string-searching/specification

import assert from 'assert';

import Hit from './Hit.js';
import StringSlice from './StringSlice.js';

/**
 * A brute-force string searching algorithm leveraging String#indexOf.
 *
 * @param {StringSlice} string
 * @param {Iterable<StringSlice>} patterns
 * @return {IterableIterator<Hit>}
 */
export default function* mock(string, patterns) {
    assert(string instanceof StringSlice);
    const s = string.s.slice(string.i, string.j);
    for (const pattern of patterns) {
        assert(pattern instanceof StringSlice);
        const p = pattern.s.slice(pattern.i, pattern.j);
        let fromIndex = 0;
        while (true) {
            const i = s.indexOf(p, fromIndex);
            if (i === -1) break;
            yield new Hit(string.i + i, pattern, pattern.i);
            if (fromIndex >= s.length) break;
            fromIndex = i + 1;
        }
    }
}