new RegExp(`^ {0,${Math.min(3, indent - 1)}}>`),
nextBulletRegex: cachedIndentRegex((indent: number) => new RegExp(`^ {0,${indent}}(?:[*+-]|\\d{1,9}[.)])((?:[ \t][^\\n]*)?(?:\\n|$))`)),
hrRegex: cachedIndentRegex((indent: number) => new RegExp(`^ {0,${indent}}((?:- *){3,}|(?:_ *){3,}|(?:\\* *){3,})(?:\\n+|$)`)),
fencesBeginRegex: cachedIndentRegex((indent: number) => new RegExp(`^ {0,${indent}}(?:\`\`\`|~~~)`)),
headingBeginRegex: cachedIndentRegex((indent: number) => new RegExp(`^ {0,${indent}}#`)),
htmlBeginRegex: cachedIndentRegex((indent: number) => new RegExp(`^ {0,${indent}}<(?:[a-z].*>|!--)`, 'i')),
blockquoteBeginRegex: cachedIndentRegex((indent: number) => new RegExp(`^ {0,${indent}}>`)),
};

/**
Expand Down
20 changes: 20 additions & 0 deletions test/unit/Lexer.test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,26 @@ function expectInlineTokens({ md, options, tokens, links = {} }) {
}

describe('Lexer', () => {
describe('rules', () => {
it('should create indentation regexes for zero indent', () => {
const {
nextBulletRegex,
hrRegex,
fencesBeginRegex,
headingBeginRegex,
htmlBeginRegex,
blockquoteBeginRegex,
} = new Lexer().tokenizer.rules.other;

assert.ok(nextBulletRegex(0).test('- item\n'));
assert.ok(hrRegex(0).test('---\n'));
assert.ok(fencesBeginRegex(0).test('```'));
assert.ok(headingBeginRegex(0).test('# heading'));
assert.ok(htmlBeginRegex(0).test('<div>'));
assert.ok(blockquoteBeginRegex(0).test('> quote'));
});
});

describe('paragraph', () => {
it('space between paragraphs', () => {
expectTokens({
Expand Down