ix/asynciterable/operators/slice.js

The Interactive Extensions for JavaScript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.slice = exports.SliceAsyncIterable = void 0;
const tslib_1 = require("tslib");
const asynciterablex_js_1 = require("../asynciterablex.js");
const withabort_js_1 = require("./withabort.js");
const aborterror_js_1 = require("../../aborterror.js");
/** @ignore */
class SliceAsyncIterable extends asynciterablex_js_1.AsyncIterableX {
    constructor(source, begin, end) {
        super();
        this._source = source;
        this._begin = begin;
        this._end = end;
    }
    [Symbol.asyncIterator](signal) {
        return tslib_1.__asyncGenerator(this, arguments, function* _a() {
            (0, aborterror_js_1.throwIfAborted)(signal);
            const source = (0, withabort_js_1.wrapWithAbort)(this._source, signal);
            const it = source[Symbol.asyncIterator]();
            let begin = this._begin;
            let next;
            while (begin > 0 && !(next = yield tslib_1.__await(it.next())).done) {
                begin--;
            }
            let end = this._end;
            if (end > 0) {
                while (!(next = yield tslib_1.__await(it.next())).done) {
                    yield yield tslib_1.__await(next.value);
                    if (--end === 0) {
                        break;
                    }
                }
            }
        });
    }
}
exports.SliceAsyncIterable = SliceAsyncIterable;
/**
 * Returns the elements from the source async-iterable sequence only after the function that returns a promise produces an element.
 *
 * @template TSource The type of elements in the source sequence.
 * @param {number} begin Zero-based index at which to begin extraction.
 * @param {number} [end=Infinity] Zero-based index before which to end extraction.
 * @returns {MonoTypeOperatorAsyncFunction<TSource>} An async-iterable containing the extracted elements.
 */
function slice(begin, end = Infinity) {
    return function sliceOperatorFunction(source) {
        return new SliceAsyncIterable(source, begin, end);
    };
}
exports.slice = slice;

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