blob: f443ad7fb99dc7cc7e5dbce89362552a0719718e [file] [log] [blame]
// 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 'intl.dart';
import 'src/intl_message.dart';
import 'dart:io';
import 'package:path/path.dart' as path;
class MessageGeneration {
/// If the import path following package: is something else, modify the
/// [intlImportPath] variable to change the import directives in the generated
/// code.
var intlImportPath = 'intl';
/// If the path to the generated files is something other than the current
/// directory, update the [generatedImportPath] variable to change the import
/// directives in the generated code.
var generatedImportPath = '';
/// Given a base file, return the file prefixed with the path to import it.
/// By default, that is in the current directory, but if [generatedImportPath]
/// has been set, then use that as a prefix.
String importForGeneratedFile(String file) =>
generatedImportPath.isEmpty ? file : "$generatedImportPath/$file";
/// 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 = [];
/// If we have more than one set of messages to generate in a particular
/// directory we may want to prefix some to distinguish them.
String generatedFilePrefix = '';
/// Should we use deferred loading for the generated libraries.
bool useDeferredLoading = true;
/// Generate a file <[generated_file_prefix]>_messages_<[locale]>.dart
/// for the [translations] in [locale] and put it in [targetDir].
void generateIndividualMessageFile(String basicLocale,
Iterable<TranslatedMessage> translations, String targetDir) {
var result = new StringBuffer();
var locale = new MainMessage()
// 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.originalMessages != null && each.message != null)
for (var each in usableTranslations) {
for (var original in each.originalMessages) {
original.addTranslation(locale, each.message);
usableTranslations.sort((a, b) =>;
for (var translation in usableTranslations) {
// Some messages we generate as methods in this class. Simpler ones
// we inline in the map from names to messages.
var messagesThatNeedMethods =
translation.originalMessages.where((each) => _hasArguments(each));
for (var original in messagesThatNeedMethods) {
..write(" ")
original.toCodeForLocale(locale, _methodNameFor(
// Some gyrations to prevent parts of the deferred libraries from being
// inlined into the main one, defeating the space savings. Issue 24356
final messages = _notInlinedMessages(_notInlinedMessages);
static _notInlinedMessages(_) => {
var entries = usableTranslations
.expand((translation) => translation.originalMessages)
.map((original) =>
' "${original.escapeAndValidateString(}" '
': ${_mapReference(original, locale)}');
result..write(entries.join(",\n"))..write("\n };\n}\n");
// To preserve compatibility, we don't use the canonical version of the
// locale in the file name.
var filename = path.join(
targetDir, "${generatedFilePrefix}messages_$basicLocale.dart");
new File(filename).writeAsStringSync(result.toString());
/// This returns the mostly constant string used in
/// [generateIndividualMessageFile] for the beginning of the file,
/// parameterized by [locale].
String prologue(String locale) => """
// DO NOT EDIT. This is code generated via package:intl/generate_localized.dart
// This is a library that provides messages for a $locale locale. All the
// messages from the main program should be duplicated here with the same
// function name.
import 'package:$intlImportPath/intl.dart';
import 'package:$intlImportPath/message_lookup_by_library.dart';
final messages = new MessageLookup();
final _keepAnalysisHappy = Intl.defaultLocale;
class MessageLookup extends MessageLookupByLibrary {
get localeName => '$locale';
/// This section generates the messages_all.dart file based on the list of
/// [allLocales].
String generateMainImportFile() {
var output = new StringBuffer();
for (var locale in allLocales) {
var baseFile = '${generatedFilePrefix}messages_$locale.dart';
var file = importForGeneratedFile(baseFile);
output.write("import '$file' ");
if (useDeferredLoading) output.write("deferred ");
output.write("as ${_libraryName(locale)};\n");
output.write("Map<String, Function> _deferredLibraries = {\n");
for (var rawLocale in allLocales) {
var locale = Intl.canonicalizedLocale(rawLocale);
var loadOperation = (useDeferredLoading)
? " '$locale': () => ${_libraryName(locale)}.loadLibrary(),\n"
: " '$locale': () => new Future.value(null),\n";
output.write("\nMessageLookupByLibrary _findExact(localeName) {\n"
" switch (localeName) {\n");
for (var rawLocale in allLocales) {
var locale = Intl.canonicalizedLocale(rawLocale);
" case '$locale':\n return ${_libraryName(locale)}.messages;\n");
return output.toString();
/// Constant string used in [generateMainImportFile] for the beginning of the
/// file.
get mainPrologue => """
// DO NOT EDIT. This is code generated via package:intl/generate_localized.dart
// This is a library that looks up messages for specific locales by
// delegating to the appropriate library.
import 'dart:async';
import 'package:$intlImportPath/intl.dart';
import 'package:$intlImportPath/message_lookup_by_library.dart';
import 'package:$intlImportPath/src/intl_helpers.dart';
/// Constant string used in [generateMainImportFile] as the end of the file.
static const closing = """
default:\n return null;
/// User programs should call this before using [localeName] for messages.
Future initializeMessages(String localeName) {
var lib = _deferredLibraries[Intl.canonicalizedLocale(localeName)];
var load = lib == null ? new Future.value(false) : lib();
return load.then((_) {
initializeInternalMessageLookup(() => new CompositeMessageLookup());
messageLookup.addLocale(localeName, _findGeneratedMessagesFor);
bool _messagesExistFor(String locale) {
var messages;
try {
messages = _findExact(locale);
} catch (e) {}
return messages != null;
MessageLookupByLibrary _findGeneratedMessagesFor(locale) {
var actualLocale = Intl.verifiedLocale(locale, _messagesExistFor,
onFailure: (_) => null);
if (actualLocale == null) return null;
return _findExact(actualLocale);
/// 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
/// 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 all the [originalMessages].
final Message translated;
/// The original messages that we are a translation of. There can
/// be more than one original message for the same translation.
List<MainMessage> _originalMessages;
List<MainMessage> get originalMessages => _originalMessages;
set originalMessages(List<MainMessage> x) {
_originalMessages = x;
/// For backward compatibility, we still have the originalMessage API.
MainMessage get originalMessage => originalMessages.first;
set originalMessage(MainMessage m) {
originalMessages = [m];
TranslatedMessage(, 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('-', '_');
bool _hasArguments(MainMessage message) => message.arguments.length != 0;
/// Simple messages are printed directly in the map of message names to
/// functions as a call that returns a lambda. e.g.
/// "foo" : simpleMessage("This is foo"),
/// This is helpful for the compiler.
/// */
String _mapReference(MainMessage original, String locale) {
if (!_hasArguments(original)) {
// No parameters, can be printed simply.
return 'MessageLookupByLibrary.simpleMessage("'
} else {
return _methodNameFor(;
/// Generated method counter for use in [_methodNameFor].
int _methodNameCounter = 0;
/// A map from Intl message names to the generated method names
/// for their translated versions.
Map<String, String> _internalMethodNames = {};
/// Generate a Dart method name of the form "m<number>".
String _methodNameFor(String name) {
return _internalMethodNames.putIfAbsent(
name, () => "m${_methodNameCounter++}");