feat: context

BetaSu · BetaSu · commit 18d25044415b · 2023-07-02T20:39:09.000+08:00
diff --git a/demos/context/index.html b/demos/context/index.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+  <meta charset="UTF-8" />
+  <link rel="icon" type="image/svg+xml" href="/vite.svg" />
+  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+  <title>context测试</title>
+</head>
+
+<body>
+  <div id="root"></div>
+  <script type="module" src="main.tsx"></script>
+</body>
+
+</html>
diff --git a/demos/context/main.tsx b/demos/context/main.tsx
@@ -0,0 +1,32 @@
+import { useState, createContext, useContext } from 'react';
+import ReactDOM from 'react-dom/client';
+
+const ctxA = createContext('deafult A');
+const ctxB = createContext('default B');
+
+function App() {
+	return (
+		<ctxA.Provider value={'A0'}>
+			<ctxB.Provider value={'B0'}>
+				<ctxA.Provider value={'A1'}>
+					<Cpn />
+				</ctxA.Provider>
+			</ctxB.Provider>
+			<Cpn />
+		</ctxA.Provider>
+	);
+}
+
+function Cpn() {
+	const a = useContext(ctxA);
+	const b = useContext(ctxB);
+	return (
+		<div>
+			A: {a} B: {b}
+		</div>
+	);
+}
+
+ReactDOM.createRoot(document.getElementById('root') as HTMLElement).render(
+	<App />
+);
diff --git a/demos/context/vite-env.d.ts b/demos/context/vite-env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vite/client" />
diff --git a/package.json b/package.json
@@ -5,7 +5,7 @@
 	"main": "index.js",
 	"scripts": {
 		"build:dev": "rm -rf dist && rollup --config scripts/rollup/dev.config.js",
-		"demo": "vite serve demos/ref --config scripts/vite/vite.config.js --force",
+		"demo": "vite serve demos/context --config scripts/vite/vite.config.js --force",
 		"lint": "eslint --ext .ts,.jsx,.tsx --fix --quiet ./packages",
 		"test": "jest --config scripts/jest/jest.config.js"
 	},
diff --git a/packages/react-reconciler/src/beginWork.ts b/packages/react-reconciler/src/beginWork.ts
@@ -5,13 +5,15 @@ import { renderWithHooks } from './fiberHooks';
 import { Lane } from './fiberLanes';
 import { processUpdateQueue, UpdateQueue } from './updateQueue';
 import {
+	ContextProvider,
 	Fragment,
 	FunctionComponent,
 	HostComponent,
 	HostRoot,
 	HostText
 } from './workTags';
 import { Ref } from './fiberFlags';
+import { pushProvider } from './fiberContext';
 
 // 递归中的递阶段
 export const beginWork = (wip: FiberNode, renderLane: Lane) => {
@@ -27,6 +29,8 @@ export const beginWork = (wip: FiberNode, renderLane: Lane) => {
 			return updateFunctionComponent(wip, renderLane);
 		case Fragment:
 			return updateFragment(wip);
+		case ContextProvider:
+			return updateContextProvider(wip);
 		default:
 			if (__DEV__) {
 				console.warn('beginWork未实现的类型');
@@ -36,6 +40,18 @@ export const beginWork = (wip: FiberNode, renderLane: Lane) => {
 	return null;
 };
 
+function updateContextProvider(wip: FiberNode) {
+	const providerType = wip.type;
+	const context = providerType._context;
+	const newProps = wip.pendingProps;
+
+	pushProvider(context, newProps.value);
+
+	const nextChildren = newProps.children;
+	reconcileChildren(wip, nextChildren);
+	return wip.child;
+}
+
 function updateFragment(wip: FiberNode) {
 	const nextChildren = wip.pendingProps;
 	reconcileChildren(wip, nextChildren);
diff --git a/packages/react-reconciler/src/childFibers.ts b/packages/react-reconciler/src/childFibers.ts
@@ -188,7 +188,9 @@ function ChildReconciler(shouldTrackEffects: boolean) {
 		if (
 			Array.isArray(element) ||
 			typeof element === 'string' ||
-			typeof element === 'number'
+			typeof element === 'number' ||
+			element === undefined ||
+			element === null
 		) {
 			return index;
 		}
diff --git a/packages/react-reconciler/src/completeWork.ts b/packages/react-reconciler/src/completeWork.ts
@@ -12,8 +12,10 @@ import {
 	HostText,
 	HostComponent,
 	FunctionComponent,
-	Fragment
+	Fragment,
+	ContextProvider
 } from './workTags';
+import { popProvider } from './fiberContext';
 
