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feat(callback): Add Observable.fromCallback
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/* globals describe, it, expect */ | ||
var Rx = require('../../dist/cjs/Rx'); | ||
var Observable = Rx.Observable; | ||
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describe('Observable.fromCallback', function () { | ||
it('should emit one value from a callback', function (done) { | ||
function callback (datum, cb) { | ||
cb(datum); | ||
} | ||
var cbToObs = Observable.fromCallback(callback); | ||
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cbToObs(42) | ||
.subscribe(function (x) { | ||
expect(x).toBe(42); | ||
}, null, | ||
function (x) { | ||
expect(x).toBe(undefined); | ||
done(); | ||
}); | ||
}); | ||
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it('should emit one value chosen by a selector', function (done) { | ||
function callback (datum, cb) { | ||
cb(null, datum); | ||
} | ||
var cbToObs = Observable.fromCallback(callback, null, function (err, datum) { return datum; }); | ||
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cbToObs(42) | ||
.subscribe(function (x) { | ||
expect(x).toBe(42); | ||
}, null, | ||
function (x) { | ||
expect(x).toBe(undefined); | ||
done(); | ||
}); | ||
}); | ||
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it('should override `this` in the callback', function (done) { | ||
function callback (cb) { | ||
cb(this.value); | ||
} | ||
var cbToObs = Observable.fromCallback(callback, {value: 42}); | ||
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cbToObs() | ||
.subscribe(function (x) { | ||
expect(x).toBe(42); | ||
}, null, | ||
function (x) { | ||
expect(x).toBe(undefined); | ||
done(); | ||
}); | ||
}); | ||
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it('should emit an error when the selector throws', function (done) { | ||
function callback (cb) { | ||
cb(42); | ||
} | ||
var cbToObs = Observable.fromCallback(callback, null, function (err) { throw new Error('Yikes!'); }); | ||
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cbToObs() | ||
.subscribe(null, | ||
function (err) { | ||
expect(err.message).toBe('Yikes!'); | ||
done(); | ||
}, | ||
null | ||
); | ||
}); | ||
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it('should not emit, throw or complete if immediately unsubscribed', function (done) { | ||
var nextSpy = jasmine.createSpy('next'); | ||
var throwSpy = jasmine.createSpy('throw'); | ||
var completeSpy = jasmine.createSpy('complete'); | ||
var timeout; | ||
function callback (datum, cb) { | ||
timeout = setTimeout(function () { | ||
cb(datum); | ||
}); | ||
} | ||
var subscription = Observable.fromCallback(callback)(42) | ||
.subscribe(nextSpy, throwSpy, completeSpy); | ||
subscription.unsubscribe(); | ||
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setTimeout(function () { | ||
expect(nextSpy).not.toHaveBeenCalled(); | ||
expect(throwSpy).not.toHaveBeenCalled(); | ||
expect(completeSpy).not.toHaveBeenCalled(); | ||
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clearTimeout(timeout); | ||
done(); | ||
}); | ||
}); | ||
}); |
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Original file line number | Diff line number | Diff line change |
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import {Observable} from '../Observable'; | ||
import {Subscriber} from '../Subscriber'; | ||
import {Scheduler} from '../Scheduler'; | ||
import {Subscription} from '../Subscription'; | ||
import {immediate} from '../schedulers/immediate'; | ||
import {tryCatch} from '../util/tryCatch'; | ||
import {errorObject} from '../util/errorObject'; | ||
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export class CallbackObservable<T> extends Observable<T> { | ||
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_isScalar: boolean = false; | ||
value: T | T[]; | ||
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static create<T>(callbackFunc: Function, ctx: Object = undefined, selector: Function = undefined, scheduler: Scheduler = immediate): Function { | ||
return (...args): Observable<T> => { | ||
return new CallbackObservable(callbackFunc, ctx, selector, args, scheduler); | ||
}; | ||
} | ||
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constructor(private callbackFunc: Function, private ctx, private selector, private args: any[], public scheduler: Scheduler = immediate) { | ||
super(); | ||
} | ||
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_subscribe(subscriber: Subscriber<T | T[]>) { | ||
const callbackFunc = this.callbackFunc; | ||
const ctx = this.ctx; | ||
const selector = this.selector; | ||
const args = this.args; | ||
const scheduler = this.scheduler; | ||
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let handler; | ||
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if (scheduler === immediate) { | ||
if (this._isScalar) { | ||
subscriber.next(this.value); | ||
subscriber.complete(); | ||
} else { | ||
handler = (...innerArgs) => { | ||
let results; | ||
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this._isScalar = true; | ||
this.value = innerArgs; | ||
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if (selector) { | ||
results = tryCatch(selector).apply(ctx, innerArgs); | ||
if (results === errorObject) { return subscriber.error(results.e); } | ||
subscriber.next(results); | ||
} else { | ||
if (innerArgs.length <= 1) { | ||
subscriber.next(innerArgs[0]); | ||
} else { | ||
subscriber.next(innerArgs); | ||
} | ||
} | ||
subscriber.complete(); | ||
}; | ||
} | ||
} else { | ||
const subscription = new Subscription(); | ||
if (this._isScalar) { | ||
const value = this.value; | ||
subscription.add(scheduler.schedule(dispatchNext, 0, { value, subscriber })); | ||
} else { | ||
handler = (...innerArgs) => { | ||
let results; | ||
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this._isScalar = true; | ||
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if (selector) { | ||
results = tryCatch(selector).apply(ctx, innerArgs); | ||
if (results === errorObject) { | ||
return subscription.add(scheduler.schedule(dispatchError, 0, { err: results.e, subscriber })); | ||
} | ||
this.value = results; | ||
} else { | ||
if (innerArgs.length <= 1) { | ||
this.value = innerArgs[0]; | ||
} else { | ||
this.value = innerArgs; | ||
} | ||
} | ||
const value = this.value; | ||
subscription.add(scheduler.schedule(dispatchNext, 0, { value, subscriber })); | ||
}; | ||
return subscription; | ||
} | ||
} | ||
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if (handler) { | ||
args.push(handler); | ||
callbackFunc.apply(ctx, args); | ||
} | ||
} | ||
} | ||
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function dispatchNext({ value, subscriber }) { | ||
subscriber.next(value); | ||
subscriber.complete(); | ||
} | ||
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function dispatchError({ err, subscriber }) { | ||
subscriber.error(err); | ||
} |