refactor(ivy): remove duplicated flatten util (#29547)

This commit removes code duplication where we had 2 versions of a
`flatten` utility. Moreover this change results in queries using
a non-recursive version of `flatten` which should result in a better
performance of query refresh operations.

PR Close #29547

packages/core/src/linker/query_list.ts

@@ -9,6 +9,7 @@
 import {Observable} from 'rxjs';
 
 import {EventEmitter} from '../event_emitter';
+import {flatten} from '../util/array_utils';
 import {getSymbolIterator} from '../util/symbol';
 
 
@@ -110,7 +111,7 @@ export class QueryList<T>/* implements Iterable<T> */ {
    * @param resultsTree The results tree to store
    */
   reset(resultsTree: Array<T|any[]>): void {
-    this._results = depthFirstFlatten(resultsTree);
+    this._results = flatten(resultsTree);
     (this as{dirty: boolean}).dirty = false;
     (this as{length: number}).length = this._results.length;
     (this as{last: T}).last = this._results[this.length - 1];
@@ -131,10 +132,3 @@ export class QueryList<T>/* implements Iterable<T> */ {
     (this.changes as EventEmitter<any>).unsubscribe();
   }
 }
-
-function depthFirstFlatten<T>(list: Array<T|T[]>): T[] {
-  return list.reduce((flat: any[], item: T | T[]): T[] => {
-    const flatItem = Array.isArray(item) ? depthFirstFlatten(item) : item;
-    return (<T[]>flat).concat(flatItem);
-  }, []);
-}

packages/core/src/render3/i18n.ts

@@ -9,7 +9,9 @@
 import {SRCSET_ATTRS, URI_ATTRS, VALID_ATTRS, VALID_ELEMENTS, getTemplateContent} from '../sanitization/html_sanitizer';
 import {InertBodyHelper} from '../sanitization/inert_body';
 import {_sanitizeUrl, sanitizeSrcset} from '../sanitization/url_sanitizer';
+import {addAllToArray} from '../util/array_utils';
 import {assertDefined, assertEqual, assertGreaterThan} from '../util/assert';
+
 import {attachPatchData} from './context_discovery';
 import {allocExpando, createNodeAtIndex, elementAttribute, load, textBinding} from './instructions/all';
 import {LContainer, NATIVE} from './interfaces/container';
@@ -22,7 +24,6 @@ import {BINDING_INDEX, HEADER_OFFSET, LView, RENDERER, TVIEW, TView, T_HOST} fro
 import {appendChild, createTextNode, nativeRemoveNode} from './node_manipulation';
 import {getIsParent, getLView, getPreviousOrParentTNode, setIsParent, setPreviousOrParentTNode} from './state';
 import {NO_CHANGE} from './tokens';
-import {addAllToArray} from './util/array_utils';
 import {renderStringify} from './util/misc_utils';
 import {getNativeByIndex, getNativeByTNode, getTNode, isLContainer} from './util/view_utils';
 

packages/core/test/render3/util_spec.ts

@@ -7,8 +7,6 @@
  */
 
 import {devModeEqual} from '@angular/core/src/change_detection/change_detection_util';
-
-import {flatten} from '../../src/render3/util/array_utils';
 import {isDifferent} from '../../src/render3/util/misc_utils';
 
 describe('util', () => {
@@ -67,19 +65,4 @@ describe('util', () => {
 
   });
 
-  describe('flatten', () => {
-
-    it('should flatten an empty array', () => { expect(flatten([])).toEqual([]); });
-
-    it('should flatten a flat array', () => { expect(flatten([1, 2, 3])).toEqual([1, 2, 3]); });
-
-    it('should flatten a nested array', () => {
-      expect(flatten([1, [2], 3])).toEqual([1, 2, 3]);
-      expect(flatten([[1], 2, [3]])).toEqual([1, 2, 3]);
-      expect(flatten([1, [2, [3]], 4])).toEqual([1, 2, 3, 4]);
-      expect(flatten([1, [2, [3]], [4]])).toEqual([1, 2, 3, 4]);
-      expect(flatten([1, [2, [3]], [[[4]]]])).toEqual([1, 2, 3, 4]);
-      expect(flatten([1, [], 2])).toEqual([1, 2]);
-    });
-  });
 });

packages/core/test/util/array_utils_spec.ts

@@ -0,0 +1,25 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {flatten} from '../../src/util/array_utils';
+
+describe('flatten', () => {
+
+  it('should flatten an empty array', () => { expect(flatten([])).toEqual([]); });
+
+  it('should flatten a flat array', () => { expect(flatten([1, 2, 3])).toEqual([1, 2, 3]); });
+
+  it('should flatten a nested array depth-first', () => {
+    expect(flatten([1, [2], 3])).toEqual([1, 2, 3]);
+    expect(flatten([[1], 2, [3]])).toEqual([1, 2, 3]);
+    expect(flatten([1, [2, [3]], 4])).toEqual([1, 2, 3, 4]);
+    expect(flatten([1, [2, [3]], [4]])).toEqual([1, 2, 3, 4]);
+    expect(flatten([1, [2, [3]], [[[4]]]])).toEqual([1, 2, 3, 4]);
+    expect(flatten([1, [], 2])).toEqual([1, 2]);
+  });
+});