Initial re-implementation of connectAdvanced using hooks

Matches changes from v7.0.0-alpha.1

Author: markerikson

src/components/Provider.js

@@ -1,63 +1,55 @@
 import React, { Component } from 'react'
 import PropTypes from 'prop-types'
 import { ReactReduxContext } from './Context'
+import Subscription from '../utils/Subscription'
 
 class Provider extends Component {
   constructor(props) {
     super(props)
 
     const { store } = props
 
+    this.notifySubscribers = this.notifySubscribers.bind(this)
+    const subscription = new Subscription(store)
+    subscription.onStateChange = this.notifySubscribers
+
     this.state = {
-      storeState: store.getState(),
-      store
+      store,
+      subscription
     }
+
+    this.previousState = store.getState()
   }
 
   componentDidMount() {
     this._isMounted = true
-    this.subscribe()
+
+    this.state.subscription.trySubscribe()
+
+    if (this.previousState !== this.props.store.getState()) {
+      this.state.subscription.notifyNestedSubs()
+    }
   }
 
   componentWillUnmount() {
     if (this.unsubscribe) this.unsubscribe()
 
+    this.state.subscription.tryUnsubscribe()
+
     this._isMounted = false
   }
 
   componentDidUpdate(prevProps) {
     if (this.props.store !== prevProps.store) {
-      if (this.unsubscribe) this.unsubscribe()
-
-      this.subscribe()
+      this.state.subscription.tryUnsubscribe()
+      const subscription = new Subscription(this.props.store)
+      subscription.onStateChange = this.notifySubscribers
+      this.setState({ store: this.props.store, subscription })
     }
   }
 
-  subscribe() {
-    const { store } = this.props
-
-    this.unsubscribe = store.subscribe(() => {
-      const newStoreState = store.getState()
-
-      if (!this._isMounted) {
-        return
-      }
-
-      this.setState(providerState => {
-        // If the value is the same, skip the unnecessary state update.
-        if (providerState.storeState === newStoreState) {
-          return null
-        }
-
-        return { storeState: newStoreState }
-      })
-    })
-
-    // Actions might have been dispatched between render and mount - handle those
-    const postMountStoreState = store.getState()
-    if (postMountStoreState !== this.state.storeState) {
-      this.setState({ storeState: postMountStoreState })
-    }
+  notifySubscribers() {
+    this.state.subscription.notifyNestedSubs()
   }
 
   render() {