@reactivex/ix-es5-esm/iterable/single.js

The Interactive Extensions for JavaScript

import { __values } from "tslib";
/**
 * Returns the only element of an 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 iterable sequence.
 *
 * @template T The type of the elements in the source sequence.
 * @param {AsyncIterable<T>} source Source iterable sequence.
 * @param {OptionalFindOptions<T>} [options] The optional options which includes a predicate for filtering,
 * and thisArg for predicate binding.
 * @returns {(T | undefined)} The single element in the iterable sequence that satisfies
 * the condition in the predicate, or undefined if no such element exists.
 */
export function single(source, options) {
    var e_1, _a;
    var _b = options || {}, thisArg = _b["thisArg"], _c = _b["predicate"], predicate = _c === void 0 ? function () { return true; } : _c;
    var result;
    var hasResult = false;
    var i = 0;
    try {
        for (var source_1 = __values(source), source_1_1 = source_1.next(); !source_1_1.done; source_1_1 = source_1.next()) {
            var item = source_1_1.value;
            if (hasResult && predicate.call(thisArg, item, i++)) {
                throw new Error('More than one element was found');
            }
            if (predicate.call(thisArg, item, i++)) {
                result = item;
                hasResult = true;
            }
        }
    }
    catch (e_1_1) { e_1 = { error: e_1_1 }; }
    finally {
        try {
            if (source_1_1 && !source_1_1.done && (_a = source_1.return)) _a.call(source_1);
        }
        finally { if (e_1) throw e_1.error; }
    }
    return result;
}

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