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Date: 2021-10-20 08:54:00 Functions: 0 0 -

          Line data    Source code
       1             : import 'package:bloc/bloc.dart';
       2             : import 'package:flutter/widgets.dart';
       3             : 
       4             : import 'package:flutter_hooks_bloc/src/bloc_builder.dart';
       5             : import 'package:flutter_hooks_bloc/src/bloc_listener.dart';
       6             : 
       7             : /// {@template bloc_consumer}
       8             : /// [BlocConsumer] exposes a [builder] and [listener] in order react to new
       9             : /// states.
      10             : /// [BlocConsumer] is analogous to a nested `BlocListener`
      11             : /// and `BlocBuilder` but reduces the amount of boilerplate needed.
      12             : /// [BlocConsumer] should only be used when it is necessary to both rebuild UI
      13             : /// and execute other reactions to state changes in the [bloc].
      14             : ///
      15             : /// [BlocConsumer] takes a required `BlocWidgetBuilder`
      16             : /// and `BlocWidgetListener` and an optional [bloc],
      17             : /// `BlocBuilderCondition`, and `BlocListenerCondition`.
      18             : ///
      19             : /// If the [bloc] parameter is omitted, [BlocConsumer] will automatically
      20             : /// perform a lookup using `BlocProvider` and the current `BuildContext`.
      21             : ///
      22             : /// ```dart
      23             : /// BlocConsumer<BlocA, BlocAState>(
      24             : ///   listener: (context, state) {
      25             : ///     // do stuff here based on BlocA's state
      26             : ///   },
      27             : ///   builder: (context, state) {
      28             : ///     // return widget here based on BlocA's state
      29             : ///   }
      30             : /// )
      31             : /// ```
      32             : ///
      33             : /// An optional [listenWhen] and [buildWhen] can be implemented for more
      34             : /// granular control over when [listener] and [builder] are called.
      35             : /// The [listenWhen] and [buildWhen] will be invoked on each [bloc] `state`
      36             : /// change.
      37             : /// They each take the previous `state` and current `state` and must return
      38             : /// a [bool] which determines whether or not the [builder] and/or [listener]
      39             : /// function will be invoked.
      40             : /// The previous `state` will be initialized to the `state` of the [bloc] when
      41             : /// the [BlocConsumer] is initialized.
      42             : /// [listenWhen] and [buildWhen] are optional and if they aren't implemented,
      43             : /// they will default to `true`.
      44             : ///
      45             : /// ```dart
      46             : /// BlocConsumer<BlocA, BlocAState>(
      47             : ///   listenWhen: (previous, current) {
      48             : ///     // return true/false to determine whether or not
      49             : ///     // to invoke listener with state
      50             : ///   },
      51             : ///   listener: (context, state) {
      52             : ///     // do stuff here based on BlocA's state
      53             : ///   },
      54             : ///   buildWhen: (previous, current) {
      55             : ///     // return true/false to determine whether or not
      56             : ///     // to rebuild the widget with state
      57             : ///   },
      58             : ///   builder: (context, state) {
      59             : ///     // return widget here based on BlocA's state
      60             : ///   }
      61             : /// )
      62             : /// ```
      63             : /// {@endtemplate}
      64             : class BlocConsumer<B extends BlocBase<S>, S extends Object>
      65             :     extends BlocListenerBase<B, S> {
      66             :   /// The [BlocConsumer] constuctor listen and rebuilds a widget
      67             :   /// when a `bloc` state change.
      68           1 :   const BlocConsumer({
      69             :     Key? key,
      70             : 
      71             :     /// The [bloc] that the [BlocConsumer] will interact with.
      72             :     /// If omitted, [BlocConsumer] will automatically perform a lookup using
      73             :     /// `BlocProvider` and the current `BuildContext`.
      74             :     B? bloc,
      75             :     BlocListenerCondition<S>? listenWhen,
      76             :     required BlocWidgetListener<S> listener,
      77             :     this.buildWhen,
      78             :     required this.builder,
      79           1 :   }) : super(
      80             :           key: key,
      81             :           bloc: bloc,
      82             :           listenWhen: listenWhen,
      83             :           listener: listener,
      84             :         );
      85             : 
      86             :   /// Takes the previous `state` and the current `state` and is responsible for
      87             :   /// returning a [bool] which determines whether or not to call [listener] of
      88             :   /// [BlocConsumer] with the current `state`.
      89             :   final BlocBuilderCondition<S>? buildWhen;
      90             : 
      91             :   /// The [builder] function which will be invoked on each widget build.
      92             :   /// The [builder] takes the `BuildContext` and current `state` and
      93             :   /// must return a widget.
      94             :   /// This is analogous to the [builder] function in [StreamBuilder].
      95             :   final BlocWidgetBuilder<S> builder;
      96             : 
      97             :   /// Takes the previous `state` and the current `state` and is responsible
      98             :   /// for returning a [bool] which determines whether or not to trigger
      99             :   /// [builder] with the current `state`.
     100           1 :   @override
     101             :   Widget build(BuildContext context) {
     102           1 :     final state = $use();
     103           1 :     return builder(context, state);
     104             :   }
     105             : 
     106           1 :   @override
     107             :   bool onStateEmitted(BuildContext context, S previous, S state) {
     108           1 :     super.onStateEmitted(context, previous, state);
     109           1 :     return buildWhen?.call(previous, state) ?? true;
     110             :   }
     111             : }

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