From a08939e91466615557729d04d5889aa46780010d Mon Sep 17 00:00:00 2001
From: Markus Ewald <cygon@nuclex.org>
Date: Mon, 4 Jul 2011 22:21:57 +0000
Subject: [PATCH] Added INotifyCollectionChanged interface to
 ObservableCollection and ObservableDictionary; added a new dictionary type,
 the MultiDictionary which is equivalent to the C++ multimap<> class

git-svn-id: file:///srv/devel/repo-conversion/nusu@215 d2e56fa2-650e-0410-a79f-9358c0239efd
---
 Nuclex.Support (net-4.0).csproj               |  14 +
 Nuclex.Support (xna-4.0-phone7).csproj        |  13 +-
 Nuclex.Support (xna-4.0-xbox360).csproj       |  13 +-
 Source/Collections/IMultiDictionary.cs        |  68 +++
 .../Collections/MultiDictionary.Interfaces.cs | 248 ++++++++++
 Source/Collections/MultiDictionary.Test.cs    | 146 ++++++
 .../MultiDictionary.ValueCollection.cs        | 269 +++++++++++
 Source/Collections/MultiDictionary.cs         | 436 ++++++++++++++++++
 Source/Collections/ObservableCollection.cs    |  80 +++-
 Source/Collections/ObservableDictionary.cs    | 133 ++++--
 10 files changed, 1350 insertions(+), 70 deletions(-)
 create mode 100644 Source/Collections/IMultiDictionary.cs
 create mode 100644 Source/Collections/MultiDictionary.Interfaces.cs
 create mode 100644 Source/Collections/MultiDictionary.Test.cs
 create mode 100644 Source/Collections/MultiDictionary.ValueCollection.cs
 create mode 100644 Source/Collections/MultiDictionary.cs

