采用React编写小程序的Remax框架的编译流程解析

Remax是蚂蚁开源的一个用React来开发小程序的框架，采用运行时无语法限制的方案。整体研究下来主要分为三大部分：运行时原理、模板渲染原理、编译流程；看了下现有大部分文章主要集中在Reamx的运行时和模板渲染原理上，而对整个React代码编译为小程序的流程介绍目前还没有看到，本文即是来补充这个空白。
 
关于模板渲染原理看这篇文章：https://juejin.cn/post/6844904131157557262
关于remax运行时原理看这篇文章：https://juejin.cn/post/6881597846307635214#heading-22 https://zhuanlan.zhihu.com/p/83324871
关于React自定义渲染器看这篇文章：https://juejin.cn/post/6844903753242378248
 
 
Remax的基本结构：
1、remax-runtime 运行时，提供自定义渲染器、宿主组件的包装、以及由React组件到小程序的App、Page、Component的配置生成器

// 自定义渲染器export { default as render } from './render';// 由app.js到小程序App构造器的配置处理export { default as createAppConfig } from './createAppConfig';// 由React到小程序Page页面构造器的一系列适配处理export { default as createPageConfig } from './createPageConfig';// 由React组件到小程序自定义组件Component构造器的一系列适配处理export { default as createComponentConfig } from './createComponentConfig';// export { default as createNativeComponent } from './createNativeComponent';// 生成宿主组件，比如小程序原生提供的View、Button、Canvas等export { default as createHostComponent } from './createHostComponent';export { createPortal } from './ReactPortal';export { RuntimeOptions, PluginDriver } from '@remax/framework-shared';export * from './hooks';import { ReactReconcilerInst } from './render';export const unstable_batchedUpdates = ReactReconcilerInst.batchedUpdates;export default { unstable_batchedUpdates,};

 

 
2、remax-wechat 小程序相关适配器
template模板相关，与模板相关的处理原则及原理可以看这个https://juejin.cn/post/6844904131157557262
templates // 与渲染相关的模板
src/api 适配与微信小程序相关的各种全局api，有的进行了promisify化

import { promisify } from '@remax/framework-shared';declare const wx: WechatMiniprogram.Wx;export const canIUse = wx.canIUse;export const base64ToArrayBuffer = wx.base64ToArrayBuffer;export const arrayBufferToBase64 = wx.arrayBufferToBase64;export const getSystemInfoSync = wx.getSystemInfoSync;export const getSystemInfo = promisify(wx.getSystemInfo);

src/types/config.ts 与小程序的Page、App相关配置内容的适配处理

/** 页面配置文件 */// reference: https://developers.weixin.qq.com/miniprogram/dev/reference/configuration/page.htmlexport interface PageConfig { /** * 默认值：#000000 * 导航栏背景颜色，如 #000000 */ navigationBarBackgroundColor?: string; /** * 默认值：white * 导航栏标题颜色，仅支持 black / white */ navigationBarTextStyle?: 'black' | 'white'; /** 全局配置文件 */// reference: https://developers.weixin.qq.com/miniprogram/dev/reference/configuration/app.htmlexport interface AppConfig { /** * 页面路径列表 */ pages: string[]; /** * 全局的默认窗口表现 */ window?: { /**  * 默认值：#000000  * 导航栏背景颜色，如 #000000  */ navigationBarBackgroundColor?: string; /**  * 默认值: white  * 导航栏标题颜色，仅支持 black / white  */ navigationBarTextStyle?: 'white' | 'black';

 

src/types/component.ts 微信内置组件相关的公共属性、事件等属性适配

import * as React from 'react';/** 微信内置组件公共属性 */// reference: https://developers.weixin.qq.com/miniprogram/dev/framework/view/component.htmlexport interface BaseProps { /** 自定义属性: 组件上触发的事件时，会发送给事件处理函数 */ readonly dataset?: DOMStringMap; /** 组件的唯一标示: 保持整个页面唯一 */ id?: string; /** 组件的样式类: 在对应的 WXSS 中定义的样式类 */ className?: string; /** 组件的内联样式: 可以动态设置的内联样式 */ style?: React.CSSProperties; /** 组件是否显示: 所有组件默认显示 */ hidden?: boolean; /** 动画对象: 由`wx.createAnimation`创建 */ animation?: Array<Record<string, any>>; // reference: https://developers.weixin.qq.com/miniprogram/dev/framework/view/w /** 点击时触发 */ onTap?: (event: TouchEvent) => void; /** 点击时触发 */ onClick?: (event: TouchEvent) => void; /** 手指触摸动作开始 */ onTouchStart?: (event: TouchEvent) => void;

