%------------------------------------------------------
:- [sets, correct].
%------------------------------------------------------

/* Fact set for a program that insert an element into
   a list via destructive updating */

/* The control-flow graph and its edge functions */
/************** Search loop *********************/
assign_var_to_var(start, n1, y, x).
identity(n1, n4).
assign_nil_to_var(n1, p2, t1).
assign_sel_to_var(p2, n2, t1, y, cdr).
assign_nil_to_var(n2, p3, y).
assign_var_to_var(p3, n3, y, t1).
identity(n3, n1).
/************** End Search loop ****************/
assign_new_to_var(n4, n5, t).
assign_nil_to_var(n5, p6, t2).
assign_sel_to_var(p6, n6, t2, y, cdr).
assign_nil_to_sel(n6, p7, t, cdr).
assign_var_to_sel(p7, n7, t, cdr, t2).
assign_nil_to_sel(n7, p8, y, cdr).
assign_var_to_sel(p8, n8, y, cdr, t).
/**************  Clean Temporaries *************/
assign_nil_to_var(n8, n9, t2).
assign_nil_to_var(n9, n10, t1).
assign_nil_to_var(n10, n11, t).
assign_nil_to_var(n11, n12, y).

/* Initial sg: x points to a list */
init_var_edge(start, x, [x]).
init_sel_edge(start, [x], cdr, []).
init_sel_edge(start, [], cdr, []).

init_is_shared(_,_) :- fail.


/* ------------------------- Queries ------------------------------------ */

var_edge_query(Var) :-
	var_edge(Var, Z, NX),
	write(var_edge(Var, Z, NX)), nl,
	fail; true.

sel_edge_query(Var) :-
	sel_edge(Var, NX1, Sel, NX2),
	write(sel_edge(Var, NX1, Sel, NX2)), nl,
	fail; true.

is_shared_query(Var) :-
	is_shared(Var, NX),
	write(is_shared(Var, NX)), nl,
	fail; true.

list_of_all_vars([n1, n2, n3, n4, n5, n6, n7, n8, n9, n10, n11, n12]).

print_one_var(Var) :-
	write('--- '),
	write(Var),
	write(' ---------------------------------------------'), nl,
	var_edge_query(Var),
	sel_edge_query(Var),
	is_shared_query(Var).

print_all_vars([]).
print_all_vars([Var|Vars]) :-
	print_one_var(Var),
	print_all_vars(Vars).

test :-	list_of_all_vars(Vars), print_all_vars(Vars).