Typescript：如何基于数据结构生成和打印 AST

我正在开始一个新项目，作为其界面的一部分，我们有一大堆“令牌”，一个带有字符串值的递归对象，如下所示：

const colors = {
  accent: '#f90',
  primary: {
    active: '#fff',
    inactive: 'silver'
  }
};

我们提供了一个实用程序，用于通过基于字符串的路径（例如，primary.active for #fff在这种情况下）。将所有可能的路径提取到数组中非常容易，但我们希望为该包的使用者提供更好的自动完成功能，因此不是“字符串”，而是这些可能路径的联合或枚举。有人可能有这方面的经验吗？我最初的方法是编写一个简单的脚本，它接受一个数组并使用模板或类似的东西将其作为联合打印，但考虑到我们希望更频繁地执行此操作并且我们的用例会增加复杂性，我认为生成打印 AST 可能是更好的方法。我之前写过 babel 和 recast codemods，我只是在寻找一些关于现有工具集、示例等的指导。我快速谷歌了一下，但找不到任何东西。理想情况下，这些将与我正常的“观看”过程一起重新编译，但这是一个延伸目标^_^。

您可以使用编译器 API 提取对象类型并创建联合类型

import * as ts from 'typescript'
import * as fs from 'fs'

var cmd = ts.parseCommandLine(['test.ts']); // replace with target file
// Create the program
let program = ts.createProgram(cmd.fileNames, cmd.options);


type ObjectDictionary = { [key: string]: string | ObjectDictionary}
function extractAllObjects(program: ts.Program, file: ts.SourceFile): ObjectDictionary {
    let empty = ()=> {};
    // Dummy transformation context
    let context: ts.TransformationContext = {
        startLexicalEnvironment: empty,
        suspendLexicalEnvironment: empty,
        resumeLexicalEnvironment: empty,
        endLexicalEnvironment: ()=> [],
        getCompilerOptions: ()=> program.getCompilerOptions(),
        hoistFunctionDeclaration: empty,
        hoistVariableDeclaration: empty,
        readEmitHelpers: ()=>undefined,
        requestEmitHelper: empty,
        enableEmitNotification: empty,
        enableSubstitution: empty,
        isEmitNotificationEnabled: ()=> false,
        isSubstitutionEnabled: ()=> false,
        onEmitNode: empty,
        onSubstituteNode: (hint, node)=>node,
    };
    let typeChecker =  program.getTypeChecker();

    function extractObject(node: ts.ObjectLiteralExpression): ObjectDictionary {
        var result : ObjectDictionary = {};
        for(let propDeclaration of node.properties){            
            if(!ts.isPropertyAssignment( propDeclaration )) continue;
            const propName = propDeclaration.name.getText()
            if(!propName) continue;
            if(ts.isObjectLiteralExpression(propDeclaration.initializer)) {
                result[propName] = extractObject(propDeclaration.initializer);
            }else{
                result[propName] = propDeclaration.initializer.getFullText()
            }
        }
        return result;
    }
    let foundVariables: ObjectDictionary = {};
    function visit(node: ts.Node, context: ts.TransformationContext): ts.Node {
        if(ts.isVariableDeclarationList(node)) {
            let triviaWidth = node.getLeadingTriviaWidth()
            let sourceText = node.getSourceFile().text;
            let trivia = sourceText.substr(node.getFullStart(), triviaWidth);
            if(trivia.indexOf("Generate_Union") != -1) // Will generate fro variables with a comment Generate_Union above them
            {
                for(let declaration of node.declarations) {
                    if(declaration.initializer && ts.isObjectLiteralExpression(declaration.initializer)){
                        foundVariables[declaration.name.getText()] = extractObject(declaration.initializer)
                    }
                }
            }
        }
        return ts.visitEachChild(node, child => visit(child, context), context);
    }
    ts.visitEachChild(file, child => visit(child, context), context);
    return foundVariables;
}



let result = extractAllObjects(program, program.getSourceFile("test.ts")!); // replace with file name 

function generateUnions(dic: ObjectDictionary) {
    function toPaths(dic: ObjectDictionary) : string[] {
        let result: string[] = []
        function extractPath(parent: string, object: ObjectDictionary) {
            for (const key of  Object.keys(object)) {
                let value = object[key]; 
                if(typeof value === "string") {
                    result.push(parent + key);
                }else{
                    extractPath(key + ".", value);
                }
            }
        }
        extractPath("", dic);
        return result;
    }

    return Object.entries(dic)
        .map(([name, values])=> 
        {
            let paths = toPaths(values as ObjectDictionary)
                .map(ts.createStringLiteral)
                .map(ts.createLiteralTypeNode);

            let unionType = ts.createUnionTypeNode(paths);
            return ts.createTypeAliasDeclaration(undefined, undefined, name + "Paths", undefined, unionType);
        })

}

var source = ts.createSourceFile("d.ts", "", ts.ScriptTarget.ES2015);
source = ts.updateSourceFileNode(source, generateUnions(result));

var printer = ts.createPrinter({ });
let r = printer.printFile(source);
fs.writeFileSync("union.ts", r);