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Add flutter_web samples (#75)
This commit is contained in:
Kevin Moore
committed by
Andrew Brogdon
Andrew Brogdon
parent
42f2dce01b
commit
3fe927cb29
513
web/vision_challenge/lib/packages/flutter_redux.dart
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513
web/vision_challenge/lib/packages/flutter_redux.dart
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@@ -0,0 +1,513 @@
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// Package flutter_redux:
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// https://pub.dev/packages/flutter_redux
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import 'dart:async';
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import 'package:flutter_web/widgets.dart';
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import 'package:meta/meta.dart';
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import 'redux.dart';
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/// Provides a Redux [Store] to all descendants of this Widget. This should
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/// generally be a root widget in your App. Connect to the Store provided
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/// by this Widget using a [StoreConnector] or [StoreBuilder].
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class StoreProvider<S> extends InheritedWidget {
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final Store<S> _store;
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/// Create a [StoreProvider] by passing in the required [store] and [child]
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/// parameters.
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const StoreProvider({
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Key key,
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@required Store<S> store,
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@required Widget child,
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}) : assert(store != null),
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assert(child != null),
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_store = store,
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super(key: key, child: child);
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/// A method that can be called by descendant Widgets to retrieve the Store
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/// from the StoreProvider.
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///
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/// Important: When using this method, pass through complete type information
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/// or Flutter will be unable to find the correct StoreProvider!
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///
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/// ### Example
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///
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/// ```
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/// class MyWidget extends StatelessWidget {
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/// @override
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/// Widget build(BuildContext context) {
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/// final store = StoreProvider.of<int>(context);
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///
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/// return Text('${store.state}');
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/// }
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/// }
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/// ```
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static Store<S> of<S>(BuildContext context) {
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final type = _typeOf<StoreProvider<S>>();
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final provider =
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context.inheritFromWidgetOfExactType(type) as StoreProvider<S>;
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if (provider == null) throw StoreProviderError(type);
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return provider._store;
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}
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// Workaround to capture generics
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static Type _typeOf<T>() => T;
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@override
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bool updateShouldNotify(StoreProvider<S> oldWidget) =>
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_store != oldWidget._store;
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}
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/// Build a Widget using the [BuildContext] and [ViewModel]. The [ViewModel] is
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/// derived from the [Store] using a [StoreConverter].
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typedef ViewModelBuilder<ViewModel> = Widget Function(
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BuildContext context,
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ViewModel vm,
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);
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/// Convert the entire [Store] into a [ViewModel]. The [ViewModel] will be used
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/// to build a Widget using the [ViewModelBuilder].
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typedef StoreConverter<S, ViewModel> = ViewModel Function(
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Store<S> store,
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);
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/// A function that will be run when the [StoreConnector] is initialized (using
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/// the [State.initState] method). This can be useful for dispatching actions
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/// that fetch data for your Widget when it is first displayed.
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typedef OnInitCallback<S> = void Function(
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Store<S> store,
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);
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/// A function that will be run when the StoreConnector is removed from the
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/// Widget Tree.
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///
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/// It is run in the [State.dispose] method.
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///
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/// This can be useful for dispatching actions that remove stale data from
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/// your State tree.
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typedef OnDisposeCallback<S> = void Function(
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Store<S> store,
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);
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/// A test of whether or not your `converter` function should run in response
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/// to a State change. For advanced use only.
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///
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/// Some changes to the State of your application will mean your `converter`
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/// function can't produce a useful ViewModel. In these cases, such as when
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/// performing exit animations on data that has been removed from your Store,
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/// it can be best to ignore the State change while your animation completes.
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///
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/// To ignore a change, provide a function that returns true or false. If the
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/// returned value is true, the change will be ignored.
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///
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/// If you ignore a change, and the framework needs to rebuild the Widget, the
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/// `builder` function will be called with the latest `ViewModel` produced by
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/// your `converter` function.
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typedef IgnoreChangeTest<S> = bool Function(S state);
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/// A function that will be run on State change, before the build method.
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///
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/// This function is passed the `ViewModel`, and if `distinct` is `true`,
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/// it will only be called if the `ViewModel` changes.
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///
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/// This can be useful for imperative calls to things like Navigator,
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/// TabController, etc
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typedef OnWillChangeCallback<ViewModel> = void Function(ViewModel viewModel);
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/// A function that will be run on State change, after the build method.
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///
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/// This function is passed the `ViewModel`, and if `distinct` is `true`,
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/// it will only be called if the `ViewModel` changes.
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///
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/// This can be useful for running certain animations after the build is
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/// complete.
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///
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/// Note: Using a [BuildContext] inside this callback can cause problems if
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/// the callback performs navigation. For navigation purposes, please use
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/// an [OnWillChangeCallback].
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typedef OnDidChangeCallback<ViewModel> = void Function(ViewModel viewModel);
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/// A function that will be run after the Widget is built the first time.
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///
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/// This function is passed the initial `ViewModel` created by the `converter`
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/// function.
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///
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/// This can be useful for starting certain animations, such as showing
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/// Snackbars, after the Widget is built the first time.
