/*****
* inst.h
* Andy Hammerlindl 2002/06/27
*
* Descibes the items and instructions that are used by the virtual machine.
*****/
#ifndef INST_H
#define INST_H
#include <iterator>
#include <iostream>
#include "errormsg.h"
#include "item.h"
#include "vm.h"
namespace vm {
// Forward declarations
struct inst; class stack; class program;
// A function "lambda," that is, the code that runs a function.
// It also needs the closure of the enclosing module or function to run.
struct lambda : public gc {
// The instructions to follow.
program *code;
// The index of the link to the parent closure in the frame corresponding to
// this function.
size_t parentIndex;
// The total number of items that will be stored in the closure of this
// function. Includes a link to the higher closure, the parameters, and the
// local variables.
// NOTE: In order to help garbage collection, this could be modified to
// have one array store escaping items, and another to store non-
// escaping items.
size_t framesize;
// States whether any of the variables escape the function, in which case a
// closure needs to be allocated when the function is called. It is
// initially set to "maybe" and it is computed the first time the function
// is called.
enum { NEEDS_CLOSURE, DOESNT_NEED_CLOSURE, MAYBE_NEEDS_CLOSURE} closureReq;
#ifdef DEBUG_FRAME
string name;
lambda()
: closureReq(MAYBE_NEEDS_CLOSURE), name("<unnamed>") {}
virtual ~lambda() {}
#else
lambda()
: closureReq(MAYBE_NEEDS_CLOSURE) {}
#endif
};
// The code run is just a string of instructions. The ops are actual commands
// to be run, but constants, labels, and other objects can be in the code.
struct inst : public gc {
enum opcode {
#define OPCODE(name,type) name,
#include "opcodes.h"
#undef OPCODE
};
opcode op;
position pos;
item ref;
};
template<typename T>
inline T get(const inst& it)
{ return get<T>(it.ref); }
} // namespace vm
#endif