fix(localize): render ICU placeholders in extracted translation files (#38484)

Previously placeholders were only rendered for dynamic interpolation
expressons in `$localize` tagged strings. But there are also potentially
dynamic values in ICU expressions too, so we need to render these as
placeholders when extracting i18n messages into translation files.

PR Close #38484

packages/localize/src/tools/src/extract/translation_files/icu_parsing.ts

@@ -0,0 +1,216 @@
+/**
+ * @license
+ * Copyright Google LLC 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
+ */
+
+/**
+ * Split the given `text` into an array of "static strings" and ICU "placeholder names".
+ *
+ * This is required because ICU expressions in `$localize` tagged messages may contain "dynamic"
+ * piece (e.g. interpolations or element markers). These markers need to be translated to
+ * placeholders in extracted translation files. So we must parse ICUs to identify them and separate
+ * them out so that the translation serializers can render them appropriately.
+ *
+ * An example of an ICU with interpolations:
+ *
+ * ```
+ * {VAR_PLURAL, plural, one {{INTERPOLATION}} other {{INTERPOLATION_1} post}}
+ * ```
+ *
+ * In this ICU, `INTERPOLATION` and `INTERPOLATION_1` are actually placeholders that will be
+ * replaced with dynamic content at runtime.
+ *
+ * Such placeholders are identifiable as text wrapped in curly braces, within an ICU case
+ * expression.
+ *
+ * To complicate matters, it is possible for ICUs to be nested indefinitely within each other. In
+ * such cases, the nested ICU expression appears enclosed in a set of curly braces in the same way
+ * as a placeholder. The nested ICU expressions can be differentiated from placeholders as they
+ * contain a comma `,`, which separates the ICU value from the ICU type.
+ *
+ * Furthermore, nested ICUs can have placeholders of their own, which need to be extracted.
+ *
+ * An example of a nested ICU containing its own placeholders:
+ *
+ * ```
+ * {VAR_SELECT_1, select,
+ *   invoice {Invoice for {INTERPOLATION}}
+ *   payment {{VAR_SELECT, select,
+ *     processor {Payment gateway}
+ *     other {{INTERPOLATION_1}}
+ *   }}
+ * ```
+ *
+ * @param text Text to be broken.
+ * @returns an array of strings, where
+ *  - even values are static strings (e.g. 0, 2, 4, etc)
+ *  - odd values are placeholder names (e.g. 1, 3, 5, etc)
+ */
+export function extractIcuPlaceholders(text: string): string[] {
+  const state = new StateStack();
+  const pieces = new IcuPieces();
+  const braces = /[{}]/g;
+
+  let lastPos = 0;
+  let match: RegExpMatchArray|null;
+  while (match = braces.exec(text)) {
+    if (match[0] == '{') {
+      state.enterBlock();
+    } else {
+      // We must have hit a `}`
+      state.leaveBlock();
+    }
+
+    if (state.getCurrent() === 'placeholder') {
+      const name = tryParsePlaceholder(text, braces.lastIndex);
+      if (name) {
+        // We found a placeholder so store it in the pieces;
+        // store the current static text (minus the opening curly brace);
+        // skip the closing brace and leave the placeholder block.
+        pieces.addText(text.substring(lastPos, braces.lastIndex - 1));
+        pieces.addPlaceholder(name);
+        braces.lastIndex += name.length + 1;
+        state.leaveBlock();
+      } else {
+        // This is not a placeholder, so it must be a nested ICU;
+        // store the current static text (including the opening curly brace).
+        pieces.addText(text.substring(lastPos, braces.lastIndex));
+        state.nestedIcu();