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typedef OnInitialBuildCallback<ViewModel> = void Function(ViewModel viewModel);
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/// Build a widget based on the state of the [Store].
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///
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/// Before the [builder] is run, the [converter] will convert the store into a
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/// more specific `ViewModel` tailored to the Widget being built.
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///
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/// Every time the store changes, the Widget will be rebuilt. As a performance
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/// optimization, the Widget can be rebuilt only when the [ViewModel] changes.
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/// In order for this to work correctly, you must implement [==] and [hashCode]
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/// for the [ViewModel], and set the [distinct] option to true when creating
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/// your StoreConnector.
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class StoreConnector<S, ViewModel> extends StatelessWidget {
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/// Build a Widget using the [BuildContext] and [ViewModel]. The [ViewModel]
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/// is created by the [converter] function.
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final ViewModelBuilder<ViewModel> builder;
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/// Convert the [Store] into a [ViewModel]. The resulting [ViewModel] will be
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/// passed to the [builder] function.
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final StoreConverter<S, ViewModel> converter;
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/// As a performance optimization, the Widget can be rebuilt only when the
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/// [ViewModel] changes. In order for this to work correctly, you must
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/// implement [==] and [hashCode] for the [ViewModel], and set the [distinct]
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/// option to true when creating your StoreConnector.
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final bool distinct;
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/// A function that will be run when the StoreConnector is initially created.
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/// It is run in the [State.initState] method.
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///
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/// This can be useful for dispatching actions that fetch data for your Widget
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/// when it is first displayed.
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final OnInitCallback<S> onInit;
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/// A function that will be run when the StoreConnector is removed from the
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/// Widget Tree.
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///
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/// It is run in the [State.dispose] method.
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///
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/// This can be useful for dispatching actions that remove stale data from
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/// your State tree.
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final OnDisposeCallback<S> onDispose;
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/// Determines whether the Widget should be rebuilt when the Store emits an
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/// onChange event.
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final bool rebuildOnChange;
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/// A test of whether or not your [converter] function should run in response
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/// to a State change. For advanced use only.
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///
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/// Some changes to the State of your application will mean your [converter]
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/// function can't produce a useful ViewModel. In these cases, such as when
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/// performing exit animations on data that has been removed from your Store,
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/// it can be best to ignore the State change while your animation completes.
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///
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/// To ignore a change, provide a function that returns true or false. If the
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/// returned value is true, the change will be ignored.
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///
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/// If you ignore a change, and the framework needs to rebuild the Widget, the
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/// [builder] function will be called with the latest [ViewModel] produced by
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/// your [converter] function.
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final IgnoreChangeTest<S> ignoreChange;
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/// A function that will be run on State change, before the Widget is built.
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///
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/// This function is passed the `ViewModel`, and if `distinct` is `true`,
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/// it will only be called if the `ViewModel` changes.
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///
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/// This can be useful for imperative calls to things like Navigator,
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/// TabController, etc
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final OnWillChangeCallback<ViewModel> onWillChange;
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/// A function that will be run on State change, after the Widget is built.
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///
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/// This function is passed the `ViewModel`, and if `distinct` is `true`,
|
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/// it will only be called if the `ViewModel` changes.
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///
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/// This can be useful for running certain animations after the build is
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/// complete.
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///
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/// Note: Using a [BuildContext] inside this callback can cause problems if
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/// the callback performs navigation. For navigation purposes, please use
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/// [onWillChange].
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final OnDidChangeCallback<ViewModel> onDidChange;
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/// A function that will be run after the Widget is built the first time.
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///
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/// This function is passed the initial `ViewModel` created by the [converter]
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/// function.
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///
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/// This can be useful for starting certain animations, such as showing
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/// Snackbars, after the Widget is built the first time.
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final OnInitialBuildCallback<ViewModel> onInitialBuild;
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/// Create a [StoreConnector] by passing in the required [converter] and
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/// [builder] functions.
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///
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/// You can also specify a number of additional parameters that allow you to
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/// modify the behavior of the StoreConnector. Please see the documentation
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/// for each option for more info.
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StoreConnector({
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Key key,
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@required this.builder,
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@required this.converter,
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this.distinct = false,
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this.onInit,
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this.onDispose,
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this.rebuildOnChange = true,
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this.ignoreChange,
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this.onWillChange,
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this.onDidChange,
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this.onInitialBuild,
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}) : assert(builder != null),
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assert(converter != null),
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super(key: key);
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@override
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Widget build(BuildContext context) {
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return _StoreStreamListener<S, ViewModel>(
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store: StoreProvider.of<S>(context),
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builder: builder,
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converter: converter,
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distinct: distinct,
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onInit: onInit,
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onDispose: onDispose,
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rebuildOnChange: rebuildOnChange,
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ignoreChange: ignoreChange,
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onWillChange: onWillChange,
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onDidChange: onDidChange,
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onInitialBuild: onInitialBuild,
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);
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}
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}
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/// Build a Widget by passing the [Store] directly to the build function.
