pass state to reducers

Author: davidmarne

README.md

@@ -103,11 +103,11 @@ import 'package:built_redux/built_redux.dart';
  * These are reducers, a pure function with (builder, action) => state signature.
  * It describes how an action transforms the state into the next state.
  */
-increment(CounterBuilder builder, Action<int> action) =>
-  builder..count = builder.build().count + action.payload;
+increment(Counter state, Action<int> action, CounterBuilder builder) =>
+  builder..count = state.count + action.payload;
 
-decrement(CounterBuilder builder, Action<int> action) =>
-  builder..count = builder.build().count - action.payload;
+decrement(Counter state, Action<int> action, CounterBuilder builder) =>
+  builder..count = state.count - action.payload;
 
 /**
  * This is a reducer builder. Use of ReducerBuilder is not required, however it

example/lib/reducers/app_state.dart

@@ -20,11 +20,11 @@ abstract class AppStateActions extends ReduxActions {
   factory AppStateActions() => new _$AppStateActions();
 }
 
+_setCurrentGroupReducer(AppState state, Action<int> action, AppStateBuilder builder) =>
+    builder..currentGroup = action.payload;
+
 final _reducers = (new ReducerBuilder<AppStateBuilder>()
-      ..add<int>(
-        AppStateActionsNames.setCurrentGroup,
-        (builder, action) => builder..currentGroup = action.payload,
-      ))
+      ..add<int>(AppStateActionsNames.setCurrentGroup, _setCurrentGroupReducer))
     .build();
 
 // Built Reducer

example/lib/reducers/groups.dart

@@ -24,15 +24,15 @@ class AddTodoToGroupPayload {
 }
 
 // Reducers
-_addTodoToGroupReducer(GroupsReducerBuilder builder, Action<AddTodoToGroupPayload> action) =>
-    builder.groupMap[action.payload.groupId] = builder.groupMap
-        .build()[action.payload.groupId]
+_addTodoToGroupReducer(
+        GroupsReducer state, Action<AddTodoToGroupPayload> action, GroupsReducerBuilder builder) =>
+    builder.groupMap[action.payload.groupId] = state.groupMap[action.payload.groupId]
         .rebuild((gbuilder) => gbuilder..todoIds.add(action.payload.todoId));
 
-_addGroupReducer(GroupsReducerBuilder builder, Action<Group> action) =>
+_addGroupReducer(GroupsReducer state, Action<Group> action, GroupsReducerBuilder builder) =>
     builder.groupMap[action.payload.id] = action.payload;
 
-_removeGroupReducer(GroupsReducerBuilder builder, Action<int> action) =>
+_removeGroupReducer(GroupsReducer state, Action<int> action, GroupsReducerBuilder builder) =>
     builder.groupMap.remove(action.payload);
 
 final _reducers = (new ReducerBuilder<GroupsReducerBuilder>()

example/lib/reducers/todos.dart

@@ -18,16 +18,16 @@ abstract class TodosActions extends ReduxActions {
 }
 
 // Reducers
-addTodoReducer(TodosReducerBuilder builder, Action<Todo> action) =>
+addTodoReducer(TodosReducer state, Action<Todo> action, TodosReducerBuilder builder) =>
     builder.todosMap[action.payload.id] = action.payload;
 
-removeTodoReducer(TodosReducerBuilder builder, Action<int> action) =>
+removeTodoReducer(TodosReducer state, Action<int> action, TodosReducerBuilder builder) =>
     builder.todosMap.remove(action.payload);
 