+      }
+    } else {
+      pieces.addText(text.substring(lastPos, braces.lastIndex));
+    }
+    lastPos = braces.lastIndex;
+  }
+
+  // Capture the last piece of text after the ICUs (if any).
+  pieces.addText(text.substring(lastPos));
+  return pieces.toArray();
+}
+
+/**
+ * A helper class to store the pieces ("static text" or "placeholder name") in an ICU.
+ */
+class IcuPieces {
+  private pieces: string[] = [''];
+
+  /**
+   * Add the given `text` to the current "static text" piece.
+   *
+   * Sequential calls to `addText()` will append to the current text piece.
+   */
+  addText(text: string): void {
+    this.pieces[this.pieces.length - 1] += text;
+  }
+
+  /**
+   * Add the given placeholder `name` to the stored pieces.
+   */
+  addPlaceholder(name: string): void {
+    this.pieces.push(name);
+    this.pieces.push('');
+  }
+
+  /**
+   * Return the stored pieces as an array of strings.
+   *
+   * Even values are static strings (e.g. 0, 2, 4, etc)
+   * Odd values are placeholder names (e.g. 1, 3, 5, etc)
+   */
+  toArray(): string[] {
+    return this.pieces;
+  }
+}
+
+/**
+ * A helper class to track the current state of parsing the strings for ICU placeholders.
+ *
+ * State changes happen when we enter or leave a curly brace block.
+ * Since ICUs can be nested the state is stored as a stack.
+ */
+class StateStack {
+  private stack: ParserState[] = [];
+
+  /**
+   * Update the state upon entering a block.
+   *
+   * The new state is computed from the current state and added to the stack.
+   */
+  enterBlock(): void {
+    const current = this.getCurrent();
+    switch (current) {
+      case 'icu':
+        this.stack.push('case');
+        break;
+      case 'case':
+        this.stack.push('placeholder');
+        break;
+      case 'placeholder':
+        this.stack.push('case');
+        break;
+      default:
+        this.stack.push('icu');
+        break;
+    }
+  }
+
+  /**
+   * Update the state upon leaving a block.
+   *
+   * The previous state is popped off the stack.
+   */
+  leaveBlock(): ParserState {
+    return this.stack.pop();
+  }
+
+  /**
+   * Update the state upon arriving at a nested ICU.
+   *
+   * In this case, the current state of "placeholder" is incorrect, so this is popped off and the
+   * correct "icu" state is stored.
+   */
+  nestedIcu(): void {
+    const current = this.stack.pop();
+    assert(current === 'placeholder', 'A nested ICU must replace a placeholder but got ' + current);
+    this.stack.push('icu');
+  }
+
+  /**
+   * Get the current (most recent) state from the stack.
+   */
+  getCurrent() {
+    return this.stack[this.stack.length - 1];
+  }
+}
+type ParserState = 'icu'|'case'|'placeholder'|undefined;
+
+/**
+ * Attempt to parse a simple placeholder name from a curly braced block.
+ *
+ * If the block contains a comma `,` then it cannot be a placeholder - and is probably a nest ICU
+ * instead.
+ *
+ * @param text the whole string that is being parsed.
+ * @param start the index of the character in the `text` string where this placeholder may start.
+ * @returns the placeholder name or `null` if it is not a placeholder.
+ */
+function tryParsePlaceholder(text: string, start: number): string|null {
+  for (let i = start; i < text.length; i++) {
+    if (text[i] === ',') {
+      break;
+    }
+    if (text[i] === '}') {
+      return text.substring(start, i);
+    }
+  }
+  return null;
+}
+
+function assert(test: boolean, message: string): void {
+  if (!test) {
+    throw new Error('Assertion failure: ' + message);
+  }
+}