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///
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/// Generally, it's considered best practice to use the [StoreConnector] and to
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/// build a `ViewModel` specifically for your Widget rather than passing through
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/// the entire [Store], but this is provided for convenience when that isn't
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/// necessary.
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class StoreBuilder<S> extends StatelessWidget {
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static Store<S> _identity<S>(Store<S> store) => store;
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/// Builds a Widget using the [BuildContext] and your [Store].
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final ViewModelBuilder<Store<S>> builder;
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/// Indicates whether or not the Widget should rebuild when the [Store] emits
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/// an `onChange` event.
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final bool rebuildOnChange;
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/// A function that will be run when the StoreConnector is initially created.
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/// It is run in the [State.initState] method.
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///
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/// This can be useful for dispatching actions that fetch data for your Widget
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/// when it is first displayed.
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final OnInitCallback<S> onInit;
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/// A function that will be run when the StoreBuilder is removed from the
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/// Widget Tree.
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///
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/// It is run in the [State.dispose] method.
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///
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/// This can be useful for dispatching actions that remove stale data from
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/// your State tree.
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final OnDisposeCallback<S> onDispose;
|
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/// A function that will be run on State change, before the Widget is built.
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///
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/// This can be useful for imperative calls to things like Navigator,
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/// TabController, etc
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final OnWillChangeCallback<Store<S>> onWillChange;
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/// A function that will be run on State change, after the Widget is built.
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///
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/// This can be useful for running certain animations after the build is
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/// complete
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///
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/// Note: Using a [BuildContext] inside this callback can cause problems if
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/// the callback performs navigation. For navigation purposes, please use
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/// [onWillChange].
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final OnDidChangeCallback<Store<S>> onDidChange;
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/// A function that will be run after the Widget is built the first time.
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///
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/// This can be useful for starting certain animations, such as showing
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/// Snackbars, after the Widget is built the first time.
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final OnInitialBuildCallback<Store<S>> onInitialBuild;
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/// Create's a Widget based on the Store.
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StoreBuilder({
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Key key,
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@required this.builder,
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this.onInit,
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this.onDispose,
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this.rebuildOnChange = true,
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this.onWillChange,
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this.onDidChange,
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this.onInitialBuild,
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}) : assert(builder != null),
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super(key: key);
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@override
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Widget build(BuildContext context) {
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return StoreConnector<S, Store<S>>(
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builder: builder,
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converter: _identity,
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rebuildOnChange: rebuildOnChange,
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onInit: onInit,
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onDispose: onDispose,
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onWillChange: onWillChange,
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onDidChange: onDidChange,
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onInitialBuild: onInitialBuild,
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);
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}
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}
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/// Listens to the [Store] and calls [builder] whenever [store] changes.
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class _StoreStreamListener<S, ViewModel> extends StatefulWidget {
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final ViewModelBuilder<ViewModel> builder;
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final StoreConverter<S, ViewModel> converter;
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final Store<S> store;
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final bool rebuildOnChange;
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final bool distinct;
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final OnInitCallback<S> onInit;
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final OnDisposeCallback<S> onDispose;
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final IgnoreChangeTest<S> ignoreChange;
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final OnWillChangeCallback<ViewModel> onWillChange;
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final OnDidChangeCallback<ViewModel> onDidChange;
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final OnInitialBuildCallback<ViewModel> onInitialBuild;
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_StoreStreamListener({
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Key key,
|
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@required this.builder,
|
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@required this.store,
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@required this.converter,
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this.distinct = false,
|
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this.onInit,
|
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this.onDispose,
|
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this.rebuildOnChange = true,
|
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this.ignoreChange,
|
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this.onWillChange,
|
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this.onDidChange,
|
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this.onInitialBuild,
|
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}) : super(key: key);
|
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@override
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State<StatefulWidget> createState() {
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return _StoreStreamListenerState<S, ViewModel>();
|
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}
|
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}
|
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class _StoreStreamListenerState<S, ViewModel>
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extends State<_StoreStreamListener<S, ViewModel>> {
|
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Stream<ViewModel> stream;
|
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ViewModel latestValue;
|
||||
|
||||
@override
|
||||
void initState() {
|
||||
_init();
|
||||
|
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super.initState();
|
||||
}
|
||||
|
||||
@override
|
||||
void dispose() {
|
||||
if (widget.onDispose != null) {
|
||||
widget.onDispose(widget.store);
|
||||
}
|
||||
|
||||
super.dispose();
|
||||
}
|
||||
|
||||
@override
|
||||
void didUpdateWidget(_StoreStreamListener<S, ViewModel> oldWidget) {
|
||||
if (widget.store != oldWidget.store) {
|
||||
_init();
|
||||
}
|
||||
|
||||
super.didUpdateWidget(oldWidget);
|
||||
}
|
||||
|
||||
void _init() {
|
||||
if (widget.onInit != null) {
|
||||
widget.onInit(widget.store);
|
||||
}
|
||||
|
||||
latestValue = widget.converter(widget.store);
|
||||
|
||||
if (widget.onInitialBuild != null) {
|
||||
WidgetsBinding.instance.addPostFrameCallback((_) {
|
||||
widget.onInitialBuild(latestValue);
|
||||
});
|
||||
}
|
||||
|
||||
var _stream = widget.store.onChange;
|
||||
|
||||
if (widget.ignoreChange != null) {
|
||||
_stream = _stream.where((state) => !widget.ignoreChange(state));
|
||||
}
|
||||
|
||||
stream = _stream.map((_) => widget.converter(widget.store));
|
||||
|
||||
// Don't use `Stream.distinct` because it cannot capture the initial
|
||||
// ViewModel produced by the `converter`.
