planning

node_modules/react-redux/src/components/Provider.js

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+import React, { useMemo } from 'react'
+import PropTypes from 'prop-types'
+import { ReactReduxContext } from './Context'
+import { createSubscription } from '../utils/Subscription'
+import { useIsomorphicLayoutEffect } from '../utils/useIsomorphicLayoutEffect'
+
+function Provider({ store, context, children }) {
+  const contextValue = useMemo(() => {
+    const subscription = createSubscription(store)
+    return {
+      store,
+      subscription,
+    }
+  }, [store])
+
+  const previousState = useMemo(() => store.getState(), [store])
+
+  useIsomorphicLayoutEffect(() => {
+    const { subscription } = contextValue
+    subscription.onStateChange = subscription.notifyNestedSubs
+    subscription.trySubscribe()
+
+    if (previousState !== store.getState()) {
+      subscription.notifyNestedSubs()
+    }
+    return () => {
+      subscription.tryUnsubscribe()
+      subscription.onStateChange = null
+    }
+  }, [contextValue, previousState])
+
+  const Context = context || ReactReduxContext
+
+  return <Context.Provider value={contextValue}>{children}</Context.Provider>
+}
+
+if (process.env.NODE_ENV !== 'production') {
+  Provider.propTypes = {
+    store: PropTypes.shape({
+      subscribe: PropTypes.func.isRequired,
+      dispatch: PropTypes.func.isRequired,
+      getState: PropTypes.func.isRequired,
+    }),
+    context: PropTypes.object,
+    children: PropTypes.any,
+  }
+}
+
+export default Provider