iteragain/dist/esm/internal/ProductIterator.js

Javascript Iterable/Iterator/Generator-function utilities.

import toArray from '../toArray';
/** Returns the cartesian product of the input `iterators`. */
export class ProductIterator {
    constructor(iterators, repeat) {
        this.done = false;
        this.pools = [];
        this.i = 0;
        const iterated = iterators.map(toArray);
        for (let i = 0; i < repeat; i++)
            this.pools.push(...iterated);
        this.indices = new Array(this.pools.length).fill(0);
    }
    [Symbol.iterator]() {
        return this;
    }
    next() {
        if (this.done)
            return { done: true, value: undefined };
        const value = this.indices.map((v, i) => this.pools[i][v]);
        for (this.i = 0; this.i < this.indices.length; this.i++) {
            if (this.indices[this.pools.length - this.i - 1] < this.pools[this.pools.length - this.i - 1].length - 1) {
                this.indices[this.pools.length - this.i - 1]++;
                break;
            }
        }
        if (this.i === this.indices.length) {
            this.done = true;
            return { done: false, value };
        }
        this.i--;
        while (this.i >= 0) {
            this.indices[this.pools.length - this.i - 1] = 0;
            this.i--;
        }
        return { done: false, value };
    }
}
export default ProductIterator;
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