avoid meta-call in system; improve goal/pred expansion

C/cdmgr.c

@@ -2151,6 +2151,7 @@ goal_expansion_support(PredEntry *p, Term tf)
 	  if (p0) {
 	    mark_preds_with_this_func(FunctorOfTerm(tg), p0);
 	  } else {
+	    CACHE_REGS
 	    Term mod = CurrentModule;
 	    PredEntry *npe;
 	    if (CurrentModule == PROLOG_MODULE)

C/exec.c

@@ -646,6 +646,117 @@ p_execute_in_mod( USES_REGS1 )
   return(do_execute(Deref(ARG1), Deref(ARG2) PASS_REGS));
 }
 
+static Int
+p_do_goal_expansion( USES_REGS1 )
+{
+  Int creeping = LOCAL_ActiveSignals & YAP_CREEP_SIGNAL;
+  Int out = FALSE;
+  PredEntry *pe;
+  Term cmod = Deref(ARG2);
+
+  ARG2 = ARG3;
+  /* disable creeping */
+  LOCK(LOCAL_SignalLock);
+  LOCAL_ActiveSignals &= ~YAP_CREEP_SIGNAL;    
+  if (!LOCAL_ActiveSignals)
+    CreepFlag = CalculateStackGap();
+  UNLOCK(LOCAL_SignalLock);
+  
+  /* CurMod:goal_expansion(A,B) */
+  if ( (pe = RepPredProp(Yap_GetPredPropByFunc(FunctorGoalExpansion2, cmod) ) ) &&
+       pe->OpcodeOfPred != FAIL_OPCODE &&
+       pe->OpcodeOfPred != UNDEF_OPCODE &&
+       CallPredicate(pe, B, pe->CodeOfPred PASS_REGS) ) {
+    out = TRUE;
+    ARG3 = ARG2;
+    goto complete;
+  }
+  /* system:goal_expansion(A,B) */
+  if ( (pe = RepPredProp(Yap_GetPredPropByFunc(FunctorGoalExpansion2, SYSTEM_MODULE ) ) ) &&
+       pe->OpcodeOfPred != FAIL_OPCODE &&
+       pe->OpcodeOfPred != UNDEF_OPCODE &&
+       CallPredicate(pe, B, pe->CodeOfPred PASS_REGS) ) {
+    out = TRUE;
+    ARG3 = ARG2;
+    goto complete;
+  }
+  ARG3 = ARG2;
+  ARG2 = cmod;
+  /* user:goal_expansion(A,CurMod,B) */
+  if ( (pe = RepPredProp(Yap_GetPredPropByFunc(FunctorGoalExpansion, USER_MODULE ) ) ) &&
+       pe->OpcodeOfPred != FAIL_OPCODE &&
+       pe->OpcodeOfPred != UNDEF_OPCODE &&
+       CallPredicate(pe, B, pe->CodeOfPred PASS_REGS) ) {
+    out = TRUE;
+    goto complete;
+  }
+  ARG2 = ARG3;
+  /* user:goal_expansion(A,B) */
+  if ( cmod != USER_MODULE && /* we have tried this before */
+       (pe = RepPredProp(Yap_GetPredPropByFunc(FunctorGoalExpansion2, USER_MODULE ) ) ) &&
+       pe->OpcodeOfPred != FAIL_OPCODE &&
+       pe->OpcodeOfPred != UNDEF_OPCODE &&
+       CallPredicate(pe, B, pe->CodeOfPred PASS_REGS) ) {
