refactor(compiler): Load the translation bundle only once in the i18n html parser (#14362)

fixes #14322

modules/@angular/compiler/src/i18n/i18n_html_parser.ts

@@ -24,11 +24,18 @@ export class I18NHtmlParser implements HtmlParser {
   // @override
   getTagDefinition: any;
 
+  private _translationBundle: TranslationBundle;
+
   constructor(
-      private _htmlParser: HtmlParser, private _translations?: string,
-      private _translationsFormat?: string,
-      private _missingTranslation: MissingTranslationStrategy = MissingTranslationStrategy.Warning,
-      private _console?: Console) {}
+      private _htmlParser: HtmlParser, translations?: string, translationsFormat?: string,
+      missingTranslation: MissingTranslationStrategy = MissingTranslationStrategy.Warning,
+      console?: Console) {
+    if (translations) {
+      const serializer = createSerializer(translationsFormat);
+      this._translationBundle =
+          TranslationBundle.load(translations, 'i18n', serializer, missingTranslation, console);
+    }
+  }
 
   parse(
       source: string, url: string, parseExpansionForms: boolean = false,
@@ -36,26 +43,22 @@ export class I18NHtmlParser implements HtmlParser {
     const parseResult =
         this._htmlParser.parse(source, url, parseExpansionForms, interpolationConfig);
 
-    if (!this._translations || this._translations === '') {
+    if (!this._translationBundle) {
       // Do not enable i18n when no translation bundle is provided
       return parseResult;
     }
 
-    // TODO(vicb): add support for implicit tags / attributes
-
     if (parseResult.errors.length) {
       return new ParseTreeResult(parseResult.rootNodes, parseResult.errors);
     }
 
-    const serializer = this._createSerializer();
-    const translationBundle = TranslationBundle.load(
-        this._translations, url, serializer, this._missingTranslation, this._console);
-
-    return mergeTranslations(parseResult.rootNodes, translationBundle, interpolationConfig, [], {});
+    return mergeTranslations(
+        parseResult.rootNodes, this._translationBundle, interpolationConfig, [], {});
   }
+}
 
-  private _createSerializer(): Serializer {
-    const format = (this._translationsFormat || 'xlf').toLowerCase();
+function createSerializer(format?: string): Serializer {
+  format = (format || 'xlf').toLowerCase();
 
   switch (format) {
     case 'xmb':
@@ -67,5 +70,4 @@ export class I18NHtmlParser implements HtmlParser {
     default:
       return new Xliff();
   }
-  }
 }

modules/@angular/compiler/test/i18n/i18n_html_parser_spec.ts

@@ -0,0 +1,47 @@
+/**
+ * @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 {I18NHtmlParser} from '@angular/compiler/src/i18n/i18n_html_parser';
+import {TranslationBundle} from '@angular/compiler/src/i18n/translation_bundle';
+import {HtmlParser} from '@angular/compiler/src/ml_parser/html_parser';
+import {ParseTreeResult} from '@angular/compiler/src/ml_parser/parser';
+
+export function main() {
+  describe('I18N html parser', () => {
+
+    it('should return the html nodes when no translations are given', () => {
+      const htmlParser = new HtmlParser();
+      const i18nHtmlParser = new I18NHtmlParser(htmlParser);
+      const ptResult = new ParseTreeResult([], []);
+
+      spyOn(htmlParser, 'parse').and.returnValue(ptResult);
+      spyOn(i18nHtmlParser, 'parse').and.callThrough();
+
+      expect(i18nHtmlParser.parse('source', 'url')).toBe(ptResult);
+
+      expect(htmlParser.parse).toHaveBeenCalledTimes(1);
+      expect(htmlParser.parse)
+          .toHaveBeenCalledWith('source', 'url', jasmine.anything(), jasmine.anything());
+    });
+
+    // https://github.com/angular/angular/issues/14322
+    it('should parse the translations only once', () => {
+      const transBundle = new TranslationBundle({}, () => 'id');
+      spyOn(TranslationBundle, 'load').and.returnValue(transBundle);
+      const htmlParser = new HtmlParser();
+      const i18nHtmlParser = new I18NHtmlParser(htmlParser, 'translations');
+
+      expect(TranslationBundle.load).toHaveBeenCalledTimes(1);
+
+      i18nHtmlParser.parse('source', 'url');
+      i18nHtmlParser.parse('source', 'url');
+      expect(TranslationBundle.load).toHaveBeenCalledTimes(1);
+    });
+
+  });
+}

modules/@angular/compiler/test/i18n/i18n_parser_spec.ts

@@ -6,13 +6,11 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {digest} from '@angular/compiler/src/i18n/digest';
+import {digest, serializeNodes} from '@angular/compiler/src/i18n/digest';
 import {extractMessages} from '@angular/compiler/src/i18n/extractor_merger';
 import {Message} from '@angular/compiler/src/i18n/i18n_ast';
-
-import {serializeNodes} from '../../src/i18n/digest';
-import {HtmlParser} from '../../src/ml_parser/html_parser';
-import {DEFAULT_INTERPOLATION_CONFIG} from '../../src/ml_parser/interpolation_config';
+import {HtmlParser} from '@angular/compiler/src/ml_parser/html_parser';
+import {DEFAULT_INTERPOLATION_CONFIG} from '@angular/compiler/src/ml_parser/interpolation_config';
 
 export function main() {
   describe('I18nParser', () => {