diff --git a/Nuclex.Support (net-4.0).csproj b/Nuclex.Support (net-4.0).csproj
index e2b6e6f..292ab3f 100644
--- a/Nuclex.Support (net-4.0).csproj	
+++ b/Nuclex.Support (net-4.0).csproj	
@@ -76,12 +76,23 @@
     <Compile Include="Source\Collections\Deque.Test.cs">
       <DependentUpon>Deque.cs</DependentUpon>
     </Compile>
+    <Compile Include="Source\Collections\IMultiDictionary.cs" />
     <Compile Include="Source\Collections\IObservableCollection.cs" />
     <Compile Include="Source\Collections\IRecyclable.cs" />
     <Compile Include="Source\Collections\ItemEventArgs.cs" />
     <Compile Include="Source\Collections\ItemEventArgs.Test.cs">
       <DependentUpon>ItemEventArgs.cs</DependentUpon>
     </Compile>
+    <Compile Include="Source\Collections\MultiDictionary.cs" />
+    <Compile Include="Source\Collections\MultiDictionary.ValueCollection.cs">
+      <DependentUpon>MultiDictionary.cs</DependentUpon>
+    </Compile>
+    <Compile Include="Source\Collections\MultiDictionary.Interfaces.cs">
+      <DependentUpon>MultiDictionary.cs</DependentUpon>
+    </Compile>
+    <Compile Include="Source\Collections\MultiDictionary.Test.cs">
+      <DependentUpon>MultiDictionary.cs</DependentUpon>
+    </Compile>
     <Compile Include="Source\Collections\ObservableCollection.cs" />
     <Compile Include="Source\Collections\ObservableCollection.Test.cs">
       <DependentUpon>ObservableCollection.cs</DependentUpon>
@@ -377,6 +388,9 @@
       <Link>Foundation.snk</Link>
     </None>
   </ItemGroup>
+  <ItemGroup>
+    <Folder Include="Source\Cloning\" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
diff --git a/Nuclex.Support (xna-4.0-phone7).csproj b/Nuclex.Support (xna-4.0-phone7).csproj
index 9d0cbba..d7da6ed 100644
--- a/Nuclex.Support (xna-4.0-phone7).csproj	
+++ b/Nuclex.Support (xna-4.0-phone7).csproj	
@@ -22,7 +22,7 @@
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
     <OutputPath>bin\xna-4.0-phone7\Debug\</OutputPath>
-    <DefineConstants>TRACE;DEBUG;WINDOWS_PHONE;NO_CLONING;NO_SERIALIZATION;NO_XMLSCHEMA;NO_SYSTEMEVENTS;NO_EXITCONTEXT</DefineConstants>
+    <DefineConstants>TRACE;DEBUG;WINDOWS_PHONE;NO_CLONING;NO_SERIALIZATION;NO_XMLSCHEMA;NO_SYSTEMEVENTS;NO_EXITCONTEXT;NO_SPECIALIZED_COLLECTIONS</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
     <NoStdLib>true</NoStdLib>
@@ -107,12 +107,23 @@
     <Compile Include="Source\Collections\Deque.Test.cs">
       <DependentUpon>Deque.cs</DependentUpon>
     </Compile>
+    <Compile Include="Source\Collections\IMultiDictionary.cs" />
     <Compile Include="Source\Collections\IObservableCollection.cs" />
     <Compile Include="Source\Collections\IRecyclable.cs" />
     <Compile Include="Source\Collections\ItemEventArgs.cs" />
     <Compile Include="Source\Collections\ItemEventArgs.Test.cs">
       <DependentUpon>ItemEventArgs.cs</DependentUpon>
     </Compile>
+    <Compile Include="Source\Collections\MultiDictionary.cs" />
+    <Compile Include="Source\Collections\MultiDictionary.ValueCollection.cs">
+      <DependentUpon>MultiDictionary.cs</DependentUpon>
+    </Compile>
+    <Compile Include="Source\Collections\MultiDictionary.Interfaces.cs">
+      <DependentUpon>MultiDictionary.cs</DependentUpon>
+    </Compile>
+    <Compile Include="Source\Collections\MultiDictionary.Test.cs">
+      <DependentUpon>MultiDictionary.cs</DependentUpon>
+    </Compile>
     <Compile Include="Source\Collections\ObservableCollection.cs" />
     <Compile Include="Source\Collections\ObservableCollection.Test.cs">
       <DependentUpon>ObservableCollection.cs</DependentUpon>
diff --git a/Nuclex.Support (xna-4.0-xbox360).csproj b/Nuclex.Support (xna-4.0-xbox360).csproj
index 6fa68c2..93a5b2f 100644
--- a/Nuclex.Support (xna-4.0-xbox360).csproj	
+++ b/Nuclex.Support (xna-4.0-xbox360).csproj	
@@ -22,7 +22,7 @@
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
     <OutputPath>bin\xna-4.0-xbox360\Debug\</OutputPath>
-    <DefineConstants>TRACE;DEBUG;XBOX;XBOX360;NO_CLONING;NO_SERIALIZATION;NO_XMLSCHEMA;NO_SYSTEMEVENTS;NO_EXITCONTEXT</DefineConstants>
+    <DefineConstants>TRACE;DEBUG;XBOX;XBOX360;NO_CLONING;NO_SERIALIZATION;NO_XMLSCHEMA;NO_SYSTEMEVENTS;NO_EXITCONTEXT;NO_SPECIALIZED_COLLECTIONS</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
     <NoStdLib>true</NoStdLib>
@@ -118,12 +118,23 @@
     <Compile Include="Source\Collections\Deque.Test.cs">
       <DependentUpon>Deque.cs</DependentUpon>
     </Compile>
+    <Compile Include="Source\Collections\IMultiDictionary.cs" />
     <Compile Include="Source\Collections\IObservableCollection.cs" />
     <Compile Include="Source\Collections\IRecyclable.cs" />
     <Compile Include="Source\Collections\ItemEventArgs.cs" />
     <Compile Include="Source\Collections\ItemEventArgs.Test.cs">
       <DependentUpon>ItemEventArgs.cs</DependentUpon>
     </Compile>
+    <Compile Include="Source\Collections\MultiDictionary.cs" />
+    <Compile Include="Source\Collections\MultiDictionary.ValueCollection.cs">
+      <DependentUpon>MultiDictionary.cs</DependentUpon>
+    </Compile>
+    <Compile Include="Source\Collections\MultiDictionary.Interfaces.cs">
+      <DependentUpon>MultiDictionary.cs</DependentUpon>
+    </Compile>
+    <Compile Include="Source\Collections\MultiDictionary.Test.cs">
+      <DependentUpon>MultiDictionary.cs</DependentUpon>
+    </Compile>
     <Compile Include="Source\Collections\ObservableCollection.cs" />
     <Compile Include="Source\Collections\ObservableCollection.Test.cs">
       <DependentUpon>ObservableCollection.cs</DependentUpon>
diff --git a/Source/Collections/IMultiDictionary.cs b/Source/Collections/IMultiDictionary.cs
new file mode 100644
index 0000000..c6b5d8c
--- /dev/null
+++ b/Source/Collections/IMultiDictionary.cs
@@ -0,0 +1,68 @@
+#region CPL License
+/*
+Nuclex Framework
+Copyright (C) 2002-2010 Nuclex Development Labs
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the IBM Common Public License as
+published by the IBM Corporation; either version 1.0 of the
+License, or (at your option) any later version.
+
+This library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+IBM Common Public License for more details.
+
+You should have received a copy of the IBM Common Public
+License along with this library
+*/
+#endregion
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace Nuclex.Support.Collections {
+
+  /// <summary>
+  ///   Associative collection that can store several values under one key and vice versa
+  /// </summary>
+  /// <typeparam name="TKey">Type of keys used within the dictionary</typeparam>
+  /// <typeparam name="TValue">Type of values stored in the dictionary</typeparam>
+  public interface IMultiDictionary<TKey, TValue> :
+    IDictionary<TKey, ICollection<TValue>>,
+    IDictionary,
+    ICollection<KeyValuePair<TKey, TValue>>,
+    IEnumerable<KeyValuePair<TKey, TValue>>,
+    IEnumerable {
+
+    /// <summary>Adds a value into the dictionary under the provided key</summary>
+    /// <param name="key">Key the value will be stored under</param>
+    /// <param name="value">Value that will be stored under the specified key</param>
+    void Add(TKey key, TValue value);
+
+    /// <summary>Determines the number of values stored under the specified key</summary>
+    /// <param name="key">Key whose values will be counted</param>
+    /// <returns>The number of values stored under the specified key</returns>
+    int CountValues(TKey key);
+
+    /// <summary>
+    ///   Removes the item with the specified key and value from the dictionary
+    /// </summary>
+    /// <param name="key">Key of the item that will be removed</param>
+    /// <param name="value">Value of the item that will be removed</param>
+    /// <returns>
+    ///   True if the specified item was contained in the dictionary and was removed
+    /// </returns>
+    /// <exception cref="NotSupportedException">If the dictionary is read-only</exception>
+    bool Remove(TKey key, TValue value);
+
+    /// <summary>Removes all items with the specified key from the dictionary</summary>
+    /// <param name="key">Key of the item that will be removed</param>
+    /// <returns>The number of items that have been removed from the dictionary</returns>
+    /// <exception cref="NotSupportedException">If the dictionary is read-only</exception>
+    int RemoveKey(TKey key);
+
+  }
+
+} // namespace Nuclex.Support.Collections
diff --git a/Source/Collections/MultiDictionary.Interfaces.cs b/Source/Collections/MultiDictionary.Interfaces.cs
new file mode 100644
index 0000000..83c37b1
--- /dev/null
+++ b/Source/Collections/MultiDictionary.Interfaces.cs
@@ -0,0 +1,248 @@
+#region CPL License
+/*
+Nuclex Framework
+Copyright (C) 2002-2010 Nuclex Development Labs
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the IBM Common Public License as
+published by the IBM Corporation; either version 1.0 of the
+License, or (at your option) any later version.
+
+This library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+IBM Common Public License for more details.
+
+You should have received a copy of the IBM Common Public
+License along with this library
+*/
+#endregion
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace Nuclex.Support.Collections {
+
+  partial class MultiDictionary<TKey, TValue> {
+
+    #region IEnumerable implementation
+
+    /// <summary>Returns a new object enumerator for the Dictionary</summary>
+    /// <returns>The new object enumerator</returns>
+    IEnumerator IEnumerable.GetEnumerator() {
+      return GetEnumerator();
+    }
+
+    #endregion
+
+    #region IDictionary implementation
+
+    /// <summary>Adds an item into the dictionary</summary>
+    /// <param name="key">Key under which the item will be added</param>
+    /// <param name="value">Item that will be added</param>
+    void IDictionary.Add(object key, object value) {
+      Add((TKey)key, (TValue)value);
+    }
+
+    /// <summary>Determines whether the specified key exists in the dictionary</summary>
+    /// <param name="key">Key that will be checked for</param>
+    /// <returns>True if an item with the specified key exists in the dictionary</returns>
+    bool IDictionary.Contains(object key) {
+      return this.objectDictionary.Contains(key);
+    }
+
+    /// <summary>Returns a new entry enumerator for the dictionary</summary>
+    /// <returns>The new entry enumerator</returns>
+    IDictionaryEnumerator IDictionary.GetEnumerator() {
+      return new Enumerator(this);
+    }
+
+    /// <summary>Whether the size of the dictionary is fixed</summary>
+    bool IDictionary.IsFixedSize {
+      get { return this.objectDictionary.IsFixedSize; }
+    }
+
+    /// <summary>Returns a collection of all keys in the dictionary</summary>
+    ICollection IDictionary.Keys {
+      get { return this.objectDictionary.Keys; }
+    }
+
+    /// <summary>Returns a collection of all values stored in the dictionary</summary>
+    ICollection IDictionary.Values {
+      get {
+        if(this.valueCollection == null) {
+          this.valueCollection = new ValueCollection(this);
+        }
+
+        return this.valueCollection;
+      }
+    }
+
+    /// <summary>Removes an item from the dictionary</summary>
+    /// <param name="key">Key of the item that will be removed</param>
+    void IDictionary.Remove(object key) {
+      RemoveKey((TKey)key);
+    }
+
+    /// <summary>Accesses an item in the dictionary by its key</summary>
+    /// <param name="key">Key of the item that will be accessed</param>
+    /// <returns>The item with the specified key</returns>
+    object IDictionary.this[object key] {
+      get { return this.objectDictionary[key]; }
+      set { this[(TKey)key] = (ICollection<TValue>)value; }
+    }
+
+    #endregion
+
+    #region ICollection<KeyValuePair<TKey, TValue>> implementation
+
+    /// <summary>Inserts an already prepared element into the dictionary</summary>
+    /// <param name="item">Prepared element that will be added to the dictionary</param>
+    void ICollection<KeyValuePair<TKey, TValue>>.Add(
+      KeyValuePair<TKey, TValue> item
+    ) {
+      Add(item.Key, item.Value);
+    }
+
+    /// <summary>Removes all items from the dictionary</summary>
