| // 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. |
| |
| /** |
| * This defines a class for loading locale data incrementally from |
| * an external source as JSON. The external sources expected are either |
| * local files or via HTTP request. |
| */ |
| |
| library lazy_locale_data; |
| import 'dart:async'; |
| import 'dart:convert'; |
| import 'intl_helpers.dart'; |
| |
| /** |
| * This implements the very basic map-type operations which are used |
| * in locale lookup, and looks them up based on a URL that defines |
| * the external source. |
| */ |
| class LazyLocaleData { |
| /// This holds the data we have loaded. |
| Map map; |
| |
| /// The object that actually does the data reading. |
| LocaleDataReader _reader; |
| |
| /** |
| * In order to avoid a potentially remote call to see if a locale |
| * is available, we hold a complete list of all the available |
| * locales. |
| */ |
| List availableLocales; |
| |
| /** |
| * Given a piece of remote data, apply [_creationFunction] to it to |
| * convert it into the right form. Typically this means converting it |
| * from a Map into an object form. |
| */ |
| Function _creationFunction; |
| |
| /** |
| * The set of available locales. |
| */ |
| Set availableLocaleSet; |
| |
| /** |
| * The constructor. The [_reader] specifies where the data comes |
| * from. The [_creationFunction] creates the appropriate data type |
| * from the remote data (which typically comes in as a Map). The |
| * [keys] lists the set of remotely available locale names so we know which |
| * things can be fetched without having to check remotely. |
| */ |
| LazyLocaleData(this._reader, this._creationFunction, List keys) { |
| map = new Map(); |
| availableLocales = keys; |
| availableLocaleSet = new Set.from(availableLocales); |
| } |
| |
| /** |
| * Tests if we have data for the locale available. Note that this returns |
| * true even if the data is known to be available remotely but not yet loaded. |
| */ |
| bool containsKey(String locale) => availableLocaleSet.contains(locale); |
| |
| /** Returns the list of keys/locale names. */ |
| List get keys => availableLocales; |
| |
| /** |
| * Returns the data stored for [localeName]. If no data has been loaded |
| * for [localeName], throws an exception. If no data is available for |
| * [localeName] then throw an exception with a different message. |
| */ |
| operator [](String localeName) { |
| if (containsKey(localeName)) { |
| var data = map[localeName]; |
| if (data == null) { |
| throw new LocaleDataException( |
| "Locale $localeName has not been initialized." |
| " Call initializeDateFormatting($localeName, <data url>) first"); |
| } else { |
| return data; |
| } |
| } else { |
| unsupportedLocale(localeName); |
| } |
| } |
| |
| /** |
| * Throw an exception indicating that the locale has no data available, |
| * either locally or remotely. |
| */ |
| unsupportedLocale(localeName) { throw new LocaleDataException( |
| 'Locale $localeName has no data available');} |
| |
| /** |
| * Initialize for locale. Internal use only. As a user, call |
| * initializeDateFormatting instead. |
| */ |
| Future initLocale(String localeName) { |
| var data = _reader.read(localeName); |
| return jsonData(data).then( (input) { |
| map[localeName] = _creationFunction(input);}); |
| } |
| |
| /** |
| * Given a Future [input] whose value is expected to be a string in JSON form, |
| * return another future that parses the JSON into a usable format. |
| */ |
| Future jsonData(Future input) { |
| return input.then( (response) => JSON.decode(response)); |
| } |
| } |