packages/localize/src/tools/src/extract/translation_files/xliff1_translation_serializer.ts

@@ -8,6 +8,7 @@
 import {AbsoluteFsPath, relative} from '@angular/compiler-cli/src/ngtsc/file_system';
 import {ɵParsedMessage, ɵSourceLocation} from '@angular/localize';
 
+import {extractIcuPlaceholders} from './icu_parsing';
 import {TranslationSerializer} from './translation_serializer';
 import {XmlFile} from './xml_file';
 
@@ -63,11 +64,22 @@ export class Xliff1TranslationSerializer implements TranslationSerializer {
   }
 
   private serializeMessage(xml: XmlFile, message: ɵParsedMessage): void {
-    xml.text(message.messageParts[0]);
+    const length = message.messageParts.length - 1;
-    for (let i = 1; i < message.messageParts.length; i++) {
+    for (let i = 0; i < length; i++) {
-      xml.startTag('x', {id: message.placeholderNames[i - 1]}, {selfClosing: true});
+      this.serializeTextPart(xml, message.messageParts[i]);
-      xml.text(message.messageParts[i]);
+      xml.startTag('x', {id: message.placeholderNames[i]}, {selfClosing: true});
     }
+    this.serializeTextPart(xml, message.messageParts[length]);
+  }
+
+  private serializeTextPart(xml: XmlFile, text: string): void {
+    const pieces = extractIcuPlaceholders(text);
+    const length = pieces.length - 1;
+    for (let i = 0; i < length; i += 2) {
+      xml.text(pieces[i]);
+      xml.startTag('x', {id: pieces[i + 1]}, {selfClosing: true});
+    }
+    xml.text(pieces[length]);
   }
 
   private serializeNote(xml: XmlFile, name: string, value: string): void {

packages/localize/src/tools/src/extract/translation_files/xliff2_translation_serializer.ts

@@ -8,6 +8,7 @@
 import {AbsoluteFsPath, relative} from '@angular/compiler-cli/src/ngtsc/file_system';
 import {ɵParsedMessage} from '@angular/localize';
 
+import {extractIcuPlaceholders} from './icu_parsing';
 import {TranslationSerializer} from './translation_serializer';
 import {XmlFile} from './xml_file';
 
@@ -22,6 +23,7 @@ const MAX_LEGACY_XLIFF_2_MESSAGE_LENGTH = 20;
  * @see Xliff2TranslationParser
  */
 export class Xliff2TranslationSerializer implements TranslationSerializer {
+  private currentPlaceholderId = 0;
   constructor(
       private sourceLocale: string, private basePath: AbsoluteFsPath,
       private useLegacyIds: boolean) {}
@@ -74,21 +76,38 @@ export class Xliff2TranslationSerializer implements TranslationSerializer {
   }
 
   private serializeMessage(xml: XmlFile, message: ɵParsedMessage): void {
-    xml.text(message.messageParts[0]);
+    this.currentPlaceholderId = 0;
-    for (let i = 1; i < message.messageParts.length; i++) {
+    const length = message.messageParts.length - 1;
-      const placeholderName = message.placeholderNames[i - 1];
+    for (let i = 0; i < length; i++) {
+      this.serializeTextPart(xml, message.messageParts[i]);
+      this.serializePlaceholder(xml, message.placeholderNames[i]);
+    }
+    this.serializeTextPart(xml, message.messageParts[length]);
+  }
+
+  private serializeTextPart(xml: XmlFile, text: string): void {
+    const pieces = extractIcuPlaceholders(text);
+    const length = pieces.length - 1;
+    for (let i = 0; i < length; i += 2) {
+      xml.text(pieces[i]);
+      this.serializePlaceholder(xml, pieces[i + 1]);
+    }
+    xml.text(pieces[length]);
+  }
+
+  private serializePlaceholder(xml: XmlFile, placeholderName: string): void {
     if (placeholderName.startsWith('START_')) {
       xml.startTag('pc', {
-          id: `${i}`,
+        id: `${this.currentPlaceholderId++}`,
         equivStart: placeholderName,
         equivEnd: placeholderName.replace(/^START/, 'CLOSE')
       });
     } else if (placeholderName.startsWith('CLOSE_')) {
       xml.endTag('pc');
     } else {
-        xml.startTag('ph', {id: `${i}`, equiv: placeholderName}, {selfClosing: true});
+      xml.startTag(
-      }
+          'ph', {id: `${this.currentPlaceholderId++}`, equiv: placeholderName},
-      xml.text(message.messageParts[i]);
+          {selfClosing: true});
     }
   }
 

packages/localize/src/tools/src/extract/translation_files/xmb_translation_serializer.ts

@@ -8,6 +8,7 @@
 import {AbsoluteFsPath, relative} from '@angular/compiler-cli/src/ngtsc/file_system';
 import {ɵParsedMessage, ɵSourceLocation} from '@angular/localize';
 
