improve store and reducers

src/background/index.js

@@ -2,12 +2,12 @@ import * as keys from './keys';
 import * as inputActions from '../actions/input';
 import * as operationActions from '../actions/operation';
 import backgroundReducers from '../reducers/background';
+import reducers from '../reducers';
 import commandReducer from '../reducers/command';
 import inputReducers from '../reducers/input';
 import * as store from '../store'
 
-const emptyReducer = (state) => state;
+const backgroundStore = store.createStore(reducers, (e) => {
-const emptyStore = store.createStore(emptyReducer, (e) => {
   console.error('Vim-Vixen:', e);
 });
 let inputState = inputReducers(undefined, {});
@@ -27,9 +27,7 @@ const keyQueueChanged = (sender, prevState, state) => {
     return Promise.resolve();
   }
   let action = keys.defaultKeymap[matched];
-  emptyStore.dispatch(operationActions.exec(action, sender), (e) => {
+  backgroundStore.dispatch(operationActions.exec(action, sender));
-    console.error('Vim-Vixen:', e);
-  });
   return handleMessage(inputActions.clearKeys(), sender).then(() => {
     return backgroundReducers(undefined, action, sender).then(() => {
       return browser.tabs.sendMessage(sender.tab.id, action);

src/reducers/index.js

@@ -0,0 +1,7 @@
+const defaultState = {
+};
+
+export default function reducer(state = defaultState/*, action = {}*/) {
+  return Object.assign({}, state, {
+  });
+}

src/store/index.js

@@ -3,21 +3,38 @@ class Store {
     this.reducer = reducer;
     this.catcher = catcher;
     this.state = this.reducer(undefined, {});
+    this.subscribers = [];
   }
 
   dispatch(action) {
     if (action instanceof Promise) {
       action.then((a) => {
-        this.state = this.reducer(this.state, a);
+        this.transitNext(a);
       }).catch(this.catcher)
     } else {
       try {
-        this.state = this.reducer(this.state, action);
+        this.transitNext(action);
       } catch (e) {
         this.catcher(e);
       }
     }
   }
+
+  getState() {
+    return this.state;
+  }
+
+  subscribe(callback) {
+    this.subscribers.push(callback);
+  }
+
+  transitNext(action) {
+    let newState = this.reducer(this.state, action);
+    if (JSON.stringify(this.state) !== JSON.stringify(newState)) {
+      this.state = newState;
+      this.subscribers.forEach(f => f.call())
+    }
+  }
 }
 
 const empty = () => {};