/*************************************************************************
* *
* YAP Prolog *
* *
* Yap Prolog was developed at NCCUP - Universidade do Porto *
* *
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
* *
**************************************************************************
* *
* File: debug.pl *
* Last rev: *
* mods: *
* comments: YAP's debugger *
* *
*************************************************************************/
/*-----------------------------------------------------------------------------
Debugging / creating spy points
-----------------------------------------------------------------------------*/
:- op(900,fx,[spy,nospy]).
% First part : setting and reseting spy points
% $suspy does most of the work
'$suspy'(V,S,M) :- var(V) , !,
'$do_error'(instantiation_error,M:spy(V,S)).
'$suspy'((M:S),P,_) :- !,
'$suspy'(S,P,M).
'$suspy'([],_,_) :- !.
'$suspy'([F|L],S,M) :- !, ( '$suspy'(F,S,M) ; '$suspy'(L,S,M) ).
'$suspy'(F/N,S,M) :- !,
functor(T,F,N),
'$do_suspy'(S, F, N, T, M).
'$suspy'(A,S,M) :- atom(A), !,
'$suspy_predicates_by_name'(A,S,M).
'$suspy'(P,spy,M) :- !,
'$do_error'(domain_error(predicate_spec,P),spy(M:P)).
'$suspy'(P,nospy,M) :-
'$do_error'(domain_error(predicate_spec,P),nospy(M:P)).
'$suspy_predicates_by_name'(A,S,M) :-
% just check one such predicate exists
(
current_predicate(A,M:_)
;
recorded('$import','$import'(EM,M,A,_),_)
),
!,
'$do_suspy_predicates_by_name'(A,S,M).
'$suspy_predicates_by_name'(A,spy,M) :- !,
'$print_message'(warning,no_match(spy(M:A))).
'$suspy_predicates_by_name'(A,nospy,M) :-
'$print_message'(warning,no_match(nospy(M:A))).
'$do_suspy_predicates_by_name'(A,S,M) :-
current_predicate(A,M:T),
functor(T,A,N),
'$do_suspy'(S, A, N, T, M).
'$do_suspy_predicates_by_name'(A, S, M) :-
recorded('$import','$import'(EM,M,A,N),_),
functor(T,A,N),
'$do_suspy'(S, A, N, T, EM).
%
% protect against evil arguments.
%
'$do_suspy'(S, F, N, T, M) :-
recorded('$import','$import'(EM,M,F,N),_), !,
'$do_suspy'(S, F, N, T, EM).
'$do_suspy'(S, F, N, T, M) :-
'$undefined'(T,M), !,
( S = spy ->
'$print_message'(warning,no_match(spy(M:F/N)))
;
'$print_message'(warning,no_match(nospy(M:F/N)))
).
'$do_suspy'(S, F, N, T, M) :-
'$system_predicate'(T,M),
'$flags'(T,Mod,F,F),
F /\ 0x118dd080 =\= 0,
( S = spy ->
'$do_error'(permission_error(access,private_procedure,T),spy(M:F/N))
;
'$do_error'(permission_error(access,private_procedure,T),nospy(M:F/N))
).
'$do_suspy'(S, F, N, T, M) :-
'$undefined'(T,M), !,
( S = spy ->
'$print_message'(warning,no_match(spy(M:F/N)))
;
'$print_message'(warning,no_match(nospy(M:F/N)))
).
'$do_suspy'(S,F,N,T,M) :-
'$suspy2'(S,F,N,T,M).
'$suspy2'(spy,F,N,T,M) :-
recorded('$spy','$spy'(T,M),_), !,
'$print_message'(informational,breakp(bp(debugger,plain,M:T,M:F/N,N),add,already)).
'$suspy2'(spy,F,N,T,M) :- !,
recorda('$spy','$spy'(T,M),_),
'$set_spy'(T,M),
'$print_message'(informational,breakp(bp(debugger,plain,M:T,M:F/N,N),add,ok)).
