attempt to improve error handliong in SWI emulation.

C/c_interface.c

@@ -1474,14 +1474,37 @@ YAP_Execute(PredEntry *pe, CPredicate exec_code)
     struct foreign_context ctx;
     UInt i;
     Int sl = 0;
+    Int ret;
+
     ctx.engine = NULL;
     for (i=pe->ArityOfPE; i > 0; i--) {
       sl = Yap_InitSlot(XREGS[i]);
     }
-    return ((codev)(sl,0,&ctx));
+    ret = ((codev)(sl,0,&ctx));
+    if (!ret) {
+      Term t;
+
+      BallTerm = EX;
+      EX = NULL;
+      if ((t = Yap_GetException())) {
+	  Yap_JumpToEnv(t);
+	  return FALSE;
+      }
+    }
+    return ret;
   }
   if (pe->PredFlags & CArgsPredFlag) {
     Int out =  execute_cargs(pe, exec_code);
+    if (!out) {
+      Term t;
+
+      BallTerm = EX;
+      EX = NULL;
+      if ((t = Yap_GetException())) {
+	  Yap_JumpToEnv(t);
+	  return FALSE;
+      }
+    }
     return out;
   } else {
     return((exec_code)());
@@ -1510,6 +1533,14 @@ YAP_ExecuteFirst(PredEntry *pe, CPredicate exec_code)
       val = ((codev)((&ARG1)-LCL0,0,ctx));
     }
     if (val == 0) {
+      Term t;
+
+      BallTerm = EX;
+      EX = NULL;
+      if ((t = Yap_GetException())) {
+	  Yap_JumpToEnv(t);
+	  return FALSE;
+      }
       cut_fail();
     } else if (val == 1) { /* TRUE */
       cut_succeed();
@@ -1541,7 +1572,16 @@ YAP_ExecuteNext(PredEntry *pe, CPredicate exec_code)
       val = ((codev)((&ARG1)-LCL0,0,ctx));
     }
     if (val == 0) {
-      cut_fail();
+      Term t;
+
+      BallTerm = EX;
+      EX = NULL;
+      if ((t = Yap_GetException())) {
+	  Yap_JumpToEnv(t);
+	  return FALSE;
+      } else {
+	cut_fail();
+      }
     } else if (val == 1) { /* TRUE */
       cut_succeed();
     } else {

C/exec.c

@@ -1710,8 +1710,8 @@ p_debug_on(void)
   return TRUE;
 }
 
-static Term 
+Term 
-GetException(void)
+Yap_GetException(void)
 {
   Term t = 0L;
   if (BallTerm) {
@@ -1743,7 +1743,7 @@ p_reset_exception(void)
 {
   Term t;
   EX = NULL;
-  t = GetException();
+  t = Yap_GetException();
   if (!t) 
     return FALSE;
   return Yap_unify(t, ARG1);
@@ -1759,7 +1759,7 @@ Yap_ResetExceptionTerm(void)
 static Int
 p_get_exception(void)
 {
-  Term t = GetException();
+  Term t = Yap_GetException();
   if (!t) 
     return FALSE;
   return Yap_unify(t, ARG1);

H/Yapproto.h

@@ -180,6 +180,7 @@ void	STD_PROTO(Yap_ResetExceptionTerm,(void));
 Int	STD_PROTO(Yap_execute_goal,(Term, int, Term));
 int	STD_PROTO(Yap_exec_absmi,(int));
 void	STD_PROTO(Yap_trust_last,(void));
+Term	STD_PROTO(Yap_GetException,(void));
 
 /* gprof.c */
 void	STD_PROTO(Yap_InitLowProf,(void));

library/dialect/swi/fli/swi.c

@@ -1271,7 +1271,7 @@ X_API int PL_put_variable(term_t t)
 
 X_API int PL_raise_exception(term_t exception)
 {
-  YAP_Throw(Yap_GetFromSlot(exception));
+  EX = Yap_StoreTermInDB(Yap_GetFromSlot(exception),0);
   return 0;
 }
 
@@ -2763,13 +2763,6 @@ PL_free(void *obj)
     free(obj);
 }
 
-static int
-PL_error(const char *pred, int arity, const char *msg, int id, ...)
-{
-  fprintf(stderr,"Internal PL_error Not implemented\n");
-  return 0;
-}
-
 X_API int
 PL_eval_expression_to_int64_ex(term_t t, int64_t *val)
 {