How to parse a TypeScript code base into ASTs

Question

I want to parse TypeScript projects into ASTs.

I can parse single file by :

import ts = require("typescript");
var fs          = require('fs');
var util      = require('util');


const ast = ts.createSourceFile('sample.ts', fs.readFileSync('sample.ts').toString(), ts.ScriptTarget.ES6, true);

console.log("AST:"+util.inspect(ast));

I can even loop through the files and filter files by extension and run above code to generate ASt.

However I want to parse the whole project in such a way that the relationships (like imports) will be preserved in AST.

For example:

If, a.ts is referencing var x from b.ts as below:

a.ts:

var y = x;

b.ts:

var x = 5;

In this case signature of x in a .ts should be resolved as : b.ts.x or equivalent.

I just want all such relationships resolved in the ASts as I parse the .ts files one by one.

Pragati Sureka · Accepted Answer · 2017-07-04 13:55:57Z

1

You can load your project using

ts.createProgram(rootNames: string[], options: CompilerOptions, host?: CompilerHost, oldProgram?: Program)

rootNames is the list of all typescript files in your project. As far as I know, unless you declare type explicitly, AST will have no reference to it.

for eg. If you have

class MyClass { 
   // some code
}

let instance1 = new MyClass();
let instance2: MyClass = new MyClass();

In AST, node for instance1 will have type property as undefined, for instance2 type property will have proper TypeReference

For type checking you can use Program.getTypeChecker(). This returns a TypeChecker which can be used to analyse files in the program.

answered Jul 4, 2017 at 13:55

Pragati Sureka

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