 

src/hostComponents 针对微信小程序宿主组件的包装和适配；node.ts是将小程序相关属性适配到React的规范

export const alias = { id: 'id', className: 'class', style: 'style', animation: 'animation', src: 'src', loop: 'loop', controls: 'controls', poster: 'poster', name: 'name', author: 'author', onError: 'binderror', onPlay: 'bindplay', onPause: 'bindpause', onTimeUpdate: 'bindtimeupdate', onEnded: 'bindended',};export const props = Object.values(alias);

 

各种组件也是利用createHostComponent生成

import * as React from 'react';import { createHostComponent } from '@remax/runtime';// 微信已不再维护export const Audio: React.ComponentType = createHostComponent('audio');

 

createHostComponent生成React的Element

import * as React from 'react';import { RuntimeOptions } from '@remax/framework-shared';export default function createHostComponent<P = any>(name: string, component?: React.ComponentType<P>) { if (component) { return component; } const Component = React.forwardRef((props, ref: React.Ref<any>) => { const { children = [] } = props; let element = React.createElement(name, { ...props, ref }, children); element = RuntimeOptions.get('pluginDriver').onCreateHostComponentElement(element) as React.DOMElement<any, any>; return element; }); return RuntimeOptions.get('pluginDriver').onCreateHostComponent(Component);}

 

 
3、remax-macro 按照官方描述是基于babel-plugin-macros的宏；所谓宏是在编译时进行字符串的静态替换，而Javascript没有编译过程，babel实现宏的方式是在将代码编译为ast树之后，对ast语法树进行操作来替换原本的代码。详细文章可以看这里https://zhuanlan.zhihu.com/p/64346538；
remax这里是利用macro来进行一些宏的替换，比如useAppEvent和usePageEvent等，替换为从remax/runtime中进行引入

import { createMacro } from 'babel-plugin-macros';import createHostComponentMacro from './createHostComponent';import requirePluginComponentMacro from './requirePluginComponent';import requirePluginMacro from './requirePlugin';import usePageEventMacro from './usePageEvent';import useAppEventMacro from './useAppEvent';function remax({ references, state }: { references: { [name: string]: NodePath[] }; state: any }) { references.createHostComponent?.forEach(path => createHostComponentMacro(path, state)); references.requirePluginComponent?.forEach(path => requirePluginComponentMacro(path, state)); references.requirePlugin?.forEach(path => requirePluginMacro(path)); const importer = slash(state.file.opts.filename); Store.appEvents.delete(importer); Store.pageEvents.delete(importer); references.useAppEvent?.forEach(path => useAppEventMacro(path, state)); references.usePageEvent?.forEach(path => usePageEventMacro(path, state));}export declare function createHostComponent<P = any>( name: string, props: Array<string | [string, string]>): React.ComponentType<P>;export declare function requirePluginComponent<P = any>(pluginName: string): React.ComponentType<P>;export declare function requirePlugin<P = any>(pluginName: string): P;export declare function usePageEvent(eventName: PageEventName, callback: (...params: any[]) => any): void;export declare function useAppEvent(eventName: AppEventName, callback: (...params: any[]) => any): void;export default createMacro(remax);

import * as t from '@babel/types';import { slash } from '@remax/shared';import { NodePath } from '@babel/traverse';import Store from '@remax/build-store';import insertImportDeclaration from './utils/insertImportDeclaration';const PACKAGE_NAME = '@remax/runtime';const FUNCTION_NAME = 'useAppEvent';function getArguments(callExpression: NodePath<t.CallExpression>, importer: string) { const args = callExpression.node.arguments; const eventName = args[0] as t.StringLiteral; const callback = args[1]; Store.appEvents.set(importer, Store.appEvents.get(importer)?.add(eventName.value) ?? new Set([eventName.value])); return [eventName, callback];}export default function useAppEvent(path: NodePath, state: any) { const program = state.file.path; const importer = slash(state.file.opts.filename); const functionName = insertImportDeclaration(program, FUNCTION_NAME, PACKAGE_NAME); const callExpression = path.findParent(p => t.isCallExpression(p)) as NodePath<t.CallExpression>; const [eventName, callback] = getArguments(callExpression, importer); callExpression.replaceWith(t.callExpression(t.identifier(functionName), [eventName, callback]));}

