redux-core.js

function createStore(reducer, initialState) {
  let currentState = initialState;
  let listeners = [];

  function subscribe(listener) {
    listeners.push(listener);
    const isSubscribed = true;
    return function unsubscribe() {
      if (!isSubscribed) return
      isSubscribed = false
      const index = listeners.indexOf(listener)
      listeners.splice(index, 1)
    }
  }

  function dispatch(action) {
    currentState = reducer(state, action);
    listeners.slice().forEach(listener => listener())
    return action;
  }
  
  dispatch({ type: 'ACTION/@@INIT' })

  return {
    dispatch,
    subscribe,
    getState() {
      return currentState;
    }
  };
}

class Provider extends React.Component {
  static propTypes = {
    store: storeShape.isRequired,
    children: PropTypes.element.isRequired
  };
  static childContextTypes = {
    store: storeShape.isRequired
  };
  getChildContext() {
    return { store: this.store }
  }
  constructor(props, context) {
    super(props, context)
    this.store = props.store
  }
  render() {
    let { children } = this.props;
    return React.Children.only(children)
  }
}

function connect(mapStateToProps, mapDispatchToProps, mergeProps, options = {}) {
  return function wrapWithConnect(WrappedComponent) {
    class Connect extends React.Component {
      constructor(props, context) {
        super(props, context)
        this.store = props.store || context.store
        const storeState = this.store.getState()
        this.state = { storeState }
      }
      componentDidMount() {
        this.trysubscribe()
      }
      componentWillUnmount() {
        this.tryUnSubscribe()
      }
      trySubscribe() {
        this.unsubscribe = this.store.subscribe(::this.handleChange)
        this.handleChange()
      }
      tryUnsubscribe() {
        this.unsubscribe()
        this.unsubscribe = null
      }
      handleChange() {
        const preivousState = this.store.storeState
        const storeState = this.store.getState()
        this.setState({ storeState })
      }
    }
  }
}