+    /// <param name="itemToRemove">Item that will be removed from the dictionary</param>
+    bool ICollection<KeyValuePair<TKey, TValue>>.Remove(
+      KeyValuePair<TKey, TValue> itemToRemove
+    ) {
+      ICollection<TValue> values;
+      if(!this.typedDictionary.TryGetValue(itemToRemove.Key, out values)) {
+        return false;
+      }
+
+      if(values.Remove(itemToRemove.Value)) {
+        if(values.Count == 0) {
+          this.typedDictionary.Remove(itemToRemove.Key);
+        }
+
+        OnRemoved(itemToRemove);
+        return true;
+      } else {
+        return false;
+      }
+    }
+
+    #endregion
+
+    #region ICollection implementation
+
+    /// <summary>Copies the contents of the Dictionary into an array</summary>
+    /// <param name="array">Array the Dictionary contents will be copied into</param>
+    /// <param name="arrayIndex">
+    ///   Starting index at which to begin filling the destination array
+    /// </param>
+    void ICollection.CopyTo(Array array, int arrayIndex) {
+      foreach(KeyValuePair<TKey, ICollection<TValue>> item in this.typedDictionary) {
+        foreach(TValue value in item.Value) {
+          array.SetValue(new KeyValuePair<TKey, TValue>(item.Key, value), arrayIndex);
+          ++arrayIndex;
+        }
+      }
+    }
+
+    /// <summary>Whether the Dictionary is synchronized for multi-threaded usage</summary>
+    bool ICollection.IsSynchronized {
+      get { return this.objectDictionary.IsSynchronized; }
+    }
+
+    /// <summary>Synchronization root on which the Dictionary locks</summary>
+    object ICollection.SyncRoot {
+      get { return this.objectDictionary.SyncRoot; }
+    }
+
+    #endregion
+
+    #region IDictionary<TKey, ICollection<TValue>> implementation
+
+    /// <summary>Adds a series of values to a dictionary</summary>
+    /// <param name="key">Key under which the values will be added</param>
+    /// <param name="values">Values that will be added to the dictionary</param>
+    void IDictionary<TKey, ICollection<TValue>>.Add(TKey key, ICollection<TValue> values) {
+      ICollection<TValue> currentValues;
+      if(!this.typedDictionary.TryGetValue(key, out currentValues)) {
+        currentValues = new ValueList(this);
+      }
+
+      foreach(TValue value in values) {
+        currentValues.Add(value);
+      }
+    }
+
+    /// <summary>Removes all values with the specified key</summary>
+    /// <param name="key">Key whose associated entries will be removed</param>
+    /// <returns>True if at least one entry has been removed from the dictionary</returns>
+    bool IDictionary<TKey, ICollection<TValue>>.Remove(TKey key) {
+      return (RemoveKey(key) > 0);
+    }
+
+    /// <summary>Returns a collection of value collections</summary>
+    ICollection<ICollection<TValue>> IDictionary<TKey, ICollection<TValue>>.Values {
+      get { return this.typedDictionary.Values; }
+    }
+
+    #endregion // IDictionary<TKey, ICollection<TValue>> implementation
+
+    #region ICollection<KeyValuePair<TKey, ICollection<TValue>>> implementation
+
+    /// <summary>Adds a series of values to a dictionary</summary>
+    /// <param name="item">Entry containing the values that will be added</param>
+    void ICollection<KeyValuePair<TKey, ICollection<TValue>>>.Add(
+      KeyValuePair<TKey, ICollection<TValue>> item
+    ) {
+      ICollection<TValue> currentValues;
+      if(!this.typedDictionary.TryGetValue(item.Key, out currentValues)) {
+        currentValues = new ValueList(this);
+      }
+
+      foreach(TValue value in item.Value) {
+        currentValues.Add(value);
+      }
+    }
+
+    /// <summary>
+    ///   Checks whether the dictionary contains the specified key/value pair
+    /// </summary>
+    /// <param name="item">Key/value pair for which the dictionary will be checked</param>
+    /// <returns>True if the dictionary contains the specified key/value pair</returns>
+    bool ICollection<KeyValuePair<TKey, ICollection<TValue>>>.Contains(
+      KeyValuePair<TKey, ICollection<TValue>> item
+    ) {
+      return this.typedDictionary.Contains(item);
+    }
+
+    /// <summary>Copies the contents of the dictionary into an array</summary>
+    /// <param name="array"></param>
+    /// <param name="arrayIndex"></param>
+    void ICollection<KeyValuePair<TKey, ICollection<TValue>>>.CopyTo(
+      KeyValuePair<TKey, ICollection<TValue>>[] array, int arrayIndex
+    ) {
+      this.typedDictionary.CopyTo(array, arrayIndex);
+    }
+
+    /// <summary>Removes the specified key/value pair from the dictionary</summary>
+    /// <param name="item">Key/value pair that will be removed</param>
+    /// <returns>True if the key/value pair was contained in the dictionary</returns>
+    bool ICollection<KeyValuePair<TKey, ICollection<TValue>>>.Remove(
+      KeyValuePair<TKey, ICollection<TValue>> item
+    ) {
+      return this.typedDictionary.Remove(item);
+    }
+
+    /// <summary>Returns an enumerator for the dictionary</summary>
+    /// <returns>An enumerator for the key/value pairs in the dictionary</returns>
+    IEnumerator<KeyValuePair<TKey, ICollection<TValue>>> IEnumerable<
+      KeyValuePair<TKey, ICollection<TValue>>
+    >.GetEnumerator() {
+      return this.typedDictionary.GetEnumerator();
+    }
+
+    #endregion // ICollection<KeyValuePair<TKey, ICollection<TValue>>> implementation
+
+  }
+
+} // namespace Nuclex.Support.Collections
diff --git a/Source/Collections/MultiDictionary.Test.cs b/Source/Collections/MultiDictionary.Test.cs
new file mode 100644
index 0000000..776b34a
--- /dev/null
+++ b/Source/Collections/MultiDictionary.Test.cs
@@ -0,0 +1,146 @@
+#region CPL License
+/*
+Nuclex Framework
+Copyright (C) 2002-2010 Nuclex Development Labs
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the IBM Common Public License as
+published by the IBM Corporation; either version 1.0 of the
+License, or (at your option) any later version.
+
+This library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+IBM Common Public License for more details.
+
+You should have received a copy of the IBM Common Public
+License along with this library
+*/
+#endregion
+
+using System;
+using System.Collections.Generic;
+
+#if UNITTEST
+
+using NUnit.Framework;
+using NMock;
+
+namespace Nuclex.Support.Collections {
+
+  /// <summary>Unit tests for the multi dictionary</summary>
+  [TestFixture]
+  public class MultiDictionaryTest {
+
+    /// <summary>
+    ///   Verifies that new instances of the multi dictionary can be created
+    /// </summary>
+    [Test]
+    public void CanConstructNewDictionary() {
+      var dictionary = new MultiDictionary<int, string>();
+      Assert.IsNotNull(dictionary); // nonsense, prevents compiler warning
+    }
+
+    /// <summary>
+    ///   Verifies that a new multi dictionary based on a read-only dictionary is
+    ///   also read-only
+    /// </summary>
+    [Test]
+    public void IsReadOnlyWhenBasedOnReadOnlyContainer() {
+      var readOnly = new ReadOnlyDictionary<int, ICollection<string>>(
+        new Dictionary<int, ICollection<string>>()
+      );
+      var dictionary = new MultiDictionary<int, string>(readOnly);
+
+      Assert.IsTrue(dictionary.IsReadOnly);
+    }
+
+    /// <summary>
+    ///   Ensures that the multi dictionary can contain the same key multiple times
+    ///   (or in other words, multiple values on the same key)
+    /// </summary>
+    [Test]
+    public void CanContainKeyMultipleTimes() {
+      var dictionary = new MultiDictionary<int, string>();
+      dictionary.Add(123, "one two three");
+      dictionary.Add(123, "eins zwei drei");
+
+      Assert.AreEqual(2, dictionary.Count);
+
+      CollectionAssert.AreEquivalent(
+        new KeyValuePair<int, string>[] {
+          new KeyValuePair<int, string>(123, "one two three"),
+          new KeyValuePair<int, string>(123, "eins zwei drei")
+        },
+        dictionary
+      );
+    }
+
+    /// <summary>
+    ///   Verifies that adding values through the indexer still updates the item count
+    /// </summary>
+    [Test]
+    public void AddingValuesFromIndexerUpdatesCount() {
+      var dictionary = new MultiDictionary<int, string>();
+      dictionary.Add(42, "the answer to everything");
+      dictionary[42].Add("21x2");
+
+      Assert.AreEqual(2, dictionary.Count);
+
+      CollectionAssert.AreEquivalent(
+        new KeyValuePair<int, string>[] {
+          new KeyValuePair<int, string>(42, "the answer to everything"),
+          new KeyValuePair<int, string>(42, "21x2")
+        },
+        dictionary
+      );
+    }
+
+    /// <summary>
+    ///   Tests whether the collection can count the number of values stored
+    ///   under a key
+    /// </summary>
+    [Test]
+    public void ValuesWithSameKeyCanBeCounted() {
+      var dictionary = new MultiDictionary<int, string>();
+      dictionary.Add(10, "ten");
+      dictionary.Add(20, "twenty");
+      dictionary.Add(30, "thirty");
+      dictionary.Add(10, "zehn");
+      dictionary.Add(20, "zwanzig");
+      dictionary.Add(10, "dix");
+
+      Assert.AreEqual(6, dictionary.Count);
+      Assert.AreEqual(3, dictionary.CountValues(10));
+      Assert.AreEqual(2, dictionary.CountValues(20));
+      Assert.AreEqual(1, dictionary.CountValues(30));
+    }
+
+    /// <summary>
+    ///   Ensures that its possible to remove values individually without affecting
+    ///   other values stored under the same key
+    /// </summary>
+    [Test]
+    public void ValuesCanBeRemovedIndividually() {
+      var dictionary = new MultiDictionary<int, string>();
+      dictionary.Add(10, "ten");
+      dictionary.Add(10, "zehn");
+      dictionary.Add(10, "dix");
+
+      dictionary.Remove(10, "zehn");
+
+      Assert.AreEqual(2, dictionary.Count);
+      CollectionAssert.AreEquivalent(
+        new KeyValuePair<int, string>[] {
+          new KeyValuePair<int, string>(10, "ten"),
+          new KeyValuePair<int, string>(10, "dix")
+        },
+        dictionary
+      );
+    }
+
+  }
+
+} // namespace Nuclex.Support.Collections
+
+#endif // UNITTEST
diff --git a/Source/Collections/MultiDictionary.ValueCollection.cs b/Source/Collections/MultiDictionary.ValueCollection.cs
new file mode 100644
index 0000000..3d651d8
--- /dev/null
+++ b/Source/Collections/MultiDictionary.ValueCollection.cs
@@ -0,0 +1,269 @@
+#region CPL License
+/*
+Nuclex Framework
+Copyright (C) 2002-2010 Nuclex Development Labs
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the IBM Common Public License as
+published by the IBM Corporation; either version 1.0 of the
+License, or (at your option) any later version.
+
+This library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+IBM Common Public License for more details.
+
+You should have received a copy of the IBM Common Public
+License along with this library
+*/
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Collections;
+
+namespace Nuclex.Support.Collections {
+
+  partial class MultiDictionary<TKey, TValue> {
+
+    /// <summary>
+    ///   Provides access to the values stored in a multi dictionary as a collection
+    /// </summary>
+    private class ValueCollection : ICollection<TValue>, ICollection {
+
+      #region class Enumerator
+
+      /// <summary>Enumerates the values stored in a multi dictionary</summary>
+      private class Enumerator : IEnumerator<TValue> {
+
+        /// <summary>Initializes a new enumerator</summary>
+        /// <param name="valueCollections">Value collections being enumerated</param>
+        public Enumerator(ICollection<ICollection<TValue>> valueCollections) {
+          this.valueCollections = valueCollections;
+
+          Reset();
+        }
+
+        /// <summary>Immediately releases all resources owned by the instance</summary>
+        public void Dispose() {
+          if(this.currentValue != null) {
+            this.currentValue.Dispose();
+            this.currentValue = null;
+          }
+          if(this.currentCollection != null) {
+            this.currentCollection.Dispose();
+            this.currentCollection = null;
+          }
+        }
+
+        /// <summary>The current value the enumerator is pointing at</summary>