|
||||
if (widget.distinct) {
|
||||
stream = stream.where((vm) {
|
||||
final isDistinct = vm != latestValue;
|
||||
|
||||
return isDistinct;
|
||||
});
|
||||
}
|
||||
|
||||
// After each ViewModel is emitted from the Stream, we update the
|
||||
// latestValue. Important: This must be done after all other optional
|
||||
// transformations, such as ignoreChange.
|
||||
stream =
|
||||
stream.transform(StreamTransformer.fromHandlers(handleData: (vm, sink) {
|
||||
latestValue = vm;
|
||||
|
||||
if (widget.onWillChange != null) {
|
||||
widget.onWillChange(latestValue);
|
||||
}
|
||||
|
||||
if (widget.onDidChange != null) {
|
||||
WidgetsBinding.instance.addPostFrameCallback((_) {
|
||||
widget.onDidChange(latestValue);
|
||||
});
|
||||
}
|
||||
|
||||
sink.add(vm);
|
||||
}));
|
||||
}
|
||||
|
||||
@override
|
||||
Widget build(BuildContext context) {
|
||||
return widget.rebuildOnChange
|
||||
? StreamBuilder<ViewModel>(
|
||||
stream: stream,
|
||||
builder: (context, snapshot) => widget.builder(
|
||||
context,
|
||||
snapshot.hasData ? snapshot.data : latestValue,
|
||||
),
|
||||
)
|
||||
: widget.builder(context, latestValue);
|
||||
}
|
||||
}
|
||||
|
||||
/// If the StoreProvider.of method fails, this error will be thrown.
|
||||
///
|
||||
/// Often, when the `of` method fails, it is difficult to understand why since
|
||||
/// there can be multiple causes. This error explains those causes so the user
|
||||
/// can understand and fix the issue.
|
||||
class StoreProviderError extends Error {
|
||||
/// The type of the class the user tried to retrieve
|
||||
Type type;
|
||||
|
||||
/// Creates a StoreProviderError
|
||||
StoreProviderError(this.type);
|
||||
|
||||
@override
|
||||
String toString() {
|
||||
return '''Error: No $type found. To fix, please try:
|
||||
|
||||
* Wrapping your MaterialApp with the StoreProvider<State>,
|
||||
rather than an individual Route
|
||||
* Providing full type information to your Store<State>,
|
||||
StoreProvider<State> and StoreConnector<State, ViewModel>
|
||||
* Ensure you are using consistent and complete imports.
|
||||
E.g. always use `import 'package:my_app/app_state.dart';
|
||||
|
||||
If none of these solutions work, please file a bug at:
|
||||
https://github.com/brianegan/flutter_redux/issues/new
|
||||
''';
|
||||
}
|
||||
}
|
||||
519
web/vision_challenge/lib/packages/redux.dart
Normal file
519
web/vision_challenge/lib/packages/redux.dart
Normal file
@@ -0,0 +1,519 @@
|
||||
// Package redux:
|
||||
// https://pub.dev/packages/redux
|
||||
|
||||
import 'dart:async';
|
||||
|
||||
/// Defines an application's state change
|
||||
///
|
||||
/// Implement this typedef to modify your app state in response to a given
|
||||
/// action.
|
||||
///
|
||||
/// ### Example
|
||||
///
|
||||
/// int counterReducer(int state, action) {
|
||||
/// switch (action) {
|
||||
/// case 'INCREMENT':
|
||||
/// return state + 1;
|
||||
/// case 'DECREMENT':
|
||||
/// return state - 1;
|
||||
/// default:
|
||||
/// return state;
|
||||
/// }
|
||||
/// }
|
||||
///
|
||||
/// final store = new Store<int>(counterReducer);
|
||||
typedef Reducer<State> = State Function(State state, dynamic action);
|
||||
|
||||
/// Defines a [Reducer] using a class interface.
|
||||
///
|
||||
/// Implement this class to modify your app state in response to a given action.
|
||||
///
|
||||
/// For some use cases, a class may be preferred to a function. In these
|
||||
/// instances, a ReducerClass can be used.
|
||||
///
|
||||
/// ### Example
|
||||
///
|
||||
/// class CounterReducer extends ReducerClass<int> {
|
||||
/// int call(int state, action) {
|
||||
/// switch (action) {
|
||||
/// case 'INCREMENT':
|
||||
/// return state + 1;
|
||||
/// case 'DECREMENT':
|
||||
/// return state - 1;
|
||||
/// default:
|
||||
/// return state;
|
||||
/// }
|
||||
/// }
|
||||
/// }
|
||||
///
|
||||
/// final store = new Store<int>(new CounterReducer());
|
||||
abstract class ReducerClass<State> {
|
||||
State call(State state, dynamic action);
|
||||
}
|
||||
|
||||
/// A function that intercepts actions and potentially transform actions before
|
||||
/// they reach the reducer.
