edit-distance/myers-1986

import assert from 'assert';

/**
 * LongestCommonPrefix.
 *
 * @param {Function} eq
 * @param {number} ai
 * @param {number} aj
 * @param {number} bi
 * @param {number} bj
 */
export default function longestCommonPrefix(eq, ai, aj, bi, bj) {
    assert(Number.isInteger(ai) && ai >= 0);
    assert(Number.isInteger(aj));
    assert(Number.isInteger(bi) && bi >= 0);
    assert(Number.isInteger(bj));
    // Assert(ai <= aj && bi <= bj); // Broken to avoid branchy hot-loops
    if (((aj - ai) | 0) <= ((bj - bi) | 0)) {
        while (ai < aj && eq(ai, bi)) {
            ai = (ai + 1) | 0;
            bi = (bi + 1) | 0;
        }
    } else {
        while (bi < bj && eq(ai, bi)) {
            ai = (ai + 1) | 0;
            bi = (bi + 1) | 0;
        }
    }

    return ai;
}