OrderedEnumerableRowCollection.cs :  » 2.6.4-mono-.net-core » System.Data » System » Data » C# / CSharp Open Source

//
// OrderedEnumerableRowCollection.cs
//
// Author:
//   Atsushi Enomoto  <atsushi@ximian.com>
//
// Copyright (C) 2008 Novell, Inc. http://www.novell.com
//

//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

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

namespace System.Data{
  public sealed class OrderedEnumerableRowCollection<TRow>
    : EnumerableRowCollection<TRow>
  {
    internal static OrderedEnumerableRowCollection<TRow> Create<TRow, TKey> (IEnumerable<TRow> source, Func<TRow, TKey> keySelector, IComparer<TKey> comparer, bool descending)
    {
      var sorter = new SortComparer<TRow> ();
      sorter.AddSort<TKey> (keySelector, comparer, descending);
      return new OrderedEnumerableRowCollection<TRow> (new SortedEnumerable <TRow> (source, sorter));
    }

    internal static OrderedEnumerableRowCollection<TRow> AddSort<TRow, TKey> (OrderedEnumerableRowCollection<TRow> source, Func<TRow, TKey> keySelector, IComparer<TKey> comparer, bool descending)
    {
      source.source.Sorter.AddSort<TKey> (keySelector, comparer, descending);
      return source;
    }

    OrderedEnumerableRowCollection (SortedEnumerable<TRow> source)
      : base (source)
    {
      this.source = source;
    }

    SortedEnumerable<TRow> source;
  }

  class SortComparer<TRow> : IComparer<TRow>
  {
    public SortComparer ()
    {
    }

    new List<Comparison<TRow>> comparers = new List<Comparison<TRow>> ();

    public void AddSort (Comparison<TRow> comparer)
    {
      comparers.Add (comparer);
    }

    public void AddSort<TKey> (Func<TRow, TKey> keySelector, IComparer<TKey> comparer, bool descending)
    {
      if (keySelector == null)
        throw new ArgumentNullException ("keySelector");
      if (comparer == null)
        comparer = Comparer<TKey>.Default;
      comparers.Add (delegate (TRow r1, TRow r2) {
        int ret = comparer.Compare (keySelector (r1), keySelector (r2));
        return descending ? -ret : ret;
        });
    }

    public int Compare (TRow r1, TRow r2)
    {
      foreach (var c in comparers) {
        int ret = c (r1, r2);
        if (ret != 0)
          return ret;
      }
      return 0;
    }
  }

  class SortedEnumerable<TRow> : IEnumerable<TRow>
  {
    IEnumerable<TRow> source;
    SortComparer<TRow> sorter;

    public SortedEnumerable (IEnumerable<TRow> source, SortComparer<TRow> sorter)
    {
      this.source = source;
      this.sorter = sorter;
    }

    public SortComparer<TRow> Sorter {
      get { return sorter; }
    }

    public IEnumerator<TRow> GetEnumerator ()
    {
      var list = new List<TRow> ();
      foreach (TRow row in source)
        list.Add (row);
      list.Sort (sorter);
      for (int i = 0, c = list.Count; i < c; i++)
        yield return list [i];
    }

    IEnumerator IEnumerable.GetEnumerator ()
    {
      return GetEnumerator ();
    }
  }
}