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intl/lib/message_lookup_by_library.dart

-// 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.
-
-/**
- * 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 'intl.dart';
-
-/**
- * This is a message lookup mechanism that delegates to one of a collection
- * of individual [MessageLookupByLibrary] instances.
- */
-class CompositeMessageLookup {
-  /** A map from locale names to the corresponding lookups. */
-  Map<String, MessageLookupByLibrary> availableMessages = new Map();
-
-  /** Return true if we have a message lookup for [localeName]. */
-  bool localeExists(localeName) => availableMessages.containsKey(localeName);
-
-  /**
-   * 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 [message_str]. The [desc] and [examples]
-   * parameters are ignored
-   */
-  String lookupMessage(String message_str, [final String desc = '',
-      final Map examples = const {}, String locale, String name,
-      List<String> args, String meaning]) {
-    var actualLocale = (locale == null) ? Intl.getCurrentLocale() : locale;
-    // For this usage, if the locale doesn't exist for messages, just return
-    // it and we'll fall back to the original version.
-    var verifiedLocale = Intl.verifiedLocale(actualLocale, localeExists,
-        onFailure: (locale) => locale);
-    var messages = availableMessages[verifiedLocale];
-    if (messages == null) return message_str;
-    return messages.lookupMessage(
-        message_str, desc, examples, locale, name, args, meaning);
-  }
-
-  /**
-   * 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.
-   */
-  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;
-    }
-  }
-}
-
-/**
- * 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
-   * [message_str] that will be translated, and which may be interpolated
-   * based on one or more variables, a [desc] providing a description of usage
-   * for the [message_str], and a map of [examples] for each data element to be
-   * substituted into the message.
-   *
-   * 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].
-   *
-   * The values of [desc] and [examples] are not used at run-time but are only
-   * made available to the translators, so they MUST be simple Strings available
-   * at compile time: no String interpolation or concatenation.
-   * The expected usage of this is inside a function that takes as parameters
-   * the variables used in the interpolated string.
-   *
-   * 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 message_str, [final String desc = '',
-      final Map examples = const {}, String locale, String name,
-      List<String> args, String meaning]) {
-    if (name == null) return message_str;
-    var function = this[name];
-    return function == null ? message_str : Function.apply(function, args);
-  }
-
-  /** Return our message with the given name */
-  operator [](String messageName) => messages[messageName];
-
-  /**
-   * Subclasses should override this to return a list of their message
-   * functions.
-   */
-  Map<String, Function> get messages;
-
-  /** Subclasses should override this to return their locale, e.g. 'en_US' */
-  String get localeName;
-
-  toString() => localeName;
-}