CODEWITHSUNDEEP
typescriptabstract-syntax-tree
Ahmed Raza
Ahmed Raza

Reputation: 99

How to Extract AST of given Typescript code using the open source Typescript compiler code?

As it is known that Typescript is completely opensource now. which is available at Tyescript. I am building an application that will get Typescript code as input and give output the AST of the given code. Provide me a proper way to extract this AST(Abstract Syntax Tree) of input Typescript code rather than comppliling it and converting it into Javascript.

Upvotes: 7

Views: 3354

Answers (2)

cancerbero
cancerbero

Reputation: 7037

TypeScript compiler doesn't support it but you can do it using recast and babylon@next. Although you will have to trust in the syntax defined by these technologies for representing TypeScript code AST and that they will keep up to date - since TypeScript has new language features release by release (short period of time) - is not like other languages (JavaScript) where you have well defined versions and released in a standard - so if your users start using new language features these technologies (mostly babylon) should keep up to date:

// npm install recast babylon@next
const source = `
interface I {
  color: string
}
class C implements I{
  color: string='blue'
}
`
const recast = require('recast')
const tsParser = require("recast/parsers/typescript")
const ast = recast.parse(source, {
  parser: tsParser
});
console.log(`
CODE: 

${source}

AST: 

${JSON.stringify(ast)}
`);

Upvotes: 0

David Sherret
David Sherret

Reputation: 106640

Basic code:

const fileNames = ["C:\\MyFile.ts"];
const compilerOptions: ts.CompilerOptions = {
    // compiler options go here if any...
    // look at ts.CompilerOptions to see what's available
};
const program = ts.createProgram(fileNames, compilerOptions);
const typeChecker = program.getTypeChecker();
const sourceFiles = program.getSourceFiles();

sourceFiles.filter(f => /MyFile\.ts$/.test(f.fileName)).forEach(sourceFile => {
    ts.forEachChild(sourceFile, node => {
        const declaration = node as ts.Declaration;
        if (declaration.name) {
            console.log(declaration.name.getText());
        }
    });
});

So if you provided that with a C:\MyFile.ts like:

class MyClass {}
interface MyInterface {}

It would output MyClass and MyInterface.

Figuring out everything beyond what I've just shown is a lot of work. It might be more beneficial for you to look at and/or help contribute to this work in progress.

Upvotes: 6

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