Internal change

PiperOrigin-RevId: 518316023

lib/acx_sharded_intl.dart

@@ -0,0 +1,101 @@
+/// This library provides storage for localized messages in a lookup table.
+/// This is used for optimizing localized string lookups for web
+/// development when using ACX sharded localization (go/acx-localization).
+
+/// This library relies on javascript features.
+
+/// Dart2js generates calls to this library when using sharded localization;
+/// clients shouldn't make the call to this library directly.
+
+library intl_message_table;
+
+import 'dart:convert';
+import 'dart:js_util' as js_util;
+
+/// Internal representation of a translated string; either a single string (for
+/// non-constructed strings) or an array of strings and argument indexes.
+/// For example, the constructed string 'My name is ${name}, how are you?'
+/// is represented as ['My name is ', 0, ', how are you?'].
+/// This representation matches the code generated by the 'generate_from_xtb'
+/// tool.
+class _Message {
+  // Each element is either a string or an integer representing the argument index.
+  final List<dynamic> values;
+
+  _Message(this.values);
+
+  _Message.fromString(String string) : this([string]);
+
+  // Most messages consist of only a single string; only constructed strings
+  // have more than one element. This function is for non-constructed strings.
+  String getString() {
+    return values.first.toString();
+  }
+
+  List<dynamic> getList() {
+    return values;
+  }
+}
+
+/// Functions for loading translations for messages based on an index.
+/// Each compilation unit registers the translations it needs in a field on the
+/// Dom under a unique id for its app as a json string. Messages are referenced
+/// by index in the code. When a message is referenced, the translations for
+/// that app are parsed and inserted into the table.
+class AcxIntlMessageTable {
+  // Indexed list of messages. If a message isn't yet loaded, the entry will be
+  // null.
+  static List<_Message?> _internalArray = [];
+
+  static String lookup(int id) {
+    return _lookupMessagebyId(id).getString();
+  }
+
+  static List<dynamic> lookupList(int id) => _lookupMessagebyId(id).getList();
+
+  static _Message? _getMessage(int id) =>
+      id < _internalArray.length ? _internalArray[id] : null;
+
+  static _Message _lookupMessagebyId(int id) {
+    var message = _getMessage(id);
+    if (message != null) {
+      return message;
+    }
+    // Copy outstanding messages locally
+    // TODO(b/274616739): Use appId provided by environment.
+    // Maybe something like:
+    //  const String.fromEnvironment('dart.dart2js.appid');
+    final appId = 'MyAppId';
+
+    for (var message in _popPendingTranslations(appId)) {
+      loadMessages(message);
+    }
+    message = _getMessage(id);
+    if (message == null) {
+      throw ArgumentError('Unable to locate string $id');
+    }
+    return message;
+  }
+
+  /// Translations for a language are lazily parsed into the map when requested on
+  /// a per-app basis.
+  static List<String> _popPendingTranslations(String appId) {
+    final result = js_util.getProperty<List<String>>(
+        js_util.getProperty(js_util.globalThis, r'$_intl_pending_translations'),
+        appId);
+    js_util.setProperty<List<String>>(
+        js_util.getProperty(js_util.globalThis, r'$_intl_pending_translations'),
+        appId, []);
+    return result;
+  }
+
+  static void loadMessages(String json_messages) {
+    var parsed = json.decode(json_messages);
+    parsed.forEach((index_string, message) {
+      int index = int.parse(index_string);
+      // Grow array to fit in new message.
+      if (index >= _internalArray.length) _internalArray.length = index + 1;
+      _internalArray[index] = _Message(message);
+    });
+  }
+}

test/acx_sharded_intl_test.dart

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+import 'package:intl/acx_sharded_intl.dart';
+import 'package:test/test.dart';
+import 'dart:js_util' as js_util;
+import 'dart:convert';
+
+void main() {
+  setUp(() {
+    final testStrings1 = {
+      '0': ['Test String 0'],
+      '1': ['Test String 1'],
+      '2': ['Test String 2']
+    };
+    final testStrings2 = {
+      '3': ['Test String 3'],
+      '4': ['Test String 4'],
+      '5': ['Test String 5'],
+      '6': ['Constructed ', 0, ' String 6']
+    };
+    final encoding1 = jsonEncode(testStrings1);
+    final encoding2 = jsonEncode(testStrings2);
+    js_util.setProperty<Object>(js_util.globalThis,
+        r'$_intl_pending_translations', js_util.newObject());
+    js_util.setProperty(
+        js_util.getProperty(js_util.globalThis, r'$_intl_pending_translations'),
+        'MyAppId',
+        [encoding1, encoding2]);
+  });
+  test('testIntlMessageTableLookup', () {
+    expect(AcxIntlMessageTable.lookup(1), equals('Test String 1'));
+    expect(AcxIntlMessageTable.lookup(5), equals('Test String 5'));
+    expect(AcxIntlMessageTable.lookup(5), equals('Test String 5'));
+    expect(AcxIntlMessageTable.lookupList(6),
+        equals(['Constructed ', 0, ' String 6']));
+  });
+}