source: branches/2994-AutoDiffForIntervals/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory-5.5.0/Utils/MultiDictionary.cs

// Copyright (c) 2010-2013 AlphaSierraPapa for the SharpDevelop Team
// 
// 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
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// DEALINGS IN THE SOFTWARE.

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

namespace ICSharpCode.NRefactory.Utils
{
  /// <summary>
  /// A dictionary that allows multiple pairs with the same key.
  /// </summary>
  public class MultiDictionary<TKey, TValue> : ILookup<TKey, TValue>
  {
    readonly Dictionary<TKey, List<TValue>> dict;
    
    public MultiDictionary()
    {
      dict = new Dictionary<TKey, List<TValue>>();
    }
    
    public MultiDictionary(IEqualityComparer<TKey> comparer)
    {
      dict = new Dictionary<TKey, List<TValue>>(comparer);
    }
    
    public void Add(TKey key, TValue value)
    {
      List<TValue> valueList;
      if (!dict.TryGetValue(key, out valueList)) {
        valueList = new List<TValue>();
        dict.Add(key, valueList);
      }
      valueList.Add(value);
    }

    public bool Remove(TKey key, TValue value)
    {
      List<TValue> valueList;
      if (dict.TryGetValue(key, out valueList)) {
        if (valueList.Remove(value)) {
          if (valueList.Count == 0)
            dict.Remove(key);
          return true;
        }
      }
      return false;
    }
    
    /// <summary>
    /// Removes all entries with the specified key.
    /// </summary>
    /// <returns>Returns true if at least one entry was removed.</returns>
    public bool RemoveAll(TKey key)
    {
      return dict.Remove(key);
    }
    
    public void Clear()
    {
      dict.Clear();
    }
    
    #if NET_4_5
    public IReadOnlyList<TValue> this[TKey key] {
    #else
    public IList<TValue> this[TKey key] {
    #endif
      get {
        List<TValue> list;
        if (dict.TryGetValue(key, out list))
          return list;
        else
          return EmptyList<TValue>.Instance;
      }
    }
    
    /// <summary>
    /// Returns the number of different keys.
    /// </summary>
    public int Count {
      get { return dict.Count; }
    }
    
    public ICollection<TKey> Keys {
      get { return dict.Keys; }
    }
    
    public IEnumerable<TValue> Values {
      get { return dict.Values.SelectMany(list => list); }
    }
    
    IEnumerable<TValue> ILookup<TKey, TValue>.this[TKey key] {
      get { return this[key]; }
    }
    
    bool ILookup<TKey, TValue>.Contains(TKey key)
    {
      return dict.ContainsKey(key);
    }
    
    public IEnumerator<IGrouping<TKey, TValue>> GetEnumerator()
    {
      foreach (var pair in dict)
        yield return new Grouping(pair.Key, pair.Value);
    }
    
    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
    {
      return GetEnumerator();
    }
    
    sealed class Grouping : IGrouping<TKey, TValue>
    {
      readonly TKey key;
      readonly List<TValue> values;
      
      public Grouping(TKey key, List<TValue> values)
      {
        this.key = key;
        this.values = values;
      }
      
      public TKey Key {
        get { return key; }
      }
      
      public IEnumerator<TValue> GetEnumerator()
      {
        return values.GetEnumerator();
      }
      
      System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
      {
        return values.GetEnumerator();
      }
    }
  }
}