'$suspy2'(nospy,F,N,T,M) :-
recorded('$spy','$spy'(T,M),R), !,
erase(R),
'$rm_spy'(T,M),
'$print_message'(informational,breakp(bp(debugger,plain,M:T,M:F/N,N),remove,last)).
'$suspy2'(nospy,F,N,_,M) :-
'$print_message'(informational,breakp(no,breakpoint_for,M:F/N)).
'$pred_being_spied'(G, M) :-
recorded('$spy','$spy'(G,M),_), !.
spy L :-
'$current_module'(M),
'$suspy'(L, spy, M), fail.
spy _ :- debug.
nospy L :-
'$current_module'(M),
'$suspy'(L, nospy, M), fail.
nospy _.
nospyall :-
recorded('$spy','$spy'(T,M),_), functor(T,F,N), '$suspy'(F/N,nospy,M), fail.
nospyall.
% debug mode -> debug flag = 1
debug :- recordaifnot('$debug',on,_), !,
'$print_message'(informational,debug(debug)).
debug.
nodebug :-
recorded('$debug',_,R), erase(R), fail.
nodebug :-
recorded('$trace',_,R), erase(R), fail.
nodebug :- nospyall,
'$set_yap_flags'(10,0),
'$print_message'(informational,debug(off)).
trace :-
recorded('$trace',on,_), !.
trace :-
recorded('$spy_skip',_,R), erase(R), fail.
trace :-
( recordaifnot('$trace',on,_) -> true ; true),
( recordaifnot('$debug',on,_) -> true ; true),
( recordaifnot('$spy_stop',on,_) -> true ; true),
'$set_yap_flags'(10,1),
'$print_message'(informational,debug(trace)),
'$creep'.
notrace :-
recorded('$debug',_,R), erase(R), fail.
notrace :-
recorded('$trace',_,R), erase(R), fail.
notrace :-
'$print_message'(informational,debug(off)).
/*-----------------------------------------------------------------------------
leash
-----------------------------------------------------------------------------*/
leash(X) :- var(X),
'$do_error'(instantiation_error,leash(X)).
leash(X) :-
'$leashcode'(X,Code),
set_value('$leash',Code),
'$show_leash'(informational,Code), !.
leash(X) :-
'$do_error'(type_error(leash_mode,X),leash(X)).
'$show_leash'(Msg,0) :-
'$print_message'(Msg,leash([])).
'$show_leash'(Msg,Code) :-
'$check_leash_bit'(Code,2'1000,L3,call,LF),
'$check_leash_bit'(Code,2'0100,L2,exit,L3),
'$check_leash_bit'(Code,2'0010,L1,redo,L2),
'$check_leash_bit'(Code,2'0001,[],fail,L1),
'$print_message'(Msg,leash(LF)).
'$check_leash_bit'(Code,Bit,L0,_,L0) :- Bit /\ Code =:= 0, !.
'$check_leash_bit'(_,_,L0,Name,[Name|L0]).
'$leashcode'(full,2'1111) :- !.
'$leashcode'(on,2'1111) :- !.
'$leashcode'(half,2'1010) :- !.
'$leashcode'(loose,2'1000) :- !.
'$leashcode'(off,2'0000) :- !.
'$leashcode'(none,2'0000) :- !.
%'$leashcode'([L|M],Code) :- !, '$leashcode_list'([L|M],Code).
'$leashcode'([L|M],Code) :- !,
'$list2Code'([L|M],Code).
'$leashcode'(N,N) :- integer(N), N >= 0, N =< 2'1111.
'$list2Code'(V,_) :- var(V), !,
'$do_error'(instantiation_error,leash(V)).
'$list2Code'([],0) :- !.
'$list2Code'([V|L],_) :- var(V), !,
'$do_error'(instantiation_error,leash([V|L])).
'$list2Code'([call|L],N) :- '$list2Code'(L,N1), N is 2'1000 + N1.
'$list2Code'([exit|L],N) :- '$list2Code'(L,N1), N is 2'0100 + N1.
