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// exportDependencies.js
const fs = require('fs')
const path = require('path')
const parser = require('@babel/parser')
const traverse = require('@babel/traverse').default
const babel = require('@babel/core')const exportDependencies = (filename)=>{const content = fs.readFileSync(filename,'utf-8')// 转为Astconst ast = parser.parse(content, {sourceType : 'module'//babel官方规定必须加这个参数，不然无法识别ES Module})const dependencies = {}//遍历AST抽象语法树traverse(ast, {//调用ImportDeclaration获取通过import引入的模块ImportDeclaration({node}){const dirname = path.dirname(filename)const newFile = './' + path.join(dirname, node.source.value)//保存所依赖的模块dependencies[node.source.value] = newFile}})//通过@babel/core和@babel/preset-env进行代码的转换const {code} = babel.transformFromAst(ast, null, {presets: ["@babel/preset-env"]})return{filename,//该文件名dependencies,//该文件所依赖的模块集合(键值对存储)code//转换后的代码}
}
module.exports = exportDependencies
 

//info.js
const a = 1
export a
// index.js
import info from'./info.js'
console.log(info)
//testExport.js
const exportDependencies = require('./exportDependencies')
console.log(exportDependencies('./src/index.js'))
 

const exportDependencies = require('./exportDependencies')
//entry为入口文件路径
const exportGraph = (entry)=>{const entryModule = exportDependencies(entry)const graphArray = [entryModule]for(let i = 0; i < graphArray.length; i++){const item = graphArray[i];//拿到文件所依赖的模块集合,dependencies的值参考exportDependenciesconst { dependencies } = item;for(let j in dependencies){graphArray.push(exportDependencies(dependencies[j]))//关键代码，目的是将入口模块及其所有相关的模块放入数组}}//接下来生成图谱const graph = {}graphArray.forEach(item => {graph[item.filename] = {dependencies: item.dependencies,code: item.code}})//可以看出，graph其实是 文件路径名：文件内容 的集合return graph
}
module.exports = exportGraph
 

const exportGraph = require('./exportGraph')
// 写入文件，可以用fs.writeFileSync等方法，写入到output.path中
const exportBundle = require('./exportBundle')
const exportCode = (entry)=>{//要先把对象转换为字符串，不然在下面的模板字符串中会默认调取对象的toString方法，参数变成[Object object]const graph = JSON.stringify(exportGraph(entry))exportBundle(`(function(graph) {//require函数的本质是执行一个模块的代码，然后将相应变量挂载到exports对象上function require(module) {//localRequire的本质是拿到依赖包的exports变量function localRequire(relativePath) {return require(graph[module].dependencies[relativePath]);}var exports = {};(function(require, exports, code) {eval(code);})(localRequire, exports, graph[module].code);return exports;//函数返回指向局部变量，形成闭包，exports变量在函数执行后不会被摧毁}require('${entry}')})(${graph})`)
}
module.exports = exportCode
        

 (function(graph) {//require函数的本质是执行一个模块的代码，然后将相应变量挂载到exports对象上function require(module) {//localRequire的本质是拿到依赖包的exports变量function localRequire(relativePath) {returnrequire(graph[module].dependencies[relativePath]);}var exports = {};(function(require, exports, code) {eval(code);})(localRequire, exports, graph[module].code);return exports;//函数返回指向局部变量，形成闭包，exports变量在函数执行后不会被摧毁}require('./src/index.js')
})({"./src/index.js":{"dependencies":{"./info.js":"./src/info.js"},"code":"\"use strict\";\n\nvar _info = _interopRequireDefault(require(\"./info.js\"));\n\nfunction _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { \"default\": obj }; }\n\nconsole.log(_info[\"default\"]);"},"./src/info.js":{"dependencies":{"./name.js":"./src/name.js"},"code":"\"use strict\";\n\nObject.defineProperty(exports, \"__esModule\", {\n  value: true\n});\nexports[\"default\"] = void 0;\n\nvar _name = require(\"./name.js\");\n\nvar info = \"\".concat(_name.name, \" is beautiful\");\nvar _default = info;\nexports[\"default\"] = _default;"},"./src/name.js":{"dependencies":{},"code":"\"use strict\";\n\nObject.defineProperty(exports, \"__esModule\", {\n  value: true\n});\nexports.name = void 0;\nvar name = 'winty';\nexports.name = name;"}})