+        public TValue Current {
+          get {
+            if(this.currentValue == null) {
+              throw new InvalidOperationException("Enumerator is not on a valid position");
+            }
+
+            return this.currentValue.Current;
+          }
+        }
+
+        /// <summary>Advances the enumerator to the next item</summary>
+        /// <returns>
+        ///   True if there was a next item, false if the enumerator reached the end
+        /// </returns>
+        public bool MoveNext() {
+          if(this.currentCollection == null) {
+            return false;
+          }
+
+          for(; ; ) {
+
+            // Try to move the enumerator in the current key's list to the next item
+            if(this.currentValue != null) {
+              if(this.currentValue.MoveNext()) {
+                return true; // We found the next item
+              } else {
+                this.currentValue.Dispose();
+              }
+            }
+
+            // Enumerator for the current key's list reached the end, go to the next key
+            if(this.currentCollection.MoveNext()) {
+              this.currentValue = this.currentCollection.Current.GetEnumerator();
+            } else {
+              this.currentValue = null; // Guaranteed to be disposed already
+              this.currentCollection.Dispose();
+              this.currentCollection = null;
+              return false;
+            }
+
+          }
+        }
+
+        /// <summary>Resets the enumerator to its initial position</summary>
+        public void Reset() {
+          if(this.currentValue != null) {
+            this.currentValue.Dispose();
+            this.currentValue = null;
+          }
+          if(this.currentCollection != null) {
+            this.currentCollection.Dispose();
+          }
+          this.currentCollection = valueCollections.GetEnumerator();
+        }
+
+        #region IEnumerator implementation
+
+        /// <summary>The current entry the enumerator is pointing at</summary>
+        object IEnumerator.Current {
+          get { return Current; }
+        }
+
+        #endregion // IEnumerator implementation
+
+        /// <summary>Value collections being enumerated</summary>
+        private ICollection<ICollection<TValue>> valueCollections;
+        /// <summary>The current value collection the enumerator is in</summary>
+        private IEnumerator<ICollection<TValue>> currentCollection;
+        /// <summary>Current value in the collection the enumerator is in</summary>
+        private IEnumerator<TValue> currentValue;
+
+      }
+
+      #endregion // class Enumerator
+
+      /// <summary>Initializes a new multi dictionary value collection</summary>
+      /// <param name="dictionary">Dictionary whose values the collection represents</param>
+      public ValueCollection(MultiDictionary<TKey, TValue> dictionary) {
+        this.dictionary = dictionary;
+        this.dictionaryAsICollection = (ICollection)dictionary;
+      }
+
+      /// <summary>Determines whether the collection contains a specific value</summary>
+      /// <param name="item">Value for which the collection will be checked</param>
+      /// <returns>True if the collection contains the specified value</returns>
+      public bool Contains(TValue item) {
+        foreach(ICollection<TValue> values in this.dictionary.Values) {
+          if(values.Contains(item)) {
+            return true;
+          }
+        }
+
+        return false;
+      }
+
+      /// <summary>Copies the contents of the collection into an array</summary>
+      /// <param name="array">Array the collection contents will be copied into</param>
+      /// <param name="arrayIndex">
+      ///   Starting index in the array where writing will begin
+      /// </param>
+      public void CopyTo(TValue[] array, int arrayIndex) {
+        foreach(ICollection<TValue> values in this.dictionary.Values) {
+          foreach(TValue value in values) {
+            array[arrayIndex] = value;
+            ++arrayIndex;
+          }
+        }
+      }
+
+      /// <summary>The number of values in the collection</summary>
+      public int Count {
+        get { return this.dictionary.count; }
+      }
+
+      /// <summary>Always true since the value collection is read-only</summary>
+      public bool IsReadOnly {
+        get { return true; }
+      }
+
+      /// <summary>Returns a new enumerator for the value collection</summary>
+      /// <returns>A new enumerator for the value collection</returns>
+      public IEnumerator<TValue> GetEnumerator() {
+        return new Enumerator(this.dictionary.typedDictionary.Values);
+      }
+
+      #region IEnumerator implementation
+
+      /// <summary>Returns a non-typesafe enumerator for the collection</summary>
+      /// <returns>The non-typesafe collection enumerator</returns>
+      IEnumerator IEnumerable.GetEnumerator() {
+        return GetEnumerator();
+      }
+
+      #endregion // IEnumerator implementation
+
+      #region ICollection<> implementation
+
+      /// <summary>Throws a NotSupportedException</summary>
+      /// <param name="item">Not used</param>
+      void ICollection<TValue>.Add(TValue item) {
+        throw new NotSupportedException(
+          "Items cannot be added to a dictionary through its values collection"
+        );
+      }
+
+      /// <summary>Throws a NotSupportedException</summary>
+      void ICollection<TValue>.Clear() {
+        throw new NotSupportedException(
+          "The values collection of a dictionary cannot be cleared"
+        );
+      }
+
+      /// <summary>Throws a NotSupportedException</summary>
+      /// <param name="item">Not used</param>
+      /// <returns>Nothing, since the method always throws an exception</returns>
+      bool ICollection<TValue>.Contains(TValue item) {
+        throw new NotImplementedException();
+      }
+
+      /// <summary>Not supported</summary>
+      /// <param name="item">Item that will not be removed</param>
+      /// <returns>Nothing because the method throws an exception</returns>
+      bool ICollection<TValue>.Remove(TValue item) {
+        throw new NotSupportedException(
+          "Items cannot be removed from a dictionary through its values collection"
+        );
+      }
+
+      #endregion ICollection<> implementation
+
+      #region ICollection implementation
+
+      /// <summary>Copies the contents of the collection into an array</summary>
+      /// <param name="array">Array the collection's contents are copied into</param>
+      /// <param name="arrayIndex">
+      ///   Starting index in the array where writing will begin
+      /// </param>
+      void ICollection.CopyTo(Array array, int arrayIndex) {
+        foreach(ICollection<TValue> values in this.dictionary.Values) {
+          foreach(TValue value in values) {
+            array.SetValue(value, arrayIndex);
+            ++arrayIndex;
+          }
+        }
+      }
+
+      /// <summary>Whether the dictionary is thread-safe</summary>
+      bool ICollection.IsSynchronized {
+        get { return this.dictionaryAsICollection.IsSynchronized; }
+      }
+
+      /// <summary>
+      ///   The synchronization root used by the dictionary for thread synchronization
+      /// </summary>
+      object ICollection.SyncRoot {
+        get { return this.dictionaryAsICollection.IsSynchronized; }
+      }
+
+      #endregion // ICollection implementation
+
+      /// <summary>Dictionary whose values the collection represents</summary>
+      private MultiDictionary<TKey, TValue> dictionary;
+      /// <summary>The dictionary under its ICollection interface</summary>
+      private ICollection dictionaryAsICollection;
+
+    }
+
+  }
+
+} // namespace Nuclex.Support.Collections
diff --git a/Source/Collections/MultiDictionary.cs b/Source/Collections/MultiDictionary.cs
new file mode 100644
index 0000000..11a5455
--- /dev/null
+++ b/Source/Collections/MultiDictionary.cs
@@ -0,0 +1,436 @@
+#region CPL License
+/*
+Nuclex Framework
+Copyright (C) 2002-2010 Nuclex Development Labs
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the IBM Common Public License as
+published by the IBM Corporation; either version 1.0 of the
+License, or (at your option) any later version.
+
+This library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+IBM Common Public License for more details.
+
+You should have received a copy of the IBM Common Public
+License along with this library
+*/
+#endregion
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+
+namespace Nuclex.Support.Collections {
+
+  /// <summary>Dictionary that can contain multiple values under the same key</summary>
+  /// <typeparam name="TKey">Type of keys used within the dictionary</typeparam>
+  /// <typeparam name="TValue">Type of values used within the dictionary</typeparam>
+  public partial class MultiDictionary<TKey, TValue> : IMultiDictionary<TKey, TValue> {
+
+    #region class Enumerator
+
+    /// <summary>Enumerates the values stored in a multi dictionary</summary>
+    private class Enumerator :
+      IEnumerator<KeyValuePair<TKey, TValue>>, IDictionaryEnumerator {
+
+      /// <summary>Initializes a new multi dictionary enumerator</summary>
+      /// <param name="dictionary">Dictionary that will be enumerated</param>
+      public Enumerator(MultiDictionary<TKey, TValue> dictionary) {
+        this.dictionary = dictionary;
+
+        Reset();
+      }
+
+      /// <summary>The current entry the enumerator is pointing at</summary>
+      public KeyValuePair<TKey, TValue> Current {
+        get {
+          if(this.currentValue == null) {
+            throw new InvalidOperationException("Enumerator is not on a valid position");
+          }
+
+          return new KeyValuePair<TKey, TValue>(
+            this.currentCollection.Current.Key, this.currentValue.Current
+          );
+        }
+      }
+
+      /// <summary>Immediately releases all resources owned by the instance</summary>
+      public void Dispose() {
+        if(this.currentValue != null) {
+          this.currentValue.Dispose();
+          this.currentValue = null;
+        }
+        if(this.currentCollection != null) {
+          this.currentCollection.Dispose();
+          this.currentCollection = null;
+        }
+      }
+
+      /// <summary>Advances the enumerator to the entry</summary>
+      /// <returns>
+      ///   True if there was a next entry, false if the end of the set has been reached
+      /// </returns>
+      public bool MoveNext() {
+        if(this.currentCollection == null) {
+          return false;
+        }
+
+        for(; ; ) {
+
+          // Try to move the enumerator in the current key's list to the next item
+          if(this.currentValue != null) {
+            if(this.currentValue.MoveNext()) {
+              return true; // We found the next item
+            } else {
+              this.currentValue.Dispose();
+            }
+          }
+
+          // Enumerator for the current key's list reached the end, go to the next key
+          if(this.currentCollection.MoveNext()) {
+            this.currentValue = this.currentCollection.Current.Value.GetEnumerator();
+          } else {
+            this.currentValue = null; // Guaranteed to be disposed already
+            this.currentCollection.Dispose();
+            this.currentCollection = null;
+            return false;
+          }
+
+        }
+      }
+
+      /// <summary>Resets the enumerator to its initial position</summary>
+      public void Reset() {
+        if(this.currentValue != null) {
+          this.currentValue.Dispose();
+          this.currentValue = null;
+        }
+        if(this.currentCollection != null) {
+          this.currentCollection.Dispose();
+        }
+        this.currentCollection = this.dictionary.GetEnumerator();
+      }
+
+      #region IEnumerator implementation
+
+      /// <summary>The item the enumerator is currently pointing at</summary>
+      object IEnumerator.Current {
+        get { return Current; }
+      }
+
+      #endregion // IEnumerator implementation
+
+      #region IDictionaryEnumerator implementation
+