+    ARG3 = ARG2;
+    out = TRUE;
+  }
+ complete:
+  LOCK(LOCAL_SignalLock);
+  if (creeping) {
+    LOCAL_ActiveSignals |= YAP_CREEP_SIGNAL;    
+  }
+  UNLOCK(LOCAL_SignalLock);
+  return out;
+}
+
+static Int
+p_do_term_expansion( USES_REGS1 )
+{
+  Int creeping = LOCAL_ActiveSignals & YAP_CREEP_SIGNAL;
+  Int out = FALSE;
+  PredEntry *pe;
+  Term cmod = CurrentModule;
+
+  /* disable creeping */
+  LOCK(LOCAL_SignalLock);
+  LOCAL_ActiveSignals &= ~YAP_CREEP_SIGNAL;    
+  if (!LOCAL_ActiveSignals)
+    CreepFlag = CalculateStackGap();
+  UNLOCK(LOCAL_SignalLock);
+  
+  /* CurMod:term_expansion(A,B) */
+  if ( (pe = RepPredProp(Yap_GetPredPropByFunc(FunctorTermExpansion, cmod) ) ) &&
+       pe->OpcodeOfPred != FAIL_OPCODE &&
+       pe->OpcodeOfPred != UNDEF_OPCODE &&
+       CallPredicate(pe, B, pe->CodeOfPred PASS_REGS) ) {
+    out = TRUE;
+    goto complete;
+  }
+  /* system:term_expansion(A,B) */
+  if ( (pe = RepPredProp(Yap_GetPredPropByFunc(FunctorTermExpansion, SYSTEM_MODULE ) ) ) &&
+       pe->OpcodeOfPred != FAIL_OPCODE &&
+       pe->OpcodeOfPred != UNDEF_OPCODE &&
+       CallPredicate(pe, B, pe->CodeOfPred PASS_REGS) ) {
+    out = TRUE;
+    goto complete;
+  }
+  /* user:term_expansion(A,B) */
+  if ( cmod != USER_MODULE && /* we have tried this before */
+       (pe = RepPredProp(Yap_GetPredPropByFunc(FunctorTermExpansion, USER_MODULE ) ) ) &&
+       pe->OpcodeOfPred != FAIL_OPCODE &&
+       pe->OpcodeOfPred != UNDEF_OPCODE &&
+       CallPredicate(pe, B, pe->CodeOfPred PASS_REGS) ) {
+    out = TRUE;
+  }
+ complete:
+  LOCK(LOCAL_SignalLock);
+  if (creeping) {
+    LOCAL_ActiveSignals |= YAP_CREEP_SIGNAL;    
+  }
+  UNLOCK(LOCAL_SignalLock);
+  return out;
+}
+
 static Int
 p_execute0( USES_REGS1 )
 {				/* '$execute0'(Goal,Mod)	 */
@@ -1838,6 +1949,8 @@ Yap_InitExecFs(void)
   Yap_InitCPred("$generate_pred_info", 4, p_generate_pred_info, 0);
   Yap_InitCPred("$uncaught_throw", 0, p_uncaught_throw, 0);
   Yap_InitCPred("$reset_exception", 1, p_reset_exception, 0);
+  Yap_InitCPred("$do_goal_expansion", 3, p_do_goal_expansion, 0);
+  Yap_InitCPred("$do_term_expansion", 2, p_do_term_expansion, 0);
   Yap_InitCPred("$get_exception", 1, p_get_exception, 0);
 }
 

