feat(common): add a titlecase pipe (#13324)

closes #11436

Author: vicb

modules/@angular/common/src/common.ts

@@ -15,6 +15,6 @@ export * from './location/index';
 export {NgLocalization} from './localization';
 export {CommonModule} from './common_module';
 export {NgClass, NgFor, NgIf, NgPlural, NgPluralCase, NgStyle, NgSwitch, NgSwitchCase, NgSwitchDefault, NgTemplateOutlet} from './directives/index';
-export {AsyncPipe, DatePipe, I18nPluralPipe, I18nSelectPipe, JsonPipe, LowerCasePipe, CurrencyPipe, DecimalPipe, PercentPipe, SlicePipe, UpperCasePipe} from './pipes/index';
+export {AsyncPipe, DatePipe, I18nPluralPipe, I18nSelectPipe, JsonPipe, LowerCasePipe, CurrencyPipe, DecimalPipe, PercentPipe, SlicePipe, UpperCasePipe, TitleCasePipe} from './pipes/index';
 export {VERSION} from './version';
 export {Version} from '@angular/core';

modules/@angular/common/src/pipes/case_conversion_pipes.ts

@@ -0,0 +1,61 @@
+/**
+ * @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 {Pipe, PipeTransform} from '@angular/core';
+import {InvalidPipeArgumentError} from './invalid_pipe_argument_error';
+
+/**
+ * Transforms text to lowercase.
+ *
+ * {@example  core/pipes/ts/lowerupper_pipe/lowerupper_pipe_example.ts region='LowerUpperPipe' }
+ *
+ * @stable
+ */
+@Pipe({name: 'lowercase'})
+export class LowerCasePipe implements PipeTransform {
+  transform(value: string): string {
+    if (!value) return value;
+    if (typeof value !== 'string') {
+      throw new InvalidPipeArgumentError(LowerCasePipe, value);
+    }
+    return value.toLowerCase();
+  }
+}
+
+/**
+ * Transforms text to titlecase.
+ *
+ * @stable
+ */
+@Pipe({name: 'titlecase'})
+export class TitleCasePipe implements PipeTransform {
+  transform(value: string): string {
+    if (!value) return value;
+    if (typeof value !== 'string') {
+      throw new InvalidPipeArgumentError(TitleCasePipe, value);
+    }
+
+    return value[0].toUpperCase() + value.substr(1).toLowerCase();
+  }
+}
+
+/**
+ * Transforms text to uppercase.
+ *
+ * @stable
+ */
+@Pipe({name: 'uppercase'})
+export class UpperCasePipe implements PipeTransform {
+  transform(value: string): string {
+    if (!value) return value;
+    if (typeof value !== 'string') {
+      throw new InvalidPipeArgumentError(UpperCasePipe, value);
+    }
+    return value.toUpperCase();
+  }
+}

modules/@angular/common/src/pipes/index.ts

@@ -12,14 +12,13 @@
  * This module provides a set of common Pipes.
  */
 import {AsyncPipe} from './async_pipe';
+import {LowerCasePipe, TitleCasePipe, UpperCasePipe} from './case_conversion_pipes';
 import {DatePipe} from './date_pipe';
 import {I18nPluralPipe} from './i18n_plural_pipe';
 import {I18nSelectPipe} from './i18n_select_pipe';
 import {JsonPipe} from './json_pipe';
-import {LowerCasePipe} from './lowercase_pipe';
 import {CurrencyPipe, DecimalPipe, PercentPipe} from './number_pipe';
 import {SlicePipe} from './slice_pipe';
-import {UpperCasePipe} from './uppercase_pipe';
 
 export {
   AsyncPipe,
@@ -32,9 +31,11 @@ export {
   LowerCasePipe,
   PercentPipe,
   SlicePipe,
+  TitleCasePipe,
   UpperCasePipe
 };
 
+
 /**
  * A collection of Angular pipes that are likely to be used in each and every application.
  */
@@ -46,6 +47,7 @@ export const COMMON_PIPES = [
   SlicePipe,
   DecimalPipe,
   PercentPipe,
+  TitleCasePipe,
   CurrencyPipe,
   DatePipe,
   I18nPluralPipe,

modules/@angular/common/src/pipes/lowercase_pipe.ts

@@ -0,0 +1,59 @@
+/**
+ * @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 {LowerCasePipe, TitleCasePipe, UpperCasePipe} from '@angular/common';
+
+export function main() {
+  describe('LowerCasePipe', () => {
+    let pipe: LowerCasePipe;
+
+    beforeEach(() => { pipe = new LowerCasePipe(); });
+
+    it('should return lowercase', () => { expect(pipe.transform('FOO')).toEqual('foo'); });
+
+    it('should lowercase when there is a new value', () => {
+      expect(pipe.transform('FOO')).toEqual('foo');
+      expect(pipe.transform('BAr')).toEqual('bar');
+    });
+
+    it('should not support other objects',
+       () => { expect(() => pipe.transform(<any>{})).toThrowError(); });
+  });
+
+  describe('TitleCasePipe', () => {
+    let pipe: TitleCasePipe;
+
+    beforeEach(() => { pipe = new TitleCasePipe(); });
+
+    it('should return titlecase', () => { expect(pipe.transform('foo')).toEqual('Foo'); });
+
+    it('should titlecase when there is a new value', () => {
+      expect(pipe.transform('bar')).toEqual('Bar');
+      expect(pipe.transform('foo')).toEqual('Foo');
+    });
+
+    it('should not support other objects',
+       () => { expect(() => pipe.transform(<any>{})).toThrowError(); });
+  });
+
+  describe('UpperCasePipe', () => {
+    let pipe: UpperCasePipe;
+
+    beforeEach(() => { pipe = new UpperCasePipe(); });
+
+    it('should return uppercase', () => { expect(pipe.transform('foo')).toEqual('FOO'); });
+
+    it('should uppercase when there is a new value', () => {
+      expect(pipe.transform('foo')).toEqual('FOO');
+      expect(pipe.transform('bar')).toEqual('BAR');
+    });
+
+    it('should not support other objects',
+       () => { expect(() => pipe.transform(<any>{})).toThrowError(); });
+  });
+}

modules/@angular/common/src/pipes/uppercase_pipe.ts

@@ -223,6 +223,11 @@ export declare class SlicePipe implements PipeTransform {
     transform(value: any, start: number, end?: number): any;
 }
 
+/** @stable */
+export declare class TitleCasePipe implements PipeTransform {
+    transform(value: string): string;
+}
+
 /** @stable */
 export declare class UpperCasePipe implements PipeTransform {
     transform(value: string): string;