@reactivex/ix-es5-esm
Version:
The Interactive Extensions for JavaScript
85 lines (83 loc) • 3.89 kB
JavaScript
import { __asyncValues, __awaiter, __generator } from "tslib";
import { wrapWithAbort } from './operators/withabort.js';
import { throwIfAborted } from '../aborterror.js';
/**
* Returns the only element of an async-iterable sequence that matches the predicate if specified,
* or undefined if no such element exists; this method reports an exception if there is more
* than one element in the async-iterable sequence.
*
* @template T The type of the elements in the source sequence.
* @param {AsyncIterable<T>} source Source async-iterable sequence.
* @param {OptionalFindOptions<T>} [options] The optional options which includes a predicate for filtering,
* thisArg for predicate binding and an abort signal for cancellation.
* @returns {(Promise<T | undefined>)} A promise with the single element in the async-iterable sequence that satisfies
* the condition in the predicate, or undefined if no such element exists.
*/
export function single(source, options) {
var _a, e_1, _b, _c;
return __awaiter(this, void 0, void 0, function () {
var _d, signal, thisArg, _e, predicate, result, hasResult, i, _f, _g, _h, item, _j, e_1_1;
var _this = this;
return __generator(this, function (_k) {
switch (_k.label) {
case 0:
_d = options || {}, signal = _d["signal"], thisArg = _d["thisArg"], _e = _d["predicate"], predicate = _e === void 0 ? function () { return __awaiter(_this, void 0, void 0, function () { return __generator(this, function (_a) {
return [2 /*return*/, true];
}); }); } : _e;
throwIfAborted(signal);
hasResult = false;
i = 0;
_k.label = 1;
case 1:
_k.trys.push([1, 9, 10, 15]);
_f = true, _g = __asyncValues(wrapWithAbort(source, signal));
_k.label = 2;
case 2: return [4 /*yield*/, _g.next()];
case 3:
if (!(_h = _k.sent(), _a = _h.done, !_a)) return [3 /*break*/, 8];
_c = _h.value;
_f = false;
item = _c;
_j = hasResult;
if (!_j) return [3 /*break*/, 5];
return [4 /*yield*/, predicate.call(thisArg, item, i++, signal)];
case 4:
_j = (_k.sent());
_k.label = 5;
case 5:
if (_j) {
throw new Error('More than one element was found');
}
return [4 /*yield*/, predicate.call(thisArg, item, i++, signal)];
case 6:
if (_k.sent()) {
result = item;
hasResult = true;
}
_k.label = 7;
case 7:
_f = true;
return [3 /*break*/, 2];
case 8: return [3 /*break*/, 15];
case 9:
e_1_1 = _k.sent();
e_1 = { error: e_1_1 };
return [3 /*break*/, 15];
case 10:
_k.trys.push([10, , 13, 14]);
if (!(!_f && !_a && (_b = _g.return))) return [3 /*break*/, 12];
return [4 /*yield*/, _b.call(_g)];
case 11:
_k.sent();
_k.label = 12;
case 12: return [3 /*break*/, 14];
case 13:
if (e_1) throw e_1.error;
return [7 /*endfinally*/];
case 14: return [7 /*endfinally*/];
case 15: return [2 /*return*/, result];
}
});
});
}
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