|
||||
///
|
||||
/// Middleware intercept actions before they reach the reducer. This gives them
|
||||
/// the ability to produce side-effects or modify the passed in action before
|
||||
/// they reach the reducer.
|
||||
///
|
||||
/// ### Example
|
||||
///
|
||||
/// loggingMiddleware(Store<int> store, action, NextDispatcher next) {
|
||||
/// print('${new DateTime.now()}: $action');
|
||||
///
|
||||
/// next(action);
|
||||
/// }
|
||||
///
|
||||
/// // Create your store with the loggingMiddleware
|
||||
/// final store = new Store<int>(
|
||||
/// counterReducer,
|
||||
/// middleware: [loggingMiddleware],
|
||||
/// );
|
||||
typedef Middleware<State> = void Function(
|
||||
Store<State> store,
|
||||
dynamic action,
|
||||
NextDispatcher next,
|
||||
);
|
||||
|
||||
/// Defines a [Middleware] using a Class interface.
|
||||
///
|
||||
/// Middleware intercept actions before they reach the reducer. This gives them
|
||||
/// the ability to produce side-effects or modify the passed in action before
|
||||
/// they reach the reducer.
|
||||
///
|
||||
/// For some use cases, a class may be preferred to a function. In these
|
||||
/// instances, a MiddlewareClass can be used.
|
||||
///
|
||||
/// ### Example
|
||||
/// class LoggingMiddleware extends MiddlewareClass<int> {
|
||||
/// call(Store<int> store, action, NextDispatcher next) {
|
||||
/// print('${new DateTime.now()}: $action');
|
||||
///
|
||||
/// next(action);
|
||||
/// }
|
||||
/// }
|
||||
///
|
||||
/// // Create your store with the loggingMiddleware
|
||||
/// final store = new Store<int>(
|
||||
/// counterReducer,
|
||||
/// middleware: [new LoggingMiddleware()],
|
||||
/// );
|
||||
abstract class MiddlewareClass<State> {
|
||||
void call(Store<State> store, dynamic action, NextDispatcher next);
|
||||
}
|
||||
|
||||
/// The contract between one piece of middleware and the next in the chain. Use
|
||||
/// it to send the current action in your [Middleware] to the next piece of
|
||||
/// [Middleware] in the chain.
|
||||
///
|
||||
/// Middleware can optionally pass the original action or a modified action to
|
||||
/// the next piece of middleware, or never call the next piece of middleware at
|
||||
/// all.
|
||||
typedef NextDispatcher = void Function(dynamic action);
|
||||
|
||||
/// Creates a Redux store that holds the app state tree.
|
||||
///
|
||||
/// The only way to change the state tree in the store is to [dispatch] an
|
||||
/// action. the action will then be intercepted by any provided [Middleware].
|
||||
/// After running through the middleware, the action will be sent to the given
|
||||
/// [Reducer] to update the state tree.
|
||||
///
|
||||
/// To access the state tree, call the [state] getter or listen to the
|
||||
/// [onChange] stream.
|
||||
///
|
||||
/// ### Basic Example
|
||||
///
|
||||
/// // Create a reducer
|
||||
/// final increment = 'INCREMENT';
|
||||
/// final decrement = 'DECREMENT';
|
||||
///
|
||||
/// int counterReducer(int state, action) {
|
||||
/// switch (action) {
|
||||
/// case increment:
|
||||
/// return state + 1;
|
||||
/// case decrement:
|
||||
/// return state - 1;
|
||||
/// default:
|
||||
/// return state;
|
||||
/// }
|
||||
/// }
|
||||
///
|
||||
/// // Create the store
|
||||
/// final store = new Store<int>(counterReducer, initialState: 0);
|
||||
///
|
||||
/// // Print the Store's state.
|
||||
/// print(store.state); // prints "0"
|
||||
///
|
||||
/// // Dispatch an action. This will be sent to the reducer to update the
|
||||
/// // state.
|
||||
/// store.dispatch(increment);
|
||||
///
|
||||
/// // Print the updated state. As an alternative, you can use the
|
||||
/// // `store.onChange.listen` to respond to all state change events.
|
||||
/// print(store.state); // prints "1"
|
||||
class Store<State> {
|
||||
/// The [Reducer] for your Store. Allows you to get the current reducer or
|
||||
/// replace it with a new one if need be.
|
||||
Reducer<State> reducer;
|
||||
|
||||
final StreamController<State> _changeController;
|
||||
State _state;
|
||||
List<NextDispatcher> _dispatchers;
|
||||
|
||||
Store(
|
||||
this.reducer, {
|
||||
State initialState,
|
||||
List<Middleware<State>> middleware = const [],
|
||||
bool syncStream = false,
|
||||
|
||||
/// If set to true, the Store will not emit onChange events if the new State
|
||||
/// that is returned from your [reducer] in response to an Action is equal
|
||||
/// to the previous state.
