feat(query): add filter and reduce to QueryList

Closes angular#4710

Author: vsavkin

modules/angular2/src/core/linker/query_list.dart

@@ -22,11 +22,6 @@ class QueryList<T> extends Object
     return _results.toString();
   }
 
-  List map(fn(T)) {
-    // Note: we need to return a list instead of iterable to match JS.
-    return this._results.map(fn).toList();
-  }
-
   /** @internal */
   void reset(List<T> newList) {
     _results = newList;

modules/angular2/src/core/linker/query_list.ts

@@ -37,10 +37,25 @@ export class QueryList<T> {
   get last(): T { return ListWrapper.last(this._results); }
 
   /**
-   * returns a new list with the passsed in function applied to each element.
+   * returns a new array with the passed in function applied to each element.
    */
   map<U>(fn: (item: T) => U): U[] { return this._results.map(fn); }
 
+  /**
+   * returns a filtered array.
+   */
+  filter(fn: (item: T) => boolean): T[] { return this._results.filter(fn); }
+
+  /**
+   * returns a reduced value.
+   */
+  reduce<U>(fn: (acc: U, item: T) => U, init: U): U { return this._results.reduce(fn, init); }
+
+  /**
+   * converts QueryList into an array
+   */
+  toArray(): T[] { return ListWrapper.clone(this._results); }
+
   [getSymbolIterator()](): any { return this._results[getSymbolIterator()](); }
 
   toString(): string { return this._results.toString(); }

modules/angular2/test/core/linker/query_list_spec.ts

@@ -10,6 +10,7 @@ import {
   fakeAsync,
   tick
 } from 'angular2/testing_internal';
+import {IS_DART} from '../../platform';
 
 import {MapWrapper, ListWrapper, iterateListLike} from 'angular2/src/core/facade/collection';
 import {StringWrapper} from 'angular2/src/core/facade/lang';
@@ -46,6 +47,28 @@ export function main() {
       expect(queryList.map((x) => x)).toEqual(['one', 'two']);
     });
 
+    if (!IS_DART) {
+      it('should support filter', () => {
+        queryList.reset(['one', 'two']);
+        expect((<any>queryList).filter((x) => x == "one")).toEqual(['one']);
+      });
+
+      it('should support reduce', () => {
+        queryList.reset(["one", "two"]);
+        expect((<any>queryList).reduce((a, x) => a + x, "start:")).toEqual("start:onetwo");
+      });
+
+      it('should support toArray', () => {
+        queryList.reset(["one", "two"]);
+        expect((<any>queryList).reduce((a, x) => a + x, "start:")).toEqual("start:onetwo");
+      });
+
+      it('should support toArray', () => {
+        queryList.reset(["one", "two"]);
+        expect((<any>queryList).toArray()).toEqual(["one", "two"]);
+      });
+    }
+
     it('should support toString', () => {
       queryList.reset(['one', 'two']);
       var listString = queryList.toString();