'$list2Code'([redo|L],N) :- '$list2Code'(L,N1), N is 2'0010 + N1.
'$list2Code'([fail|L],N) :- '$list2Code'(L,N1), N is 2'0001 + N1.
/*-----------------------------------------------------------------------------
debugging
-----------------------------------------------------------------------------*/
debugging :-
( recorded('$debug',on,_) ->
'$print_message'(help,debug(debug))
;
'$print_message'(help,debug(off))
),
findall(M:(N/A),(recorded('$spy','$spy'(T,M),_),functor(T,N,A)),L),
'$print_message'(help,breakpoints(L)),
get_value('$leash',Leash),
'$show_leash'(help,Leash).
/*-----------------------------------------------------------------------------
spy
-----------------------------------------------------------------------------*/
% ok, I may have a spy point for this goal, or not.
% if I do, I should check what mode I am in.
% Goal/Mode Have Spy Not Spied
% Creep Stop Stop
% Leap Stop Create CP
% Skip Create CP Create CP
% FastLeap Stop Ignore
% FastIgnore Ignore Ignore
% flag description initial possible values
% spy_gn goal number 1 1...
% spy_trace trace 0 0, 1
% spy_skip leap off Num (stop level)
% spy_stop stop at spy points on on,off
% a flip-flop is also used
% when 1 spying is enabled *(the same as spy stop).
%'$spy'(G) :- write(user_error,'$spy'(G)), nl, fail.
%
% handle suspended goals
% take care with hidden goals.
%
% $spy may be called from user code, so be careful.
'$spy'([Mod|G]) :-
CP is '$last_choice_pt',
'$do_spy'(G, Mod, CP, yes).
% last argument to do_spy says that we are at the end of a context. It
% is required to know whether we are controlled by the debugger.
'$do_spy'(_, _, _, _) :-
'$do_not_creep', fail.
'$do_spy'(!, _, CP, _) :- !, '$cut_by'(CP).
'$do_spy'('$cut_by'(M), _, _, _) :- !, '$cut_by'(M).
'$do_spy'(true, _, _, _) :- !.
%'$do_spy'(fail, _, _, _) :- !, fail.
'$do_spy'(M:G, _, CP, InControl) :- !,
'$do_spy'(G, M, CP, InControl).
'$do_spy'((A,B), M, CP, InControl) :- !,
'$do_spy'(A, M, CP, yes),
'$do_spy'(B, M, CP, InControl).
'$do_spy'((T->A;B), M, CP, InControl) :- !,
( '$do_spy'(T, M, CP, yes) -> '$do_spy'(A, M, CP, yes)
;
'$do_spy'(B, M, CP, InControl)
).
'$do_spy'((T->A|B), M, CP, InControl) :- !,
( '$do_spy'(T, M, CP, yes) -> '$do_spy'(A, M, CP, yes)
;
'$do_spy'(B, M, CP, InControl)
).
'$do_spy'((T->A), M, CP, InControl) :- !,
( '$do_spy'(T, M, CP, yes) -> '$do_spy'(A, M, CP, yes) ).
'$do_spy'((A;B), M, CP, InControl) :- !,
(
'$do_spy'(A, M, CP, yes)
;
'$do_spy'(B, M, CP, InControl)
).
'$do_spy'((A|B), M, CP, InControl) :- !,
(
'$do_spy'(A, M, CP, yes)
;
'$do_spy'(B, M, CP, InControl)
).
'$do_spy'((\+G), M, CP, InControl) :- !,
\+ '$do_spy'(G, M, CP, InControl).
'$do_spy'((not(G)), M, InControl) :- !,
\+ '$do_spy'(G, M, CP, InControl).
'$do_spy'(G, Module, _, InControl) :-
get_value(spy_gn,L), /* get goal no. */
L1 is L+1, /* bump it */
set_value(spy_gn,L1), /* and save it globaly */
'$loop_spy'(L, G, Module, InControl). /* set creep on */
% we are skipping, so we can just call the goal,
% while leaving the minimal structure in place.
