这篇文章主要介绍了采用React编写小程序的Remax框架的编译流程解析(推荐),本文通过实例代码给大家介绍的非常详细，对大家的学习或工作具有一定的参考借鉴价值，需要的朋友可以参考下
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://www.ufcn.cn/article/132635.htm
关于remax运行时原理看这篇文章：https://www.ufcn.cn/article/210293.htm
关于React自定义渲染器看这篇文章：https://www.ufcn.cn/article/198425.htm
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://www.ufcn.cn/article/145552.htm
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.html export 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.html export 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.html export 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>; // reference: https://developers.weixin.qq.com/miniprogram/dev/framework/view/wxml/event.html /** 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(name: string, component?: React.ComponentType
) { if (component) { return component; } const Component = React.forwardRef((props, ref: React.Ref) => { const { children = [] } = props; let element = React.createElement(name, { ...props, ref }, children); element = RuntimeOptions.get('pluginDriver').onCreateHostComponentElement(element) as React.DOMElement; 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( name: string, props: Array ): React.ComponentType
; export declare function requirePluginComponent
(pluginName: string): React.ComponentType
; export declare function requirePlugin
(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, 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; 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 ( 编辑 src/pages/index/index.js开始 ); };
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, name: string) { const app = getApp() as any; const config: any = { data: { root: { children: [], }, modalRoot: { children: [], }, }, wrapperRef: React.createRef(), 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.$spliceData( { [this.normalizeUpdatePath([...update.path, 'children'])]: [ update.start, update.deleteCount, ...update.items, ], }, callback ); } if (update.type === 'set') { this.context.setData( { [this.normalizeUpdatePath([...update.path, update.name])]: update.value, }, callback ); } }); }); this.updateQueue = []; return; } const updatePayload = this.updateQueue.reduce((acc, update) => { if (update.node.isDeleted()) { return acc; } if (update.type === 'splice') { acc[this.normalizeUpdatePath([...update.path, 'nodes', update.id.toString()])] = update.items[0] || null; if (update.children) { acc[this.normalizeUpdatePath([...update.path, 'children'])] = (update.children || []).map(c => c.id); } } else { acc[this.normalizeUpdatePath([...update.path, update.name])] = update.value; } return acc; }, {}); // 更新渲染视图 this.context.setData(updatePayload, () => { nativeEffector.run(); /* istanbul ignore next */ if (RuntimeOptions.get('debug')) { console.log(`setData => 回调时间：${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 wxml wxss js组成，由React组件到这些文件的处理过程在remax-cli/src/build/webpack/plugins/ComponentAsset中处理，生成wxml、wxss和js文件
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。
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