Ts-morph: Constant types break isXType functions

[Gerrit0]

I might be missing something obvious here... but getting types for constant variable declarations doesn't work as expected, getting the apparent type doesn't seem to resolve the problem.

Demo:

import Project, { TypeGuards } from 'ts-simple-ast'

const project = new Project()

const file = project.createSourceFile('file.ts', `
  export const a = 'hi'
  export const b = 1
`)

file.getExportedDeclarations()
  .filter(TypeGuards.isVariableDeclaration)
  .forEach(declaration => {
    const type = declaration.getType()
    const apparentType = type.getApparentType()
    console.log(declaration.getName())
    console.log(type.getText(), type.isNumberType(), type.isStringType())
    console.log(apparentType.getText(), apparentType.isNumberType(), apparentType.isStringType())
    console.log()
  })

Output:

a
"hi" false false // => Expected false, true
String false false // => I'd like to get type string

b
1 false false // => Expected true, false
Number false false // => I'd like to get type number

[dsherret]

Hi @Gerrit0, those are TypeFlags.NumberLiteral and TypeFlags.StringLiteral types. The isStringType() is seeing if the type has a flag of TypeFlags.String, which in this case it doesn't.

I'll add methods for NumberLiteral, StringLiteral, and BooleanLiteral because those are currently missing.

[dsherret]

Opened #291 for this.

[Gerrit0]

Ah, that makes sense, thanks!

Is there any way for me to convert a type from, say, a numeric literal to type number?

[dsherret]

Found it! There's a getBaseTypeOfLiteralType() on ts.TypeChecker.

If you want, you can temporarily fall back to the compiler API...

const baseType = project.getTypeChecker().compilerObject.getBaseTypeOfLiteralType(type.compilerType);

...but I will open up an issue and wrap this soon.

[dsherret]

Ok, I implemented all this. I'll comment back when v10 is released (sometime this week or next... feel free to clone the dev branch in case you need this now).

// this will work in v10
const numberType = numberLiteralType.getBaseTypeOfLiteralType();

I'm going to close this issue for now, but let me know if there's anything else you need.

[Gerrit0]

Thanks much! I'm using the code you posted above for now, but will certainly switch to V10 once released. type.isLiteralType might be useful, but is also trivial to write myself.

[dsherret]

Good point. I meant to add that. Thanks!

That will be in v10 as well.