个人感觉这个设计有些过于复杂，可能跟remax的设计有关，在remax/runtime中，useAppEvent实际从remax-framework-shared中导出；
不过也倒是让我学到了一种对代码修改的处理方式。
 
4、remax-cli remax的脚手架，整个remax工程，生成到小程序的编译流程也是在这里处理。
先来看一下一个作为Page的React文件是如何与小程序的原生Page构造器关联起来的。
假设原先页面代码是这个样子，

import * as React from 'react';import { View, Text, Image } from 'remax/wechat';import styles from './index.css';export default () => { return ( <View className={styles.app}>  <View className={styles.header}>  <Image   src="https://gw.alipayobjects.com/mdn/rms_b5fcc5/afts/img/A*OGyZSI087zkAAAAAAAAAAABkARQnAQ"   className={styles.logo}   alt="logo"  />  <View className={styles.text}>   编辑 <Text className={styles.path}>src/pages/index/index.js</Text>开始  </View>  </View> </View> );};

 
这部分处理在remax-cli/src/build/entries/PageEntries.ts代码中，可以看到这里是对源码进行了修改，引入了runtime中的createPageConfig函数来对齐React组件与小程序原生Page需要的属性，同时调用原生的Page构造器来实例化页面。

import * as path from 'path';import VirtualEntry from './VirtualEntry';export default class PageEntry extends VirtualEntry { outputSource() { return `  import { createPageConfig } from '@remax/runtime';  import Entry from './${path.basename(this.filename)}';  Page(createPageConfig(Entry, '${this.name}')); `; }}

 

createPageConfig来负责将React组件挂载到remax自定义的渲染容器中，同时对小程序Page的各个生命周期与remax提供的各种hook进行关联

export default function createPageConfig(Page: React.ComponentType<any>, name: string) { const app = getApp() as any; const config: any = { data: {  root: {  children: [],  },  modalRoot: {  children: [],  }, }, wrapperRef: React.createRef<any>(), lifecycleCallback: {}, onLoad(this: any, query: any) {  const PageWrapper = createPageWrapper(Page, name);  this.pageId = generatePageId();  this.lifecycleCallback = {};  this.data = { // Page中定义的data实际是remax在内存中生成的一颗镜像树  root: {   children: [],  },  modalRoot: {   children: [],  },  };  this.query = query;  // 生成自定义渲染器需要定义的容器  this.container = new Container(this, 'root');  this.modalContainer = new Container(this, 'modalRoot');  // 这里生成页面级别的React组件  const pageElement = React.createElement(PageWrapper, {  page: this,  query,  modalContainer: this.modalContainer,  ref: this.wrapperRef,  });  if (app && app._mount) {  this.element = createPortal(pageElement, this.container, this.pageId);  app._mount(this);  } else {   // 调用自定义渲染器进行渲染  this.element = render(pageElement, this.container);  }  // 调用生命周期中的钩子函数  return this.callLifecycle(Lifecycle.load, query); }, onUnload(this: any) {  this.callLifecycle(Lifecycle.unload);  this.unloaded = true;  this.container.clearUpdate();  app._unmount(this); },

 

Container是按照React自定义渲染规范定义的根容器，最终是在applyUpdate方法中调用小程序原生的setData方法来更新渲染视图

applyUpdate() { if (this.stopUpdate || this.updateQueue.length === 0) { return; } const startTime = new Date().getTime(); if (typeof this.context.$spliceData === 'function') { let $batchedUpdates = (callback: () => void) => {  callback(); }; if (typeof this.context.$batchedUpdates === 'function') {  $batchedUpdates = this.context.$batchedUpdates; } $batchedUpdates(() => {  this.updateQueue.map((update, index) => {  let callback = undefined;  if (index + 1 === this.updateQueue.length) {   callback = () => {   nativeEffector.run();   /* istanbul ignore next */   if (RuntimeOptions.get('debug')) {    console.log(`setData => 回调时间：${new Date().getTime() - startTime}ms`);   }   };  }  if (update.type === 'splice') {   this.context.$spliceData(   {    [this.normalizeUpdatePath([...update.path, 'children'])]: [    update.start,    update.deleteCount,    ...update.items,    ],   },   callback   );  }  if (update.type === 'set') {   this.context.setData(   {    [this.normalizeUpdatePath([...update.path, update.name])]: update.value,   },   callback   );  }  }); }); this.updateQueue = []; return; } const updatePayload = this.updateQueue.reduce<{ [key: string]: any }>((acc, update) => { if (update.node.isDeleted()) {  return acc; } if (update.type === 'splice') {  acc[this.normalizeUpdatePath([...update.path, 'nodes', update.id.toString()])] = update.items[0] || null;  if (update.children) {  acc[this.normalizeUpdatePath([...update.path, 'children'])] = (update.children || []).map(c => c.id);  } } else {  acc[this.normalizeUpdatePath([...update.path, update.name])] = update.value; } return acc; }, {}); // 更新渲染视图 this.context.setData(updatePayload, () => { nativeEffector.run(); /* istanbul ignore next */ if (RuntimeOptions.get('debug')) {  console.log(`setData => 回调时间：${new Date().getTime() - startTime}ms`, updatePayload); } }); this.updateQueue = [];}

