@reactivex/ix-es5-esm/asynciterable/reduceright.js

The Interactive Extensions for JavaScript

import { __awaiter, __generator } from "tslib";
import { toArray } from './toarray.js';
import { throwIfAborted } from '../aborterror.js';
/**
 * Applies an accumulator function over an async-iterable sequence from the end, returning the result of the aggregation as a
 * single element in the result sequence. The seed value, if specified, is used as the initial accumulator value.
 * For aggregation behavior with incremental intermediate results, scan.
 *
 * @template T The type of the elements in the source sequence.
 * @template R The type of the result of the aggregation.
 * @param {AsyncIterable<T>} source An async-iterable sequence to aggregate over from the right.
 * @param {ReduceOptions<T, R>} options The options which contains a callback, with optional seed and an optional abort signal for cancellation.
 * @returns {Promise<R>} A promise with the final accumulator value.
 */
export function reduceRight(source, options) {
    return __awaiter(this, void 0, void 0, function () {
        var seed, signal, callback, hasSeed, array, hasValue, acc, offset, item;
        return __generator(this, function (_a) {
            switch (_a.label) {
                case 0:
                    seed = options["seed"], signal = options["signal"], callback = options["callback"];
                    hasSeed = options.hasOwnProperty('seed');
                    throwIfAborted(signal);
                    return [4 /*yield*/, toArray(source, signal)];
                case 1:
                    array = _a.sent();
                    hasValue = false;
                    acc = seed;
                    offset = array.length - 1;
                    _a.label = 2;
                case 2:
                    if (!(offset >= 0)) return [3 /*break*/, 6];
                    item = array[offset];
                    if (!(hasValue || (hasValue = hasSeed))) return [3 /*break*/, 4];
                    return [4 /*yield*/, callback(acc, item, offset, signal)];
                case 3:
                    acc = _a.sent();
                    return [3 /*break*/, 5];
                case 4:
                    acc = item;
                    hasValue = true;
                    _a.label = 5;
                case 5:
                    offset--;
                    return [3 /*break*/, 2];
                case 6:
                    if (!(hasSeed || hasValue)) {
                        throw new Error('Sequence contains no elements');
                    }
                    return [2 /*return*/, acc];
            }
        });
    });
}

//# sourceMappingURL=reduceright.js.map