H/iatoms.h

@@ -289,6 +289,7 @@
   AtomSystemLibraryDir = Yap_LookupAtom("system_library_directory");
   AtomTerm = Yap_LookupAtom("term");
   AtomTerms = Yap_LookupAtom("terms");
+  AtomTermExpansion = Yap_LookupAtom("term_expansion");
   AtomTextStream = Yap_LookupAtom("text_stream");
   AtomThreads = Yap_LookupAtom("threads");
   AtomThrow = Yap_LookupAtom("throw");
@@ -424,6 +425,7 @@
   FunctorStreamPos = Yap_MkFunctor(AtomStreamPos,4);
   FunctorSyntaxError = Yap_MkFunctor(AtomSyntaxError,7);
   FunctorShortSyntaxError = Yap_MkFunctor(AtomSyntaxError,1);
+  FunctorTermExpansion = Yap_MkFunctor(AtomTermExpansion,2);
   FunctorThreadRun = Yap_MkFunctor(AtomTopThreadGoal,2);
   FunctorThrow = Yap_MkFunctor(AtomThrow,1);
   FunctorTimeoutError = Yap_MkFunctor(AtomTimeoutError,2);

H/ratoms.h

@@ -289,6 +289,7 @@
   AtomSystemLibraryDir = AtomAdjust(AtomSystemLibraryDir);
   AtomTerm = AtomAdjust(AtomTerm);
   AtomTerms = AtomAdjust(AtomTerms);
+  AtomTermExpansion = AtomAdjust(AtomTermExpansion);
   AtomTextStream = AtomAdjust(AtomTextStream);
   AtomThreads = AtomAdjust(AtomThreads);
   AtomThrow = AtomAdjust(AtomThrow);
@@ -424,6 +425,7 @@
   FunctorStreamPos = FuncAdjust(FunctorStreamPos);
   FunctorSyntaxError = FuncAdjust(FunctorSyntaxError);
   FunctorShortSyntaxError = FuncAdjust(FunctorShortSyntaxError);
+  FunctorTermExpansion = FuncAdjust(FunctorTermExpansion);
   FunctorThreadRun = FuncAdjust(FunctorThreadRun);
   FunctorThrow = FuncAdjust(FunctorThrow);
   FunctorTimeoutError = FuncAdjust(FunctorTimeoutError);

H/tatoms.h

@@ -576,6 +576,8 @@
 #define AtomTerm Yap_heap_regs->AtomTerm_
   Atom AtomTerms_;
 #define AtomTerms Yap_heap_regs->AtomTerms_
+  Atom AtomTermExpansion_;
+#define AtomTermExpansion Yap_heap_regs->AtomTermExpansion_
   Atom AtomTextStream_;
 #define AtomTextStream Yap_heap_regs->AtomTextStream_
   Atom AtomThreads_;
@@ -846,6 +848,8 @@
 #define FunctorSyntaxError Yap_heap_regs->FunctorSyntaxError_
   Functor FunctorShortSyntaxError_;
 #define FunctorShortSyntaxError Yap_heap_regs->FunctorShortSyntaxError_
+  Functor FunctorTermExpansion_;
+#define FunctorTermExpansion Yap_heap_regs->FunctorTermExpansion_
   Functor FunctorThreadRun_;
 #define FunctorThreadRun Yap_heap_regs->FunctorThreadRun_
   Functor FunctorThrow_;

misc/ATOMS

@@ -294,6 +294,7 @@ A	SystemError		N	"system_error"
 A	SystemLibraryDir	N	"system_library_directory"
 A	Term			N	"term"
 A	Terms			N	"terms"
+A	TermExpansion		N	"term_expansion"
 A	TextStream		N	"text_stream"
 A	Threads			N	"threads"
 A	Throw			N	"throw"
@@ -429,6 +430,7 @@ F	StreamEOS		EndOfStream	1
 F	StreamPos		StreamPos	4
 F	SyntaxError		SyntaxError	7
 F	ShortSyntaxError	SyntaxError	1
+F	TermExpansion		TermExpansion	2
 F	ThreadRun		TopThreadGoal	2
 F	Throw			Throw		1
 F	TimeoutError		TimeoutError	2

pl/boot.yap

@@ -434,7 +434,7 @@ true :- true.
 	 ->
 	  '$assertz_dynamic'(L,G,G0,Mod)
 	 ;
-	  catch(nb_getval('$assert_all',on),_,fail)
+	  '$nb_getval'('$assert_all',on,fail)
 	 ->
 	  functor(H,N,A),
 	  '$dynamic'(N/A,Mod),
@@ -571,7 +571,7 @@ true :- true.
         flush_output,
 	fail.
 '$present_answer'((?-), Answ) :-
-	nb_getval('$break',BL),
+	'$nb_getval'('$break',BL,fail),
 	( BL \= 0 -> 	format(user_error, '[~p] ',[BL]) ;
 			true ),
         ( recorded('$print_options','$toplevel'(Opts),_) ->
@@ -900,7 +900,7 @@ not(G) :-    \+ '$execute'(G).
 '$call'(G, CP, G0, CurMod) :-
 	( '$is_expand_goal_or_meta_predicate'(G,CurMod) ->
 	   (
-	     '$notrace'(('$pred_exists'(goal_expansion(G,NG), CurMod), CurMod:goal_expansion(G,NG) ;  system:goal_expansion(G,NG) ; user:goal_expansion(G, CurMod, NG) ; user:goal_expansion(G,NG) )) ->
+	     '$do_goal_expansion'(G, CurMod, NG) ->
 	     '$call'(NG, CP, G0,CurMod)
 	     ;
 	       % repeat other code.
@@ -994,39 +994,6 @@ not(G) :-    \+ '$execute'(G).
 	throw(Ball).
 