+import {extractIcuPlaceholders} from './icu_parsing';
 import {TranslationSerializer} from './translation_serializer';
 import {XmlFile} from './xml_file';
 
@@ -77,11 +78,22 @@ export class XmbTranslationSerializer implements TranslationSerializer {
   }
 
   private serializeMessage(xml: XmlFile, message: ɵParsedMessage): void {
-    xml.text(message.messageParts[0]);
+    const length = message.messageParts.length - 1;
-    for (let i = 1; i < message.messageParts.length; i++) {
+    for (let i = 0; i < length; i++) {
-      xml.startTag('ph', {name: message.placeholderNames[i - 1]}, {selfClosing: true});
+      this.serializeTextPart(xml, message.messageParts[i]);
-      xml.text(message.messageParts[i]);
+      xml.startTag('ph', {name: message.placeholderNames[i]}, {selfClosing: true});
     }
+    this.serializeTextPart(xml, message.messageParts[length]);
+  }
+
+  private serializeTextPart(xml: XmlFile, text: string): void {
+    const pieces = extractIcuPlaceholders(text);
+    const length = pieces.length - 1;
+    for (let i = 0; i < length; i += 2) {
+      xml.text(pieces[i]);
+      xml.startTag('ph', {name: pieces[i + 1]}, {selfClosing: true});
+    }
+    xml.text(pieces[length]);
   }
 
   /**

packages/localize/src/tools/test/extract/integration/main_spec.ts

@@ -175,12 +175,12 @@ runInEachFileSystem(() => {
         `  <file>`,
         `    <unit id="3291030485717846467">`,
         `      <segment>`,
-        `        <source>Hello, <ph id="1" equiv="PH"/>!</source>`,
+        `        <source>Hello, <ph id="0" equiv="PH"/>!</source>`,
         `      </segment>`,
         `    </unit>`,
         `    <unit id="8669027859022295761">`,
         `      <segment>`,
-        `        <source>try<ph id="1" equiv="PH"/>me</source>`,
+        `        <source>try<ph id="0" equiv="PH"/>me</source>`,
         `      </segment>`,
         `    </unit>`,
         `  </file>`,

packages/localize/src/tools/test/extract/translation_files/icu_parsing_spec.ts

@@ -0,0 +1,76 @@
+/**
+ * @license
+ * Copyright Google LLC 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 {extractIcuPlaceholders} from '../../../src/extract/translation_files/icu_parsing';
+
+describe('extractIcuPlaceholders()', () => {
+  it('should return a single string if there is no ICU', () => {
+    expect(extractIcuPlaceholders('')).toEqual(['']);
+    expect(extractIcuPlaceholders('some text')).toEqual(['some text']);
+    expect(extractIcuPlaceholders('some } text')).toEqual(['some } text']);
+    expect(extractIcuPlaceholders('this is {not an ICU}')).toEqual(['this is {not an ICU}']);
+  });
+
+  it('should return a single string if there are no ICU placeholders', () => {
+    expect(extractIcuPlaceholders('{VAR_PLURAL, plural, one {SOME} few {FEW} other {OTHER}}'))
+        .toEqual(['{VAR_PLURAL, plural, one {SOME} few {FEW} other {OTHER}}']);
+    expect(extractIcuPlaceholders('{VAR_SELECT, select, male {HE} female {SHE} other {XE}}'))
+        .toEqual(['{VAR_SELECT, select, male {HE} female {SHE} other {XE}}']);
+  });
+
+  it('should split out simple interpolation placeholders', () => {
+    expect(
+        extractIcuPlaceholders(
+            '{VAR_PLURAL, plural, one {{INTERPOLATION}} few {pre {INTERPOLATION_1}} other {{INTERPOLATION_2} post}}'))
+        .toEqual([
+          '{VAR_PLURAL, plural, one {',
+          'INTERPOLATION',
+          '} few {pre ',
+          'INTERPOLATION_1',
+          '} other {',
+          'INTERPOLATION_2',
+          ' post}}',
+        ]);
+  });
+
+  it('should split out element placeholders', () => {
+    expect(
+        extractIcuPlaceholders(
+            '{VAR_PLURAL, plural, one {{START_BOLD_TEXT}something bold{CLOSE_BOLD_TEXT}} other {pre {START_TAG_SPAN}middle{CLOSE_TAG_SPAN} post}}'))
+        .toEqual([
+          '{VAR_PLURAL, plural, one {',
+          'START_BOLD_TEXT',
+          'something bold',
+          'CLOSE_BOLD_TEXT',
+          '} other {pre ',
+          'START_TAG_SPAN',
+          'middle',
+          'CLOSE_TAG_SPAN',
+          ' post}}',
+        ]);
+  });
+
+  it('should handle nested ICUs', () => {
+    expect(extractIcuPlaceholders([
+      '{VAR_SELECT_1, select,',
+      '  invoice {Invoice for {INTERPOLATION}}',
+      '  payment {{VAR_SELECT, select,',
+      '    processor {Payment gateway}',
+      '    other {{INTERPOLATION_1}}',
+      '  }}',
+      '}',
+    ].join('\n')))
+        .toEqual([
+          '{VAR_SELECT_1, select,\n  invoice {Invoice for ',
+          'INTERPOLATION',
+          '}\n  payment {{VAR_SELECT, select,\n    processor {Payment gateway}\n    other {',
+          'INTERPOLATION_1',
+          '}\n  }}\n}',
+        ]);
+  });
+});

