feat(Observable.prototype.pipe): Now supports passing an array of ope…

…rators directly

resolves ReactiveX#4177

spec-dtslint/Observable-spec.ts

@@ -56,17 +56,18 @@ describe('pipe', () => {
     const o: Observable<'10'> = of('foo').pipe(a('1'), a('2'), a('3'), a('4'), a('5'), a('6'), a('7'), a('8'), a('9'), a('10')); // $ExpectError
   });
 
-  it('should infer any for a spread of an array of operators', () => {
-    const operators = ['1', '2', '3', '4'].map(n => a(n));
-    const o = of('foo').pipe(...operators); // $ExpectType Observable<any>
+  it('should support an array of operators but require typing', () => {
+    const operators = Array.from({ length: 100 }, n => '' + n).map(a);
+    const o = of('foo').pipe(operators); // $ExpectType Observable<{}>
+    const o2 = of('foo').pipe<string>(operators); // $ExpectType Observable<string>
   });
 
   it('should enforce types for the 1st argument', () => {
     const o = of('foo').pipe(a('#', '1')); // $ExpectError
   });
 
   it('should enforce types for the 2nd argument', () => {
-    const o = of('foo').pipe(a('1'), a('#', '2')); // $ExpectError
+    const o = of('foo').pipe(a('1'), (source: Observable<number>) => new Observable<string>()); // $ExpectError
   });
 
   it('should enforce types for the 3rd argument', () => {

src/internal/Observable.ts

@@ -302,7 +302,7 @@ export class Observable<T> implements Subscribable<T> {
   pipe<A, B, C, D, E, F, G, H>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>, op6: OperatorFunction<E, F>, op7: OperatorFunction<F, G>, op8: OperatorFunction<G, H>): Observable<H>;
   pipe<A, B, C, D, E, F, G, H, I>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>, op6: OperatorFunction<E, F>, op7: OperatorFunction<F, G>, op8: OperatorFunction<G, H>, op9: OperatorFunction<H, I>): Observable<I>;
   pipe<A, B, C, D, E, F, G, H, I>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>, op6: OperatorFunction<E, F>, op7: OperatorFunction<F, G>, op8: OperatorFunction<G, H>, op9: OperatorFunction<H, I>, ...operations: OperatorFunction<any, any>[]): Observable<{}>;
-  pipe(...operators: OperatorFunction<any, any>[]): Observable<any>;
+  pipe<R>(operations: OperatorFunction<any, any>[]): Observable<R>;
   /* tslint:enable:max-line-length */
 
   /**
@@ -324,12 +324,17 @@ export class Observable<T> implements Subscribable<T> {
    *   .subscribe(x => console.log(x))
    * ```
    */
-  pipe(...operations: OperatorFunction<any, any>[]): Observable<any> {
-    if (operations.length === 0) {
+  pipe(...args: any[]): Observable<any> {
+    if (args.length === 0) {
       return this as any;
     }
 
-    return pipeFromArray(operations)(this);
+    const first = args[0];
+    if (Array.isArray(first)) {
+      return pipeFromArray(first)(this) as Observable<any>;
+    }
+
+    return pipeFromArray(args)(this) as Observable<any>;
   }
 
   /* tslint:disable:max-line-length */