source: branches/RemoveBackwardsCompatibility/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory-5.5.0/Utils/KeyComparer.cs @ 17912

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// 
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// to whom the Software is furnished to do so, subject to the following conditions:
// 
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// substantial portions of the Software.
// 
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using System;
using System.Collections.Generic;

namespace ICSharpCode.NRefactory.Utils
{
  public static class KeyComparer
  {
    public static KeyComparer<TElement, TKey> Create<TElement, TKey>(Func<TElement, TKey> keySelector)
    {
      return new KeyComparer<TElement, TKey>(keySelector, Comparer<TKey>.Default, EqualityComparer<TKey>.Default);
    }
    
    public static KeyComparer<TElement, TKey> Create<TElement, TKey>(Func<TElement, TKey> keySelector, IComparer<TKey> comparer, IEqualityComparer<TKey> equalityComparer)
    {
      return new KeyComparer<TElement, TKey>(keySelector, comparer, equalityComparer);
    }
    
    public static IComparer<TElement> Create<TElement, TKey>(Func<TElement, TKey> keySelector, IComparer<TKey> comparer)
    {
      return new KeyComparer<TElement, TKey>(keySelector, comparer, EqualityComparer<TKey>.Default);
    }
    
    public static IEqualityComparer<TElement> Create<TElement, TKey>(Func<TElement, TKey> keySelector, IEqualityComparer<TKey> equalityComparer)
    {
      return new KeyComparer<TElement, TKey>(keySelector, Comparer<TKey>.Default, equalityComparer);
    }
  }
  
  public class KeyComparer<TElement, TKey> : IComparer<TElement>, IEqualityComparer<TElement>
  {
    readonly Func<TElement, TKey> keySelector;
    readonly IComparer<TKey> keyComparer;
    readonly IEqualityComparer<TKey> keyEqualityComparer;
    
    public KeyComparer(Func<TElement, TKey> keySelector, IComparer<TKey> keyComparer, IEqualityComparer<TKey> keyEqualityComparer)
    {
      if (keySelector == null)
        throw new ArgumentNullException("keySelector");
      if (keyComparer == null)
        throw new ArgumentNullException("keyComparer");
      if (keyEqualityComparer == null)
        throw new ArgumentNullException("keyEqualityComparer");
      this.keySelector = keySelector;
      this.keyComparer = keyComparer;
      this.keyEqualityComparer = keyEqualityComparer;
    }
    
    public int Compare(TElement x, TElement y)
    {
      return keyComparer.Compare(keySelector(x), keySelector(y));
    }
    
    public bool Equals(TElement x, TElement y)
    {
      return keyEqualityComparer.Equals(keySelector(x), keySelector(y));
    }
    
    public int GetHashCode(TElement obj)
    {
      return keyEqualityComparer.GetHashCode(keySelector(obj));
    }
  }
}