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 - 1) / pageSize;
            PageIndex = pageIndex;
            PageSize = pageSize;
            HasPrev = pageIndex > 1;
            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 - 1) * 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 - 1) * pageSize).Take(pageSize).Select(selector);
            return new PaginatedList<TResult>(items, count, pageIndex, pageSize);
        }
    }
}