import React, { Component } from ‘react‘;
import Context from ‘./context‘;

// 给connect等方法提供store
export default class Provider extends Component {
  render() {
    return (
      <Context.Provider value={{store: this.props.store}}>
        {this.props.children}
      </Context.Provider>
    )
  }
}

 1. 给使用connect方法的组件属性自动绑定了dispatch方法；this.props.dispatch
 2. 给使用connect方法的组件的setState方法自动添加了对仓库的state的订阅
 3. 给使用connect方法的组件的属性绑定仓库的state值；this.props.XXXX
    不再使用store.getState方法
 4. 给使用connect方法的组件的actions自动使用bindActionCreators方法

import React, { Component } from ‘react‘;
import Context from ‘./context‘;
import { bindActionCreators } from ‘redux‘;

/**
 * 
 * @param {function} mapStateToProps 绑定state到组件的props
 * @param {funtion|object} mapDispatchToProps  返回actions对象
 */
export default function(mapStateToProps, mapDispatchToProps) {
  return function(WrappedComponent) {
    return class extends Component {
      static contextType = Context;
      constructor(props, context) {
        super(props);
         // 被映射的state, 即mapStateToProps的返回值, 绑定到组件的props上
        this.state = mapStateToProps(context.store.getState());
      }
      componentDidMount() {
        this.unsubscribe = this.context.store.subscribe(() => {
          // setState的用法；传一个state对象
          this.setState(mapStateToProps(this.context.store.getState()));
        })
      }
      componentWillUnmount() {
        this.unsubscribe();
      }
      render() {      
        const { dispatch } = this.context.store;
        let actions = {};
        if (typeof mapDispatchToProps === ‘object‘){
          actions = mapDispatchToProps;
        } 
        if (typeof mapDispatchToProps === ‘function‘) {
          actions = mapDispatchToProps(dispatch);
        }
        const bindActions = bindActionCreators(actions, dispatch)
        return (
          <WrappedComponent dispatch={dispatch} {...this.state} {...bindActions} />          
        )
      }
    }
  }
}