react之自定义react-redux的provider、connect

Provider

// Provider把store放到context里，所有的子元素可以直接取到store
import React from 'react'
import PropTypes from 'prop-types'
import {bindActionCreators} from './utils.js'

export const connect = (mapStateToProps=state=>state,mapDispatchToProps={})=>(WrapComponent)=>{
	return class ConnectComponent extends React.Component{
		static contextTypes = {
			store:PropTypes.object
		}
		constructor(props, context){
			super(props, context)
			this.state = {
				props:{}
			}
		}
		componentDidMount(){
			const {store} = this.context
			store.subscribe(()=>this.update())
			this.update()
		}
		update(){
			const {store} = this.context
			const stateProps = mapStateToProps(store.getState())
			const dispatchProps = bindActionCreators(mapDispatchToProps, store.dispatch)
			this.setState({
				props:{
					...this.state.props,
					...stateProps,
					...dispatchProps	
				}
			})
		}
		render(){
			return <WrapComponent {...this.state.props}></WrapComponent>
		}
	}
}

export class Provider extends React.Component{
	static childContextTypes = {
		store: PropTypes.object
	}
	getChildContext(){
		return {store:this.store}
	}
	constructor(props, context){
		super(props, context)
		this.store = props.store
	}
	render(){
		return this.props.children
	}
}

utils.js

export function createStore(reducer, enhancer){
	if (enhancer) {
		return enhancer(createStore)(reducer)
	}
	let currentState = {}
	let currentListeners = []

	function getState(){
		return currentState
	}
	function subscribe(listener){
		currentListeners.push(listener)
	}
	function dispatch(action){
		currentState = reducer(currentState, action)
		currentListeners.forEach(v=>v())
		return action
	}
	dispatch({type:'@IMOOC/WONIU-REDUX'})
	return { getState, subscribe, dispatch}
}

// 自定义applyMiddleware函数
export function applyMiddleware(...middlewares){
	return createStore=>(...args)=>{
		const store = createStore(...args)
		let dispatch = store.dispatch

		const midApi = {
			getState:store.getState,
			dispatch:(...args)=>dispatch(...args)
		}
		const middlewareChain = middlewares.map(middleware=>middleware(midApi))
		dispatch = compose(...middlewareChain)(store.dispatch)
		return {
			...store,
			dispatch
		}

	}
}
// 自定义compose函数
export function compose(...funcs){
	if (funcs.length==0) {
		return arg=>arg
	}
	if (funcs.length==1) {
		return funcs[0]
	}
	return funcs.reduce((ret,item)=> (...args)=>ret(item(...args)))
}
function bindActionCreator(creator, dispatch){
	return (...args) => dispatch(creator(...args))
}
export function bindActionCreators(creators,dispatch){
	return Object.keys(creators).reduce((ret,item)=>{
		ret[item] = bindActionCreator(creators[item],dispatch)
		return ret
	},{})
}