locutus/esm/tcl/string/map.js

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

function normalizeMapEntries(mappings) {
    if (Array.isArray(mappings)) {
        if (mappings.every((entry) => Array.isArray(entry) && entry.length === 2)) {
            return mappings.map((entry) => [String(entry[0]), String(entry[1])]);
        }
        const out = [];
        for (let i = 0; i + 1 < mappings.length; i += 2) {
            out.push([String(mappings[i]), String(mappings[i + 1])]);
        }
        return out;
    }
    return Object.entries(mappings).map(([key, value]) => [String(key), String(value)]);
}
export function map(mappings, str) {
    //      discuss at: https://locutus.io/tcl/map/
    // parity verified: Tcl 8.6
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Applies key/value replacements in left-to-right single-pass order like Tcl string map.
    //       example 1: map(['abc', 'X', 'a', 'Y'], 'abc abca')
    //       returns 1: 'X XY'
    //       example 2: map(['cat', 'dog', ' ', '_'], 'cat cat')
    //       returns 2: 'dog_dog'
    //       example 3: map(['ab', 'X', 'a', 'Y'], 'ababa')
    //       returns 3: 'XXY'
    const source = String(str);
    const entries = normalizeMapEntries(mappings).filter(([key]) => key.length > 0);
    if (entries.length === 0) {
        return source;
    }
    let out = '';
    let cursor = 0;
    while (cursor < source.length) {
        let matched = false;
        for (const [key, value] of entries) {
            if (source.startsWith(key, cursor)) {
                out += value;
                cursor += key.length;
                matched = true;
                break;
            }
        }
        if (!matched) {
            out += source[cursor];
            cursor += 1;
        }
    }
    return out;
}