Add operator overloading.

[Dich0tomy]

Status

Nothing implemented yet.
Just leaving it here for further updates and notes.

TBD.

Conversion operators parse.
Started implementing them, the progress is saved on the experimental-operator-overloading branch.

Checklist

• In-class syntax, maybe outside of classes too
• Syntax parsing
• Proper implementation of simple operator overloading (See Implementation idea)
• ??? Probably template operator overloading

Syntax idea

This is how a method declaration looks right now:

class Ooga {
  fooga(arg: Int32) {
    ret 5 + 1;
  }
}

I suggest this syntax for operators:

class Ooga {
  operator ==(arg: Int32) {
    return arg == 1;
  }
}

For a differentation between prefix and postfix I suggest special keywords pre and post (the C++ approach of putting an int parameter is simply weird and misleading):

class Ooga {
  operator post ++ {
    return ;
  }
  operator pre ++ {
    return ;
  }
}

(The idea of having pre and post operators may be completely ditched)

For conversion operators this syntax has been decided upon:

class Ooga {
  operator as Int32 { return 5; }
}

Implementation idea

Every operator goes through the same function in ExpressionExecutor.
Each operator generally does some kind of preprocessing first.

I suggest that each operator does it's preprocessing and calls a special function that looks for operator overloads for a type, with the types provided by the caller.
If it fails, it throws a runtime error, if it succeeds, it returns the result of calling that function.

Syntax preview

Nothing yet.