|
||||
///
|
||||
/// Under the hood, it will use the `==` method from your State class to
|
||||
/// determine whether or not the two States are equal.
|
||||
bool distinct = false,
|
||||
}) : _changeController = StreamController.broadcast(sync: syncStream) {
|
||||
_state = initialState;
|
||||
_dispatchers = _createDispatchers(
|
||||
middleware,
|
||||
_createReduceAndNotify(distinct),
|
||||
);
|
||||
}
|
||||
|
||||
/// Returns the current state of the app
|
||||
State get state => _state;
|
||||
|
||||
/// A stream that emits the current state when it changes.
|
||||
///
|
||||
/// ### Example
|
||||
///
|
||||
/// // First, create the Store
|
||||
/// final store = new Store<int>(counterReducer, 0);
|
||||
///
|
||||
/// // Next, listen to the Store's onChange stream, and print the latest
|
||||
/// // state to your console whenever the reducer produces a new State.
|
||||
/// //
|
||||
/// // We'll store the StreamSubscription as a variable so we can stop
|
||||
/// // listening later.
|
||||
/// final subscription = store.onChange.listen(print);
|
||||
///
|
||||
/// // Dispatch some actions, and see the printing magic!
|
||||
/// store.dispatch("INCREMENT"); // prints 1
|
||||
/// store.dispatch("INCREMENT"); // prints 2
|
||||
/// store.dispatch("DECREMENT"); // prints 1
|
||||
///
|
||||
/// // When you want to stop printing the state to the console, simply
|
||||
/// `cancel` your `subscription`.
|
||||
/// subscription.cancel();
|
||||
Stream<State> get onChange => _changeController.stream;
|
||||
|
||||
// Creates the base [NextDispatcher].
|
||||
//
|
||||
// The base NextDispatcher will be called after all other middleware provided
|
||||
// by the user have been run. Its job is simple: Run the current state through
|
||||
// the reducer, save the result, and notify any subscribers.
|
||||
NextDispatcher _createReduceAndNotify(bool distinct) {
|
||||
return (dynamic action) {
|
||||
final state = reducer(_state, action);
|
||||
|
||||
if (distinct && state == _state) return;
|
||||
|
||||
_state = state;
|
||||
_changeController.add(state);
|
||||
};
|
||||
}
|
||||
|
||||
List<NextDispatcher> _createDispatchers(
|
||||
List<Middleware<State>> middleware,
|
||||
NextDispatcher reduceAndNotify,
|
||||
) {
|
||||
final dispatchers = <NextDispatcher>[]..add(reduceAndNotify);
|
||||
|
||||
// Convert each [Middleware] into a [NextDispatcher]
|
||||
for (var nextMiddleware in middleware.reversed) {
|
||||
final next = dispatchers.last;
|
||||
|
||||
dispatchers.add(
|
||||
(dynamic action) => nextMiddleware(this, action, next),
|
||||
);
|
||||
}
|
||||
|
||||
return dispatchers.reversed.toList();
|
||||
}
|
||||
|
||||
/// Runs the action through all provided [Middleware], then applies an action
|
||||
/// to the state using the given [Reducer]. Please note: [Middleware] can
|
||||
/// intercept actions, and can modify actions or stop them from passing
|
||||
/// through to the reducer.
|
||||
void dispatch(dynamic action) {
|
||||
_dispatchers[0](action);
|
||||
}
|
||||
|
||||
/// Closes down the Store so it will no longer be operational. Only use this
|
||||
/// if you want to destroy the Store while your app is running. Do not use
|
||||
/// this method as a way to stop listening to [onChange] state changes. For
|
||||
/// that purpose, view the [onChange] documentation.
|
||||
Future teardown() async {
|
||||
_state = null;
|
||||
return _changeController.close();
|
||||
}
|
||||
}
|
||||
|
||||
/// A convenience class for binding Reducers to Actions of a given Type. This
|
||||
/// allows for type safe [Reducer]s and reduces boilerplate.
|
||||
///
|
||||
/// ### Example
|
||||
///
|
||||
/// In order to see what this utility function does, let's take a look at a
|
||||
/// regular example of using reducers based on the Type of an action.
|
||||
///
|
||||
/// ```
|
||||
/// // We define out State and Action classes.
|
||||
/// class AppState {
|
||||
/// final List<Item> items;
|
||||
///
|
||||
/// AppState(this.items);
|
||||
/// }
|
||||
///
|
||||
/// class LoadItemsAction {}
|
||||
/// class UpdateItemsAction {}
|
||||
/// class AddItemAction{}
|
||||
/// class RemoveItemAction {}
|
||||
/// class ShuffleItemsAction {}
|
||||
/// class ReverseItemsAction {}
|
||||
/// class ItemsLoadedAction<Item> {
|
||||
/// final List<Item> items;
|
||||
///
|
||||
/// ItemsLoadedAction(this.items);
|
||||
/// }
|
||||
///
|
||||
/// // Then we define our reducer. Since we handle different actions in our
|
||||
/// // reducer, we need to determine what kind of action we're working with
|
||||
/// // using if statements, and then run some computation in response.
