feat(@angular-devkit/core): add trimNewlines literal tag

Author: filipesilva

packages/angular_devkit/core/src/utils/literals.ts

@@ -55,3 +55,14 @@ export function stripIndents(strings: TemplateStringsArray, ...values: any[]) {
     .join('\n')
     .trim();
 }
+
+// tslint:disable-next-line:no-any
+export function trimNewlines(strings: TemplateStringsArray, ...values: any[]) {
+  const endResult = String.raw(strings, ...values);
+
+  return endResult
+    // Remove the newline at the start.
+    .replace(/^(?:\r?\n)+/, '')
+    // Remove the newline at the end and following whitespace.
+    .replace(/(?:\r?\n(?:\s*))$/, '');
+}

packages/angular_devkit/core/src/utils/literals_spec.ts

@@ -5,7 +5,7 @@
  * 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 { oneLine, stripIndent, stripIndents } from './literals';
+import { oneLine, stripIndent, stripIndents, trimNewlines } from './literals';
 
 describe('literals', () => {
   describe('stripIndent', () => {
@@ -43,4 +43,14 @@ describe('literals', () => {
       expect(test).toBe('hello world how are you?  blue  red test');
     });
   });
+
+  describe('trimNewlines', () => {
+    it('works', () => {
+      const test = trimNewlines`
+        hello world
+      `;
+
+      expect(test).toBe('        hello world');
+    });
+  });
 });