locutus/esm/python/re/findall.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

const PY_RE_IGNORECASE = 2;
const PY_RE_MULTILINE = 8;
const PY_RE_DOTALL = 16;
export function findall(pattern, source, flags = 0) {
    //      discuss at: https://locutus.io/python/re/findall/
    // parity verified: Python 3.12
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Returns all regex matches, following Python re.findall capture-shape behavior.
    //          note 2: Supports a subset of numeric flags (IGNORECASE=2, MULTILINE=8, DOTALL=16).
    //       example 1: findall('\\d+', 'a1b22c333')
    //       returns 1: ['1', '22', '333']
    //       example 2: findall('(\\w+)-(\\d+)', 'x-1 y-20')
    //       returns 2: [['x', '1'], ['y', '20']]
    //       example 3: findall('abc', 'ABC abc', 2)
    //       returns 3: ['ABC', 'abc']
    const input = String(source);
    const regex = createGlobalRegex(pattern, flags);
    const out = [];
    regex.lastIndex = 0;
    while (true) {
        const match = regex.exec(input);
        if (!match) {
            break;
        }
        if (match.length <= 1) {
            out.push(match[0] ?? '');
        }
        else if (match.length === 2) {
            out.push(match[1] ?? '');
        }
        else {
            out.push(match.slice(1).map((value) => value ?? ''));
        }
        // Advance zero-width matches manually so the global scan always makes progress.
        if ((match[0] ?? '') === '') {
            if (regex.lastIndex >= input.length) {
                break;
            }
            regex.lastIndex += 1;
        }
    }
    return out;
}
function createGlobalRegex(pattern, flags) {
    const source = pattern instanceof RegExp ? pattern.source : String(pattern);
    const base = pattern instanceof RegExp ? pattern.flags : '';
    const extra = normalizeRegexFlags(flags);
    const combined = dedupeFlags((base + extra).replace(/g/g, '').replace(/y/g, ''));
    return new RegExp(source, `${combined}g`);
}
function normalizeRegexFlags(flags) {
    if (typeof flags === 'string') {
        return dedupeFlags(flags.replace(/[^dgimsuvy]/g, ''));
    }
    let out = '';
    if (flags & PY_RE_IGNORECASE) {
        out += 'i';
    }
    if (flags & PY_RE_MULTILINE) {
        out += 'm';
    }
    if (flags & PY_RE_DOTALL) {
        out += 's';
    }
    return out;
}
function dedupeFlags(flags) {
    const seen = new Set();
    let out = '';
    for (const flag of flags) {
        if (!seen.has(flag)) {
            seen.add(flag);
            out += flag;
        }
    }
    return out;
}