feat(ivy): i18n - render legacy message ids in $localize if requested (#32937)

The `$localize` library uses a new message digest function for
computing message ids. This means that translations in legacy
translation files will no longer match the message ids in the code
and so will not be translated.

This commit adds the ability to specify the format of your legacy
translation files, so that the appropriate message id can be rendered
in the `$localize` tagged strings. This results in larger code size
and requires that all translations are in the legacy format.

Going forward the developer should migrate their translation files
to use the new message id format.

PR Close #32937

packages/compiler/src/i18n/digest.ts

@@ -10,15 +10,31 @@ import {newArray, utf8Encode} from '../util';
 
 import * as i18n from './i18n_ast';
 
+/**
+ * Return the message id or compute it using the XLIFF1 digest.
+ */
 export function digest(message: i18n.Message): string {
-  return message.id || sha1(serializeNodes(message.nodes).join('') + `[${message.meaning}]`);
+  return message.id || computeDigest(message);
 }
 
-export function decimalDigest(message: i18n.Message): string {
-  if (message.id) {
-    return message.id;
-  }
+/**
+ * Compute the message id using the XLIFF1 digest.
+ */
+export function computeDigest(message: i18n.Message): string {
+  return sha1(serializeNodes(message.nodes).join('') + `[${message.meaning}]`);
+}
 
+/**
+ * Return the message id or compute it using the XLIFF2/XMB/$localize digest.
+ */
+export function decimalDigest(message: i18n.Message): string {
+  return message.id || computeDecimalDigest(message);
+}
+
+/**
+ * Compute the message id using the XLIFF2/XMB/$localize digest.
+ */
+export function computeDecimalDigest(message: i18n.Message): string {
   const visitor = new _SerializerIgnoreIcuExpVisitor();
   const parts = message.nodes.map(a => a.visit(visitor, null));
   return computeMsgId(parts.join(''), message.meaning);

packages/compiler/src/i18n/i18n_ast.ts

@@ -11,6 +11,8 @@ import {ParseSourceSpan} from '../parse_util';
 export class Message {
   sources: MessageSpan[];
   id: string = this.customId;
+  /** The id to use if there is no custom id and if `i18nLegacyMessageIdFormat` is true */
+  legacyId?: string = '';
 
   /**
    * @param nodes message AST
@@ -18,7 +20,7 @@ export class Message {
    * @param placeholderToMessage maps placeholder names to messages (used for nested ICU messages)
    * @param meaning
    * @param description
-   * @param id
+   * @param customId
    */
   constructor(
       public nodes: Node[], public placeholders: {[phName: string]: string},

packages/compiler/src/render3/view/i18n/meta.ts

@@ -6,12 +6,11 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {decimalDigest} from '../../../i18n/digest';
+import {computeDecimalDigest, computeDigest, decimalDigest} from '../../../i18n/digest';
 import * as i18n from '../../../i18n/i18n_ast';
 import {createI18nMessageFactory} from '../../../i18n/i18n_parser';
 import * as html from '../../../ml_parser/ast';
 import {DEFAULT_INTERPOLATION_CONFIG, InterpolationConfig} from '../../../ml_parser/interpolation_config';
-import {ParseTreeResult} from '../../../ml_parser/parser';
 import * as o from '../../../output/output_ast';
 
 import {I18N_ATTR, I18N_ATTR_PREFIX, hasI18nAttrs, icuFromI18nMessage} from './util';
@@ -19,6 +18,7 @@ import {I18N_ATTR, I18N_ATTR_PREFIX, hasI18nAttrs, icuFromI18nMessage} from './u
 export type I18nMeta = {
   id?: string,
   customId?: string,
+  legacyId?: string,
   description?: string,
   meaning?: string
 };
@@ -51,6 +51,19 @@ export class I18nMetaVisitor implements html.Visitor {
       // generate (or restore) message id if not specified in template
       message.id = typeof meta !== 'string' && (meta as i18n.Message).id || decimalDigest(message);
     }
+
+    if (this.i18nLegacyMessageIdFormat === 'xlf') {
+      message.legacyId = computeDigest(message);
+    } else if (
+        this.i18nLegacyMessageIdFormat === 'xlf2' || this.i18nLegacyMessageIdFormat === 'xmb') {
+      message.legacyId = computeDecimalDigest(message);
+    } else if (typeof meta !== 'string') {
+      // This occurs if we are doing the 2nd pass after whitespace removal
+      // In that case we want to reuse the legacy message generated in the 1st pass
+      // See `parseTemplate()` in `packages/compiler/src/render3/view/template.ts`
+      message.legacyId = (meta as i18n.Message).legacyId;
+    }
+
     return message;
   }
 
@@ -130,6 +143,7 @@ export function metaFromI18nMessage(message: i18n.Message, id: string | null = n
   return {
     id: typeof id === 'string' ? id : message.id || '',
     customId: message.customId,
+    legacyId: message.legacyId,
     meaning: message.meaning || '',
     description: message.description || ''
   };
@@ -180,8 +194,8 @@ export function serializeI18nHead(meta: I18nMeta, messagePart: string): string {
   if (meta.meaning) {
     metaBlock = `${meta.meaning}|${metaBlock}`;
   }
-  if (meta.customId) {
-    metaBlock = `${metaBlock}@@${meta.customId}`;
+  if (meta.customId || meta.legacyId) {
+    metaBlock = `${metaBlock}@@${meta.customId || meta.legacyId}`;
   }
   if (metaBlock === '') {
     // There is no metaBlock, so we must ensure that any starting colon is escaped.

packages/compiler/src/render3/view/template.ts

@@ -1905,6 +1905,19 @@ export interface ParseTemplateOptions {
    * included in source-map segments.  A common example is whitespace.
    */
   leadingTriviaChars?: string[];
+
+  /**
+   * Render `$localize` message ids with the specified legacy format (xlf, xlf2 or xmb).
+   *
+   * Use this option when use are using the `$localize` based localization messages but
+   * have not migrated the translation files to use the new `$localize` message id format.
+   *
+   * @deprecated
+   * `i18nLegacyMessageIdFormat` should only be used while migrating from legacy message id
+   * formatted translation files and will be removed at the same time as ViewEngine support is
+   * removed.
+   */
+  i18nLegacyMessageIdFormat?: string;
 }
 
 /**
@@ -1917,7 +1930,7 @@ export interface ParseTemplateOptions {
 export function parseTemplate(
     template: string, templateUrl: string, options: ParseTemplateOptions = {}):
     {errors?: ParseError[], nodes: t.Node[], styleUrls: string[], styles: string[]} {
-  const {interpolationConfig, preserveWhitespaces} = options;
+  const {interpolationConfig, preserveWhitespaces, i18nLegacyMessageIdFormat} = options;
   const bindingParser = makeBindingParser(interpolationConfig);
   const htmlParser = new HtmlParser();
   const parseResult = htmlParser.parse(
@@ -1934,8 +1947,9 @@ export function parseTemplate(
   // before we run whitespace removal process, because existing i18n
   // extraction process (ng xi18n) relies on a raw content to generate
   // message ids
-  rootNodes =
-      html.visitAll(new I18nMetaVisitor(interpolationConfig, !preserveWhitespaces), rootNodes);
+  rootNodes = html.visitAll(
+      new I18nMetaVisitor(interpolationConfig, !preserveWhitespaces, i18nLegacyMessageIdFormat),
+      rootNodes);
 
   if (!preserveWhitespaces) {
     rootNodes = html.visitAll(new WhitespaceVisitor(), rootNodes);