protected override Expression VisitUnknown(Expression E)
{
Expression LE = Call.L(E, t, s);
// Try applying a rule to E.
Expression TLE = rules.Transform(LE);
if (!ReferenceEquals(TLE, LE))
{
return(TLE);
}
// Try expanding E.
Expression Ex = E.Expand(s);
if (!Equals(E, Ex))
{
return(Visit(Ex));
}
// Try -L(-E, s, t)
// TODO: It would be nice to handle this case in LinearTransform somehow.
Expression NE = Unary.Negate(E);
Expression NEx = NE.Evaluate();
if (!Equals(NE, NEx))
{
return(Unary.Negate(Visit(NEx)));
}
// Give up.
return(LE);
}
public void Simplify_NegativeNegations_success()
{
SillyParser p = new SillyParser(null);
Unary node = (Unary)p.m("-", p.m("a"));
Unary neg = (Unary)node.Negate();
Leaf negSimp = (Leaf)neg.Simplify();
Assert.AreEqual("--a", neg.Unparse());
Assert.AreEqual("a", negSimp.Unparse());
p.SetVar("a", 2);
Assert.AreEqual(-2, node.Eval());
Assert.AreEqual(2, neg.Eval());
Assert.AreEqual(2, negSimp.Eval());
}
public static LazyExpression operator -(LazyExpression L, LazyExpression R)
{
return(new LazyExpression(Sum.New(L.value, Unary.Negate(R.value))));
}