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如何在内存中键入检查TypeScript代码片段?

typescript-compiler-api transpiler typechecking typescript

Ashley Davis · 技术社区 · 6 年前

我正在我的应用程序中实现TypeScript支持 .

编译似乎没有问题,我正在使用 transpileModule 如下图所示,将TS代码片段转换为可计算的JavaScript代码:

import { transpileModule, TranspileOptions } from "typescript";

const transpileOptions: TranspileOptions = {
    compilerOptions: {},
    reportDiagnostics: true,
};

const tsCodeSnippet = " /* TS code goes here */ ";
const jsOutput = transpileModule(tsCodeSnippet, transpileOptions);
console.log(JSON.stringify(jsOutput, null, 4));

但是,当我尝试编译有错误的TS代码时,会出现问题。

function foo(): string {
    return 5;
}

传输是伟大的,但我也希望能够显示错误给我的用户。

是如何做到这一点,但也做类型检查和产生错误的语义错误?

注意,我不想将TypeScript代码保存到文件中。这对我的应用程序来说是一个不必要的性能负担。我只想编译并键入保存在内存中的代码片段。

2 回复 | 直到 6 年前

David Sherret 4 年前

情况1-仅使用内存-无法访问文件系统(例如,在web上)

实施 ts.CompilerHost 方法在哪里 fileExists , readFile , directoryExists , getDirectories()
lib 根据需要将文件放入内存中的文件系统(例如。或 lib.dom.d.ts
创建一个程序(使用 ts.createProgram )把你的习惯传下去 编译主机 .
呼叫 ts.getPreEmitDiagnostics(program) 获取诊断信息。

不完美的例子

program program.getGlobalDiagnostics() . 注意 ts.getPreEmitDiagnostics here

import * as ts from "typescript";

console.log(getDiagnosticsForText("const t: number = '';").map(d => d.messageText));

function getDiagnosticsForText(text: string) {
    const dummyFilePath = "/file.ts";
    const textAst = ts.createSourceFile(dummyFilePath, text, ts.ScriptTarget.Latest);
    const options: ts.CompilerOptions = {};
    const host: ts.CompilerHost = {
        fileExists: filePath => filePath === dummyFilePath,
        directoryExists: dirPath => dirPath === "/",
        getCurrentDirectory: () => "/",
        getDirectories: () => [],
        getCanonicalFileName: fileName => fileName,
        getNewLine: () => "\n",
        getDefaultLibFileName: () => "",
        getSourceFile: filePath => filePath === dummyFilePath ? textAst : undefined,
        readFile: filePath => filePath === dummyFilePath ? text : undefined,
        useCaseSensitiveFileNames: () => true,
        writeFile: () => {}
    };
    const program = ts.createProgram({
        options,
        rootNames: [dummyFilePath],
        host
    });

    return ts.getPreEmitDiagnostics(program);
}

情形2-访问文件系统

如果您有权访问文件系统,那么这就容易多了,您可以使用类似于以下功能的功能:

import * as path from "path";

function getDiagnosticsForText(
    rootDir: string,
    text: string,
    options?: ts.CompilerOptions,
    cancellationToken?: ts.CancellationToken
) {
    options = options || ts.getDefaultCompilerOptions();
    const inMemoryFilePath = path.resolve(path.join(rootDir, "__dummy-file.ts"));
    const textAst = ts.createSourceFile(inMemoryFilePath, text, options.target || ts.ScriptTarget.Latest);
    const host = ts.createCompilerHost(options, true);

    overrideIfInMemoryFile("getSourceFile", textAst);
    overrideIfInMemoryFile("readFile", text);
    overrideIfInMemoryFile("fileExists", true);

    const program = ts.createProgram({
        options,
        rootNames: [inMemoryFilePath],
        host
    });

    return ts.getPreEmitDiagnostics(program, textAst, cancellationToken);

    function overrideIfInMemoryFile(methodName: keyof ts.CompilerHost, inMemoryValue: any) {
        const originalMethod = host[methodName] as Function;
        host[methodName] = (...args: unknown[]) => {
            // resolve the path because typescript will normalize it
            // to forward slashes on windows
            const filePath = path.resolve(args[0] as string);
            if (filePath === inMemoryFilePath)
                return inMemoryValue;
            return originalMethod.apply(host, args);
        };
    }
}