'$loop_spy'(GoalNumber, G, Module, InControl) :-
'$system_catch'('$loop_spy2'(GoalNumber, G, Module, InControl),
Module, Event,
'$loop_spy_event'(Event, GoalNumber, G, Module, InControl)).
% handle weird things happening in the debugger.
'$loop_spy_event'(_, _, _, _, _) :-
'$do_not_creep', fail.
'$loop_spy_event'('$retry_spy'(G0), GoalNumber, G, Module, InControl) :-
G0 >= GoalNumber, !,
'$loop_spy'(GoalNumber, G, Module, InControl).
'$loop_spy_event'('$retry_spy'(GoalNumber), _, _, _, _) :- !,
throw('$retry_spy'(GoalNumber)).
'$loop_spy_event'('$fail_spy'(G0), GoalNumber, G, Module, InControl) :-
G0 >= GoalNumber, !,
'$loop_fail'(GoalNumber, G, Module, InControl).
'$loop_spy_event'('$fail_spy'(GoalNumber), _, _, _, _) :- !,
throw('$fail_spy'(GoalNumber)).
'$loop_spy_event'(abort, _, _, _, _) :- !,
throw('$abort').
'$loop_spy_event'(Event, GoalNumber, G, Module, InControl) :- !,
'$system_catch'(
('$trace'(exception(Event),G,Module,GoalNumber),fail),
Module,NewEvent,
'$loop_spy_event'(NewEvent, GoalNumber, G, Module, InControl)).
'$loop_fail'(GoalNumber, G, Module, InControl) :-
'$system_catch'(('$trace'(fail, G, Module, GoalNumber),
fail ),
Module, Event,
'$loop_spy_event'(Event, GoalNumber, G, Module, InControl)).
% if we are in
'$loop_spy2'(GoalNumber, G, Module, InControl) :-
/* the following choice point is where the predicate is called */
(
'$enter_goal'(GoalNumber, G, Module),
'$spycall'(G, Module, InControl),
/* go execute the predicate */
(
'$do_not_creep',
'$show_trace'(exit,G,Module,GoalNumber), /* output message at exit */
'$continue_debugging'(InControl)
;
/* exit */
/* we get here when we want to redo a goal */
'$do_not_creep',
'$show_trace'(redo,G,Module,GoalNumber), /* inform user_error */
'$continue_debugging'(InControl,G,Module),
fail /* to backtrack to spycalls */
)
;
'$do_not_creep',
'$show_trace'(fail,G,Module,GoalNumber), /* inform at fail port */
'$continue_debugging'(InControl,G,Module),
fail
).
'$enter_goal'(GoalNumber, G, Module) :-
'$avoid_goal'(GoalNumber, G, Module), !.
'$enter_goal'(GoalNumber, G, Module) :-
'$trace'(call, G, Module, GoalNumber).
'$show_trace'(_, G, Module, GoalNumber) :-
'$avoid_goal'(GoalNumber, G, Module), !.
'$show_trace'(P,G,Module,GoalNumber) :-
'$trace'(P,G,Module,GoalNumber).
'$avoid_goal'(GoalNumber, G, Module) :-
\+ recorded('$debug',on,_), !.
'$avoid_goal'(GoalNumber, G, Module) :-
recorded('$spy_skip', Value, _),
'$continue_avoid_goal'(GoalNumber, G, Module, Value).
% for leap keep on going until finding something spied.
'$continue_avoid_goal'(_, G, Module, _) :-
recorded('$spy_stop', on, _), !,
\+ '$pred_being_spied'(G, Module).
% for skip keep on going until we get back.
'$continue_avoid_goal'(GoalNumber, _, _, Value) :-
number(Value),
Value < GoalNumber.
%
'$spycall'(G, M, _) :-
( '$access_yap_flags'(10,0);
'$system_predicate'(G,M), \+ '$is_metapredicate'(G,M)
), !,
'$execute_nonstop'(G, M).
