fix(ConfigProvider): Isolate multiple context data

Closes #43

docs/dialog/demo/quick.md

@@ -15,7 +15,7 @@ The Dialog provides quick methods called alert and confirm, as well as a lower-l
 ---
 
 ````jsx
-import { Button, Dialog } from '@alifd/next';
+import { Button, Dialog, ConfigProvider } from '@alifd/next';
 
 
 const popupAlert = () => {
@@ -47,9 +47,14 @@ const popupCustom = () => {
     });
 };
 
-ReactDOM.render(<span>
-    <Button onClick={popupAlert}>Alert</Button> &nbsp;
-    <Button onClick={popupConfirm}>Confirm</Button> &nbsp;
-    <Button onClick={popupCustom}>Custom</Button>
-</span>, mountNode);
+ReactDOM.render(
+    <ConfigProvider locale={{ Dialog: { ok: 'OK', cancel: 'Cancel' } }}>
+        <span>
+            <Button onClick={popupAlert}>Alert</Button> &nbsp;
+            <Button onClick={popupConfirm}>Confirm</Button> &nbsp;
+            <Button onClick={popupCustom}>Custom</Button>
+        </span>
+    </ConfigProvider>,
+    mountNode
+);
 ````

src/config-provider/cache.js

@@ -0,0 +1,44 @@
+class Cache {
+  constructor() {
+    this._root = null;
+    this._store = new Map();
+  }
+
+  empty() {
+    return this._store.size === 0;
+  }
+
+  has(key) {
+    return this._store.has(key)
+  }
+
+  get(key, defaultValue) {
+    const res = this.has(key) ? this._store.get(key) : this.root()
+    return (typeof res === 'undefined' || res === null) ?
+      defaultValue : res
+  }
+
+  add(key, value) {
+    const store = this._store;
+    if (this.empty()) {
+      this._root = key;
+    }
+    this._store.set(key, value);
+  }
+
+  update(key, value) {
+    if (this.has(key)) {
+      this._store.set(key, value)
+    }
+  }
+
+  remove(key) {
+    this._store.delete(key);
+  }
+
+  root() {
+    return this._store.get(this._root)
+  }
+}
+
+export default Cache;

src/config-provider/index.jsx

@@ -3,8 +3,9 @@ import PropTypes from 'prop-types';
 import getContextProps from './get-context-props';
 import { config, initLocales, setLanguage, setLocale, getLocale, getLanguage } from './config';
 import Consumer from './consumer';
+import Cache from './cache'
 
-let childContextCache = {};
+let childContextCache = new Cache();
 
 /**
  * ConfigProvider
@@ -62,7 +63,7 @@ class ConfigProvider extends Component {
      * @returns {Object} 新的 context props
      */
     static getContextProps = (props, displayName) => {
-        return getContextProps(props, childContextCache, displayName);
+        return getContextProps(props, childContextCache.root(), displayName);
     };
 
     static initLocales = initLocales;
@@ -73,7 +74,7 @@ class ConfigProvider extends Component {
     static Consumer = Consumer;
 
     static getContext = () => {
-        const { nextPrefix, nextLocale, nextPure, nextWarning } = childContextCache;
+        const { nextPrefix, nextLocale, nextPure, nextWarning } = childContextCache.root();
 
         return {
             prefix: nextPrefix,
@@ -99,7 +100,10 @@ class ConfigProvider extends Component {
     }
 
     componentDidMount() {
-        childContextCache = Object.assign({}, this.getChildContext(), childContextCache);
+        childContextCache.add(
+            this,
+            Object.assign({}, childContextCache.get(this, {}), this.getChildContext())
+        );
     }
 
     componentWillReceiveProps(nextProps) {
@@ -109,11 +113,14 @@ class ConfigProvider extends Component {
     }
 
     componentDidUpdate() {
-        childContextCache = this.getChildContext();
+        childContextCache.add(
+            this,
+            Object.assign({}, childContextCache.get(this, {}), this.getChildContext())
+        );
     }
 
     componentWillUnmount() {
-        childContextCache = {};
+        childContextCache.remove(this);
     }
 
     setMomentLocale(locale) {