Allow a single translation to be from multiple differently-named sources

pkg/intl/lib/generate_localized.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * This provides utilities for generating localized versions of
  * messages. It does not stand alone, but expects to be given
  * TranslatedMessage objects and generate code for a particular locale
  * based on them.
  *
@@ skipping 50 matching lines @@
  */
 abstract class TranslatedMessage {
   /**
    * The identifier for this message. In the simplest case, this is the name
    * parameter from the Intl.message call,
    * but it can be any identifier that this program and the output of the
    * translation can agree on as identifying a message.
    */
   final String id;
 
-  /** Our translated version of [originalMessage]. */
+  /** Our translated version of all the [originalMessages]. */
   final Message translated;
 
-  /** The original message that we are a translation of. */
-  MainMessage originalMessage;
+  /**
+   * The original messages that we are a translation of. There can
+   *  be more than one original message for the same translation.
+   */
+  List<MainMessage> originalMessages;
+
+  /**
+   * For backward compatibility, we still have the originalMessage API.
+   */
+  MainMessage get originalMessage => originalMessages.first;
+  set originalMessage(MainMessage m) => originalMessages = [m];
 
   TranslatedMessage(this.id, this.translated);
 
   Message get message => translated;
 
   toString() => id.toString();
 }
 
 /**
  * We can't use a hyphen in a Dart library name, so convert the locale
  * separator to an underscore.
  */
 String _libraryName(String x) => 'messages_' + x.replaceAll('-', '_');
 
 /**
  * Generate a file <[generated_file_prefix]>_messages_<[locale]>.dart
  * for the [translations] in [locale] and put it in [targetDir].
  */
 void generateIndividualMessageFile(String locale,
     Iterable<TranslatedMessage> translations, String targetDir) {
   var result = new StringBuffer();
   locale = new MainMessage().escapeAndValidateString(locale);
   result.write(prologue(locale));
   // Exclude messages with no translation and translations with no matching
   // original message (e.g. if we're using some messages from a larger catalog)
   var usableTranslations =  translations.where(
-      (each) => each.originalMessage != null && each.message != null).toList();
+      (each) => each.originalMessages != null && each.message != null).toList();
   for (var each in usableTranslations) {
-      each.originalMessage.addTranslation(locale, each.message);
+    for (var original in each.originalMessages) {
+      original.addTranslation(locale, each.message);
+    }
   }
   usableTranslations.sort((a, b) =>
-      a.originalMessage.name.compareTo(b.originalMessage.name));
+      a.originalMessages.first.name.compareTo(b.originalMessages.first.name));
   for (var translation in usableTranslations) {
-    result
-        ..write("  ")
-        ..write(translation.originalMessage.toCodeForLocale(locale))
-        ..write("\n\n");
+    for (var original in translation.originalMessages) {
+      result
+          ..write("  ")
+          ..write(original.toCodeForLocale(locale))
+          ..write("\n\n");
+    }
   }
   result.write("\n  final messages = const {\n");
   var entries = usableTranslations
-      .map((translation) => translation.originalMessage.name)
+      .expand((translation) => translation.originalMessages)
+      .map((original) => original.name)
       .map((name) => "    \"$name\" : $name");
   result
       ..write(entries.join(",\n"))
       ..write("\n  };\n}");
 
   new File(path.join(targetDir,"${generatedFilePrefix}messages_$locale.dart"))
       ..writeAsStringSync(result.toString());
 }
 
 /**
@@ skipping 98 matching lines @@
   return new Future.value(true);
 }
 
 MessageLookupByLibrary _findGeneratedMessagesFor(locale) {
   var actualLocale = Intl.verifiedLocale(locale, (x) => _findExact(x) != null,
       onFailure: (_) => null);
   if (actualLocale == null) return null;
   return _findExact(actualLocale);
 }
 """;