packages/localize/src/tools/test/extract/translation_files/json_translation_serializer_spec.ts

@@ -22,6 +22,19 @@ describe('JsonTranslationSerializer', () => {
         mockMessage('13579', ['', 'b', ''], ['START_BOLD_TEXT', 'CLOSE_BOLD_TEXT'], {}),
         mockMessage('24680', ['a'], [], {meaning: 'meaning', description: 'and description'}),
         mockMessage('80808', ['multi\nlines'], [], {}),
+        mockMessage('90000', ['<escape', 'me>'], ['double-quotes-"'], {}),
+        mockMessage(
+            '100000',
+            [
+              'pre-ICU {VAR_SELECT, select, a {a} b {{INTERPOLATION}} c {pre {INTERPOLATION_1} post}} post-ICU'
+            ],
+            [], {}),
+        mockMessage(
+            '100001',
+            [
+              '{VAR_PLURAL, plural, one {{START_BOLD_TEXT}something bold{CLOSE_BOLD_TEXT}} other {pre {START_TAG_SPAN}middle{CLOSE_TAG_SPAN} post}}'
+            ],
+            [], {}),
       ];
       const serializer = new SimpleJsonTranslationSerializer('xx');
       const output = serializer.serialize(messages);
@@ -33,7 +46,10 @@ describe('JsonTranslationSerializer', () => {
         `    "13579": "{$START_BOLD_TEXT}b{$CLOSE_BOLD_TEXT}",`,
         `    "24680": "a",`,
         `    "67890": "a{$START_TAG_SPAN}{$CLOSE_TAG_SPAN}c",`,
-        `    "80808": "multi\\nlines"`,
+        `    "80808": "multi\\nlines",`,
+        `    "90000": "<escape{$double-quotes-\\"}me>",`,
+        `    "100000": "pre-ICU {VAR_SELECT, select, a {a} b {{INTERPOLATION}} c {pre {INTERPOLATION_1} post}} post-ICU",`,
+        `    "100001": "{VAR_PLURAL, plural, one {{START_BOLD_TEXT}something bold{CLOSE_BOLD_TEXT}} other {pre {START_TAG_SPAN}middle{CLOSE_TAG_SPAN} post}}"`,
         `  }`,
         `}`,
       ].join('\n'));

packages/localize/src/tools/test/extract/translation_files/xliff1_translation_serializer_spec.ts

