| // Copyright (c) 2012, 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. |
| // @dart=2.9 |
| |
| /// Message/plural format library with locale support. This can have different |
| /// implementations based on the mechanism for finding the localized versions of |
| /// messages. This version expects them to be in a library named e.g. |
| /// 'messages_en_US'. The prefix is set in the "initializeMessages" call, which |
| /// must be made for a locale before any lookups can be done. |
| /// |
| /// See Intl class comment or `tests/message_format_test.dart` for more |
| /// examples. |
| library message_lookup_by_library; |
| |
| import 'package:intl/intl.dart'; |
| import 'package:intl/src/intl_helpers.dart'; |
| |
| /// This is a message lookup mechanism that delegates to one of a collection |
| /// of individual [MessageLookupByLibrary] instances. |
| class CompositeMessageLookup implements MessageLookup { |
| /// A map from locale names to the corresponding lookups. |
| Map<String, MessageLookupByLibrary> availableMessages = Map(); |
| |
| /// Return true if we have a message lookup for [localeName]. |
| bool localeExists(localeName) => availableMessages.containsKey(localeName); |
| |
| /// The last locale in which we looked up messages. |
| /// |
| /// If this locale matches the new one then we can skip looking up the |
| /// messages and assume they will be the same as last time. |
| String _lastLocale; |
| |
| /// Caches the last messages that we found |
| MessageLookupByLibrary _lastLookup; |
| |
| /// Look up the message with the given [name] and [locale] and return the |
| /// translated version with the values in [args] interpolated. If nothing is |
| /// found, return the result of [ifAbsent] or [messageText]. |
| String lookupMessage(String messageText, String locale, String name, |
| List<dynamic> args, String meaning, |
| {MessageIfAbsent ifAbsent}) { |
| // If passed null, use the default. |
| var knownLocale = locale ?? Intl.getCurrentLocale(); |
| var messages = (knownLocale == _lastLocale) |
| ? _lastLookup |
| : _lookupMessageCatalog(knownLocale); |
| // If we didn't find any messages for this locale, use the original string, |
| // faking interpolations if necessary. |
| if (messages == null) { |
| return ifAbsent == null ? messageText : ifAbsent(messageText, args); |
| } |
| return messages.lookupMessage(messageText, locale, name, args, meaning, |
| ifAbsent: ifAbsent); |
| } |
| |
| /// Find the right message lookup for [locale]. |
| MessageLookupByLibrary _lookupMessageCatalog(String locale) { |
| var verifiedLocale = Intl.verifiedLocale(locale, localeExists, |
| onFailure: (locale) => locale); |
| _lastLocale = locale; |
| _lastLookup = availableMessages[verifiedLocale]; |
| return _lastLookup; |
| } |
| |
| /// If we do not already have a locale for [localeName] then |
| /// [findLocale] will be called and the result stored as the lookup |
| /// mechanism for that locale. |
| void addLocale(String localeName, Function findLocale) { |
| if (localeExists(localeName)) return; |
| var canonical = Intl.canonicalizedLocale(localeName); |
| var newLocale = findLocale(canonical); |
| if (newLocale != null) { |
| availableMessages[localeName] = newLocale; |
| availableMessages[canonical] = newLocale; |
| // If there was already a failed lookup for [newLocale], null the cache. |
| if (_lastLocale == newLocale) { |
| _lastLocale = null; |
| _lastLookup = null; |
| } |
| } |
| } |
| } |
| |
| /// This provides an abstract class for messages looked up in generated code. |
| /// Each locale will have a separate subclass of this class with its set of |
| /// messages. See generate_localized.dart. |
| abstract class MessageLookupByLibrary { |
| /// Return the localized version of a message. We are passed the original |
| /// version of the message, which consists of a |
| /// [messageText] that will be translated, and which may be interpolated |
| /// based on one or more variables. |
| /// |
| /// For example, if message="Hello, $name", then |
| /// examples = {'name': 'Sparky'}. If not using the user's default locale, or |
| /// if the locale is not easily detectable, explicitly pass [locale]. |
| /// |
| /// Ultimately, the information about the enclosing function and its arguments |
| /// will be extracted automatically but for the time being it must be passed |
| /// explicitly in the [name] and [args] arguments. |
| String lookupMessage(String messageText, String locale, String name, |
| List<dynamic> args, String meaning, |
| {MessageIfAbsent ifAbsent}) { |
| var notFound = false; |
| var actualName = computeMessageName(name, messageText, meaning); |
| if (actualName == null) notFound = true; |
| var translation = this[actualName]; |
| notFound = notFound || (translation == null); |
| if (notFound) { |
| return ifAbsent == null ? messageText : ifAbsent(messageText, args); |
| } else { |
| args = args ?? const []; |
| return evaluateMessage(translation, args); |
| } |
| } |
| |
| /// Evaluate the translated message and return the translated string. |
| String evaluateMessage(translation, List<dynamic> args) { |
| return Function.apply(translation, args); |
| } |
| |
| /// Return our message with the given name |
| dynamic operator [](String messageName) => messages[messageName]; |
| |
| /// Subclasses should override this to return a list of their message |
| /// implementations. In this class these are functions, but subclasses may |
| /// implement them differently. |
| Map<String, dynamic> get messages; |
| |
| /// Subclasses should override this to return their locale, e.g. 'en_US' |
| String get localeName; |
| |
| String toString() => localeName; |
| |
| /// Return a function that returns the given string. |
| /// An optimization for dart2js, used from the generated code. |
| static String Function() simpleMessage(translatedString) => |
| () => translatedString; |
| } |