+      /// <summary>The current entry the enumerator is pointing to</summary>
+      DictionaryEntry IDictionaryEnumerator.Entry {
+        get {
+          enforceEnumeratorOnValidPosition();
+
+          return new DictionaryEntry(
+            this.currentCollection.Current.Key, this.currentValue.Current
+          );
+        }
+      }
+
+      /// <summary>
+      ///   Throws an exception if the enumerator is not on a valid position
+      /// </summary>
+      private void enforceEnumeratorOnValidPosition() {
+        if(this.currentValue == null) {
+          throw new InvalidOperationException("Enumerator is not on a valid position");
+        }
+      }
+
+      /// <summary>The current dictionary key</summary>
+      object IDictionaryEnumerator.Key {
+        get {
+          enforceEnumeratorOnValidPosition();
+          return this.currentCollection.Current.Key;
+        }
+      }
+
+      /// <summary>The current dictionary value</summary>
+      object IDictionaryEnumerator.Value {
+        get {
+          enforceEnumeratorOnValidPosition();
+          return this.currentValue.Current;
+        }
+      }
+
+      #endregion // IDictionaryEnumerator implementation
+
+      /// <summary>Dictionary over whose entries the enumerator is enumerating</summary>
+      private IDictionary<TKey, ICollection<TValue>> dictionary;
+      /// <summary>Current key the enumerator is at</summary>
+      private IEnumerator<KeyValuePair<TKey, ICollection<TValue>>> currentCollection;
+      /// <summary>Current value in the current key the enumerator is at</summary>
+      private IEnumerator<TValue> currentValue;
+
+    }
+
+    #endregion // class Enumerator
+
+    #region class ValueList
+
+    /// <summary>Stores the list of values for a dictionary key</summary>
+    private class ValueList : Collection<TValue> {
+
+      /// <summary>Initializes a new value list</summary>
+      /// <param name="dictionary">Dictionary the value list belongs to</param>
+      public ValueList(MultiDictionary<TKey, TValue> dictionary) {
+        this.dictionary = dictionary;
+      }
+
+      /// <summary>Called when the value list is being cleared</summary>
+      protected override void ClearItems() {
+        this.dictionary.count -= Count;
+        base.ClearItems();
+      }
+
+      /// <summary>Called when an item is inserted into the value list</summary>
+      /// <param name="index">Index at which the item is being inserted</param>
+      /// <param name="item">Item that is being inserted</param>
+      protected override void InsertItem(int index, TValue item) {
+        base.InsertItem(index, item);
+        ++this.dictionary.count;
+      }
+
+      /// <summary>Called when an item is removed from the value list</summary>
+      /// <param name="index">Index at which the item is being removed</param>
+      protected override void RemoveItem(int index) {
+        base.RemoveItem(index);
+        --this.dictionary.count;
+      }
+
+      /// <summary>The dictionary the value list belongs to</summary>
+      private MultiDictionary<TKey, TValue> dictionary;
+
+    }
+
+    #endregion // class ValueList
+
+    /// <summary>Initializes a new multi dictionary</summary>
+    public MultiDictionary() : this(new Dictionary<TKey, ICollection<TValue>>()) { }
+
+    /// <summary>Initializes a new multi dictionary</summary>
+    /// <param name="dictionary">Dictionary the multi dictionary will be based on</param>
+    internal MultiDictionary(IDictionary<TKey, ICollection<TValue>> dictionary) {
+      this.typedDictionary = dictionary;
+      this.objectDictionary = (this.typedDictionary as IDictionary);
+
+      foreach(ICollection<TValue> values in dictionary.Values) {
+        this.count += values.Count;
+      }
+    }
+
+    /// <summary>Whether the dictionary is write-protected</summary>
+    public bool IsReadOnly {
+      get { return this.typedDictionary.IsReadOnly; }
+    }
+
+    /// <summary>Determines the number of values stored under the specified key</summary>
+    /// <param name="key">Key whose values will be counted</param>
+    /// <returns>The number of values stored under the specified key</returns>
+    public int CountValues(TKey key) {
+      ICollection<TValue> values;
+      if(this.typedDictionary.TryGetValue(key, out values)) {
+        return values.Count;
+      } else {
+        return 0;
+      }
+    }
+
+    /// <summary>
+    ///   Determines whether the specified KeyValuePair is contained in the dictionary
+    /// </summary>
+    /// <param name="item">KeyValuePair that will be checked for</param>
+    /// <returns>True if the provided KeyValuePair was contained in the dictionary</returns>
+    public bool Contains(KeyValuePair<TKey, TValue> item) {
+      ICollection<TValue> values;
+      if(this.typedDictionary.TryGetValue(item.Key, out values)) {
+        return values.Contains(item.Value);
+      } else {
+        return false;
+      }
+    }
+
+    /// <summary>Determines whether the Dictionary contains the specified key</summary>
+    /// <param name="key">Key that will be checked for</param>
+    /// <returns>
+    ///   True if an entry with the specified key was contained in the Dictionary
+    /// </returns>
+    public bool ContainsKey(TKey key) {
+      return this.typedDictionary.ContainsKey(key);
+    }
+
+    /// <summary>Copies the contents of the Dictionary into an array</summary>
+    /// <param name="array">Array the Dictionary will be copied into</param>
+    /// <param name="arrayIndex">
+    ///   Starting index at which to begin filling the destination array
+    /// </param>
+    public void CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex) {
+      foreach(KeyValuePair<TKey, ICollection<TValue>> item in this.typedDictionary) {
+        foreach(TValue value in item.Value) {
+          array[arrayIndex] = new KeyValuePair<TKey, TValue>(item.Key, value);
+          ++arrayIndex;
+        }
+      }
+    }
+
+    /// <summary>Number of elements contained in the Dictionary</summary>
+    public int Count {
+      get { return this.count; }
+    }
+
+    /// <summary>Creates a new enumerator for the dictionary</summary>
+    /// <returns>The new dictionary enumerator</returns>
+    public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator() {
+      return new Enumerator(this);
+    }
+
+    /// <summary>Collection of all keys contained in the dictionary</summary>
+    public ICollection<TKey> Keys {
+      get { return this.typedDictionary.Keys; }
+    }
+
+    /// <summary>Collection of all values contained in the dictionary</summary>
+    public ICollection<TValue> Values {
+      get {
+        if(this.valueCollection == null) {
+          this.valueCollection = new ValueCollection(this);
+        }
+
+        return this.valueCollection;
+      }
+    }
+
+    /// <summary>
+    ///   Attempts to retrieve the item with the specified key from the dictionary
+    /// </summary>
+    /// <param name="key">Key of the item to attempt to retrieve</param>
+    /// <param name="values">
+    ///   Output parameter that will receive the values upon successful completion
+    /// </param>
+    /// <returns>
+    ///   True if the item was found and has been placed in the output parameter
+    /// </returns>
+    public bool TryGetValue(TKey key, out ICollection<TValue> values) {
+      return this.typedDictionary.TryGetValue(key, out values);
+    }
+
+    /// <summary>Accesses an item in the dictionary by its key</summary>
+    /// <param name="key">Key of the item that will be accessed</param>
+    public ICollection<TValue> this[TKey key] {
+      get { return this.typedDictionary[key]; }
+      set {
+        ICollection<TValue> currentValues;
+        if(this.typedDictionary.TryGetValue(key, out currentValues)) {
+          currentValues.Clear();
+        } else {
+          currentValues = new ValueList(this);
+          this.typedDictionary.Add(key, currentValues);
+        }
+
+        foreach(TValue addedValue in value) {
+          currentValues.Add(addedValue);
+          OnAdded(new KeyValuePair<TKey, TValue>(key, addedValue));
+        }
+      }
+    }
+
+    /// <summary>Inserts an item into the dictionary</summary>
+    /// <param name="key">Key under which to add the new item</param>
+    /// <param name="value">Item that will be added to the dictionary</param>
+    public void Add(TKey key, TValue value) {
+      ICollection<TValue> values;
+      if(!this.typedDictionary.TryGetValue(key, out values)) {
+        values = new ValueList(this);
+        this.typedDictionary.Add(key, values);
+      }
+
+      values.Add(value);
+      OnAdded(new KeyValuePair<TKey, TValue>(key, value));
+    }
+
+    /// <summary>
+    ///   Removes the item with the specified key and value from the dictionary
+    /// </summary>
+    /// <param name="key">Key of the item that will be removed</param>
+    /// <param name="value">Value of the item that will be removed</param>
+    /// <returns>
+    ///   True if the specified item was contained in the dictionary and was removed
+    /// </returns>
+    /// <exception cref="NotSupportedException">If the dictionary is read-only</exception>
+    public bool Remove(TKey key, TValue value) {
+      ICollection<TValue> values;
+      if(this.typedDictionary.TryGetValue(key, out values)) {
+        values.Remove(value);
+
+        if(values.Count == 0) {
+          this.typedDictionary.Remove(key);
+        }
+
+        OnRemoved(new KeyValuePair<TKey, TValue>(key, value));
+        return true;
+      } else {
+        return false;
+      }
+    }
+
+    /// <summary>Removes all items with the specified key from the dictionary</summary>
+    /// <param name="key">Key of the item that will be removed</param>
+    /// <returns>The number of items that have been removed from the dictionary</returns>
+    /// <exception cref="NotSupportedException">If the dictionary is read-only</exception>
+    public int RemoveKey(TKey key) {
+      ICollection<TValue> values;
+      if(this.typedDictionary.TryGetValue(key, out values)) {
+        this.count -= values.Count;
+        this.typedDictionary.Remove(key);
+
+        foreach(TValue value in values) {
+          OnRemoved(new KeyValuePair<TKey, TValue>(key, value));
+        }
+        return values.Count;
+      } else {
+        return 0;
+      }
+    }
+
+    /// <summary>Removes all items from the Dictionary</summary>
+    public void Clear() {
+      OnClearing();
+      this.typedDictionary.Clear();
+      this.count = 0;
+      OnCleared();
+    }
+
+    /// <summary>Fires the 'ItemAdded' event</summary>
+    /// <param name="item">Item that has been added to the collection</param>
+    protected virtual void OnAdded(KeyValuePair<TKey, TValue> item) { }
+
+    /// <summary>Fires the 'ItemRemoved' event</summary>
+    /// <param name="item">Item that has been removed from the collection</param>
+    protected virtual void OnRemoved(KeyValuePair<TKey, TValue> item) { }
+
+    /// <summary>Fires the 'Clearing' event</summary>
+    protected virtual void OnClearing() { }
+
+    /// <summary>Fires the 'Cleared' event</summary>
+    protected virtual void OnCleared() { }
+
+    /// <summary>The wrapped Dictionary under its type-safe interface</summary>
+    private IDictionary<TKey, ICollection<TValue>> typedDictionary;
+    /// <summary>The wrapped Dictionary under its object interface</summary>
+    private IDictionary objectDictionary;
+    /// <summary>The number of items currently in the multi dictionary</summary>
+    private int count;
+    /// <summary>Provides the values stores in the dictionary in sequence</summary>
+    private ValueCollection valueCollection;
+
+  }
+
+} // namespace Nuclex.Support.Collections
diff --git a/Source/Collections/ObservableCollection.cs b/Source/Collections/ObservableCollection.cs
index 0347f4d..0c6a42a 100644
--- a/Source/Collections/ObservableCollection.cs
+++ b/Source/Collections/ObservableCollection.cs
@@ -21,17 +21,25 @@ License along with this library
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+#if !NO_SPECIALIZED_COLLECTIONS
+using System.Collections.Specialized;
+#endif
 
