/*-------------------------------------------------------------------------*
* PL_CALL_PROLOG *
* *
* Call_Prolog runs the execution of one prolog goal. *
* The current choice point is updated to set ALTB to Call_Prolog_Fail and *
* CP is set to Call_Prolog_Success. At the end ALTB and CP are restored. *
* To ensure that a choice point always exists before invoking Call_Prolog,*
* Start_Prolog reserve the space for a feint choice point, i.e ALTB can be*
* safely modified. *
* *
* Call_Prolog returns TRUE if the predicate has succeed, FALSE otherwise. *
* The called predicate can be non-deterministic. *
*-------------------------------------------------------------------------*/
Bool
Pl_Call_Prolog(CodePtr codep)
{
WamWord *query_b = B;
WamCont save_CP = CP;
WamCont save_ALTB = ALTB(query_b);
Bool ok;
ALTB(query_b) = (CodePtr) Call_Prolog_Fail; /* modify choice point */
CP = Adjust_CP(Call_Prolog_Success);
#if defined(_WIN32) || defined(__CYGWIN__)
SEH_PUSH(Win32_SEH_Handler);
#endif
ok = Call_Next(codep);
#if defined(_WIN32) || defined(__CYGWIN__)
SEH_POP;
#endif
CP = save_CP; /* restore continuation */
ALTB(query_b) = save_ALTB; /* restore choice point */
return ok;
}
void
test_jump_and_c_ret(void)
{
printf("jump/c_ret...\n");
ALTB(B) = (WamCont) error;
Init_CP(error);
ma_test_jump_and_c_ret();
}
/*-------------------------------------------------------------------------*
* PL_CALL_PROLOG_NEXT_SOL *
* *
* Call_Prolog_Next_Sol bactracks over the next solution. *
*-------------------------------------------------------------------------*/
Bool
Pl_Call_Prolog_Next_Sol(WamWord *query_b)
{
WamCont save_CP = CP;
WamCont save_ALTB = ALTB(query_b);
Bool ok;
ALTB(query_b) = (CodePtr) Call_Prolog_Fail; /* modify choice point */
CP = Adjust_CP(Call_Prolog_Success); /* should be useless since */
/* alternative will restore CP */
ok = Call_Next(ALTB(B));
CP = save_CP; /* restore continuation */
ALTB(query_b) = save_ALTB; /* restore choice point */
return ok;
}
/*-------------------------------------------------------------------------*
* PL_CALL_PROLOG *
* *
* Call_Prolog runs the execution of one prolog goal. *
* The current choice point is updated to set ALTB to Call_Prolog_Fail and *
* CP is set to Call_Prolog_Success. At the end ALTB and CP are restored. *
* To ensure that a choice point always exists before invoking Call_Prolog,*
* Start_Prolog reserve the space for a feint choice point, i.e ALTB can be*
* safely modified. *
* *
* Call_Prolog returns TRUE if the predicate has succeed, FALSE otherwise. *
* The called predicate can be non-deterministic. *
*-------------------------------------------------------------------------*/
Bool
Pl_Call_Prolog(CodePtr codep)
{
WamWord *query_b = B;
WamCont save_CP = CP;
WamCont save_ALTB = ALTB(query_b);
Bool ok;
ALTB(query_b) = (CodePtr) Call_Prolog_Fail; /* modify choice point */
CP = Adjust_CP(Call_Prolog_Success);
ok = Call_Next(codep);
CP = save_CP; /* restore continuation */
ALTB(query_b) = save_ALTB; /* restore choice point */
return ok;
}
void
test_switch_ret(void)
{
printf("call_c()+switch_ret...\n");
ALTB(B) = (WamCont) error;
for (i = 0; swt[i] >= 0; i++)
Call_Pl(ma_test_switch_ret, 1);
Call_Pl(ma_test_switch_ret, 0); /* here swt[i]= -1 switch should fail */
}
/*-------------------------------------------------------------------------*
* PL_QUERY_END *
* *
*-------------------------------------------------------------------------*/
void
Pl_Query_End(int op)
{
WamWord *query_b, *prev_b, *b;
Bool recoverable;
if (query_stack_top == query_stack)
Pl_Fatal_Error("Pl_Query_End() but no query remaining");
query_b = *--query_stack_top;
pl_query_top_b = query_stack_top[-1];
recoverable =
(ALTB(query_b) == Prolog_Predicate(PL_QUERY_RECOVER_ALT, 0));
prev_b = BB(query_b);
switch (op)
{
case PL_RECOVER:
Assign_B(query_b);
if (!recoverable)
Pl_Fatal_Error("Pl_Query_End(PL_RECOVER) but unrecoverable query");
Pl_Delete_Choice_Point(0); /* remove recover chc-point */
break;
case PL_CUT:
Assign_B((recoverable) ? prev_b : query_b);
break;
default: /* case PL_KEEP_FOR_PROLOG */
if (recoverable)
{
if (B == query_b)
Assign_B(prev_b);
else
for (b = B; b > query_b; b = BB(b)) /* unlink recover chc-point */
if (BB(b) == query_b)
BB(b) = prev_b;
}
Pl_Keep_Rest_For_Prolog(query_b);
}
}
void
TRANS_pl_fail()
{
M_Indirect_Goto(ALTB(B));
}
