%% -------------------------  T r a c e r  ------------------------------------
%%
%% RELFUN-part of the tracer.                                     mh, Jan. 93


%% tracer_print_enter(Head, Clause-n, Redo-p, Print-p, Print-f, Hn_or_ft)

tracer_print_enter(Head, Clause-n, Redo-p, false, Print-f, _) :-
	% do not print but possible inc. level
	tracer_inc_level(Redo-p).
tracer_print_enter(Head, Clause-n, false, true, Print-f, Hn_or_ft) :-
	% no redo, printing enabled.
	tracer-increment-level(),
	Indent .= tracer-print-heading(">"),
	% Print-f returns the cursor position
	tracer-print-hn-or-ft(Hn_or_ft, Print-f(head, Indent, Clause-n, Head)),
	rf-terpri().
tracer_print_enter(Head, Clause-n, true, true, Print-f, Hn_or_ft) :-
	% redo, printing is enabled.
	Indent .= tracer-print-heading("|"),
	% Print-f returns the cursor position:
	tracer-print-hn-or-ft(Hn_or_ft, Print-f(head, Indent, Clause-n, Head)),
	rf-terpri().


tracer_print_exit(Head, Clause-n, false, Print-f|Foot) :-
	% do not print but dec. level
	tracer-check-max(),
	tracer-decrement-level().
tracer_print_exit(Head, Clause-n, true, Print-f) :-
	% hornish clause, printing is enabled
	Post_head .= Print-f(head, tracer-print-heading("<"), Clause-n, Head),
	tracer-print-hn-or-ft(hn-exit, Post_head),
	rf-terpri(),
	tracer-check-max(),
	tracer-decrement-level ().
tracer_print_exit(Head, Clause-n, true, Print-f, Foot) :-
	% footed clause, printing is enabled
        Post_head .= Print-f(head, tracer-print-heading("<"), Clause-n, Head), 
        Post_tag .= tracer-print-hn-or-ft(ft-exit, Post_head),
	Print-f(foot, Post_tag, Foot),
	tracer-check-max(),
	tracer-decrement-level().


%% tracer_print_fail(Functor, Redo-p, Print-p, Print-f)

tracer_print_fail(Functor, Redo-p, false, Print-f) :-
	% do not print but poss. dec. level
	tracer_dec_level(Redo-p).
tracer_print_fail(Functor, true, true, Print-f) :-	
	% printing is enabled, at least one head has been unified
	Print-f(head, tracer-print-heading("~ "), Functor),
	tracer_dec_level(true),
	rf-terpri().
tracer_print_fail(Functor, false, true, Print-f) :-	
	% printing is enabled, no head has been unified
	Print-f(head, tracer-print-heading("~> "), Functor),
	rf-terpri().


%% tracer_cut_message(Head, Clause-n, Print-flag, Print-f)

tracer_cut_message(_, _, _, _).
tracer_cut_message(Head, Clause-n, true, Print-f) :-
	%% Printing enabled
	Print-f(head, tracer-print-heading("~!"), Clause-n, Head),
	tracer-decrement-level(),
	rf-terpri(),
	unknown.
tracer_cut_message(Head, Clause-n, false, Print-f) :-
	%% Printing disabled
	tracer-decrement-level(),
	unknown.


tracer_inc_level(false) :- tracer-increment-level(). % false = Redo-p
tracer_inc_level(true).		        	     % true = Redo-p


tracer_dec_level(true) :- tracer-decrement-level(). % true = Redo-p
tracer_dec_level(false).			    % false = Redo-p


% The print-function must return the cursor-pos.

tracer_default_printer(head, Indent, Clause-n, Head) :- &
	tracer-print-head(Indent, Head, Clause-n).
tracer_default_printer(head, Indent, Head) :- &
	tracer-print-head(Indent, Head).
tracer_default_printer(foot, Indent, Foot) :-
        the_foot[Real_foot] .= Foot &
	tracer-print-foot(Indent, Real_foot).


tracer_get_redo_p(Clause_n, Redo_functor, Head) :- &
        Redo_functor(Clause_n, tracer-cps(Head)).


tracer_get_print_flag(Head, Pred, true) :- Pred(Head).
tracer_get_print_flag(Head, Pred, false).


%% -----------------------  T r a c e r   E n d  ------------------------------