/*****
* frame.h
* Andy Hammerlindl 2002/07/22
*
* Describes the frame levels for the functions of the language.
* Also creates accesses for the variable for automated loading
* and saving of variables.
*****/

#ifndef FRAME_H
#define FRAME_H

#include <cassert>

#include "access.h"

namespace trans {

class frame : public gc {
 frame *parent;
 size_t numFormals;
 Int numLocals;

 // With the SIMPLE_FRAME flag, the size of frames cannot be changed at
 // runtime.  This is an issue for runnable-at-a-time mode, where global
 // variables can be continually added.  To handle this, the frame for
 // global variables is an "indirect" frame.  It holds one variable, which is
 // a link to another frame.  When the subframe is too small, a larger
 // runtime array is allocated, and the link is changed.
 enum {DIRECT_FRAME, INDIRECT_FRAME} style;

#ifdef DEBUG_FRAME
 string name;
#endif

 frame(string name)
   : parent(new frame("<subframe of " + name + ">", 0, 0)),
     numFormals(0), numLocals(1), style(INDIRECT_FRAME)
#ifdef DEBUG_FRAME
   , name(name)
#endif
 {}

public:
 frame(string name, frame *parent, size_t numFormals)
   : parent(parent), numFormals(numFormals), numLocals(0),
     style(DIRECT_FRAME)
#ifdef DEBUG_FRAME
   , name(name)
#endif
 {}

 static frame *indirect_frame(string name) {
   return new frame(name);
 }

 frame *getParent() {
   return parent;
 }

 // Which variable stores the link to the parent frame.
 Int parentIndex() {
   return numFormals;
 }

 Int size() {
   if (style == DIRECT_FRAME)
     return (Int) (1+numFormals+numLocals);
   else
     return parent->size();
 }

 access *accessFormal(size_t index) {
   assert(index < numFormals);
   assert(style == DIRECT_FRAME);
   return new localAccess((Int) (index), this);
 }

 access *allocLocal() {
   if (style == DIRECT_FRAME)
     return new localAccess((Int) (1 + numFormals + numLocals++), this);
   else
     return parent->allocLocal();
 }
};

inline void print(ostream& out, frame *f) {
 out << f;
 if (f != 0) {
   out << " -> ";
   print(out, f->getParent());
 }
}

} // namespace trans

#endif