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/*****
* 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
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