ix/asynciterable/operators/distinct.mjs

The Interactive Extensions for JavaScript

import { __asyncGenerator, __asyncValues, __await } from "tslib";
import { AsyncIterableX } from './../asynciterablex.mjs';
import { identityAsync } from '../../util/identity.mjs';
import { arrayIndexOfAsync } from '../../util/arrayindexof.mjs';
import { comparerAsync } from '../../util/comparer.mjs';
import { wrapWithAbort } from './withabort.mjs';
import { throwIfAborted } from '../../aborterror.mjs';
/** @ignore */
export class DistinctAsyncIterable extends AsyncIterableX {
    constructor(source, keySelector, comparer) {
        super();
        this._source = source;
        this._keySelector = keySelector;
        this._comparer = comparer;
    }
    [Symbol.asyncIterator](signal) {
        return __asyncGenerator(this, arguments, function* _a() {
            var _b, e_1, _c, _d;
            throwIfAborted(signal);
            const set = [];
            try {
                for (var _e = true, _f = __asyncValues(wrapWithAbort(this._source, signal)), _g; _g = yield __await(_f.next()), _b = _g.done, !_b; _e = true) {
                    _d = _g.value;
                    _e = false;
                    const item = _d;
                    const key = yield __await(this._keySelector(item, signal));
                    if ((yield __await(arrayIndexOfAsync(set, key, this._comparer))) === -1) {
                        set.push(key);
                        yield yield __await(item);
                    }
                }
            }
            catch (e_1_1) { e_1 = { error: e_1_1 }; }
            finally {
                try {
                    if (!_e && !_b && (_c = _f.return)) yield __await(_c.call(_f));
                }
                finally { if (e_1) throw e_1.error; }
            }
        });
    }
}
/**
 * Returns an async-iterable sequence that contains only distinct elements according to the keySelector and comparer.
 *
 * @template TSource The type of the elements in the source sequence.
 * @template TKey The type of the discriminator key computed for each element in the source sequence.
 * @param {DistinctOptions<TSource, TKey = TSource>} [options] The optional arguments for a key selector and comparer function.
 * @returns {MonoTypeOperatorAsyncFunction<TSource>} An operator that returns distinct elements according to the keySelector and options.
 */
export function distinct(options) {
    return function distinctOperatorFunction(source) {
        const { ['keySelector']: keySelector = identityAsync, ['comparer']: comparer = comparerAsync } = options || {};
        return new DistinctAsyncIterable(source, keySelector, comparer);
    };
}

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