ix/asynciterable/operators/memoize.js

The Interactive Extensions for JavaScript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.memoize = exports.MemoizeAsyncBuffer = void 0;
const tslib_1 = require("tslib");
const asynciterablex_js_1 = require("../asynciterablex.js");
const _refcountlist_js_1 = require("../../iterable/operators/_refcountlist.js");
const create_js_1 = require("../create.js");
const aborterror_js_1 = require("../../aborterror.js");
/** @ignore */
class MemoizeAsyncBuffer extends asynciterablex_js_1.AsyncIterableX {
    constructor(source, buffer) {
        super();
        this._error = null;
        this._shared = null;
        this._stopped = false;
        this._source = source;
        this._buffer = buffer;
    }
    [Symbol.asyncIterator](signal) {
        (0, aborterror_js_1.throwIfAborted)(signal);
        return this._getIterable(0);
    }
    _getIterable(offset = 0) {
        return tslib_1.__asyncGenerator(this, arguments, function* _getIterable_1() {
            let i = offset - 1;
            let done = false;
            const buffer = this._buffer;
            try {
                do {
                    if (++i < buffer.count) {
                        yield yield tslib_1.__await(buffer.get(i));
                        continue;
                    }
                    if (this._stopped) {
                        throw this._error;
                    }
                    if (this._shared === null) {
                        this._shared = this._source.next().then((r) => {
                            this._shared = null;
                            if (!r.done) {
                                buffer.push(r.value);
                            }
                            return r;
                        });
                    }
                    ({ done } = yield tslib_1.__await(this._shared.catch((e) => {
                        this._error = e;
                        this._stopped = true;
                        throw e;
                    })));
                    if (!done) {
                        yield yield tslib_1.__await(buffer.get(i));
                    }
                } while (!done);
            }
            finally {
                buffer.done();
            }
        });
    }
}
exports.MemoizeAsyncBuffer = MemoizeAsyncBuffer;
/**
 * Memoizes the source sequence within a selector function where a specified number of iterators can get access
 * to all of the sequence's elements without causing multiple iterations over the source.
 *
 * @template TSource Source sequence element type.
 * @template TResult Result sequence element type.
 * @param {number} [readerCount=-1] Number of iterators that can access the underlying buffer. Once every
 * iterator has obtained an element from the buffer, the element is removed from the buffer.
 * @param {(value: AsyncIterable<TSource>) => AsyncIterable<TResult>} [selector] Selector function with memoized access
 * to the source sequence for a specified number of iterators.
 * @returns {(OperatorAsyncFunction<TSource, TSource | TResult>)} Sequence resulting from applying the selector function to the
 * memoized view over the source sequence.
 */
function memoize(readerCount = -1, selector) {
    return function memoizeOperatorFunction(source) {
        if (!selector) {
            return readerCount === -1
                ? new MemoizeAsyncBuffer(source[Symbol.asyncIterator](), new _refcountlist_js_1.MaxRefCountList())
                : new MemoizeAsyncBuffer(source[Symbol.asyncIterator](), new _refcountlist_js_1.RefCountList(readerCount));
        }
        return (0, create_js_1.create)(() => selector(memoize(readerCount)(source))[Symbol.asyncIterator]());
    };
}
exports.memoize = memoize;

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