/**
* Helper method that returns the constraint that the sig has exactly "n" elements, or at most "n"
* elements
*/
private Formula size(Sig sig, int n, boolean exact) {
Expression a = sol.a2k(sig);
if (n <= 0) return a.no();
if (n == 1) return exact ? a.one() : a.lone();
Formula f = exact ? Formula.TRUE : null;
Decls d = null;
Expression sum = null;
while (n > 0) {
n--;
Variable v = Variable.unary("");
kodkod.ast.Decl dd = v.oneOf(a);
if (d == null) d = dd;
else d = dd.and(d);
if (sum == null) sum = v;
else {
if (f != null) f = v.intersection(sum).no().and(f);
sum = v.union(sum);
}
}
if (f != null) return sum.eq(a).and(f).forSome(d);
else return a.no().or(sum.eq(a).forSome(d));
}