'$spycall'(G, M, InControl) :-
'$flags'(G,M,F,F),
F /\ 0x8402000 =\= 0, !, % dynamic procedure, logical semantics, or source
% use the interpreter
CP is '$last_choice_pt',
'$clause'(G, M, Cl),
'$do_not_creep',
'$do_spy'(Cl, M, CP, InControl).
'$spycall'(G, M, InControl) :-
% I lost control here.
'$continue_debugging'(InControl,G,M),
'$execute_nonstop'(G, M).
'$trace'(P,G,Module,L) :-
flush_output(user_output),
flush_output(user_error),
recorded('$debug',on,R0), erase(R0),
repeat,
('$pred_being_spied'(G,Module) -> CSPY = '*' ; CSPY = ' '),
( SL = L -> SLL = '>' ; SLL = ' '),
( recorded('$debug',on, R), erase(R), fail ; true),
( Module\=prolog,
Module\=user ->
format(user_error,"~a~a (~d) ~q: ~a:",[CSPY,SLL,L,P,Module])
;
format(user_error,"~a~a (~d) ~q:",[CSPY,SLL,L,P])
),
'$debugger_write'(user_error,G),
( nonvar(R0), recordaifnot('$debug',on,_), fail ; true),
(
'$unleashed'(P),
'$action'(10,P,L,G,Module)
;
write(user_error,' ? '), get0(user_input,C),
'$action'(C,P,L,G,Module)
),
!.
'$unleashed'(call) :- get_value('$leash',L), L /\ 2'1000 =:= 0.
'$unleashed'(exit) :- get_value('$leash',L), L /\ 2'0100 =:= 0.
'$unleashed'(redo) :- get_value('$leash',L), L /\ 2'0010 =:= 0.
'$unleashed'(fail) :- get_value('$leash',L), L /\ 2'0001 =:= 0.
% the same as fail.
'$unleashed'(exception(_)) :- get_value('$leash',L), L /\ 2'0001 =:= 0.
'$debugger_write'(Stream, G) :-
recorded('$print_options','$debugger'(OUT),_), !,
write_term(Stream, G, OUT).
'$debugger_write'(Stream, G) :-
writeq(Stream, G).
'$action'(10,_,_,_,_) :- % newline creep
( recorded('$spy_skip',_,R), erase(R), fail ; true ),
'$set_yap_flags'(10,1).
'$action'(0'!,_,_,_,_) :- !, % ! g execute
read(user,G),
% don't allow yourself to be caught by creep.
'$access_yap_flags'(10, CL),
'$set_yap_flags'(10, 0),
( '$execute'(G) -> true ; true),
'$set_yap_flags'(10, CL),
% '$skipeol'(0'!),
fail.
'$action'(0'<,_,_,_,_) :- !, % <Depth
'$new_deb_depth',
'$skipeol'(0'<),
fail.
'$action'(0'^,_,_,G,_) :- !,
'$print_deb_sterm'(G),
'$skipeol'(0'^),
fail.
'$action'(0'a,_,_,_,_) :- !, % a abort
'$skipeol'(0'^),
abort.
'$action'(0'b,_,_,_,_) :- !, % b break
'$skipeol'(0'b),
break,
fail.
'$action'(0'c,_,_,_,_) :- !, % c creep
'$set_yap_flags'(10,1),
'$skipeol'(0'c).
'$action'(0'e,_,_,_,_) :- !, % e exit
'$skipeol'(0'e),
halt.
'$action'(0'f,_,CallId,_,_) :- !, % f fail
'$scan_number'(0'f, CallId, GoalId),
throw('$fail_spy'(GoalId)).
'$action'(0'h,_,_,_,_) :- !, % h help
'$action_help',
'$skipeol'(104),
fail.
'$action'(0'?,_,_,_,_) :- !, % ? help
'$action_help',
'$skipeol'(104),
fail.
