@extra-array/search-subsequence/index.js

Finds first index of a subsequence.

'use strict';
function id(v) {
    return v;
}
function cmp(a, b) {
    return a < b ? -1 : (a > b ? 1 : 0);
}
function searchSubsequence(x, y, fc = null, fm = null) {
    var fc = fc || cmp, fm = fm || id;
    var y1 = [...y].map(fm), Y = y1.length;
    var a = -1, i = -1, j = 0;
    for (var u of x) {
        var u1 = fm(u, ++i, x);
        if (fc(u1, y1[j]) !== 0)
            continue;
        if (a < 0)
            a = i;
        if (++j >= Y)
            return a;
    }
    return -1;
}
module.exports = searchSubsequence;