// example...
console.log(getDiagnosticsForText(
    __dirname,
    "import * as ts from 'typescript';\n const t: string = ts.createProgram;"
));

这样做,编译器将搜索提供的 rootDir node_modules 文件夹并使用其中的打字(它们不需要以其他方式加载到内存中)。

更新:最简单的解决方案

我创建了一个名为 @ts-morph/bootstrap 这使得使用编译器API进行设置变得更加容易。即使使用内存文件系统,它也会为您加载TypeScript库文件。

import { createProject, ts } from "@ts-morph/bootstrap";

const project = await createProject({ useInMemoryFileSystem: true });

const myClassFile = project.createSourceFile(
    "MyClass.ts",
    "export class MyClass { prop: string; }",
);

const program = project.createProgram();
ts.getPreEmitDiagnostics(program); // check these

Ashley Davis 6 年前

我在David Sherret的一些原始帮助和Fabian Pirklbauer的提示的基础上解决了这个问题( creator of TypeScript Playground ).

我创建了一个代理编译器主机来包装一个真正的编译器主机。代理能够返回内存中的TypeScript代码进行编译。底层real CompilerHost能够加载默认的TypeScript库。这些库是必需的,否则会导致与内置TypeScript数据类型相关的大量错误。

import * as ts from "typescript";

//
// A snippet of TypeScript code that has a semantic/type error in it.
//
const code 
    = "function foo(input: number) {\n" 
    + "    console.log('Hello!');\n"
    + "};\n" 
    + "foo('x');"
    ;

//
// Result of compiling TypeScript code.
//
export interface CompilationResult {
    code?: string;
    diagnostics: ts.Diagnostic[]
};

//
// Check and compile in-memory TypeScript code for errors.
//
function compileTypeScriptCode(code: string, libs: string[]): CompilationResult {
    const options = ts.getDefaultCompilerOptions();
    const realHost = ts.createCompilerHost(options, true);

    const dummyFilePath = "/in-memory-file.ts";
    const dummySourceFile = ts.createSourceFile(dummyFilePath, code, ts.ScriptTarget.Latest);
    let outputCode: string | undefined = undefined;

    const host: ts.CompilerHost = {
        fileExists: filePath => filePath === dummyFilePath || realHost.fileExists(filePath),
        directoryExists: realHost.directoryExists && realHost.directoryExists.bind(realHost),
        getCurrentDirectory: realHost.getCurrentDirectory.bind(realHost),
        getDirectories: realHost.getDirectories.bind(realHost),
        getCanonicalFileName: fileName => realHost.getCanonicalFileName(fileName),
        getNewLine: realHost.getNewLine.bind(realHost),
        getDefaultLibFileName: realHost.getDefaultLibFileName.bind(realHost),
        getSourceFile: (fileName, languageVersion, onError, shouldCreateNewSourceFile) => fileName === dummyFilePath 
            ? dummySourceFile 
            : realHost.getSourceFile(fileName, languageVersion, onError, shouldCreateNewSourceFile),
        readFile: filePath => filePath === dummyFilePath 
            ? code 
            : realHost.readFile(filePath),
        useCaseSensitiveFileNames: () => realHost.useCaseSensitiveFileNames(),
        writeFile: (fileName, data) => outputCode = data,
    };

    const rootNames = libs.map(lib => require.resolve(`typescript/lib/lib.${lib}.d.ts`));
    const program = ts.createProgram(rootNames.concat([dummyFilePath]), options, host);
    const emitResult = program.emit();
    const diagnostics = ts.getPreEmitDiagnostics(program);
    return {
        code: outputCode,
        diagnostics: emitResult.diagnostics.concat(diagnostics)
    };
}

console.log("==== Evaluating code ====");
console.log(code);
console.log();

const libs = [ 'es2015' ];
const result = compileTypeScriptCode(code, libs);

console.log("==== Output code ====");
console.log(result.code);
console.log();

console.log("==== Diagnostics ====");
for (const diagnostic of result.diagnostics) {
    console.log(diagnostic.messageText);
}
console.log();

输出

==== Evaluating code ====
function foo(input: number) {
    console.log('Hello!');
};
foo('x');
=========================
Diagnosics:
Argument of type '"x"' is not assignable to parameter of type 'number'.

Full working example available on my Github .