 namespace Nuclex.Support.Collections {
 
   /// <summary>Collection which fires events when items are added or removed</summary>
-  public class ObservableCollection<ItemType> :
-    Collection<ItemType>, IObservableCollection<ItemType> {
+  /// <typeparam name="TItem">Type of items the collection manages</typeparam>
+  public class ObservableCollection<TItem> :
+    Collection<TItem>,
+#if !NO_SPECIALIZED_COLLECTIONS
+    INotifyCollectionChanged,
+#endif
+    IObservableCollection<TItem> {
 
     /// <summary>Raised when an item has been added to the collection</summary>
-    public event EventHandler<ItemEventArgs<ItemType>> ItemAdded;
+    public event EventHandler<ItemEventArgs<TItem>> ItemAdded;
     /// <summary>Raised when an item is removed from the collection</summary>
-    public event EventHandler<ItemEventArgs<ItemType>> ItemRemoved;
+    public event EventHandler<ItemEventArgs<TItem>> ItemRemoved;
     /// <summary>Raised when the collection is about to be cleared</summary>
     /// <remarks>
     ///   This could be covered by calling ItemRemoved for each item currently
@@ -42,6 +50,11 @@ namespace Nuclex.Support.Collections {
     /// <summary>Raised when the collection has been cleared</summary>
     public event EventHandler Cleared;
 
+#if !NO_SPECIALIZED_COLLECTIONS
+    /// <summary>Called when the collection has changed</summary>
+    public event NotifyCollectionChangedEventHandler CollectionChanged;
+#endif
+
     /// <summary>
     ///   Initializes a new instance of the ObservableCollection class that is empty.
     /// </summary>
@@ -52,18 +65,35 @@ namespace Nuclex.Support.Collections {
     ///   for the specified list.
     /// </summary>
     /// <param name="list">The list that is wrapped by the new collection.</param>
-    /// <exception cref="System.ArgumentNullException">
-    ///    List is null.
-    /// </exception>
-    public ObservableCollection(IList<ItemType> list) : base(list) { }
+    /// <exception cref="System.ArgumentNullException">List is null</exception>
+    public ObservableCollection(IList<TItem> list) : base(list) { }
 
     /// <summary>Removes all elements from the Collection</summary>
     protected override void ClearItems() {
       OnClearing();
       base.ClearItems();
       OnCleared();
+#if !NO_SPECIALIZED_COLLECTIONS
+      OnCollectionChanged(NotifyCollectionChangedAction.Reset, default(TItem), -1);
+#endif
     }
 
+#if !NO_SPECIALIZED_COLLECTIONS
+    /// <summary>Fires the CollectionChanged event</summary>
+    /// <param name="action">Type of change that has occured</param>
+    /// <param name="item">The item that has been added, removed or replaced</param>
+    /// <param name="index">Index of the changed item</param>
+    protected virtual void OnCollectionChanged(
+      NotifyCollectionChangedAction action, TItem item, int index
+    ) {
+      if (CollectionChanged != null) {
+        CollectionChanged(
+          this, new NotifyCollectionChangedEventArgs(action, item, index)
+         );
+      }
+    }
+#endif
+
     /// <summary>
     ///   Inserts an element into the ObservableCollection at the specified index
     /// </summary>
@@ -71,9 +101,12 @@ namespace Nuclex.Support.Collections {
     ///   The object to insert. The value can be null for reference types.
     /// </param>
     /// <param name="item">The zero-based index at which item should be inserted</param>
-    protected override void InsertItem(int index, ItemType item) {
+    protected override void InsertItem(int index, TItem item) {
       base.InsertItem(index, item);
       OnAdded(item);
+#if !NO_SPECIALIZED_COLLECTIONS
+      OnCollectionChanged(NotifyCollectionChangedAction.Add, item, index);
+#endif
     }
 
