/*****
* refaccess.h
* Andy Hammerlindl 2003/12/03
*
* An access which refers to a variable or other object in C++.
*****/

#ifndef REFACCESS_H
#define REFACCESS_H

#include "access.h"
#include "inst.h"
#include "coder.h"
#include "stack.h"

namespace trans {

// Access refers to a piece of data, represented by an item, somewhere in the
// C++ code.
class itemRefAccess : public access {
 vm::item *ref;

public:
 itemRefAccess(vm::item *ref)
   : ref(ref) {}

 void encode(action act, position pos, coder &e);
 void encode(action act, position pos, coder &e, frame *);
};

// Access refers to an arbitrary piece of data of type T.
template <class T>
class refAccess : public access {
 T *ref;

public:
 refAccess(T *ref)
   : ref(ref) {}

 void encode(action act, position pos, coder &e);
 void encode(action act, position pos, coder &e, frame *);
};

template <class T>
void pointerRead(vm::stack *s) {
 T *ptr=vm::pop<T *>(s);
 s->push(*ptr);
}

template <class T>
void pointerWrite(vm::stack *s) {
 T *ptr=vm::pop<T *>(s);
 T value=vm::pop<T>(s);
 *ptr=value;
 s->push(value);
}

template <class T>
void refAccess<T>::encode(action act, position, coder &e)
{
 // You may be able to use typeid(T).name() to get a better label.
 REGISTER_BLTIN((bltin) pointerRead<T>, "pointerRead");
 REGISTER_BLTIN((bltin) pointerWrite<T>, "pointerWrite");

 e.encode(vm::inst::constpush, (vm::item)ref);

 switch (act) {
   case READ:
     e.encode(vm::inst::builtin, (bltin) pointerRead<T>);
     break;
   case WRITE:
     e.encode(vm::inst::builtin, (bltin) pointerWrite<T>);
     break;
   case CALL:
     e.encode(vm::inst::builtin, (bltin) pointerRead<T>);
     e.encode(vm::inst::popcall);
     break;
 };
}

template <class T>
void refAccess<T>::encode(action act, position pos, coder &e, frame *)
{
 // Get rid of the useless top frame.
 e.encode(vm::inst::pop);
 encode(act, pos, e);
}

}
#endif