boot

C/cdmgr.c

@@ -2852,10 +2852,14 @@ static Int undefp_handler(USES_REGS1) { /* '$undefp_handler'(P,Mod)	 */
   PredEntry *pe;
 
   pe = Yap_get_pred(Deref(ARG1), Deref(ARG2), "undefined/1");
-  if (EndOfPAEntr(pe))
-    return false;
   PELOCK(59, pe);
+  if (EndOfPAEntr(pe)) {
+    UndefCode = FAILCODE;
+    UNLOCKPE(59, pe);
+    return false;
+  }
   if (pe->OpcodeOfPred == UNDEF_OPCODE) {
+    UndefCode = FAILCODE;
     UNLOCKPE(59, pe);
     return false;
   }

C/exec.c

@@ -189,11 +189,10 @@ static bool CallError(yap_error_number err, Term t, Term mod USES_REGS) {
 
 /** @pred current_choice_point( -CP )
  *
- * unify the logic variable _CP_ with a number that gives the offset of the
+ * unify the logic variable _CP_ with a number that identifies the
- * current choice-point. This number is only valid as long as we do not
+ * last alternative taken, or current choice-point. This number is
- *backtrack by or cut
+ * only valid as long as we do not backtrack by or cut _CP_, and is
- * _CP_, and is safe in the presence of stack shifting and/or garbage
+ * safe in the presence of stack shifting and/or garbage collection.
- *collection.
  */
 static Int current_choice_point(USES_REGS1) {
   Term t = Deref(ARG1);
@@ -208,6 +207,29 @@ static Int current_choice_point(USES_REGS1) {
   return TRUE;
 }
 
+/** @pred parent_choice_point( +CP, -PCP )
+ *
+ * given that _CP_  identifies an
+ *  alternative taken, or  choice-point, _PCP_ identifies its parent.
+ *
+ * The call will fail if _CP_ is topmost in the search tree. 
+ */
+static Int parent_choice_point(USES_REGS1) {
+  Term t = Deref(ARG1);
+  Term td;
+#if SHADOW_HB
+  register CELL *HBREG = HB;
+#endif
+  if (!IsVarTerm(t))
+    return (FALSE);
+  choiceptr cp =  cp_from_integer(t);
+  if (cp == NULL || cp->cp_b == NULL)
+    return false;
+  td = cp_as_integer(cp->cp_b PASS_REGS);
+  YapBind((CELL *)t, td);
+  return TRUE;
+}
+
 static Int save_env_b(USES_REGS1) {
   Term t = Deref(ARG1);
   Term td;
@@ -2302,6 +2324,7 @@ void Yap_InitExecFs(void) {
   Yap_InitCPred("current_choice_point", 1, current_choice_point, 0);
   Yap_InitCPred("current_choicepoint", 1, current_choice_point, 0);
   Yap_InitCPred("env_choice_point", 1, save_env_b, 0);
+  Yap_InitCPred("parent_choice_point", 1, parent_choice_point, 0);
   Yap_InitCPred("cut_at", 1, clean_ifcp, SafePredFlag);
   CurrentModule = cm;
   Yap_InitCPred("$restore_regs", 1, restore_regs,

C/yap-args.c

@@ -1206,6 +1206,7 @@ X_API void YAP_Init(YAP_init_args *yap_init) {
     }
     LOCAL_consult_level = -1;
   }
+  Yap_do_low_level_trace=1;
   YAP_RunGoalOnce(TermInitProlog);
   if (yap_init->install && Yap_OUTPUT_STARTUP) {
     Term t = MkAtomTerm(Yap_LookupAtom(Yap_OUTPUT_STARTUP));
@@ -1214,6 +1215,7 @@ X_API void YAP_Init(YAP_init_args *yap_init) {
 
     YAP_RunGoalOnce(g);
   }
+  Yap_do_low_level_trace=0;
 
   end_init(yap_init);
 }

library/hacks.yap

@@ -10,6 +10,8 @@
 
 :- module(yap_hacks, [
 		      current_choicepoint/1,
+		      parent_choicepoint/1,
+		      parent_choicepoint/2,
 		      cut_by/1,
 		      cut_at/1,
 		      current_choicepoints/1,
@@ -66,6 +68,16 @@ run_formats([], _).
 run_formats([Com-Args|StackInfo], Stream) :-
 	format(Stream, Com, Args),
 	run_formats(StackInfo, user_error).
+/**
+ * @pred parent_choicepoint(+_ChoicePoint_)
+ *
+ * _ChoicePoint_ is the parent of the current choice-point.
+ *
+ */
+parent_choicepoint(BP) :-
+	current_choicepoint(B),
+	parent_choicepoint(B, BP).
+
 
 /**
  * @pred virtual_alarm(+Interval, 0:Goal, -Left)

pl/boot.yap

@@ -41,7 +41,7 @@ system_module(Mod, SysExps) :-
 
 use_system_module(_Module, _SysExps).
 
-system_module(_Mod, SysExps, _Decls) :-
+system_module(_Mod, _SysExps, _Decls) :-
       % '$new_system_predicates'(SysExps),
        fail.
  system_module(_Mod, _SysExps, _Decls) :-
@@ -100,9 +100,9 @@ print_message(L,E) :-
 	).
 