 
-/* This is the break predicate,
-	it saves the importante data about current streams and
-	debugger state */
-
-break :-
-	nb_getval('$system_mode',SystemMode),
-	nb_getval('$trace',Trace),
-	nb_setval('$trace',off),
-	nb_getval('$debug_jump',Jump),
-	nb_getval('$debug_run',Run),
-	'$debug_on'(Debug),
-	'$debug_on'(false),
-	nb_getval('$break',BL), NBL is BL+1,
-	nb_getval('$spy_gn',SPY_GN),
-	b_getval('$spy_glist',GList),
-	b_setval('$spy_glist',[]),
-	nb_setval('$break',NBL),
-	current_output(OutStream), current_input(InpStream),
-	format(user_error, '% Break (level ~w)~n', [NBL]),
-	'$do_live',
-	!,
-	set_value('$live','$true'),
-	b_setval('$spy_glist',GList),
-	nb_setval('$spy_gn',SPY_GN),
-	set_input(InpStream), 
-	set_output(OutStream),
-	'$debug_on'(Debug),
-	nb_setval('$debug_jump',Jump),
-	nb_setval('$debug_run',Run),
-	nb_setval('$trace',Trace),
-	nb_setval('$break',BL),
-	nb_setval('$system_mode',SystemMode).
-
 '$silent_bootstrap'(F) :-
 	'$init_globals',
 	nb_setval('$if_level',0),
@@ -1150,18 +1117,12 @@ bootstrap(F) :-
 	
 
 expand_term(Term,Expanded) :-
-	'$current_module'(Mod), 
+	( '$do_term_expansion'(Term,Expanded)
-	( \+ '$undefined'(term_expansion(_,_), Mod),
+        ->
-	  '$notrace'(Mod:term_expansion(Term,Expanded))
+	   true
-        ; \+ '$undefined'(term_expansion(_,_), system),
-	  '$notrace'(system:term_expansion(Term,Expanded))
-        ;  Mod \= user, \+ '$undefined'(term_expansion(_,_), user),
-	  '$notrace'(user:term_expansion(Term,Expanded))
         ;
 	  '$expand_term_grammar'(Term,Expanded)
-	),
+	).
-	!.
-
 
 %
 % Grammar Rules expansion
@@ -1170,15 +1131,6 @@ expand_term(Term,Expanded) :-
 	'$translate_rule'((A-->B),C), !.
 '$expand_term_grammar'(A, A).
 
-%
-% Arithmetic expansion
-%
-'$expand_term_arith'(G1, G2) :-
-	get_value('$c_arith',true),
-	'$c_arith'(G1, G2), !.
-'$expand_term_arith'(G,G).
-
-
 %
 % Arithmetic expansion
 %
@@ -1258,8 +1210,9 @@ catch_ball(Ball, V) :-
 catch_ball(C, C).
 
 '$run_toplevel_hooks' :-
-	nb_getval('$break',0),
+	'$nb_getval'('$break', 0, fail),
-	recorded('$toplevel_hooks',H,_), !,
+	recorded('$toplevel_hooks',H,_), 
+	H \= fail, !,
 	( '$oncenotrace'(H) -> true ; true).
 '$run_toplevel_hooks'.
 
@@ -1268,7 +1221,7 @@ catch_ball(C, C).
 
 '$exit_system_mode' :-
 	nb_setval('$system_mode',off),
-	( catch(nb_getval('$trace',on),_,fail) -> '$creep' ; true).
+	( '$nb_getval'('$trace',on,fail) -> '$creep' ; true).
 
 %
 % just prevent creeping from going on...
@@ -1298,20 +1251,6 @@ catch_ball(C, C).
 '$notrace'(G) :-
 	'$execute'(G).
 
-'$oncenotrace'(G) :-
-	'$disable_creep', !,
-	(
-	 '$execute'(G)
-	->
-	 '$creep'
-	;
-	 '$creep',
-	 fail
-	).	
-'$oncenotrace'(G) :-
-	'$execute'(G), !.
-
-
 '$run_at_thread_start' :-
 	recorded('$thread_initialization',M:D,_),
 	'$notrace'(M:D),
@@ -1319,31 +1258,5 @@ catch_ball(C, C).
 '$run_at_thread_start'.
 