|
||||
/// //
|
||||
/// // This isn't a big deal if we have relatively few cases to handle, but your
|
||||
/// // reducer function can quickly grow large and take on too many
|
||||
/// // responsibilities as demonstrated here with pseudo-code.
|
||||
/// final appReducer = (AppState state, action) {
|
||||
/// if (action is ItemsLoadedAction) {
|
||||
/// return new AppState(action.items);
|
||||
/// } else if (action is UpdateItemsAction) {
|
||||
/// return ...;
|
||||
/// } else if (action is AddItemAction) {
|
||||
/// return ...;
|
||||
/// } else if (action is RemoveItemAction) {
|
||||
/// return ...;
|
||||
/// } else if (action is ShuffleItemsAction) {
|
||||
/// return ...;
|
||||
/// } else if (action is ReverseItemsAction) {
|
||||
/// return ...;
|
||||
/// } else {
|
||||
/// return state;
|
||||
/// }
|
||||
/// };
|
||||
/// ```
|
||||
///
|
||||
/// What would be nice would be to break our big reducer up into smaller
|
||||
/// reducers. It would also be nice to bind specific Types of Actions to
|
||||
/// specific reducers so we can ensure type safety for our reducers while
|
||||
/// avoiding large trees of `if` statements.
|
||||
///
|
||||
/// ```
|
||||
/// // First, we'll break out all of our individual State Changes into
|
||||
/// // individual reducers. These can be easily tested or composed!
|
||||
/// final loadItemsReducer = (AppState state, LoadTodosAction action) =>
|
||||
/// return new AppState(action.items);
|
||||
///
|
||||
/// final updateItemsReducer = (AppState state, UpdateItemsAction action) {
|
||||
/// return ...;
|
||||
/// }
|
||||
///
|
||||
/// final addItemReducer = (AppState state, AddItemAction action) {
|
||||
/// return ...;
|
||||
/// }
|
||||
///
|
||||
/// final removeItemReducer = (AppState state, RemoveItemAction action) {
|
||||
/// return ...;
|
||||
/// }
|
||||
///
|
||||
/// final shuffleItemsReducer = (AppState state, ShuffleItemAction action) {
|
||||
/// return ...;
|
||||
/// }
|
||||
///
|
||||
/// final reverseItemsReducer = (AppState state, ReverseItemAction action) {
|
||||
/// return ...;
|
||||
/// }
|
||||
///
|
||||
/// // We will then wire up specific types of actions to our reducer functions
|
||||
/// // above. This will return a new Reducer<AppState> which puts everything
|
||||
/// // together!.
|
||||
/// final Reducer<AppState> appReducer = combineReducers([
|
||||
/// new TypedReducer<AppState, LoadTodosAction>(loadItemsReducer),
|
||||
/// new TypedReducer<AppState, UpdateItemsAction>(updateItemsReducer),
|
||||
/// new TypedReducer<AppState, AddItemAction>(addItemReducer),
|
||||
/// new TypedReducer<AppState, RemoveItemAction>(removeItemReducer),
|
||||
/// new TypedReducer<AppState, ShuffleItemAction>(shuffleItemsReducer),
|
||||
/// new TypedReducer<AppState, ReverseItemAction>(reverseItemsReducer),
|
||||
/// ]);
|
||||
/// ```
|
||||
class TypedReducer<State, Action> implements ReducerClass<State> {
|
||||
final State Function(State state, Action action) reducer;
|
||||
|
||||
TypedReducer(this.reducer);
|
||||
|
||||
@override
|
||||
State call(State state, dynamic action) {
|
||||
if (action is Action) {
|
||||
return reducer(state, action);
|
||||
}
|
||||
|
||||
return state;
|
||||
}
|
||||
}
|
||||
|
||||
/// A convenience type for binding a piece of Middleware to an Action
|
||||
/// of a specific type. Allows for Type Safe Middleware and reduces boilerplate.
|
||||
///
|
||||
/// ### Example
|
||||
///
|
||||
/// In order to see what this utility function does, let's take a look at a
|
||||
/// regular example of running Middleware based on the Type of an action.