'$action'(0'p,_,_,G,Module) :- !, % p print
((Module = prolog ; Module = user) ->
print(user_error,G), nl(user_error)
;
print(user_error,Module:G), nl(user_error)
),
'$skipeol'(0'p),
fail.
'$action'(0'd,_,_,G,Module) :- !, % d display
((Module = prolog ; Module = user) ->
display(user_error,G), nl(user_error)
;
display(user_error,Module:G), nl(user_error)
),
'$skipeol'(0'd),
fail.
'$action'(0'l,_,CallNumber,_,_) :- !, % l leap
'$skipeol'(0'l),
( recorded('$spy_skip',_,R), erase(R), fail ; recorda('$spy_skip',CallNumber,_) ),
( recordaifnot('$spy_stop',on,_) -> true ; true ),
'$set_yap_flags'(10,1).
'$action'(0'n,_,_,_,_) :- !, % n nodebug
'$skipeol'(0'n),
'$set_yap_flags'(10,0),
( recorded('$spy_stop',_,R), erase(R), fail ; true),
nodebug.
'$action'(0'k,_,CallNumber,_,_) :- !, % k quasi leap
'$skipeol'(0'k),
( recorded('$spy_skip',_,R), erase(R), fail ; recorda('$spy_skip',CallNumber,_) ),
( recordaifnot('$spy_stop',on,_) -> true ; true ),
'$set_yap_flags'(10,0).
% skip first call (for current goal),
% stop next time.
'$action'(0'r,P,CallId,_,_) :- !, % r retry
'$scan_number'(0'r,CallId,ScanNumber),
throw('$retry_spy'(ScanNumber)).
'$action'(0's,P,CallNumber,_,_) :- !, % s skip
'$skipeol'(0's),
( (P=call; P=redo) ->
'$set_yap_flags'(10,1),
( recorded('$spy_skip',_,R), erase(R), fail ; recorda('$spy_skip',CallNumber,_) ),
( recorded('$spy_stop',_,R), erase(R), fail ; true)
;
'$ilgl'(0's)
).
'$action'(0't,P,CallNumber,_,_) :- !, % t fast skip
'$skipeol'(0't),
( (P=call; P=redo) ->
( recorded('$spy_skip',_,R), erase(R), fail ; recorda('$spy_skip',CallNumber,_) ),
( recorded('$spy_stop',_,R), erase(R), fail ; true),
'$set_yap_flags'(10,0)
;
'$ilgl'(0't)
).
'$action'(0'+,_,_,G,M) :- !, % + spy this
functor(G,F,N), spy(M:(F/N)),
'$skipeol'(0'+),
fail.
'$action'(0'-,_,_,G,M) :- !, % - nospy this
functor(G,F,N), nospy(M:(F/N)),
'$skipeol'(0'-),
fail.
'$action'(C,_,_,_,_) :-
'$skipeol'(C),
'$ilgl'(C),
fail.
% if we are in the interpreter, don't need to care about forcing a trace, do we?
'$continue_debugging'(no,_,_) :- !.
'$continue_debugging'(Flag,G,M) :-
'$system_predicate'(G,M), !,
( '$access_yap_flags'(10,1) -> '$late_creep' ; true).
'$continue_debugging'(Flag,_,_) :-
'$continue_debugging'(Flag).
'$continue_debugging'(_) :-
'$access_yap_flags'(10,1), !,
'$creep'.
'$continue_debugging'(_).
'$action_help' :-
format(user_error,"newline creep a abort~n", []),
format(user_error,"c creep e exit~n", []),
format(user_error,"f Goal fail h help~n", []),
format(user_error,"l leap r Goal retry~n", []),
format(user_error,"s skip t fastskip~n", []),
format(user_error,"q quasiskip k quasileap~n", []),
format(user_error,"b break n no debug~n", []),
format(user_error,"p print d display~n", []),
format(user_error,"<D depth D < full term~n", []),
format(user_error,"+ spy this - nospy this~n", []),
format(user_error,"^ view subg ^^ view using~n", []),
format(user_error,"! g execute goal~n", []).
