public Func <IEnumerable <T>, IEnumerable <T> > CreateFunction <T>()
{
ParameterExpression param = Expression.Parameter(typeof(IEnumerable <T>), "arg");
IEnumerable <OrderByItem> items = OrderByItems; // this does a recursive search - cache it since we are using it twice
OrderByItem first = items.First();
Debug.Assert(first != null);
MethodCallExpression call = first.CreateExpression(param, typeof(T));
foreach (OrderByItem orderby in items.Except(new OrderByItem[] { first }))
{
call = orderby.CreateThenByExpression(call, typeof(T));
}
return(Expression.Lambda <Func <IEnumerable <T>, IEnumerable <T> > >(call, param).Compile());
}
public Func <IEnumerable <T>, IEnumerable <T> > CreateEvaluator <T>()
{
ParameterExpression param = Expression.Parameter(typeof(IEnumerable <T>), "arg");
IEnumerable <OrderByItem> items = OrderByItems; // this does a recursive search - cache it since we are using it twice
OrderByItem first = items.First();
Debug.Assert(first != null);
// since ordering after the first uses the ThenBy* methods first create the OrderBy call
// and then all of the subsequent ThenBy valls
MethodCallExpression call = first.CreateExpression(param, typeof(T));
foreach (OrderByItem orderby in items.Skip(1)) // skip the first one because that was used above
{
call = orderby.CreateThenByExpression(call, typeof(T));
}
return(Expression.Lambda <Func <IEnumerable <T>, IEnumerable <T> > >(call, param).Compile());
}
