total-order/lex

/**
 * Generates a binary colexicographical comparator for ranges of arrays.
 *
 * https://en.wikipedia.org/wiki/Lexicographical_order#Colexicographic_order
 *
 * compare( a , b ) should always return
 *   - a negative value if a < b
 *   - a positive value if a > b
 *   - zero if a === b
 *
 */

export default function rangedcolexicographical(compare, begin, end) {
    /**
     * Compares the range [begin, end[ of 2 arrays a and b colexicographically.
     */

    return function (a, b) {
        for (let i = end; i-- > begin; ) {
            const d = compare(a[i], b[i]);

            if (d !== 0) return d;
        }

        return 0;
    };
}