 
-nb_getval(GlobalVariable, Val) :-
-	'$nb_getval'(GlobalVariable, Val, Error),
-	(var(Error)
-	->
-	 true
-	;
-	 '$getval_exception'(GlobalVariable, Val, nb_getval(GlobalVariable, Val)) ->
-	 nb_getval(GlobalVariable, Val)
-	;
-	 '$do_error'(existence_error(variable, GlobalVariable),nb_getval(GlobalVariable, Val))
-	).
-		    
-
-b_getval(GlobalVariable, Val) :-
-	'$nb_getval'(GlobalVariable, Val, Error),
-	(var(Error)
-	->
-	 true
-	;
-	 '$getval_exception'(GlobalVariable, Val, b_getval(GlobalVariable, Val)) ->
-	 true
-	;
-	 '$do_error'(existence_error(variable, GlobalVariable),b_getval(GlobalVariable, Val))
-	).
-
-
 
 

pl/consult.yap

@@ -290,26 +290,26 @@ use_module(M,F,Is) :-
 	!.
 
 '$reset_if'(OldIfLevel) :-
-	catch(nb_getval('$if_level',OldIfLevel),_,fail), !,
+	'$nb_getval'('$if_level', OldIfLevel, fail), !,
 	nb_setval('$if_level',0).
 '$reset_if'(0) :-
 	nb_setval('$if_level',0).
 
 '$get_if'(Level0) :-
-	catch(nb_getval('$if_level',Level),_,fail), !,
+	'$nb_getval'('$if_level', Level, fail), !,
 	Level0 = Level.
 '$get_if'(0).
 
 '$into_system_mode'(OldMode) :-
-	( catch(nb_getval('$system_mode', OldMode),_,fail) -> true ; OldMode = off),
+	( '$nb_getval'('$system_mode', OldMode, fail) -> true ; OldMode = off),
         ( OldMode == off -> '$enter_system_mode' ; true ).
 
 '$ensure_consulting_file'(OldF, Stream) :-
-	( catch(nb_getval('$consulting_file',OldF), _, fail) -> true ; OldF = []),
+	( '$nb_getval'('$consulting_file',OldF, fail) -> true ; OldF = []),
 	'$set_consulting_file'(Stream).
 
 '$ensure_consulting'(Old, New) :-
-	( catch(nb_getval('$consulting',Old), _, fail) -> true ; Old = false ),
+	( '$nb_getval'('$consulting',Old, fail) -> true ; Old = false ),
 	nb_setval('$consulting', New).
 
 '$bind_module'(_, load_files).
@@ -409,12 +409,12 @@ initialization(G,OPT) :-
 '$exec_initialisation_goals' :-
 	'$show_consult_level'(Level),
 	'$current_module'(M),
-	findall(
+	recorded('$initialisation',do(Level,_),_),
-		G,
+	findall(G,
-		(recorded('$initialisation',do(Level,G),R), erase(R), G\='$'),
+	        '$fetch_init_goal'(Level, G),
 		LGs),
 	lists:member(G,LGs),
-	nb_getval('$system_mode', OldMode),
+	'$nb_getval'('$system_mode', OldMode, fail),
         ( OldMode == on -> '$exit_system_mode' ; true ),
 	% run initialization under user control (so allow debugging this stuff).
 	(
@@ -428,6 +428,12 @@ initialization(G,OPT) :-
 '$exec_initialisation_goals' :-
 	nb_setval('$initialization_goals',off).
 
+
+'$fetch_init_goal'(Level, G) :-
+	recorded('$initialisation',do(Level,G),R),
+	erase(R),
+	G\='$'.
+
 '$include'(V, _) :- var(V), !,
 	'$do_error'(instantiation_error,include(V)).
 '$include'([], _) :- !.
@@ -437,7 +443,7 @@ initialization(G,OPT) :-
 '$include'(X, Status) :-
 	get_value('$lf_verbose',Verbosity),
 	'$full_filename'(X,Y,include(X)),
-	( catch( nb_getval('$included_file',OY), _, fail ) -> true ; OY = [] ),
+	( '$nb_getval'('$included_file', OY, fail ) -> true ; OY = [] ),
 	nb_setval('$included_file', Y),
 	'$current_module'(Mod),
 	H0 is heapused, '$cputime'(T0,_),
@@ -489,13 +495,13 @@ source_file(Mod:Pred, FileName) :-
 	'$owner_file'(T, Mod, FileName).
 