     /// <summary>
@@ -81,9 +114,12 @@ namespace Nuclex.Support.Collections {
     /// </summary>
     /// <param name="index">The zero-based index of the element to remove</param>
     protected override void RemoveItem(int index) {
-      ItemType item = base[index];
+      TItem item = base[index];
       base.RemoveItem(index);
       OnRemoved(item);
+#if !NO_SPECIALIZED_COLLECTIONS
+      OnCollectionChanged(NotifyCollectionChangedAction.Remove, item, index);
+#endif
     }
 
     /// <summary>Replaces the element at the specified index</summary>
@@ -92,39 +128,43 @@ namespace Nuclex.Support.Collections {
     ///   for reference types
     /// </param>
     /// <param name="item">The zero-based index of the element to replace</param>
-    protected override void SetItem(int index, ItemType item) {
-      ItemType oldItem = base[index];
+    protected override void SetItem(int index, TItem item) {
+      TItem oldItem = base[index];
       base.SetItem(index, item);
       OnRemoved(oldItem);
       OnAdded(item);
+#if !NO_SPECIALIZED_COLLECTIONS
+      OnCollectionChanged(NotifyCollectionChangedAction.Replace, item, index);
+#endif
     }
 
     /// <summary>Fires the 'ItemAdded' event</summary>
     /// <param name="item">Item that has been added to the collection</param>
-    protected virtual void OnAdded(ItemType item) {
-      if(ItemAdded != null)
-        ItemAdded(this, new ItemEventArgs<ItemType>(item));
+    protected virtual void OnAdded(TItem item) {
+      if (ItemAdded != null)
+        ItemAdded(this, new ItemEventArgs<TItem>(item));
     }
 
     /// <summary>Fires the 'ItemRemoved' event</summary>
     /// <param name="item">Item that has been removed from the collection</param>
-    protected virtual void OnRemoved(ItemType item) {
-      if(ItemRemoved != null)
-        ItemRemoved(this, new ItemEventArgs<ItemType>(item));
+    protected virtual void OnRemoved(TItem item) {
+      if (ItemRemoved != null)
+        ItemRemoved(this, new ItemEventArgs<TItem>(item));
     }
 
     /// <summary>Fires the 'Clearing' event</summary>
     protected virtual void OnClearing() {
-      if(Clearing != null)
+      if (Clearing != null)
         Clearing(this, EventArgs.Empty);
     }
 
     /// <summary>Fires the 'Cleared' event</summary>
     protected virtual void OnCleared() {
-      if(Cleared != null)
+      if (Cleared != null)
         Cleared(this, EventArgs.Empty);
     }
 
+
   }
 
 } // namespace Nuclex.Support.Collections
diff --git a/Source/Collections/ObservableDictionary.cs b/Source/Collections/ObservableDictionary.cs
index 0bd86fe..c8fcc50 100644
--- a/Source/Collections/ObservableDictionary.cs
+++ b/Source/Collections/ObservableDictionary.cs
@@ -19,27 +19,32 @@ License along with this library
 #endregion
 
 using System;
-using System.Collections.Generic;
 using System.Collections;
-using System.Collections.ObjectModel;
+using System.Collections.Generic;
+#if !NO_SPECIALIZED_COLLECTIONS
+using System.Collections.Specialized;
+#endif
 using System.Runtime.Serialization;
 
 namespace Nuclex.Support.Collections {
 
   /// <summary>A dictionary that sneds out change notifications</summary>
-  /// <typeparam name="KeyType">Type of the keys used in the dictionary</typeparam>
-  /// <typeparam name="ValueType">Type of the values used in the dictionary</typeparam>
+  /// <typeparam name="TKey">Type of the keys used in the dictionary</typeparam>
+  /// <typeparam name="TValue">Type of the values used in the dictionary</typeparam>
 #if !NO_SERIALIZATION
   [Serializable]
 #endif
-  public class ObservableDictionary<KeyType, ValueType> :
+  public class ObservableDictionary<TKey, TValue> :
 #if !NO_SERIALIZATION
- ISerializable,
+    ISerializable,
     IDeserializationCallback,
 #endif
- IDictionary<KeyType, ValueType>,
+    IDictionary<TKey, TValue>,
     IDictionary,
-    IObservableCollection<KeyValuePair<KeyType, ValueType>> {
+#if !NO_SPECIALIZED_COLLECTIONS
+    INotifyCollectionChanged,
+#endif
+    IObservableCollection<KeyValuePair<TKey, TValue>> {
 
 #if !NO_SERIALIZATION
     #region class SerializedDictionary
@@ -47,7 +52,7 @@ namespace Nuclex.Support.Collections {
     /// <summary>
     ///   Dictionary wrapped used to reconstruct a serialized read only dictionary
     /// </summary>
-    private class SerializedDictionary : Dictionary<KeyType, ValueType> {
+    private class SerializedDictionary : Dictionary<TKey, TValue> {
 
       /// <summary>
       ///   Initializes a new instance of the System.WeakReference class, using deserialized
@@ -70,23 +75,28 @@ namespace Nuclex.Support.Collections {
     }
 
     #endregion // class SerializedDictionary
-#endif // !COMPACTFRAMEWORK
+#endif // !NO_SERIALIZATION
 
     /// <summary>Raised when an item has been added to the dictionary</summary>
-    public event EventHandler<ItemEventArgs<KeyValuePair<KeyType, ValueType>>> ItemAdded;
+    public event EventHandler<ItemEventArgs<KeyValuePair<TKey, TValue>>> ItemAdded;
     /// <summary>Raised when an item is removed from the dictionary</summary>
-    public event EventHandler<ItemEventArgs<KeyValuePair<KeyType, ValueType>>> ItemRemoved;
+    public event EventHandler<ItemEventArgs<KeyValuePair<TKey, TValue>>> ItemRemoved;
     /// <summary>Raised when the dictionary is about to be cleared</summary>
     public event EventHandler Clearing;
     /// <summary>Raised when the dictionary has been cleared</summary>
     public event EventHandler Cleared;
 
+#if !NO_SPECIALIZED_COLLECTIONS
+    /// <summary>Called when the collection has changed</summary>
+    public event NotifyCollectionChangedEventHandler CollectionChanged;
+#endif
+
     /// <summary>Initializes a new observable dictionary</summary>
-    public ObservableDictionary() : this(new Dictionary<KeyType, ValueType>()) { }
+    public ObservableDictionary() : this(new Dictionary<TKey, TValue>()) { }
 
     /// <summary>Initializes a new observable Dictionary wrapper</summary>
     /// <param name="dictionary">Dictionary that will be wrapped</param>
-    public ObservableDictionary(IDictionary<KeyType, ValueType> dictionary) {
+    public ObservableDictionary(IDictionary<TKey, TValue> dictionary) {
       this.typedDictionary = dictionary;
       this.objectDictionary = (this.typedDictionary as IDictionary);
     }
@@ -123,7 +133,7 @@ namespace Nuclex.Support.Collections {
     /// </summary>
     /// <param name="item">KeyValuePair that will be checked for</param>
     /// <returns>True if the provided KeyValuePair was contained in the Dictionary</returns>
-    public bool Contains(KeyValuePair<KeyType, ValueType> item) {
+    public bool Contains(KeyValuePair<TKey, TValue> item) {
       return this.typedDictionary.Contains(item);
     }
 
@@ -132,7 +142,7 @@ namespace Nuclex.Support.Collections {
     /// <returns>
     ///   True if an entry with the specified key was contained in the Dictionary
     /// </returns>
-    public bool ContainsKey(KeyType key) {
+    public bool ContainsKey(TKey key) {
       return this.typedDictionary.ContainsKey(key);
     }
 
@@ -141,7 +151,7 @@ namespace Nuclex.Support.Collections {
     /// <param name="arrayIndex">
     ///   Starting index at which to begin filling the destination array
     /// </param>
-    public void CopyTo(KeyValuePair<KeyType, ValueType>[] array, int arrayIndex) {
+    public void CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex) {
       this.typedDictionary.CopyTo(array, arrayIndex);
     }
 
@@ -152,17 +162,17 @@ namespace Nuclex.Support.Collections {
 
     /// <summary>Creates a new enumerator for the Dictionary</summary>
     /// <returns>The new Dictionary enumerator</returns>
-    public IEnumerator<KeyValuePair<KeyType, ValueType>> GetEnumerator() {
+    public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator() {
       return this.typedDictionary.GetEnumerator();
     }
 
     /// <summary>Collection of all keys contained in the Dictionary</summary>
-    public ICollection<KeyType> Keys {
+    public ICollection<TKey> Keys {
       get { return this.typedDictionary.Keys; }
     }
 
     /// <summary>Collection of all values contained in the Dictionary</summary>
-    public ICollection<ValueType> Values {
+    public ICollection<TValue> Values {
       get { return this.typedDictionary.Values; }
     }
 
