% generates a .dot file for graphviz to create a graph

dotgen(Str,Edge):- dotgen_head(Str), dotgen_body(Str,Edge), dotgen_foot(Str).

dotgen_head(Str) :-
        write(Str,'digraph G {\n'),
        write(Str,' rankdir=LR\n'),
        write(Str,' node [shape=box]\n').
dotgen_foot(Str):-
        write(Str,'}').

dotgen_body(Str,Edge) :- 
	Edge = EdgePredicateName / EdgeNumberOfArgs,
	functor(EdgePredicate,EdgePredicateName,EdgeNumberOfArgs),
	EdgePredicate,
	EdgePredicate =.. [_,FromNode, ToNode|_],

	write(Str,'"'), 
	write(Str,FromNode),
	write(Str,'"'), 
	write(Str,' -> '), 
	write(Str,'"'),
	write(Str,ToNode),
	write(Str,'"\n'),	
	fail.
dotgen_body(Str,_).