Adds facilities for extracting Intl.message calls and generating code from translations

pkg/intl/lib/generate_localized.dart

Index: pkg/intl/lib/generate_localized.dart
diff --git a/pkg/intl/lib/generate_localized.dart b/pkg/intl/lib/generate_localized.dart
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+// 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.
+ *
+ * An example of usage can be found
+ * in test/message_extract/generate_from_json.dart
+ */
+library generate_localized;
+
+import 'extract_messages.dart';
+import 'src/intl_message.dart';
+import 'dart:io';
+import 'package:pathos/path.dart' as path;
+
+/**
+ * A list of all the locales for which we have translations. Code that does
+ * the reading of translations should add to this.
+ */
+List<String> allLocales = [];
+
+/**
+ * This represents a message and its translation. We assume that the translation
+ * has some identifier that allows us to figure out the original message it
+ * corresponds to, and that it may want to transform the translated text in
+ * some way, e.g. to turn whatever format the translation uses for variables
+ * into a Dart string interpolation. Specific translation
+ * mechanisms are expected to subclass this.
+ */
+abstract class TranslatedMessage {
+  /** The identifier for this message. In the simplest case, this is the name.*/
+  var id;
+
+  String translatedString;
+  IntlMessage originalMessage;
+  TranslatedMessage(this.id, this.translatedString);
+
+  String get message => translatedString;
+}
+
+/**
+ * We can't use a hyphen in a Dart library name, so convert the locale
+ * separator to an underscore.
+ */
+String asLibraryName(String x) => x.replaceAll('-', '_');
+
+/**
+ * Generate a file messages_<locale>.dart for the [translations] in
+ * [locale].
+ */
+void generateIndividualMessageFile(String locale,
+    Iterable<TranslatedMessage> translations, String targetDir) {
+  var result = new StringBuffer();
+  locale = new IntlMessage().escapeAndValidate(locale, locale);
+  result.write(prologue(locale));
+  for (var each in translations) {
+    var message = each.originalMessage;
+    if (each.message != null) {
+      message.addTranslation(locale, each.message);
+    }
+  }
+  var sorted = translations.where((each) => each.message != null).toList();
+  sorted.sort((a, b) =>
+      a.originalMessage.name.compareTo(b.originalMessage.name));
+  for (var each in sorted) {
+    result.write("  ");
+    result.write(each.originalMessage.toCode(locale));
+    result.write("\n\n");
+  }
+  result.write("\n  final messages = const {\n");
+  var entries = sorted
+      .map((translation) => translation.originalMessage.name)
+      .map((name) => "    \"$name\" : $name");
+  result.write(entries.join(",\n"));
+  result.write("\n  };\n}");
+
+  var output = new File(path.join(targetDir, "messages_$locale.dart"));
+  output.writeAsStringSync(result.toString());
+}
+
+/**
+ * This returns the mostly constant string used in [generated] for the
+ * beginning of the file, parameterized by [locale].
+ */
+String prologue(String locale) => """
+/**
+ * DO NOT EDIT. This is code generated via pkg/intl/generate_localized.dart
+ * This is a library that provides messages for a $locale locale. All the
+ * messages from the main program should be duplicated here with the same
+ * function name.
+ */
+
+library messages_${locale.replaceAll('-','_')};
+import 'package:intl/intl.dart';
+import 'package:intl/message_lookup_by_library.dart';
+
+final messages = new MessageLookup();
+
+class MessageLookup extends MessageLookupByLibrary {
+
+  get localeName => '$locale';
+""";
+
+/**
+ * This section generates the messages_all.dart file based on the list of
+ * [allLocales].
+ */
+String generateMainImportFile() {
+  var output = new StringBuffer();
+  output.write(mainPrologue);
+  for (var each in allLocales) {
+    output.write("import 'messages_$each.dart' as ${asLibraryName(each)};\n");
+  }
+  output.write(
+    "\nMessageLookupByLibrary _findExact(localeName) {\n"
+    "  switch (localeName) {\n");
+  for (var each in allLocales) {
+    output.write(
+        "    case '$each' : return ${asLibraryName(each)}.messages;\n");
+  }
+  output.write(closing);
+  return output.toString();
+}
+
+/**
+ * Constant string used in [generateMainImportFile] for the beginning of the
+ * file.
+ */
+const mainPrologue = """
+/**
+ * DO NOT EDIT. This is code generated via pkg/intl/generate_localized.dart
+ * This is a library that looks up messages for specific locales by
+ * delegating to the appropriate library.
+ */
+
+library messages_all;
+
+import 'dart:async';
+import 'package:intl/message_lookup_by_library.dart';
+import 'package:intl/src/intl_helpers.dart';
+import 'package:intl/intl.dart';
+
+""";
+
+/**
+ * Constant string used in [generateMainImportfile] as the end of the file.
+ */
+const closing = """
+    default: return null;
+  }
+}
+
+/** User programs should call this before using [localeName] for messages.*/
+initializeMessages(localeName) {
+  initializeInternalMessageLookup(() => new CompositeMessageLookup());
+  messageLookup.addLocale(localeName, _findGeneratedMessagesFor);
+  return new Future.immediate(null);
+}
+
+MessageLookupByLibrary _findGeneratedMessagesFor(locale) {
+  var actualLocale = Intl.verifiedLocale(locale, (x) => _findExact(x) != null);
+  if (actualLocale == null) return null;
+  return _findExact(actualLocale);
+}
+""";