@@ -176,46 +186,46 @@ namespace Nuclex.Support.Collections {
     /// <returns>
     ///   True if the item was found and has been placed in the output parameter
     /// </returns>
-    public bool TryGetValue(KeyType key, out ValueType value) {
+    public bool TryGetValue(TKey key, out TValue value) {
       return this.typedDictionary.TryGetValue(key, out value);
     }
 
     /// <summary>Accesses an item in the Dictionary by its key</summary>
     /// <param name="key">Key of the item that will be accessed</param>
-    public ValueType this[KeyType key] {
+    public TValue this[TKey key] {
       get { return this.typedDictionary[key]; }
       set {
         bool removed;
-        ValueType oldValue;
+        TValue oldValue;
         removed = this.typedDictionary.TryGetValue(key, out oldValue);
 
         this.typedDictionary[key] = value;
 
         if(removed) {
-          OnRemoved(new KeyValuePair<KeyType, ValueType>(key, oldValue));
+          OnRemoved(new KeyValuePair<TKey, TValue>(key, oldValue));
         }
-        OnAdded(new KeyValuePair<KeyType, ValueType>(key, value));
+        OnAdded(new KeyValuePair<TKey, TValue>(key, value));
       }
     }
 
     /// <summary>Inserts an item into the Dictionary</summary>
     /// <param name="key">Key under which to add the new item</param>
     /// <param name="value">Item that will be added to the Dictionary</param>
-    public void Add(KeyType key, ValueType value) {
+    public void Add(TKey key, TValue value) {
       this.typedDictionary.Add(key, value);
-      OnAdded(new KeyValuePair<KeyType, ValueType>(key, value));
+      OnAdded(new KeyValuePair<TKey, TValue>(key, value));
     }
 
     /// <summary>Removes the item with the specified key from the Dictionary</summary>
     /// <param name="key">Key of the elementes that will be removed</param>
     /// <returns>True if an item with the specified key was found and removed</returns>
-    public bool Remove(KeyType key) {
-      ValueType oldValue;
+    public bool Remove(TKey key) {
+      TValue oldValue;
       this.typedDictionary.TryGetValue(key, out oldValue);
 
       bool removed = this.typedDictionary.Remove(key);
       if(removed) {
-        OnRemoved(new KeyValuePair<KeyType, ValueType>(key, oldValue));
+        OnRemoved(new KeyValuePair<TKey, TValue>(key, oldValue));
       }
       return removed;
     }
@@ -229,16 +239,32 @@ namespace Nuclex.Support.Collections {
 
     /// <summary>Fires the 'ItemAdded' event</summary>
     /// <param name="item">Item that has been added to the collection</param>
-    protected virtual void OnAdded(KeyValuePair<KeyType, ValueType> item) {
+    protected virtual void OnAdded(KeyValuePair<TKey, TValue> item) {
       if(ItemAdded != null)
-        ItemAdded(this, new ItemEventArgs<KeyValuePair<KeyType, ValueType>>(item));
+        ItemAdded(this, new ItemEventArgs<KeyValuePair<TKey, TValue>>(item));
+#if !NO_SPECIALIZED_COLLECTIONS
+      if(CollectionChanged != null)
+        CollectionChanged(
+          this, new NotifyCollectionChangedEventArgs(
+            NotifyCollectionChangedAction.Add, item
+          )
+        );
+#endif
     }
 
     /// <summary>Fires the 'ItemRemoved' event</summary>
     /// <param name="item">Item that has been removed from the collection</param>
-    protected virtual void OnRemoved(KeyValuePair<KeyType, ValueType> item) {
+    protected virtual void OnRemoved(KeyValuePair<TKey, TValue> item) {
       if(ItemRemoved != null)
-        ItemRemoved(this, new ItemEventArgs<KeyValuePair<KeyType, ValueType>>(item));
+        ItemRemoved(this, new ItemEventArgs<KeyValuePair<TKey, TValue>>(item));
+#if !NO_SPECIALIZED_COLLECTIONS
+      if(CollectionChanged != null)
+        CollectionChanged(
+          this, new NotifyCollectionChangedEventArgs(
+            NotifyCollectionChangedAction.Remove, item
+          )
+        );
+#endif
     }
 
     /// <summary>Fires the 'Clearing' event</summary>
@@ -251,6 +277,10 @@ namespace Nuclex.Support.Collections {
     protected virtual void OnCleared() {
       if(Cleared != null)
         Cleared(this, EventArgs.Empty);
+#if !NO_SPECIALIZED_COLLECTIONS
+      if(CollectionChanged != null)
+        CollectionChanged(this, CollectionResetEventArgs);
+#endif
     }
 
     #region IEnumerable implementation
@@ -270,7 +300,7 @@ namespace Nuclex.Support.Collections {
     /// <param name="value">Item that will be added</param>
     void IDictionary.Add(object key, object value) {
       this.objectDictionary.Add(key, value);
-      OnAdded(new KeyValuePair<KeyType, ValueType>((KeyType)key, (ValueType)value));
+      OnAdded(new KeyValuePair<TKey, TValue>((TKey)key, (TValue)value));
     }
 
     /// <summary>Determines whether the specified key exists in the Dictionary</summary>
@@ -304,11 +334,11 @@ namespace Nuclex.Support.Collections {
     /// <summary>Removes an item from the Dictionary</summary>
     /// <param name="key">Key of the item that will be removed</param>
     void IDictionary.Remove(object key) {
-      ValueType value;
-      bool removed = this.typedDictionary.TryGetValue((KeyType)key, out value);
+      TValue value;
+      bool removed = this.typedDictionary.TryGetValue((TKey)key, out value);
       this.objectDictionary.Remove(key);
       if(removed) {
-        OnRemoved(new KeyValuePair<KeyType, ValueType>((KeyType)key, (ValueType)value));
+        OnRemoved(new KeyValuePair<TKey, TValue>((TKey)key, (TValue)value));
       }
     }
 
@@ -319,15 +349,15 @@ namespace Nuclex.Support.Collections {
       get { return this.objectDictionary[key]; }
       set {
         bool removed;
-        ValueType oldValue;
-        removed = this.typedDictionary.TryGetValue((KeyType)key, out oldValue);
+        TValue oldValue;
+        removed = this.typedDictionary.TryGetValue((TKey)key, out oldValue);
 
         this.objectDictionary[key] = value;
 
         if(removed) {
-          OnRemoved(new KeyValuePair<KeyType, ValueType>((KeyType)key, oldValue));
+          OnRemoved(new KeyValuePair<TKey, TValue>((TKey)key, oldValue));
         }
-        OnAdded(new KeyValuePair<KeyType, ValueType>((KeyType)key, (ValueType)value));
+        OnAdded(new KeyValuePair<TKey, TValue>((TKey)key, (TValue)value));
       }
     }
 
@@ -337,15 +367,15 @@ namespace Nuclex.Support.Collections {
 
     /// <summary>Inserts an already prepared element into the Dictionary</summary>
     /// <param name="item">Prepared element that will be added to the Dictionary</param>
-    void ICollection<KeyValuePair<KeyType, ValueType>>.Add(
-      KeyValuePair<KeyType, ValueType> item
+    void ICollection<KeyValuePair<TKey, TValue>>.Add(
+      KeyValuePair<TKey, TValue> item
     ) {
       this.typedDictionary.Add(item);
       OnAdded(item);
     }
 
     /// <summary>Removes all items from the Dictionary</summary>
-    void ICollection<KeyValuePair<KeyType, ValueType>>.Clear() {
+    void ICollection<KeyValuePair<TKey, TValue>>.Clear() {
       OnClearing();
       this.typedDictionary.Clear();
       OnCleared();
@@ -353,8 +383,8 @@ namespace Nuclex.Support.Collections {
 
     /// <summary>Removes all items from the Dictionary</summary>
     /// <param name="itemToRemove">Item that will be removed from the Dictionary</param>
-    bool ICollection<KeyValuePair<KeyType, ValueType>>.Remove(
-      KeyValuePair<KeyType, ValueType> itemToRemove
+    bool ICollection<KeyValuePair<TKey, TValue>>.Remove(
+      KeyValuePair<TKey, TValue> itemToRemove
     ) {
       bool removed = this.typedDictionary.Remove(itemToRemove);
       if(removed) {
@@ -412,9 +442,16 @@ namespace Nuclex.Support.Collections {
 #endif //!NO_SERIALIZATION
 
     /// <summary>The wrapped Dictionary under its type-safe interface</summary>
-    private IDictionary<KeyType, ValueType> typedDictionary;
+    private IDictionary<TKey, TValue> typedDictionary;
     /// <summary>The wrapped Dictionary under its object interface</summary>
     private IDictionary objectDictionary;
+
+#if !NO_SPECIALIZED_COLLECTIONS
+    /// <summary>Fixed event args used to notify that the collection has reset</summary>
+    private static readonly NotifyCollectionChangedEventArgs CollectionResetEventArgs =
+      new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset);
+#endif
+
   }
 
 } // namespace Nuclex.Support.Collections