c# 分页 PaginatedList<TResult>

 using System;
 using System.Collections.Generic;
 using System.Linq;

 namespace Microestc.PaginatedList
 {
     public class PaginatedList<TResult> : List<TResult>
     {
         public PaginatedList() : base() { }

         public PaginatedList(IEnumerable<TResult> items, int totalCount, int pageIndex, int pageSize) : base(items)
         {
             TotalCount = totalCount;
             PageCount = (totalCount + pageSize - ) / pageSize;
             PageIndex = pageIndex;
             PageSize = pageSize;
             HasPrev = pageIndex > ;
             HasNext = pageIndex < PageCount;
         }

         public virtual int TotalCount { get; private set; }

         public virtual int PageCount { get; private set; }

         public virtual int PageIndex { get; private set; }

         public virtual int PageSize { get; private set; }

         public virtual bool HasPrev { get; private set; }

         public virtual bool HasNext { get; private set; }
     }

     public static class PaginatedListExtensions
     {
         public static PaginatedList<TResult> PaginatedList<TResult>(this IEnumerable<TResult> source, int pageIndex, int pageSize)
         {
             var count = source.Count();
             var items = source.Skip((pageIndex - ) * pageSize).Take(pageSize);
             return new PaginatedList<TResult>(items, count, pageIndex, pageSize);
         }

         public static PaginatedList<TResult> PaginatedList<TSource, TResult>(this IEnumerable<TSource> source, Func<TSource, TResult> selector, int pageIndex, int pageSize)
         {
             var count = source.Count();
             var items = source.Skip((pageIndex - ) * pageSize).Take(pageSize).Select(selector);
             return new PaginatedList<TResult>(items, count, pageIndex, pageSize);
         }
     }
 }