@@ -34,7 +34,19 @@ runInEachFileSystem(() => {
             mockMessage('13579', ['', 'b', ''], ['START_BOLD_TEXT', 'CLOSE_BOLD_TEXT'], {}),
             mockMessage('24680', ['a'], [], {meaning: 'meaning', description: 'and description'}),
             mockMessage('80808', ['multi\nlines'], [], {}),
-            mockMessage('90000', ['<escape', 'me>'], ['double-quotes-"'], {})
+            mockMessage('90000', ['<escape', 'me>'], ['double-quotes-"'], {}),
+            mockMessage(
+                '100000',
+                [
+                  'pre-ICU {VAR_SELECT, select, a {a} b {{INTERPOLATION}} c {pre {INTERPOLATION_1} post}} post-ICU'
+                ],
+                [], {}),
+            mockMessage(
+                '100001',
+                [
+                  '{VAR_PLURAL, plural, one {{START_BOLD_TEXT}something bold{CLOSE_BOLD_TEXT}} other {pre {START_TAG_SPAN}middle{CLOSE_TAG_SPAN} post}}'
+                ],
+                [], {}),
           ];
           const serializer =
               new Xliff1TranslationSerializer('xx', absoluteFrom('/project'), useLegacyIds);
@@ -73,6 +85,12 @@ runInEachFileSystem(() => {
             `      <trans-unit id="90000" datatype="html">`,
             `        <source>&lt;escape<x id="double-quotes-&quot;"/>me&gt;</source>`,
             `      </trans-unit>`,
+            `      <trans-unit id="100000" datatype="html">`,
+            `        <source>pre-ICU {VAR_SELECT, select, a {a} b {<x id="INTERPOLATION"/>} c {pre <x id="INTERPOLATION_1"/> post}} post-ICU</source>`,
+            `      </trans-unit>`,
+            `      <trans-unit id="100001" datatype="html">`,
+            `        <source>{VAR_PLURAL, plural, one {<x id="START_BOLD_TEXT"/>something bold<x id="CLOSE_BOLD_TEXT"/>} other {pre <x id="START_TAG_SPAN"/>middle<x id="CLOSE_TAG_SPAN"/> post}}</source>`,
+            `      </trans-unit>`,
             `    </body>`,
             `  </file>`,
             `</xliff>\n`,

packages/localize/src/tools/test/extract/translation_files/xliff2_translation_serializer_spec.ts

@@ -40,7 +40,19 @@ runInEachFileSystem(() => {
             mockMessage('13579', ['', 'b', ''], ['START_BOLD_TEXT', 'CLOSE_BOLD_TEXT'], {}),
             mockMessage('24680', ['a'], [], {meaning: 'meaning', description: 'and description'}),
             mockMessage('80808', ['multi\nlines'], [], {}),
-            mockMessage('90000', ['<escape', 'me>'], ['double-quotes-"'], {})
+            mockMessage('90000', ['<escape', 'me>'], ['double-quotes-"'], {}),
+            mockMessage(
+                '100000',
+                [
+                  'pre-ICU {VAR_SELECT, select, a {a} b {{INTERPOLATION}} c {pre {INTERPOLATION_1} post}} post-ICU'
+                ],
+                [], {}),
+            mockMessage(
+                '100001',
+                [
+                  '{VAR_PLURAL, plural, one {{START_BOLD_TEXT}something bold{CLOSE_BOLD_TEXT}} other {pre {START_TAG_SPAN}middle{CLOSE_TAG_SPAN} post}}'
+                ],
+                [], {}),
           ];
           const serializer =
               new Xliff2TranslationSerializer('xx', absoluteFrom('/project'), useLegacyIds);
@@ -55,7 +67,7 @@ runInEachFileSystem(() => {
             `        <note category="meaning">some meaning</note>`,
             `      </notes>`,
             `      <segment>`,
-            `        <source>a<ph id="1" equiv="PH"/>b<ph id="2" equiv="PH_1"/>c</source>`,
+            `        <source>a<ph id="0" equiv="PH"/>b<ph id="1" equiv="PH_1"/>c</source>`,
             `      </segment>`,
             `    </unit>`,
             `    <unit id="67890">`,
@@ -64,12 +76,12 @@ runInEachFileSystem(() => {
             `        <note category="description">some description</note>`,
             `      </notes>`,
             `      <segment>`,
-            `        <source>a<pc id="1" equivStart="START_TAG_SPAN" equivEnd="CLOSE_TAG_SPAN"></pc>c</source>`,
+            `        <source>a<pc id="0" equivStart="START_TAG_SPAN" equivEnd="CLOSE_TAG_SPAN"></pc>c</source>`,
             `      </segment>`,
             `    </unit>`,
             `    <unit id="13579">`,
             `      <segment>`,
-            `        <source><pc id="1" equivStart="START_BOLD_TEXT" equivEnd="CLOSE_BOLD_TEXT">b</pc></source>`,
+            `        <source><pc id="0" equivStart="START_BOLD_TEXT" equivEnd="CLOSE_BOLD_TEXT">b</pc></source>`,
             `      </segment>`,
             `    </unit>`,
             `    <unit id="24680">`,
@@ -89,7 +101,17 @@ runInEachFileSystem(() => {
             `    </unit>`,
             `    <unit id="90000">`,
             `      <segment>`,
-            `        <source>&lt;escape<ph id="1" equiv="double-quotes-&quot;"/>me&gt;</source>`,
+            `        <source>&lt;escape<ph id="0" equiv="double-quotes-&quot;"/>me&gt;</source>`,
+            `      </segment>`,
+            `    </unit>`,
+            `    <unit id="100000">`,
+            `      <segment>`,
+            `        <source>pre-ICU {VAR_SELECT, select, a {a} b {<ph id="0" equiv="INTERPOLATION"/>} c {pre <ph id="1" equiv="INTERPOLATION_1"/> post}} post-ICU</source>`,
+            `      </segment>`,
+            `    </unit>`,
+            `    <unit id="100001">`,
+            `      <segment>`,
+            `        <source>{VAR_PLURAL, plural, one {<pc id="0" equivStart="START_BOLD_TEXT" equivEnd="CLOSE_BOLD_TEXT">something bold</pc>} other {pre <pc id="1" equivStart="START_TAG_SPAN" equivEnd="CLOSE_TAG_SPAN">middle</pc> post}}</source>`,
             `      </segment>`,
             `    </unit>`,
             `  </file>`,

