single.js

/** PURE_IMPORTS_START tslib,_Subscriber,_util_EmptyError PURE_IMPORTS_END */
import * as tslib_1 from "tslib";
import { Subscriber } from '../Subscriber';
import { EmptyError } from '../util/EmptyError';
export function single(predicate) {
    return function (source) { return source.lift(new SingleOperator(predicate, source)); };
}
var SingleOperator = /*@__PURE__*/ (function () {
    function SingleOperator(predicate, source) {
        this.predicate = predicate;
        this.source = source;
    }
    SingleOperator.prototype.call = function (subscriber, source) {
        return source.subscribe(new SingleSubscriber(subscriber, this.predicate, this.source));
    };
    return SingleOperator;
}());
var SingleSubscriber = /*@__PURE__*/ (function (_super) {
    tslib_1.__extends(SingleSubscriber, _super);
    function SingleSubscriber(destination, predicate, source) {
        var _this = _super.call(this, destination) || this;
        _this.predicate = predicate;
        _this.source = source;
        _this.seenValue = false;
        _this.index = 0;
        return _this;
    }
    SingleSubscriber.prototype.applySingleValue = function (value) {
        if (this.seenValue) {
            this.destination.error('Sequence contains more than one element');
        }
        else {
            this.seenValue = true;
            this.singleValue = value;
        }
    };
    SingleSubscriber.prototype._next = function (value) {
        var index = this.index++;
        if (this.predicate) {
            this.tryNext(value, index);
        }
        else {
            this.applySingleValue(value);
        }
    };
    SingleSubscriber.prototype.tryNext = function (value, index) {
        try {
            if (this.predicate(value, index, this.source)) {
                this.applySingleValue(value);
            }
        }
        catch (err) {
            this.destination.error(err);
        }
    };
    SingleSubscriber.prototype._complete = function () {
        var destination = this.destination;
        if (this.index > 0) {
            destination.next(this.seenValue ? this.singleValue : undefined);
            destination.complete();
        }
        else {
            destination.error(new EmptyError);
        }
    };
    return SingleSubscriber;
}(Subscriber));
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