|
||||
///
|
||||
/// ```
|
||||
/// class AppState {
|
||||
/// final List<Item> items;
|
||||
///
|
||||
/// AppState(this.items);
|
||||
/// }
|
||||
/// class LoadItemsAction {}
|
||||
/// class UpdateItemsAction {}
|
||||
/// class AddItemAction{}
|
||||
/// class RemoveItemAction {}
|
||||
/// class ShuffleItemsAction {}
|
||||
/// class ReverseItemsAction {}
|
||||
/// class ItemsLoadedAction<Item> {
|
||||
/// final List<Item> items;
|
||||
///
|
||||
/// ItemsLoadedAction(this.items);
|
||||
/// }
|
||||
///
|
||||
/// final loadItems = () { /* Function that loads a Future<List<Item>> */}
|
||||
/// final saveItems = (List<Item> items) { /* Function that persists items */}
|
||||
///
|
||||
/// final middleware = (Store<AppState> store, action, NextDispatcher next) {
|
||||
/// if (action is LoadItemsAction) {
|
||||
/// loadItems()
|
||||
/// .then((items) => store.dispatch(new ItemsLoaded(items))
|
||||
/// .catchError((_) => store.dispatch(new ItemsNotLoaded());
|
||||
///
|
||||
/// next(action);
|
||||
/// } else if (action is UpdateItemsAction ||
|
||||
/// action is AddItemAction ||
|
||||
/// action is RemoveItemAction ||
|
||||
/// action is ShuffleItemsAction ||
|
||||
/// action is ReverseItemsAction) {
|
||||
/// next(action);
|
||||
///
|
||||
/// saveItems(store.state.items);
|
||||
/// } else {
|
||||
/// next(action);
|
||||
/// }
|
||||
/// };
|
||||
/// ```
|
||||
///
|
||||
/// This works fine if you have one or two actions to handle, but you might
|
||||
/// notice it's getting a bit messy already. Let's see how this lib helps clean
|
||||
/// it up.
|
||||
///
|
||||
/// ```
|
||||
/// // First, let's start by breaking up our functionality into two middleware
|
||||
/// // functions.
|
||||
/// //
|
||||
/// // The loadItemsMiddleware will only handle the `LoadItemsAction`s that
|
||||
/// // are dispatched, so we can annotate the Type of action.
|
||||
/// final loadItemsMiddleware = (
|
||||
/// Store<AppState> store,
|
||||
/// LoadItemsAction action,
|
||||
/// NextDispatcher next,
|
||||
/// ) {
|
||||
/// loadItems()
|
||||
/// .then((items) => store.dispatch(new ItemsLoaded(items))
|
||||
/// .catchError((_) => store.dispatch(new ItemsNotLoaded());
|
||||
///
|
||||
/// next(action);
|
||||
/// }
|
||||
///
|
||||
/// // The saveItemsMiddleware handles all actions that change the Items, but
|
||||
/// // does not depend on the payload of the action. Therefore, `action` will
|
||||
/// // remain dynamic.
|
||||
/// final saveItemsMiddleware = (
|
||||
/// Store<AppState> store,
|
||||
/// dynamic action,
|
||||
/// NextDispatcher next,
|
||||
/// ) {
|
||||
/// next(action);
|
||||
///
|
||||
/// saveItems(store.state.items);
|
||||
/// }
|
||||
///
|
||||
/// // We will then wire up specific types of actions to a List of Middleware
|
||||
/// // that handle those actions.
|
||||
/// final List<Middleware<AppState>> middleware = [
|
||||
/// new TypedMiddleware<AppState, LoadTodosAction>(loadItemsMiddleware),
|
||||
/// new TypedMiddleware<AppState, AddTodoAction>(saveItemsMiddleware),
|
||||
/// new TypedMiddleware<AppState, ClearCompletedAction>(saveItemsMiddleware),
|
||||
/// new TypedMiddleware<AppState, ToggleAllAction>(saveItemsMiddleware),
|
||||
/// new TypedMiddleware<AppState, UpdateTodoAction>(saveItemsMiddleware),
|
||||
/// new TypedMiddleware<AppState, TodosLoadedAction>(saveItemsMiddleware),
|
||||
/// ];
|
||||
/// ```
|
||||
class TypedMiddleware<State, Action> implements MiddlewareClass<State> {
|
||||
final void Function(
|
||||
Store<State> store,
|
||||
Action action,
|
||||
NextDispatcher next,
|
||||
) middleware;
|
||||
|
||||
TypedMiddleware(this.middleware);
|
||||
|
||||
@override
|
||||
void call(Store<State> store, dynamic action, NextDispatcher next) {
|
||||
if (action is Action) {
|
||||
middleware(store, action, next);
|
||||
} else {
|
||||
next(action);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Defines a utility function that combines several reducers.
|
||||
///
|
||||
/// In order to prevent having one large, monolithic reducer in your app, it can
|
||||
/// be convenient to break reducers up into smaller parts that handle more
|
||||
/// specific functionality that can be decoupled and easily tested.
|
||||
///
|
||||
/// ### Example
|
||||
///
|
||||
/// helloReducer(state, action) {
|
||||
/// return "hello";
|
||||
/// }
|
||||
///
|
||||
/// friendReducer(state, action) {
|
||||
/// return state + " friend";
|
||||
/// }
|
||||
///
|
||||
/// final helloFriendReducer = combineReducers(
|
||||
/// helloReducer,
|
||||
/// friendReducer,
|
||||
/// );
|
||||
Reducer<State> combineReducers<State>(Iterable<Reducer<State>> reducers) {
|
||||
return (State state, dynamic action) {
|
||||
for (final reducer in reducers) {
|
||||
state = reducer(state, action);
|
||||
}
|
||||
return state;
|
||||
};
|
||||
}
|
||||
Reference in New Issue
Block a user