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

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

namespace System.Windows.Data{

  class PropertyComparer : IComparer, IComparer <object> {

    List<ListSortDirection> Directions {
      get; set;
    }

    List <PropertyPathWalker> Walkers {
      get; set;
    }

    public PropertyComparer (SortDescriptionCollection sortDescriptions)
    {
      Directions = new List <ListSortDirection> ();
      Walkers = new List <PropertyPathWalker> ();

      foreach (var sorter in sortDescriptions) {
        Directions.Add (sorter.Direction);
        if (string.IsNullOrEmpty (sorter.PropertyName))
          Walkers.Add (null);
        else
          Walkers.Add (new PropertyPathWalker (sorter.PropertyName));
      }
    }

    public int Compare (object x, object y)
    {
      object left = null;
      object right = null;

      for (int i = 0; i < Directions.Count; i++) {
        var walker = Walkers [i];
        if (walker == null) {
          left = x;
          right = y;
        } else {
          walker.Update (x);
          left = walker.Value;
  
          walker.Update (y);
          right = walker.Value;

          walker.Update (null);
        }

        int result = Comparer.Default.Compare (left, right);
        if (result != 0)
          return Directions [i] == ListSortDirection.Ascending ? result : -result;
      }

      return 0;
    }
  }
}