BoundNodeCallbackObservable.js 7.63 KB
"use strict";
var __extends = (this && this.__extends) || function (d, b) {
    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
    function __() { this.constructor = d; }
    d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
var Observable_1 = require('../Observable');
var tryCatch_1 = require('../util/tryCatch');
var errorObject_1 = require('../util/errorObject');
var AsyncSubject_1 = require('../AsyncSubject');
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @extends {Ignored}
 * @hide true
 */
var BoundNodeCallbackObservable = (function (_super) {
    __extends(BoundNodeCallbackObservable, _super);
    function BoundNodeCallbackObservable(callbackFunc, selector, args, scheduler) {
        _super.call(this);
        this.callbackFunc = callbackFunc;
        this.selector = selector;
        this.args = args;
        this.scheduler = scheduler;
    }
    /* tslint:enable:max-line-length */
    /**
     * Converts a Node.js-style callback API to a function that returns an
     * Observable.
     *
     * <span class="informal">It's just like {@link bindCallback}, but the
     * callback is expected to be of type `callback(error, result)`.</span>
     *
     * `bindNodeCallback` is not an operator because its input and output are not
     * Observables. The input is a function `func` with some parameters, but the
     * last parameter must be a callback function that `func` calls when it is
     * done. The callback function is expected to follow Node.js conventions,
     * where the first argument to the callback is an error, while remaining
     * arguments are the callback result. The output of `bindNodeCallback` is a
     * function that takes the same parameters as `func`, except the last one (the
     * callback). When the output function is called with arguments, it will
     * return an Observable where the results will be delivered to.
     *
     * @example <caption>Read a file from the filesystem and get the data as an Observable</caption>
     * import * as fs from 'fs';
     * var readFileAsObservable = Rx.Observable.bindNodeCallback(fs.readFile);
     * var result = readFileAsObservable('./roadNames.txt', 'utf8');
     * result.subscribe(x => console.log(x), e => console.error(e));
     *
     * @see {@link bindCallback}
     * @see {@link from}
     * @see {@link fromPromise}
     *
     * @param {function} func Function with a callback as the last parameter.
     * @param {function} [selector] A function which takes the arguments from the
     * callback and maps those a value to emit on the output Observable.
     * @param {Scheduler} [scheduler] The scheduler on which to schedule the
     * callbacks.
     * @return {function(...params: *): Observable} A function which returns the
     * Observable that delivers the same values the Node.js callback would
     * deliver.
     * @static true
     * @name bindNodeCallback
     * @owner Observable
     */
    BoundNodeCallbackObservable.create = function (func, selector, scheduler) {
        if (selector === void 0) { selector = undefined; }
        return function () {
            var args = [];
            for (var _i = 0; _i < arguments.length; _i++) {
                args[_i - 0] = arguments[_i];
            }
            return new BoundNodeCallbackObservable(func, selector, args, scheduler);
        };
    };
    BoundNodeCallbackObservable.prototype._subscribe = function (subscriber) {
        var callbackFunc = this.callbackFunc;
        var args = this.args;
        var scheduler = this.scheduler;
        var subject = this.subject;
        if (!scheduler) {
            if (!subject) {
                subject = this.subject = new AsyncSubject_1.AsyncSubject();
                var handler = function handlerFn() {
                    var innerArgs = [];
                    for (var _i = 0; _i < arguments.length; _i++) {
                        innerArgs[_i - 0] = arguments[_i];
                    }
                    var source = handlerFn.source;
                    var selector = source.selector, subject = source.subject;
                    var err = innerArgs.shift();
                    if (err) {
                        subject.error(err);
                    }
                    else if (selector) {
                        var result_1 = tryCatch_1.tryCatch(selector).apply(this, innerArgs);
                        if (result_1 === errorObject_1.errorObject) {
                            subject.error(errorObject_1.errorObject.e);
                        }
                        else {
                            subject.next(result_1);
                            subject.complete();
                        }
                    }
                    else {
                        subject.next(innerArgs.length === 1 ? innerArgs[0] : innerArgs);
                        subject.complete();
                    }
                };
                // use named function instance to avoid closure.
                handler.source = this;
                var result = tryCatch_1.tryCatch(callbackFunc).apply(this, args.concat(handler));
                if (result === errorObject_1.errorObject) {
                    subject.error(errorObject_1.errorObject.e);
                }
            }
            return subject.subscribe(subscriber);
        }
        else {
            return scheduler.schedule(dispatch, 0, { source: this, subscriber: subscriber });
        }
    };
    return BoundNodeCallbackObservable;
}(Observable_1.Observable));
exports.BoundNodeCallbackObservable = BoundNodeCallbackObservable;
function dispatch(state) {
    var self = this;
    var source = state.source, subscriber = state.subscriber;
    // XXX: cast to `any` to access to the private field in `source`.
    var _a = source, callbackFunc = _a.callbackFunc, args = _a.args, scheduler = _a.scheduler;
    var subject = source.subject;
    if (!subject) {
        subject = source.subject = new AsyncSubject_1.AsyncSubject();
        var handler = function handlerFn() {
            var innerArgs = [];
            for (var _i = 0; _i < arguments.length; _i++) {
                innerArgs[_i - 0] = arguments[_i];
            }
            var source = handlerFn.source;
            var selector = source.selector, subject = source.subject;
            var err = innerArgs.shift();
            if (err) {
                subject.error(err);
            }
            else if (selector) {
                var result_2 = tryCatch_1.tryCatch(selector).apply(this, innerArgs);
                if (result_2 === errorObject_1.errorObject) {
                    self.add(scheduler.schedule(dispatchError, 0, { err: errorObject_1.errorObject.e, subject: subject }));
                }
                else {
                    self.add(scheduler.schedule(dispatchNext, 0, { value: result_2, subject: subject }));
                }
            }
            else {
                var value = innerArgs.length === 1 ? innerArgs[0] : innerArgs;
                self.add(scheduler.schedule(dispatchNext, 0, { value: value, subject: subject }));
            }
        };
        // use named function to pass values in without closure
        handler.source = source;
        var result = tryCatch_1.tryCatch(callbackFunc).apply(this, args.concat(handler));
        if (result === errorObject_1.errorObject) {
            subject.error(errorObject_1.errorObject.e);
        }
    }
    self.add(subject.subscribe(subscriber));
}
function dispatchNext(arg) {
    var value = arg.value, subject = arg.subject;
    subject.next(value);
    subject.complete();
}
function dispatchError(arg) {
    var err = arg.err, subject = arg.subject;
    subject.error(err);
}
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