es6/operator/first.js

import { Subscriber } from '../Subscriber';
import { EmptyError } from '../util/EmptyError';
/* tslint:disable:max-line-length */
export function first(predicate, resultSelector, defaultValue) {
    return this.lift(new FirstOperator(predicate, resultSelector, defaultValue, this));
}
var FirstOperator = (function () {
    function FirstOperator(predicate, resultSelector, defaultValue, source) {
        this.predicate = predicate;
        this.resultSelector = resultSelector;
        this.defaultValue = defaultValue;
        this.source = source;
    }
    FirstOperator.prototype.call = function (observer, source) {
        return source._subscribe(new FirstSubscriber(observer, this.predicate, this.resultSelector, this.defaultValue, this.source));
    };
    return FirstOperator;
}());
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
var FirstSubscriber = (function (_super) {
    __extends(FirstSubscriber, _super);
    function FirstSubscriber(destination, predicate, resultSelector, defaultValue, source) {
        _super.call(this, destination);
        this.predicate = predicate;
        this.resultSelector = resultSelector;
        this.defaultValue = defaultValue;
        this.source = source;
        this.index = 0;
        this.hasCompleted = false;
        this._emitted = false;
    }
    FirstSubscriber.prototype._next = function (value) {
        var index = this.index++;
        if (this.predicate) {
            this._tryPredicate(value, index);
        }
        else {
            this._emit(value, index);
        }
    };
    FirstSubscriber.prototype._tryPredicate = function (value, index) {
        var result;
        try {
            result = this.predicate(value, index, this.source);
        }
        catch (err) {
            this.destination.error(err);
            return;
        }
        if (result) {
            this._emit(value, index);
        }
    };
    FirstSubscriber.prototype._emit = function (value, index) {
        if (this.resultSelector) {
            this._tryResultSelector(value, index);
            return;
        }
        this._emitFinal(value);
    };
    FirstSubscriber.prototype._tryResultSelector = function (value, index) {
        var result;
        try {
            result = this.resultSelector(value, index);
        }
        catch (err) {
            this.destination.error(err);
            return;
        }
        this._emitFinal(result);
    };
    FirstSubscriber.prototype._emitFinal = function (value) {
        var destination = this.destination;
        if (!this._emitted) {
            this._emitted = true;
            destination.next(value);
            destination.complete();
            this.hasCompleted = true;
        }
    };
    FirstSubscriber.prototype._complete = function () {
        var destination = this.destination;
        if (!this.hasCompleted && typeof this.defaultValue !== 'undefined') {
            destination.next(this.defaultValue);
            destination.complete();
        }
        else if (!this.hasCompleted) {
            destination.error(new EmptyError);
        }
    };
    return FirstSubscriber;
}(Subscriber));
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