blob: 07d46f7bce4540bbedf611cc40eb8da2ba3f090c [file] [log] [blame]
// 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 {
/// 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 =;
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));