-updateTodoStatusReducer(TodosReducerBuilder builder, Action<int> action) =>
-    builder.todosMap[action.payload] = builder.todosMap.build()[action.payload].rebuild(
-          (tbuilder) => tbuilder..done = !tbuilder.done,
-        );
+updateTodoStatusReducer(TodosReducer state, Action<int> action, TodosReducerBuilder builder) =>
+    builder.todosMap[action.payload] = state.todosMap[action.payload].rebuild(
+      (tbuilder) => tbuilder..done = !tbuilder.done,
+    );
 
 final _reducers = (new ReducerBuilder<TodosReducerBuilder>()
       ..add<Todo>(TodosActionsNames.addTodo, addTodoReducer)

example/pubspec.lock

@@ -63,10 +63,10 @@ packages:
     version: "1.4.0"
   built_redux:
     description:
-      name: built_redux
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.0.1"
+      path: ".."
+      relative: true
+    source: path
+    version: "0.0.3"
   built_value:
     description:
       name: built_value

example/pubspec.yaml

@@ -12,6 +12,10 @@ dev_dependencies:
   built_value_generator: ^1.0.0
   test: "^0.12.6+2"
 
+dependency_overrides:
+  built_redux:
+    path: ../.
+
 transformers:
   - built_redux
   - $dart2js

lib/src/action.dart

@@ -1,4 +1,4 @@
-/// [Action]
+/// [Action] is the object passed to your reducer to signify the state change that needs to take place.
 /// Action [name]s should always be unique!
 class Action<Payload> {
   /// A unique action name.
@@ -17,7 +17,7 @@ class ActionMgr<P> {
 
   String get name => _name;
 
-  call(P payload) => _dispatcher(new Action()
+  call(P payload) => _dispatcher(new Action<P>()
     ..name = name
     ..payload = payload);
 

lib/src/built_reducer.dart

@@ -9,17 +9,17 @@ abstract class BuiltReducer<V extends Built<V, B>, B extends Builder<V, B>> impl
   /// This is so each reducer can have the action payload generic be a different non dynamic value
   Map<String, Reducer<V, B, dynamic>> get reducers;
 
-  void reduce(B builder, Action<dynamic> a) {
+  void reduce(V state, Action<dynamic> a, B builder) {
     var reducer = reducers[a.name];
     // TODO: warn if payload type doesn't match reducer
-    if (reducer != null) reducer(builder, a);
+    if (reducer != null) reducer(state, a, builder);
 
-    reduceChildren(builder, a);
+    reduceChildren(state, a, builder);
   }
 
   /// Generated by the transformer for developer convienience
   /// Is implemented here as a noop to avoid anaylisis issues
-  void reduceChildren(B builder, Action<dynamic> a) {}
+  void reduceChildren(V state, Action<dynamic> a, B builder) {}
 }
 
 class ReducerBuilder<B> {

lib/src/store.dart

@@ -32,10 +32,10 @@ class Store<State extends BuiltReducer, Actions extends ReduxActions> {
 
     // setup the middleware dispatch chain
     ActionHandler handler = (action) {
-      var state = _state.rebuild((b) => _state.reduce(b, action));
+      var state = _state.rebuild((b) => _state.reduce(_state, action, b));
 
       // if the hashcode did not change bail
-      if (identical(_state, state)) return;
+      if (_state == state) return;
 
       // update the internal state and publish the change
       _state = state;

lib/transformer.dart

@@ -58,7 +58,7 @@ class BuiltStoreTransformer extends Transformer {
       var name = superclass.name.name;
       if (name == 'BuiltReducer') {
         String reduceChildrenBody =
-            "\n\n  @override\n  reduceChildren(dynamic b, Action<dynamic> a) {\n  }";
+            "\n\n  @override\n  reduceChildren(dynamic state, Action<dynamic> a, dynamic builder) {\n  }";
 
         for (ClassMember m in cd.members) {
           if (m is! MethodDeclaration) continue;
@@ -67,8 +67,8 @@ class BuiltStoreTransformer extends Transformer {
           if (!md.isGetter || md.returnType == null) continue;
 
           if (builtReducers.contains(md.returnType.name.name))
-            reduceChildrenBody =
-                reduceChildrenBody.replaceFirst("{", "{\n    ${md.name}.reduce(b.${md.name}, a);");
+            reduceChildrenBody = reduceChildrenBody.replaceFirst(
+                "{", "{\n    ${md.name}.reduce(state.${md.name}, a, builder.${md.name});");
         }
 
         transformedFile.insert(