iteragain/dist/es5/internal/PermutationsIterator.js

Javascript Iterable/Iterator/Generator-function utilities.

import RangeIterator from './RangeIterator';
import toArray from '../toArray';
/** Returns all successive `size` length permutations of the input `iterator`. */
var PermutationsIterator = /** @class */ (function () {
    function PermutationsIterator(iterator, size) {
        this.started = false;
        this.pool = toArray(iterator);
        this.size = size !== null && size !== void 0 ? size : this.pool.length;
        if (this.size > this.pool.length)
            this.next = function () { return ({ done: true, value: undefined }); };
        this.indices = toArray(new RangeIterator(0, this.pool.length));
        this.cycles = toArray(new RangeIterator(this.pool.length, this.pool.length - this.size, -1));
    }
    Object.defineProperty(PermutationsIterator.prototype, "value", {
        get: function () {
            var _this = this;
            return this.indices.slice(0, this.size).map(function (i) { return _this.pool[i]; });
        },
        enumerable: false,
        configurable: true
    });
    PermutationsIterator.prototype[Symbol.iterator] = function () {
        return this;
    };
    PermutationsIterator.prototype.next = function () {
        var _a;
        if (!this.started) {
            this.started = true;
            return { done: false, value: this.value };
        }
        for (var i = this.size - 1; i > -1; i--) {
            this.cycles[i]--;
            if (this.cycles[i] === 0) {
                var first = this.indices[i];
                for (var j = i; j < this.indices.length - 1; j++)
                    this.indices[j] = this.indices[j + 1];
                this.indices[this.indices.length - 1] = first;
                this.cycles[i] = this.pool.length - i;
            }
            else {
                var j = this.cycles[i];
                var negJ = this.pool.length - j;
                _a = [this.indices[negJ], this.indices[i]], this.indices[i] = _a[0], this.indices[negJ] = _a[1];
                return { done: false, value: this.value };
            }
        }
        return { done: true, value: undefined };
    };
    return PermutationsIterator;
}());
export { PermutationsIterator };
export default PermutationsIterator;
//# sourceMappingURL=PermutationsIterator.js.map