Note that "context free grammars", in the technical sense, is completely the wrong thing. Eg, enforcing consistent indentation is not context free:

  foo()
      {
      return;
      }
  ↓↓↓↓↓↓↓↓↓↓↓
  aaaa{
  bbbbreturn;
  cccc}
  ↓↓↓↓↓↓↓↓↓↓↓
  aaaabbbbcccc

This is equivalent to aⁿbⁿcⁿ, which is pretty much the canonical example of a non-context-free language.

What you acually want is not context-free grammar, but, as TFA says:

> the code should be parseable without having to look things up in a symbol table