edit-distance/myers-1986

import assert from 'assert';

import StackEntry from './StackEntry.js';
import recurseDeeperStep from './recurseDeeperStep.js';

export default class RecurseDeeper {
    /**
     *
     * @param {Int8Array|Int16Array|Int32Array} B
     * @param {StackEntry[]} stack
     * @param {Function} eq
     */
    constructor(B, stack, eq) {
        this.B = B;
        this._stack = stack;
        this._eq = eq;
    }

    [Symbol.iterator]() {
        return this;
    }

    /**
     * @return {IteratorResult<number[]>}
     */
    next() {
        if (this._stack.length === 0) return {done: true, value: undefined};
        assert(this._stack.at(-1) instanceof StackEntry);
        return {
            done: false,
            value: recurseDeeperStep(this.B, this._stack, this._eq),
        };
    }
}