add comments

Author: Slartbartfast1

src/components/Provider.js

@@ -3,6 +3,7 @@ import PropTypes from 'prop-types'
 import { ReactReduxContext } from './Context'
 import Subscription from '../utils/Subscription'
 
+// Provider实际上是用高阶组件(HOCHigher-order component)包裹App结合react的Context进行状态管理
 class Provider extends Component {
   constructor(props) {
     super(props)
@@ -36,6 +37,7 @@ class Provider extends Component {
   }
 
   componentDidUpdate(prevProps) {
+    // 重新订阅
     if (this.props.store !== prevProps.store) {
       this.state.subscription.tryUnsubscribe()
       const subscription = new Subscription(this.props.store)

src/connect/connect.js

@@ -74,7 +74,7 @@ export function createConnect({
       'mapDispatchToProps'
     )
     const initMergeProps = match(mergeProps, mergePropsFactories, 'mergeProps')
-
+    // 调用时传入组件
     return connectHOC(selectorFactory, {
       // used in error messages
       methodName: 'connect',
@@ -101,4 +101,4 @@ export function createConnect({
   }
 }
 
-export default createConnect()
+export default createConnect() // 实际export的是connect createConnect() 可以加入更多配置项

src/utils/Subscription.js

@@ -3,7 +3,8 @@ import { getBatch } from './batch'
 // encapsulates the subscription logic for connecting a component to the redux store, as
 // well as nesting subscriptions of descendant components, so that we can ensure the
 // ancestor components re-render before descendants
-
+// 订阅逻辑的封装
+// 嵌套订阅
 const CLEARED = null
 const nullListeners = { notify() {} }
 
@@ -15,11 +16,12 @@ function createListenerCollection() {
   let next = []
 
   return {
+    // 订阅清空
     clear() {
       next = CLEARED
       current = CLEARED
     },
-
+    // 发布订阅
     notify() {
       const listeners = (current = next)
       batch(() => {
@@ -28,7 +30,7 @@ function createListenerCollection() {
         }
       })
     },
-
+    
     get() {
       return next
     },
@@ -58,12 +60,12 @@ export default class Subscription {
 
     this.handleChangeWrapper = this.handleChangeWrapper.bind(this)
   }
-
+  //嵌套订阅
   addNestedSub(listener) {
     this.trySubscribe()
     return this.listeners.subscribe(listener)
   }
-
+  //嵌套发布
   notifyNestedSubs() {
     this.listeners.notify()
   }

src/utils/batch.js

@@ -1,4 +1,5 @@
 // Default to a dummy "batch" implementation that just runs the callback
+// 批处理
 function defaultNoopBatch(callback) {
   callback()
 }

src/utils/isPlainObject.js

@@ -2,12 +2,18 @@
  * @param {any} obj The object to inspect.
  * @returns {boolean} True if the argument appears to be a plain object.
  */
+
+// 简单对象只能是{}和new object()
+// typeof [] === "object",但不是简单对象
 export default function isPlainObject(obj) {
   if (typeof obj !== 'object' || obj === null) return false
 
   let proto = Object.getPrototypeOf(obj)
   if (proto === null) return true
-
+  // 基于原型链查找
+  // new出来的对象的原型是function 
+  // function的原型是object 
+  // 二者不相等 所以不是简单对象
   let baseProto = proto
   while (Object.getPrototypeOf(baseProto) !== null) {
     baseProto = Object.getPrototypeOf(baseProto)