 '$undefp0'([M|G], _Action) :-
- functor(G,N,A),
+	functor(G,N,A),
-    print_message( error, error(error(unknown, M:N/A),M:G)),
+	print_message( error, error(error(unknown, M:N/A),M:G)),
-    fail.
+	fail.
 
 :- '$undefp_handler'('$undefp0'(_,_),prolog).
 

pl/init.yap

@@ -114,7 +114,7 @@
     module(user),
     fail.
 '$startup_goals' :- 
-    recorded('$startup_goal',G,_),
+   recorded('$startup_goal',G,_),
     catch(once(user:G),Error,user:'$Error'(Error)),
     fail.
 '$startup_goals' :-
@@ -187,7 +187,7 @@
 	get_value('$consult_on_boot',X), X \= [],
 	set_value('$consult_on_boot',[]),
 	'$do_startup_reconsult'(X),
-	!.
+	fail.
 '$init_from_saved_state_and_args' :-
 	recorded('$restore_flag', init_file(M:B), R),
 	erase(R),

pl/top.yap

@@ -177,11 +177,11 @@ live :-
 	catch( '$expand_term0'(T,Con,O), _,( '$disable_debugging', fail) ),
       	!.
 
-		'$expand_term0'(T,consult,O) :-
+'$expand_term0'(T,consult,O) :-
-		expand_term( T,  O).
+	expand_term( T,  O).
-		'$expand_term0'(T,reconsult,O) :-
+'$expand_term0'(T,reconsult,O) :-
-		expand_term( T,  O).
+	expand_term( T,  O).
-		'$expand_term0'(T,top,O) :-
+'$expand_term0'(T,top,O) :-
 	expand_term( T,  T1),
 	!,
  	'$expand_term1'(T1,O).
@@ -879,8 +879,7 @@ gated_call(Setup, Goal, Catcher, Cleanup) :-
 '$precompile_term'(Term, Term, Term).
 
 '$expand_clause'(InputCl, C1, CO) :-
-    source_module(SM),
+    '$yap_strip_clause'(InputCl, M, ICl),
-    '$yap_strip_clause'(SM:InputCl, M, ICl),
     '$expand_a_clause'( M:ICl, SM, C1, CO),
     !.
 '$expand_clause'(Cl, Cl, Cl).

pl/undefined.yap

@@ -97,26 +97,27 @@ undefined_query(G0, M0, Cut) :-
 '$undefp'([M0|G0],MG) :-
     % make sure we do not loop on undefined predicates
     '$undef_setup'(M0:G0, Action,Debug,Current, MGI),
-    ('$get_undefined_predicates'( MGI, MG )                                                  , MG) 
+    ('$get_undefined_predicates'( MGI, MG )                                  
     ->
         true
     ;
     '$undef_error'(Current, M0:G0, MGI,  MG)
     ,
-    '$undef_cleanup'(Action,Debug,Current).
+     '$undef_cleanup'(Action,Debug,Current)
+    ).
 
 '$undef_error'(_, M0:G0, _, MG) :-
     '$pred_exists'(unknown_predicate_handler(_,_,_,_), user),
     '$yap_strip_module'(M0:G0,  EM0, GM0),
     user:unknown_predicate_handler(GM0,EM0,MG),
     !.
-'$handle_error'(error,  Mod:Goal, I,_) :-
+'$undef_error'(error,  Mod:Goal, I,_) :-
     '$do_error'(existence_error(procedure,I), Mod:Goal).
-'$handle_error'(warning,Mod:Goal,I,_) :-
+'$undef_error'(warning,Mod:Goal,I,_) :-
     'program_continuation'(PMod,PName,PAr),
     print_message(warning,error(existence_error(procedure,I), context(Mod:Goal,PMod:PName/PAr))),
     fail.
-'$handle_error'(fail,_Goal,_Mod) :-
+'$undef_error'(fail,_Goal,_Mod) :-
     fail.
 
 '$undef_setup'(G0,Action,Debug,Current,GI) :-
@@ -127,20 +128,20 @@ undefined_query(G0, M0, Cut) :-
 
 '$g2i'(user:G, Na/Ar ) :-
         !,
-functor(G, Na, Ar).
+	functor(G, Na, Ar).
 '$g2i'(prolog:G, Na/Ar ) :-
         !,
-            functor(G, Na, Ar).
+	functor(G, Na, Ar).
 '$g2i'(M:G, M:Na/Ar ) :-
         !,
-functor(G, Na, Ar).
+	functor(G, Na, Ar).
 
 '$undef_cleanup'(Action,Debug,_Current) :-
     yap_flag( unknown, _, Action),
     yap_flag( debug, _, Debug),
     '$start_creep'([prolog|true], creep).
 
-    :- '$undefp_handler'('$undefp'(_,_), prolog).
+:- '$undefp_handler'('$undefp'(_,_), prolog).
 
 /** @pred  unknown(- _O_,+ _N_)
 
@@ -154,7 +155,7 @@ The unknown predicate, informs about what the user wants to be done
 */
 
 unknown(P, NP) :-
-    prolog_flag( unknown, P, NP ).
+    yap_flag( unknown, P, NP ).
 
 /**
 @}