linguist-js
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Analyse the programming languages used in a folder or from raw content, using the same rules that GitHub Linguist does.
36 lines (35 loc) • 1.24 kB
JavaScript
/** Convert a PCRE regex into JS. */
export default function pcre(regex) {
let finalRegex = regex;
const replace = (search, replace) => finalRegex = finalRegex.replace(search, replace);
const finalFlags = new Set();
// Convert inline flag declarations
const inlineMatches = regex.matchAll(/\?(-)?([a-z]):/g);
const startMatches = regex.matchAll(/\(\?(-)?([a-z]+)\)/g);
for (const [match, isNegative, flags] of [...inlineMatches, ...startMatches]) {
replace(match, '');
const func = (flag) => isNegative ? finalFlags.delete(flag) : finalFlags.add(flag);
[...flags].forEach(func);
}
// Remove PCRE-only syntax
replace(/([*+]){2}/g, '$1');
replace(/\(\?>/g, '(?:');
// Remove start/end-of-file markers
if (/\\[AZ]/.test(finalRegex)) {
replace(/\\A/g, '^');
replace(/\\Z/g, '$');
finalFlags.delete('m');
}
else {
finalFlags.add('m');
}
// Reformat free-spacing mode
if (finalFlags.has('x')) {
finalFlags.delete('x');
replace(/#.+/g, '');
replace(/^\s+|\s+$|\n/gm, '');
replace(/\s+/g, ' ');
}
// Return final regex
return RegExp(finalRegex, [...finalFlags].join(''));
}