 function markUpdate(fiber: FiberNode) {
 	fiber.flags |= Update;
@@ -76,6 +78,11 @@ export const completeWork = (wip: FiberNode) => {
 		case Fragment:
 			bubbleProperties(wip);
 			return null;
+		case ContextProvider:
+			const context = wip.type._context;
+			popProvider(context);
+			bubbleProperties(wip);
+			return null;
 		default:
 			if (__DEV__) {
 				console.warn('未处理的completeWork情况', wip);
diff --git a/packages/react-reconciler/src/fiber.ts b/packages/react-reconciler/src/fiber.ts
@@ -1,5 +1,6 @@
 import { Props, Key, Ref, ReactElementType } from 'shared/ReactTypes';
 import {
+	ContextProvider,
 	Fragment,
 	FunctionComponent,
 	HostComponent,
@@ -10,6 +11,7 @@ import { Container } from 'hostConfig';
 import { Lane, Lanes, NoLane, NoLanes } from './fiberLanes';
 import { Effect } from './fiberHooks';
 import { CallbackNode } from 'scheduler';
+import { REACT_PROVIDER_TYPE } from 'shared/ReactSymbols';
 
 export class FiberNode {
 	type: any;
@@ -134,6 +136,11 @@ export function createFiberFromElement(element: ReactElementType): FiberNode {
 	if (typeof type === 'string') {
 		// <div/> type: 'div'
 		fiberTag = HostComponent;
+	} else if (
+		typeof type === 'object' &&
+		type.$$typeof === REACT_PROVIDER_TYPE
+	) {
+		fiberTag = ContextProvider;
 	} else if (typeof type !== 'function' && __DEV__) {
 		console.warn('为定义的type类型', element);
 	}
diff --git a/packages/react-reconciler/src/fiberContext.ts b/packages/react-reconciler/src/fiberContext.ts
@@ -0,0 +1,17 @@
+import { ReactContext } from 'shared/ReactTypes';
+
+let prevContextValue: any = null;
+const prevContextValueStack: any[] = [];
+
+export function pushProvider<T>(context: ReactContext<T>, newValue: T) {
+	prevContextValueStack.push(prevContextValue);
+
+	prevContextValue = context._currentValue;
+	context._currentValue = newValue;
+}
+
+export function popProvider<T>(context: ReactContext<T>) {
+	context._currentValue = prevContextValue;
+
+	prevContextValue = prevContextValueStack.pop();
+}
diff --git a/packages/react-reconciler/src/fiberHooks.ts b/packages/react-reconciler/src/fiberHooks.ts
@@ -2,7 +2,7 @@ import { Dispatch } from 'react/src/currentDispatcher';
 import { Dispatcher } from 'react/src/currentDispatcher';
 import currentBatchConfig from 'react/src/currentBatchConfig';
 import internals from 'shared/internals';
-import { Action } from 'shared/ReactTypes';
+import { Action, ReactContext } from 'shared/ReactTypes';
 import { FiberNode } from './fiber';
 import { Flags, PassiveEffect } from './fiberFlags';
 import { Lane, NoLane, requestUpdateLane } from './fiberLanes';
@@ -82,14 +82,16 @@ const HooksDispatcherOnMount: Dispatcher = {
 	useState: mountState,
 	useEffect: mountEffect,
 	useTransition: mountTransition,
-	useRef: mountRef
+	useRef: mountRef,
+	useContext: readContext
 };
 
 const HooksDispatcherOnUpdate: Dispatcher = {
 	useState: updateState,
 	useEffect: updateEffect,
 	useTransition: updateTransition,
-	useRef: updateRef
+	useRef: updateRef,
+	useContext: readContext
 };
 
