From 5278affb0ee912188fbf7868550885e450a45289 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADtor=20Santos=20Costa?= <vsc@dcc.fc.up.pt>
Date: Thu, 5 Nov 2015 17:14:31 +0000
Subject: [PATCH] Edinburgh IO, still useful.

---
 os/edio.yap | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 pl/init.yap |  1 +
 2 files changed, 54 insertions(+)
 create mode 100644 os/edio.yap

diff --git a/os/edio.yap b/os/edio.yap
new file mode 100644
index 000000000..83bc62c2a
--- /dev/null
+++ b/os/edio.yap
@@ -0,0 +1,53 @@
+%
+% 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).
+
diff --git a/pl/init.yap b/pl/init.yap
index edb480a58..12977dbbf 100644
--- a/pl/init.yap
+++ b/pl/init.yap
@@ -250,6 +250,7 @@ rules.
 :- use_module('../swi/library/menu.pl').
 :- use_module('../library/ypp.yap').
 :- use_module('../os/chartypes.yap').
+:- ensure_loaded('../os/edio.yap').
 
 yap_hacks:cut_by(CP) :- '$$cut_by'(CP).