From c42ac8fac48f9d56b54af4818917082fda9af21e Mon Sep 17 00:00:00 2001
From: Shin'ya Ueoka <ueokande@i-beam.org>
Date: Thu, 14 Sep 2017 21:14:13 +0900
Subject: improve store and reducers

---
 src/store/index.js | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

(limited to 'src/store')

diff --git a/src/store/index.js b/src/store/index.js
index bcb65d6..841fd17 100644
--- a/src/store/index.js
+++ b/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 = () => {};
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