public static void EmitCast(this ILGenerator g, Type from, Type to)
{
if (from == to)
{
return;
}
if (to == typeof(object))
{
g.EmitBox(from);
}
else if (from == typeof(object))
{
g.EmitUnBoxAnyOrCastClass(to);
}
else
{
var method = MethodInfoEx.FindCastOperator(from, to);
if (method != null)
{
g.EmitMethodCall(method);
}
else if (!to.IsAssignableFrom(from))
{
g.Emit(OpCodes.Castclass, to);
}
}
}
public void FindCastWorks()
{
var t1 = typeof(Cast1);
var t2 = typeof(Cast2);
Assert.Equal(typeof(int), MethodInfoEx.FindCastOperator(t1, typeof(int)).ReturnType);
Assert.Equal(typeof(double), MethodInfoEx.FindCastOperator(t1, typeof(double)).ReturnType);
Assert.Null(MethodInfoEx.FindCastToOperator(t1, typeof(string)));
Assert.Null(MethodInfoEx.FindCastToOperator(t1, typeof(decimal)));
Assert.Equal(typeof(int), MethodInfoEx.FindCastOperator(typeof(int), t2).GetParameterTypes()[0]);
Assert.Equal(typeof(double), MethodInfoEx.FindCastOperator(typeof(double), t2).GetParameterTypes()[0]);
Assert.Equal(t2, MethodInfoEx.FindCastOperator(t2, t1).GetParameterTypes()[0]);
Assert.Null(MethodInfoEx.FindCastOperator(typeof(string), t2));
Assert.Null(MethodInfoEx.FindCastOperator(typeof(decimal), t2));
Assert.Throws <AmbiguousMatchException>(() => MethodInfoEx.FindCastOperator(t1, t2));
}