 prolog_load_context(_, _) :-
-	nb_getval('$consulting_file',[]), !, fail.
+	'$nb_getval'('$consulting_file', [], fail), !, fail.
 prolog_load_context(directory, DirName) :- 
 	getcwd(DirName).
 prolog_load_context(file, FileName) :- 
-	( catch( nb_getval('$included_file',IncFileName), _, fail ) -> true ; IncFileName = [] ),
+	( '$nb_getval'('$included_file', IncFileName, fail ) -> true ; IncFileName = [] ),
 	( IncFileName = [] ->
-	  nb_getval('$consulting_file',FileName),
+	  '$nb_getval'('$consulting_file', FileName, fail),
 	  FileName \= []
         ;
            FileName  = IncFileName
@@ -1008,7 +1014,7 @@ absolute_file_name(File,Opts,TrueFileName) :-
 	'$set_yap_flags'(11,0).
 
 '$fetch_comp_status'(assert_all) :-
-	catch(nb_getval('$assert_all',on), _, fail), !.
+	'$nb_getval'('$assert_all',on, fail), !.
 '$fetch_comp_status'(source) :-
 	 '$access_yap_flags'(11,1).
 '$fetch_comp_status'(compact).
@@ -1051,7 +1057,7 @@ make_library_index(_Directory).
 	).
 	    
 '$current_loop_stream'(Stream) :-
-	catch(nb_getval('$loop_stream',Stream), _, fail).
+	'$nb_getval'('$loop_stream',Stream, fail).
 
 exists_source(File) :-
 	'$full_filename'(File, AbsFile, exists_source(File)).

pl/control.yap

@@ -145,7 +145,7 @@ setup_call_catcher_cleanup(Setup, Goal, Catcher, Cleanup) :-
 '$clean_call'(_, _).
 
 '$cc_check_throw' :-
-	nb_getval('$catch',Ball),
+	'$nb_getval'('$catch', Ball, fail),
 	throw(Ball).	
 
 %%% The unknown predicate,
@@ -289,6 +289,97 @@ version(T) :-
 	fail.
 '$set_toplevel_hook'(_).
 
+'$oncenotrace'(G) :-
+	'$disable_creep', !,
+	(
+	 '$execute'(G)
+	->
+	 '$creep'
+	;
+	 '$creep',
+	 fail
+	).	
+'$oncenotrace'(G) :-
+	'$execute'(G), !.
+
+
+'$once0'(G, M) :-
+	'$pred_exists'(G, M),
+	(
+	 '$disable_creep'
+	->
+	  (
+	   '$execute_nonstop'(G, M)
+	   ->
+	   '$creep'
+	  ;
+	   '$creep',
+	    fail
+	  )
+       ;
+	  '$execute_nonstop'(G,M)
+        ).
+
+nb_getval(GlobalVariable, Val) :-
+	'$nb_getval'(GlobalVariable, Val, Error),
+	(var(Error)
+	->
+	 true
+	;
+	 '$getval_exception'(GlobalVariable, Val, nb_getval(GlobalVariable, Val)) ->
+	 nb_getval(GlobalVariable, Val)
+	;
+	 '$do_error'(existence_error(variable, GlobalVariable),nb_getval(GlobalVariable, Val))
+	).
+		    
+
+b_getval(GlobalVariable, Val) :-
+	'$nb_getval'(GlobalVariable, Val, Error),
+	(var(Error)
+	->
+	 true
+	;
+	 '$getval_exception'(GlobalVariable, Val, b_getval(GlobalVariable, Val)) ->
+	 true
+	;
+	 '$do_error'(existence_error(variable, GlobalVariable),b_getval(GlobalVariable, Val))
+	).
+
+
+/* This is the break predicate,
+	it saves the importante data about current streams and
+	debugger state */
+
+break :-
+	nb_getval('$system_mode',SystemMode),
+	nb_getval('$trace',Trace),
+	nb_setval('$trace',off),
+	nb_getval('$debug_jump',Jump),
+	nb_getval('$debug_run',Run),
+	'$debug_on'(Debug),
+	'$debug_on'(false),
+	nb_getval('$break',BL), NBL is BL+1,
+	nb_getval('$spy_gn',SPY_GN),
+	b_getval('$spy_glist',GList),
+	b_setval('$spy_glist',[]),
+	nb_setval('$break',NBL),
+	current_output(OutStream), current_input(InpStream),
+	format(user_error, '% Break (level ~w)~n', [NBL]),
+	'$do_live',
+	!,
+	set_value('$live','$true'),
+	b_setval('$spy_glist',GList),
+	nb_setval('$spy_gn',SPY_GN),
+	set_input(InpStream), 
+	set_output(OutStream),
+	'$debug_on'(Debug),
+	nb_setval('$debug_jump',Jump),
+	nb_setval('$debug_run',Run),
+	nb_setval('$trace',Trace),
+	nb_setval('$break',BL),
+	nb_setval('$system_mode',SystemMode).
+
+
 at_halt(G) :-
 	recorda('$halt', G, _),
 	fail.

