//******************************************************************************************************//  PagedList.cs - Gbtc////  Copyright © 2016, Grid Protection Alliance.  All Rights Reserved.////  Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See//  the NOTICE file distributed with this work for additional information regarding copyright ownership.//  The GPA licenses this file to you under the MIT License (MIT), the "License"; you may not use this//  file except in compliance with the License. You may obtain a copy of the License at:////      http://opensource.org/licenses/MIT////  Unless agreed to in writing, the subject software distributed under the License is distributed on an//  "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the//  License for the specific language governing permissions and limitations.////  Code Modification History://  ----------------------------------------------------------------------------------------------------//  02/17/2016 - J. Ritchie Carroll//       Generated original version of source code.////****************************************************************************************************** using System.Collections.Generic;using System.Linq; // ReSharper disable PossibleMultipleEnumerationnamespace GSF.Collections{    /// <summary>    /// Defines a paged list for an enumeration.    /// </summary>    /// <typeparam name="T">Type of <see cref="IEnumerable{T}"/> to paginate.</typeparam>    /// <remarks>    /// This class returns the elements for the specified page number for a given page size and    /// also provides the calculated page count based on input parameters.    /// </remarks>    public class PagedList<T> : List<T>, IPagedList    {        #region [ Constructors ]         /// <summary>        /// Creates a new <see cref="PagedList{T}"/>.        /// </summary>        /// <param name="source">Source enumeration to paginate.</param>        /// <param name="page">Page number (1-based).</param>        /// <param name="pageSize">Page size.</param>        /// <param name="count">Total records in source if known.</param>        /// <remarks>        /// If count is known or can be calculated early, specify the value in the        /// <paramref name="count"/> parameter as an optimization to prevent a full        /// enumeration on <paramref name="source"/> to get a count.        /// </remarks>        public PagedList(IEnumerable<T> source, int page, int pageSize, int count = -1)        {            // For many enumeration sources, Count() will map to Length or Count            TotalCount = count > -1 ? count : source.Count();             PageCount = CalculatePageCount(pageSize, TotalCount);            Page = page < 1 ? 0 : page - 1;            PageSize = pageSize;             AddRange(source.Skip(Page * PageSize).Take(PageSize));        }         #endregion         #region [ Properties ]         /// <summary>        /// Gets total count of elements in enumeration.        /// </summary>        public int TotalCount        {            get;        }         /// <summary>        /// Gets calculated page count based on page size and total items count.        /// </summary>        public int PageCount        {            get;        }         /// <summary>        /// Gets current page number.        /// </summary>        public int Page        {            get;        }         /// <summary>        /// Gets current page size.        /// </summary>        public int PageSize        {            get;        }         #endregion         #region [ Methods ]         // Calculate page count based on page size and total item count        private int CalculatePageCount(int pageSize, int totalCount)        {            if (pageSize == 0)                return 0;             int remainder = totalCount % pageSize;            return (totalCount / pageSize) + (remainder == 0 ? 0 : 1);        }         #endregion    }}