packages/localize/src/tools/test/extract/translation_files/xmb_translation_serializer_spec.ts

@@ -30,6 +30,18 @@ runInEachFileSystem(() => {
             mockMessage('24680', ['a'], [], {meaning: 'meaning', description: 'and description'}),
             mockMessage('80808', ['multi\nlines'], [], {}),
             mockMessage('90000', ['<escape', 'me>'], ['double-quotes-"'], {}),
+            mockMessage(
+                '100000',
+                [
+                  'pre-ICU {VAR_SELECT, select, a {a} b {{INTERPOLATION}} c {pre {INTERPOLATION_1} post}} post-ICU'
+                ],
+                [], {}),
+            mockMessage(
+                '100001',
+                [
+                  '{VAR_PLURAL, plural, one {{START_BOLD_TEXT}something bold{CLOSE_BOLD_TEXT}} other {pre {START_TAG_SPAN}middle{CLOSE_TAG_SPAN} post}}'
+                ],
+                [], {}),
           ];
           const serializer = new XmbTranslationSerializer(absoluteFrom('/project'), useLegacyIds);
           const output = serializer.serialize(messages);
@@ -44,6 +56,8 @@ runInEachFileSystem(() => {
             `  <msg id="24680" desc="and description" meaning="meaning">a</msg>`,
             `  <msg id="80808">multi`, `lines</msg>`,
             `  <msg id="90000">&lt;escape<ph name="double-quotes-&quot;"/>me&gt;</msg>`,
+            `  <msg id="100000">pre-ICU {VAR_SELECT, select, a {a} b {<ph name="INTERPOLATION"/>} c {pre <ph name="INTERPOLATION_1"/> post}} post-ICU</msg>`,
+            `  <msg id="100001">{VAR_PLURAL, plural, one {<ph name="START_BOLD_TEXT"/>something bold<ph name="CLOSE_BOLD_TEXT"/>} other {pre <ph name="START_TAG_SPAN"/>middle<ph name="CLOSE_TAG_SPAN"/> post}}</msg>`,
             `</messagebundle>\n`
           ].join('\n'));
         });