 

而对于容器的更新是在render文件中的render方法进行的，

function getPublicRootInstance(container: ReactReconciler.FiberRoot) { const containerFiber = container.current; if (!containerFiber.child) { return null; } return containerFiber.child.stateNode;}export default function render(rootElement: React.ReactElement | null, container: Container | AppContainer) { // Create a root Container if it doesnt exist if (!container._rootContainer) { container._rootContainer = ReactReconcilerInst.createContainer(container, false, false); } ReactReconcilerInst.updateContainer(rootElement, container._rootContainer, null, () => { // ignore }); return getPublicRootInstance(container._rootContainer);}

 

另外这里渲染的组件，其实也是经过了createPageWrapper包装了一层，主要是为了处理一些forward-ref相关操作。
现在已经把页面级别的React组件与小程序原生Page关联起来了。
对于Component的处理与这个类似，可以看remax-cli/src/build/entries/ComponentEntry.ts文件

import * as path from 'path';import VirtualEntry from './VirtualEntry';export default class ComponentEntry extends VirtualEntry { outputSource() { return `  import { createComponentConfig } from '@remax/runtime';  import Entry from './${path.basename(this.filename)}';  Component(createComponentConfig(Entry)); `; }}

 
那么对于普通的组件，remax会把他们编译称为自定义组件，小程序的自定义组件是由json w

export default class ComponentAssetPlugin { builder: Builder; cache: SourceCache = new SourceCache(); constructor(builder: Builder) { this.builder = builder; } apply(compiler: Compiler) { compiler.hooks.emit.tapAsync(PLUGIN_NAME, async (compilation, callback) => {  const { options, api } = this.builder;  const meta = api.getMeta();  const { entries } = this.builder.entryCollection;  await Promise.all(  Array.from(entries.values()).map(async component => {   if (!(component instanceof ComponentEntry)) {   return Promise.resolve();   }   const chunk = compilation.chunks.find(c => {   return c.name === component.name;   });   const modules = [...getModules(chunk), component.filename];   let templatePromise;   if (options.turboRenders) {   // turbo page   templatePromise = createTurboTemplate(this.builder.api, options, component, modules, meta, compilation);   } else {   templatePromise = createTemplate(component, options, meta, compilation, this.cache);   }   await Promise.all([   await templatePromise,   await createManifest(this.builder, component, compilation, this.cache),   ]);  })  );  callback(); }); }}

而Page的一系列文件在remax-cli/src/build/webpack/plugins/PageAsset中进行处理，同时在createMainifest中会分析Page与自定义组件之间的依赖关系，自动生成usingComponents的关联关系。
 
 
 
 
 
 
 

原文转载：http://www.shaoqun.com/a/698763.html

跨境电商：https://www.ikjzd.com/

周宁：https://www.ikjzd.com/w/1647

heap：https://www.ikjzd.com/w/2012

Remax是蚂蚁开源的一个用React来开发小程序的框架，采用运行时无语法限制的方案。整体研究下来主要分为三大部分：运行时原理、模板渲染原理、编译流程；看了下现有大部分文章主要集中在Reamx的运行时和模板渲染原理上，而对整个React代码编译为小程序的流程介绍目前还没有看到，本文即是来补充这个空白。关于模板渲染原理看这篇文章：https://juejin.cn/post/684490413115
启明星软件：https://www.ikjzd.com/w/1436
电霸：https://www.ikjzd.com/w/2597
史泰博办公用品：https://www.ikjzd.com/w/2112
嗯啊,,奶水。老师 好爽 嗯啊,口述那晚与家教老师疯狂缠绵：http://www.30bags.com/m/a/254560.html
商务部：欢迎更多国外优质产品和服务进入中国！：https://www.ikjzd.com/home/113299
亚马逊新品如何定价？：https://www.ikjzd.com/home/143236