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yap-6.3/os/edio.yap
2015-11-05 17:14:31 +00:00

54 lines
1.3 KiB
Prolog

%
% Edinburgh IO.
%
see(user) :- !, set_input(user_input).
see(F) :- var(F), !,
'$do_error'(instantiation_error,see(F)).
see(F) :- current_input(Stream),
'$user_file_name'(Stream,F).
see(F) :- current_stream(_,read,Stream), '$user_file_name'(Stream,F), !,
set_input(Stream).
see(Stream) :- '$stream'(Stream), current_stream(_,read,Stream), !,
set_input(Stream).
see(F) :- open(F,read,Stream), set_input(Stream).
seeing(File) :- current_input(Stream),
stream_property(Stream,file_name(NFile)),
(
stream_property(user_input,file_name(NFile))
->
File = user
;
NFile = File
).
seen :- current_input(Stream), close(Stream), set_input(user).
tell(user) :- !, set_output(user_output).
tell(F) :- var(F), !,
'$do_error'(instantiation_error,tell(F)).
tell(F) :-
current_output(Stream),
stream_property(Stream,file_name(F)),
!.
tell(F) :- current_stream(_,write,Stream), '$user_file_name'(Stream, F), !,
set_output(Stream).
tell(Stream) :-
'$stream'(Stream),
current_stream(_,write,Stream), !,
set_output(Stream).
tell(F) :-
open(F,write,Stream),
set_output(Stream).
telling(File) :-
current_output(Stream),
stream_property(Stream,file_name(NFile)),
( stream_property(user_output,file_name(NFile)) -> File = user ; File = NFile ).
told :- current_output(Stream),
set_output(user),
close(Stream).