protected override Completion ExecuteImpl(ExecutionEnvironment enviroment)
{
if (String == null)
{
return(Completion.Exception(Language.NullException, this));
}
var c = String.Execute(enviroment);
if (!c.IsValue)
{
return(c);
}
if (!(c.ReturnValue is string))
{
return(Completion.Exception(Language.NotStringException, String));
}
if (SubString == null)
{
return(Completion.Exception(Language.NotStringException, this));
}
var f = SubString.Execute(enviroment);
if (!f.IsValue)
{
return(f);
}
if (!(f.ReturnValue is string))
{
return(Completion.Exception(Language.NotStringException, SubString));
}
return(new Completion((c.ReturnValue as string).LastIndexOf(f.ReturnValue as string)));
}