Is there a way to parse an expression from a string and resolve its type in a scope using JDT?

Question

Suppose I have the following code

class A{
  public void f(int i, int j){
    // line
  }
}

what I want to do is to

1. parse the code using JDT parser;
2. take an input string, e.g. i + j, from somewhere, parse the string using JDT parser and get an AST of type Expression; and
3. resolve the type of that Expression AST and get it's type int.

1 and 2 seem easy enough. But I couldn't figure out how 3 can be done in JDT. Has anyone any idea?

Thanks.

Answer 1

You will have to work with bindings (link is deprecated but information still valid).

Note: how binding resolving is activated - an answer I gave.

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With bindings available you can I do the following:

Expression expr = ...;
ITypeBinding binding = expr.resolveTypeBinding();
// binding is e.g. 'int' for 'i + j';

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Note: to have valid Java code you must insert a statement and not an expression. So an naive approach could be:

1. add expression as statement e.g. Object $expr = i + j;

2. save type-binding binding = expr.resolveTypeBinding() // e.g. ITypeBinding 'int';

3. replace Object $expr placeholder with type according to binding - going from binding back to ASTNode (most likely PrimitiveType) must be done manually.

If you need a simple code sample, just ask.