Varnumbers predicate (originally in QP)

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1741 b08c6af1-5177-4d33-ba66-4b1c6b8b522a

library/varnumbers.yap

@@ -0,0 +1,60 @@
+%   File   : varnumbers.yap
+%   Author : Vitor Santos Costa
+%   Updated: 2006
+%   Purpose: opposite to numbervars
+
+:- module(varnumbers, [
+		  numbervars/1,
+		  max_var_number/3,
+		  varnumbers/2
+              ]).
+
+
+numbervars(Term) :-
+	numbervars(Term, 0, _).
+
+max_var_number(V,Max,Max) :- var(V), !.
+max_var_number('$VAR'(I),Max0,Max) :- !,
+	Max is max(I,Max0).
+max_var_number(S,Max0,Max) :-
+	functor(S,_,Ar),
+	max_var_numberl(0,Ar,S,Max0,Max).
+
+max_var_numberl(I0,Ar,T,Max0,Max) :-
+	( I0 =:= Ar ->
+	    Max0 = Max
+	;
+	    I is I0+1,
+	    arg(I,T,A),
+	    max_var_number(A,Max0,MaxI),
+	    max_var_numberl(I,Ar,T,MaxI,Max)
+	).
+
+varnumbers(GT, VT) :-
+	max_var_number(GT,0,Max),
+	Max1 is Max+1,
+	functor(Vars,vars,Max1),
+	varnumbers(GT, Vars, VT).
+
+varnumbers(V,_,V) :- var(V), !.
+varnumbers('$VAR'(I),Vs,V) :- !,
+	I1 is I+1,
+	arg(I1,Vs,V).
+varnumbers(S,Vs,NS) :-
+	functor(S,N,Ar),
+	functor(NS,N,Ar),
+	varnumbersl(0,Ar,Vs,S,NS).
+
+varnumbersl(I0,Ar,Vs,S,NS) :-
+	(I0 =:= Ar ->
+	    true
+	;
+	    I is I0+1,
+	    arg(I,S,A),
+	    arg(I,NS,NA),
+	    varnumbers(A,Vs,NA),
+	    varnumbersl(I,Ar,Vs,S,NS)
+	).
+
+
+