pl/errors.yap

@@ -248,7 +248,7 @@ print_message(Severity, Term) :-
 	% first step at hook processing
 	'$message_to_lines'(Term, Lines),
 	(   nonvar(Term),
-	    '$oncenotrace'(user:message_hook(Term, Severity, Lines))
+	    '$once0'(message_hook(Term, Severity, Lines), user)
 	->
            true
 	;
@@ -263,9 +263,9 @@ print_message(_, Term) :-
 	format(user_error,'~q~n',[Term]).
 
 '$message_to_lines'(Term, Lines) :-
-	'$oncenotrace'(user:generate_message_hook(Term, [], Lines)), !.
+	'$once0'(generate_message_hook(Term, [], Lines), user), !.
 '$message_to_lines'(Term, Lines) :-
-	'$oncenotrace'(prolog:message(Term, Lines, [])), !.
+	'$once0'(message(Term, Lines, []), prolog), !.
 '$message_to_lines'(Term, Lines) :-
 	'$messages':generate_message(Term, Lines, []), !.
 	

pl/modules.yap

@@ -396,11 +396,7 @@ expand_goal(G, G).
 	% make built-in processing transparent.
 	'$match_mod'(G, M, ORIG, HM, G1),
 	'$c_built_in'(G1, M, Gi),
-	(Gi \== G1 ->
+	G1 = G2.
-	 '$module_expansion'(Gi, G2, _, M, CM, HM, HVars)
-	;
-	 G2 = G1
-	).
 '$complete_goal_expansion'(G, GMod, _, HM, NG, NG, _) :-
 	'$match_mod'(G, GMod, GMod, HM, NG).
 

pl/signals.yap

@@ -36,7 +36,7 @@
 '$do_signal'(sig_creep, [M|G]) :-
 	'$creep_allowed', !,
 	(
-	 ( G = '$notrace'(G0) ;  G = '$oncenotrace'(G0) ; G = '$execute0'(G0,M) ; '$system_module'(M), G = G0 )
+	 ( G = '$notrace'(G0) ;  G = '$oncenotrace'(G0) ; G = '$once0'(G0) ; G = '$execute0'(G0,M) ; '$system_module'(M), G = G0 )
 	->
 	 (
 	  '$execute_nonstop'(G0,M),
@@ -50,7 +50,7 @@
 	).
 % 
 '$do_signal'(sig_creep, [M|G]) :-
-	( G = '$notrace'(G0) ;  G = '$oncenotrace'(G0) ; G = '$execute0'(G0,M) ; '$system_module'(M), G = G0 ),
+	( G = '$notrace'(G0) ;  G = '$oncenotrace'(G0) ; G = '$once0'(G0) ; G = '$execute0'(G0,M) ; '$system_module'(M), G = G0 ),
 	!,
 	(
 	 '$execute_nonstop'(G0,M),
@@ -168,6 +168,18 @@
 	 '$creep',
 	 fail	   
 	).
+'$start_creep'([M0|'$once0'(G)]) :-
+	!,
+	('$execute_nonstop'(G,M0),
+	 CP1 is '$last_choice_pt',
+	 % exit port: creep
+	 '$creep',
+	 !
+	;
+	   % put it back again on fail
+	 '$creep',
+	 fail	   
+	).
 % do not debug if we are not in debug mode. 
 '$start_creep'([Mod|G]) :-
 	'$debug_on'(DBON), DBON = false, !,