 function mountEffect(create: EffectCallback | void, deps: EffectDeps | void) {
@@ -379,3 +381,12 @@ function mountWorkInProgressHook(): Hook {
 	}
 	return workInProgressHook;
 }
+
+function readContext<T>(context: ReactContext<T>): T {
+	const consumer = currentlyRenderingFiber;
+	if (consumer === null) {
+		throw new Error('只能在函数组件中调用useContext');
+	}
+	const value = context._currentValue;
+	return value;
+}
diff --git a/packages/react-reconciler/src/workTags.ts b/packages/react-reconciler/src/workTags.ts
@@ -3,7 +3,8 @@ export type WorkTag =
 	| typeof HostRoot
 	| typeof HostComponent
 	| typeof HostText
-	| typeof Fragment;
+	| typeof Fragment
+	| typeof ContextProvider;
 
 export const FunctionComponent = 0;
 export const HostRoot = 3;
@@ -12,3 +13,4 @@ export const HostComponent = 5;
 // <div>123</div>
 export const HostText = 6;
 export const Fragment = 7;
+export const ContextProvider = 8;
diff --git a/packages/react/index.ts b/packages/react/index.ts
@@ -6,6 +6,7 @@ import {
 	isValidElement as isValidElementFn
 } from './src/jsx';
 export { REACT_FRAGMENT_TYPE as Fragment } from 'shared/ReactSymbols';
+export { createContext } from './src/context';
 // React
 
 export const useState: Dispatcher['useState'] = (initialState) => {
@@ -28,6 +29,11 @@ export const useRef: Dispatcher['useRef'] = (initialValue) => {
 	return dispatcher.useRef(initialValue);
 };
 
+export const useContext: Dispatcher['useContext'] = (context) => {
+	const dispatcher = resolveDispatcher() as Dispatcher;
+	return dispatcher.useContext(context);
+};
+
 // 内部数据共享层
 export const __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED = {
 	currentDispatcher,
diff --git a/packages/react/src/context.ts b/packages/react/src/context.ts
@@ -0,0 +1,15 @@
+import { REACT_CONTEXT_TYPE, REACT_PROVIDER_TYPE } from 'shared/ReactSymbols';
+import { ReactContext } from 'shared/ReactTypes';
+
+export function createContext<T>(defaultValue: T): ReactContext<T> {
+	const context: ReactContext<T> = {
+		$$typeof: REACT_CONTEXT_TYPE,
+		Provider: null,
+		_currentValue: defaultValue
+	};
+	context.Provider = {
+		$$typeof: REACT_PROVIDER_TYPE,
+		_context: context
+	};
+	return context;
+}
diff --git a/packages/react/src/currentDispatcher.ts b/packages/react/src/currentDispatcher.ts
@@ -1,10 +1,11 @@
-import { Action } from 'shared/ReactTypes';
+import { Action, ReactContext } from 'shared/ReactTypes';
 
 export interface Dispatcher {
 	useState: <T>(initialState: (() => T) | T) => [T, Dispatch<T>];
 	useEffect: (callback: () => void | void, deps: any[] | void) => void;
 	useTransition: () => [boolean, (callback: () => void) => void];
 	useRef: <T>(initialValue: T) => { current: T };
+	useContext: <T>(context: ReactContext<T>) => T;
 }
 
 export type Dispatch<State> = (action: Action<State>) => void;
diff --git a/packages/shared/ReactSymbols.ts b/packages/shared/ReactSymbols.ts
@@ -6,4 +6,12 @@ export const REACT_ELEMENT_TYPE = supportSymbol
 
 export const REACT_FRAGMENT_TYPE = supportSymbol
 	? Symbol.for('react.fragment')
-	: 0xeacb;
+	: 0xeaca;
+
+export const REACT_CONTEXT_TYPE = supportSymbol
+	? Symbol.for('react.context')
+	: 0xeacc;
+
+export const REACT_PROVIDER_TYPE = supportSymbol
+	? Symbol.for('react.provider')
+	: 0xeac2;
diff --git a/packages/shared/ReactTypes.ts b/packages/shared/ReactTypes.ts
@@ -14,3 +14,14 @@ export interface ReactElementType {
 }
 
 export type Action<State> = State | ((prevState: State) => State);
+
+export type ReactContext<T> = {
+	$$typeof: symbol | number;
+	Provider: ReactProviderType<T> | null;
+	_currentValue: T;
+};
+
+export type ReactProviderType<T> = {
+	$$typeof: symbol | number;
+	_context: ReactContext<T> | null;
+};