'$ilgl'(C) :-
'$print_message'(warning, trace_command(C)),
'$print_message'(help, trace_help),
fail.
'$skipeol'(10) :- !.
'$skipeol'(_) :- get0(user,C), '$skipeol'(C).
'$scan_number'(_, _, Nb) :-
get0(user,C),
'$scan_number2'(C, Nb), !.
'$scan_number'(_, CallId, CallId).
'$scan_number2'(10, _) :- !, fail.
'$scan_number2'(0' , Nb) :- !,
get0(user,C),
'$scan_number2'(C , Nb).
'$scan_number2'(0' , Nb) :- !,
get0(user,C),
'$scan_number2'(C, Nb).
'$scan_number2'(C, Nb) :-
'$scan_number3'(C, 0, Nb).
'$scan_number3'(10, Nb, Nb) :- !, Nb > 0.
'$scan_number3'( C, Nb0, Nb) :-
C >= 0'0, C =< 0'9,
NbI is Nb0*10+(C-0'0),
get0(user, NC),
'$scan_number3'( NC, NbI, Nb).
'$print_deb_sterm'(G) :-
'$get_sterm_list'(L), !,
'$deb_get_sterm_in_g'(L,G,A),
recorda('$debug_sub_skel',L,_),
format(user_error,"~n~w~n~n",[A]).
'$print_deb_sterm'(_) :- '$skipeol'(94).
'$get_sterm_list'(L) :-
get0(user_input,C),
'$deb_inc_in_sterm_oldie'(C,L0,CN),
'$get_sterm_list'(L0,CN,0,L).
'$deb_inc_in_sterm_oldie'(94,L0,CN) :- !,
get0(user_input,CN),
( recorded('$debug_sub_skel',L0,_) -> true ;
CN = [] ).
'$deb_inc_in_sterm_oldie'(C,[],C).
'$get_sterm_list'(L0,C,N,L) :-
( C =:= "^", N =\= 0 -> get0(CN),
'$get_sterm_list'([N|L0],CN,0,L) ;
C >= "0", C =< "9" -> NN is 10*N+C-"0", get0(CN),
'$get_sterm_list'(L0,CN,NN,L);
C =:= 10 -> (N =:= 0 -> L = L0 ; L=[N|L0]) ).
'$deb_get_sterm_in_g'([],G,G).
'$deb_get_sterm_in_g'([H|T],G,A) :-
'$deb_get_sterm_in_g'(T,G,A1),
arg(H,A1,A).
'$new_deb_depth' :-
get0(user_input,C),
'$get_deb_depth'(C,D),
'$set_deb_depth'(D).
'$get_deb_depth'(10,10) :- !. % default depth is 0
'$get_deb_depth'(C,XF) :-
'$get_deb_depth_char_by_char'(C,0,XF).
'$get_deb_depth_char_by_char'(10,X,X) :- !.
'$get_deb_depth_char_by_char'(C,X0,XF) :-
C >= "0", C =< "9", !,
XI is X0*10+C-"0",
get0(user_input,NC),
'$get_deb_depth_char_by_char'(NC,XI,XF).
% reset when given garbage.
'$get_deb_depth_char_by_char'(C,_,10) :- '$skipeol'(C).
'$set_deb_depth'(D) :-
recorded('$print_options','$debugger'(L),R), !,
'$delete_if_there'(L, max_depth(_), LN),
erase(R),
recorda('$print_options','$debugger'([max_depth(D)|LN]),_).
'$set_deb_depth'(D) :-
recorda('$print_options','$debugger'([quoted(true),numbervars(true),portrayed(true),max_depth(D)]),_).
'$delete_if_there'([], _, []).
'$delete_if_there'([T|L], T, LN) :- !,
'$delete_if_there'(L, T, LN).
'$delete_if_there'([Q|L], T, [Q|LN]) :-
'$delete_if_there'(L, T, LN).