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/*****
* access.cc
* Andy Hammerlindl 2003/12/03
* Describes an "access," a representation of where a variable will be
* stored at runtime, so that read, write, and call instructions can be
* made.
*****/
#include "access.h"
#include "frame.h"
#include "coder.h"
#include "callable.h"
using vm::item;
namespace trans {
/* access */
access::~access()
{}
/* identAccess */
void identAccess::encode(action act, position pos, coder& e)
{
if (act != CALL) {
access::encode(act, pos, e);
}
// else - do nothing
}
/* bltinAccess */
static void bltinError(position pos)
{
em.error(pos);
em << "built-in functions cannot be modified";
}
void bltinAccess::encode(action act, position pos, coder &e)
{
switch (act) {
case READ:
e.encode(inst::constpush,(item)(vm::callable*)new vm::bfunc(f));
break;
case WRITE:
bltinError(pos);
break;
case CALL:
e.encode(inst::builtin, f);
break;
}
}
void bltinAccess::encode(action act, position pos, coder &e, frame *)
{
e.encode(inst::pop);
encode(act, pos, e);
}
/* frameAccess */
void frameAccess::encode(action act, position pos, coder &e)
{
if (act == READ) {
if (!e.encode(f)) {
em.compiler(pos);
em << "encoding frame out of context";
}
}
else
access::encode(act, pos, e);
}
void frameAccess::encode(action act, position pos, coder &e, frame *top)
{
if (act == READ) {
if (!e.encode(f, top)) {
em.compiler(pos);
em << "encoding frame out of context";
}
}
else
access::encode(act, pos, e, top);
}
/* localAccess */
void localAccess::encode(action act, position pos, coder &e)
{
// Get the active frame of the virtual machine.
frame *active = e.getFrame();
if (level == active) {
e.encode(act == WRITE ? inst::varsave : inst::varpush,
offset);
if (act == CALL)
e.encode(inst::popcall);
}
else {
// Put the parent frame (in local variable 0) on the stack.
e.encode(inst::varpush,0);
// Encode the access from that frame.
this->encode(act, pos, e, active->getParent());
}
}
void localAccess::encode(action act, position pos, coder &e, frame *top)
{
if (e.encode(level,top)) {
e.encode(act == WRITE ? inst::fieldsave : inst::fieldpush,
offset);
if (act == CALL)
e.encode(inst::popcall);
}
else {
// The local variable is being used when its frame is not active.
em.error(pos);
em << "static use of dynamic variable";
}
}
void qualifiedAccess::encode(action act, position pos, coder &e)
{
qualifier->encode(READ, pos, e);
field->encode(act, pos, e, qualifierLevel);
}
void qualifiedAccess::encode(action act, position pos, coder &e, frame *top)
{
qualifier->encode(READ, pos, e, top);
field->encode(act, pos, e, qualifierLevel);
}
} // namespace trans
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