/** f0 -> "HALLOCATE" f1 -> Exp() */
public PGValue visit(HAllocate n, Node argu) {
int old_hp = HP;
PGValue exp;
n.f0.accept(this, argu);
exp = n.f1.accept(this, argu);
HP = HP + exp.GetVal();
return new Const(old_hp);
}
/** f0 -> "CJUMP" f1 -> Exp() f2 -> Label() */
public PGValue visit(CJumpStmt n, Node argu) {
PGValue p = n.f1.accept(this, argu);
int cond = 0;
if (p == null) return null;
else cond = p.GetVal();
if (cond == 1) return null;
String l_name = (n.f2.accept(this, argu)).GetLabel();
label_name = l_name;
start = false;
stop = false;
// System.out.println("CJUMP " + l_name);
argu.accept(this, argu);
stop = true;
start = true;
return null;
}
/** f0 -> "CALL" f1 -> Exp() f2 -> "(" f3 -> ( Exp() )* f4 -> ")" */
public PGValue visit(Call n, Node argu) {
// NOTE: bug fix by jurgens@cs 10/30/07, kgo@cs 11/14/07
//
// details: local_arg_size was previously initialized to 20.
// This resulted in TEMP values being overwritten by the caller.
// For recursive calls, the overwritten values were bugs if any
// thing stored in an overwritten temp was used after the
// recursive call. For this reason, we now make a copy of the
// entire temp space before each call.
n.f0.accept(this, argu);
PGValue function_addr = n.f1.accept(this, argu);
if (!(function_addr instanceof Label_pg)) {
System.err.println("error in CALL");
System.exit(0);
return null; // Will never actually be reached.
}
String m_name = function_addr.GetLabel();
n.f2.accept(this, argu);
// Caller saves all local variables.
PGValue[] saved_locals = new PGValue[TPV.length];
System.arraycopy(TPV, 0, saved_locals, 0, TPV.length);
// Copy call args into first N temps.
ParamList_pg pl = (ParamList_pg) n.f3.accept(this, argu);
// NOTE: we save and return the TEMPs for the caller, so we are
// free to update the TPV array at this point. kgo@cs fixed a
// bug where this statement caused the callee to have TPV
// side-effects for the caller.
// NOTE: that if the method had no parameters, pl will be null.
// This bug was discovered by Prof. Todd Millstein todd@cs.
// check to see if the callee has any arguments and if so, pass
// them into the TPV temp array using the caller's parameters
if (pl != null) {
int num_params = pl.GetVal();
PGValue[] param_list = pl.GetList();
for (int i = 0; i < num_params; i++) {
TPV[i] = param_list[i];
}
}
n.f4.accept(this, argu);
met_name = m_name;
boolean old_start = start;
boolean old_stop = stop;
start = true;
stop = false;
// System.out.println("No NO NO 222" + met_name);
PGValue _ret = pg_root.accept(this, pg_root);
// System.out.println("No NO NO");
start = old_start;
stop = old_stop;
// Restore saved local variables.
TPV = saved_locals;
return _ret;
}
/** f0 -> "PRINT" f1 -> Exp() */
public PGValue visit(PrintStmt n, Node argu) {
PGValue _ret = n.f1.accept(this, argu);
System.out.println(_ret.GetVal());
return null;
}