ix/asynciterable/operators/scanright.js

The Interactive Extensions for JavaScript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.scanRight = exports.ScanRightAsyncIterable = void 0;
const tslib_1 = require("tslib");
const asynciterablex_js_1 = require("../asynciterablex.js");
const toarray_js_1 = require("../toarray.js");
const aborterror_js_1 = require("../../aborterror.js");
/** @ignore */
class ScanRightAsyncIterable extends asynciterablex_js_1.AsyncIterableX {
    constructor(source, options) {
        super();
        this._source = source;
        this._fn = options['callback'];
        this._hasSeed = options.hasOwnProperty('seed');
        this._seed = options['seed'];
    }
    [Symbol.asyncIterator](signal) {
        return tslib_1.__asyncGenerator(this, arguments, function* _a() {
            (0, aborterror_js_1.throwIfAborted)(signal);
            let hasValue = false;
            let acc = this._seed;
            const source = yield tslib_1.__await((0, toarray_js_1.toArray)(this._source, signal));
            for (let offset = source.length - 1; offset >= 0; offset--) {
                const item = source[offset];
                if (hasValue || (hasValue = this._hasSeed)) {
                    acc = yield tslib_1.__await(this._fn(acc, item, offset, signal));
                    yield yield tslib_1.__await(acc);
                }
                else {
                    acc = item;
                    hasValue = true;
                }
            }
        });
    }
}
exports.ScanRightAsyncIterable = ScanRightAsyncIterable;
/**
 * Applies an accumulator function over an async-iterable sequence from the right and returns each intermediate result.
 * The specified seed value, if given, is used as the initial accumulator value.
 *
 * @template T The type of the elements in the source sequence.
 * @template R The type of the result of the aggregation.
 * @param {ScanOptions<T, R>} options The options including the accumulator function and seed.
 * @returns {OperatorAsyncFunction<T, R>} An async-enumerable sequence containing the accumulated values from the right.
 */
function scanRight(options) {
    return function scanRightOperatorFunction(source) {
        return new ScanRightAsyncIterable(source, options);
    };
}
exports.scanRight = scanRight;

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