From d488984753fcbeb4e32fcbd5d872146f654ddb1d Mon Sep 17 00:00:00 2001
From: ubu32 <vitor@ubuntu.(none)>
Date: Mon, 11 Jul 2011 07:40:58 -0700
Subject: [PATCH] get rid of loop alias.

---
 pl/boot.yap    |  2 --
 pl/consult.yap | 27 +++++++++++++++++++++------
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/pl/boot.yap b/pl/boot.yap
index c94ee5477..642671b3d 100755
--- a/pl/boot.yap
+++ b/pl/boot.yap
@@ -36,7 +36,6 @@ true :- true.
 		'$system_catch'('$enter_top_level',Module,Error,user:'$Error'(Error)).
 
 '$init_system' :-
-	set_stream(user_input,alias('$loop_stream')),
         % do catch as early as possible
 	(
 	 '$access_yap_flags'(15, 0),
@@ -1068,7 +1067,6 @@ break :-
 	nb_setval('$if_level',0),
 	get_value('$lf_verbose',OldSilent),
 	set_value('$lf_verbose',silent),
-	set_stream(user_input,alias('$loop_stream')),
 	bootstrap(F),
 	% -p option must be processed after initializing the system
 	'$init_path_extensions',
diff --git a/pl/consult.yap b/pl/consult.yap
index 742a1a6b0..195f32b69 100755
--- a/pl/consult.yap
+++ b/pl/consult.yap
@@ -248,8 +248,7 @@ use_module(M,F,Is) :-
 	'$set_consulting_file'(Stream),
 	H0 is heapused, '$cputime'(T0,_),
 	'$file_name'(Stream,File),
-	'$fetch_stream_alias'(OldStream,'$loop_stream'),
-	set_stream(Stream,alias('$loop_stream')),
+	'$set_current_loop_stream'(OldStream, Stream),
 	nb_getval('$consulting',Old),
 	nb_setval('$consulting',false),
 	'$access_yap_flags'(18,GenerateDebug),
@@ -285,7 +284,7 @@ use_module(M,F,Is) :-
 	;
 	    true
 	),
-	set_stream(OldStream,alias('$loop_stream')),
+	'$set_current_loop_stream'(_, OldStream),
 	'$set_yap_flags'(18,GenerateDebug),
 	'$comp_mode'(CompMode, OldCompMode),
 	nb_setval('$consulting',Old),
@@ -494,10 +493,10 @@ prolog_load_context(module, X) :-
 prolog_load_context(source, FileName) :-
 	nb_getval('$consulting_file',FileName).
 prolog_load_context(stream, Stream) :- 
-	'$fetch_stream_alias'(Stream,'$loop_stream').
+	'$current_loop_stream'(Stream).
 % return this term for SWI compatibility.
 prolog_load_context(term_position, '$stream_position'(0,Line,0,0,0)) :- 
-	'$fetch_stream_alias'(Stream,'$loop_stream'), !,
+	'$current_loop_stream'(Stream),
 	stream_property(Stream, position(Position)),
 	stream_position_data(line_count, Position, Line).
 
@@ -660,7 +659,7 @@ remove_from_path(New) :- '$check_path'(New,Path),
 	'$do_error'(instantiation_error, encoding(V)).
 '$set_encoding'(EncAtom) :-
 	'$valid_encoding'(EncAtom, Enc), !,
-	'$fetch_stream_alias'(Stream,'$loop_stream'),
+	'$current_loop_stream'(Stream),
 	'$encoding'(Stream, Enc).
 '$set_encoding'(EncAtom) :-
 	atom(EncAtom), !,
@@ -1067,3 +1066,19 @@ make.
 	assert_static(Clause).
 
 
+'$set_current_loop_stream'(OldStream, Stream) :-
+	'$current_loop_stream'(OldStream), !,
+	'$new_loop_stream'(Stream).
+'$set_current_loop_stream'(OldStream, Stream) :-
+	'$new_loop_stream'(Stream).
+
+'$new_loop_stream'(Stream) :-
+	(var(Stream) ->
+	    nb_delete('$loop_stream')
+	;
+	    nb_setval('$loop_stream',Stream)
+	).
+	    
+'$current_loop_stream'(Stream) :-
+	catch(nb_getval('$loop_stream',Stream), _, fail).
+