/Utilities/Collections/MultiDictionary.cs

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using System;

using System.Collections.Generic;

using Delta.Utilities.Helpers;

using NUnit.Framework;



namespace Delta.Utilities.Collections

{

	/// <summary>

	/// <para>The MultiDictionary class that associates values with a key.

	/// Unlike an Dictionary, each key can have multiple values associated with

	/// it. When indexing an MultiDictionary, instead of a single value

	/// associated with a key, you retrieve an enumeration of values.</para>

	/// <para>When constructed, you can chose to allow the same value to be

	/// associated with a key multiple times, or only one time. </para>

	/// </summary>

	/// <typeparam name="TKey">Key type</typeparam>

	/// <typeparam name="TValue">Value type</typeparam>

	/// <seealso cref="Dictionary{TKey,TValue}"/>

	public class MultiDictionary<TKey, TValue>

		: MultiDictionaryBase<TKey, TValue>,

		  ICloneable<MultiDictionary<TKey, TValue>>

	{

		#region KeyAndValues Struct

		/// <summary>

		/// A structure to hold the key and the values associated with the key.

		/// The number of values must always be 1 or greater in a version that is

		/// stored, but can be zero in a dummy version used only for lookups.

		/// </summary>

		private struct KeyAndValues

		{

			#region Copy (Static)

			/// <summary>

			/// Make a copy of a KeyAndValues, copying the array.

			/// </summary>

			/// <param name="x">KeyAndValues to copy.</param>

			/// <returns>A copied version.</returns>

			public static KeyAndValues Copy(KeyAndValues x)

			{

				KeyAndValues result;



				result.Key = x.Key;

				result.Count = x.Count;



				if (x.Values != null)

				{

					result.Values = (TValue[])x.Values.Clone();

				}

				else

				{

					result.Values = null;

				}



				return result;

			}

			#endregion



			#region Key (Public)

			/// <summary>

			/// The key.

			/// </summary>

			public TKey Key;

			#endregion



			#region Count (Public)

			/// <summary>

			/// The number of values. Always at least 1 except in a dummy version

			/// for lookups.

			/// </summary>

			public int Count;

			#endregion



			#region Values (Public)

			/// <summary>

			/// An array of values. 

			/// </summary>

			public TValue[] Values;

			#endregion



			#region Constructors

			/// <summary>

			/// Create a dummy KeyAndValues with just the key, for lookups.

			/// </summary>

			/// <param name="key">The key to use.</param>

			public KeyAndValues(TKey key)

			{

				Key = key;

				Count = 0;

				Values = null;

			}

			#endregion

		}

		#endregion



		#region KeyAndValuesEqualityComparer Class

		/// <summary>

		/// This class implements IEqualityComparer for KeysAndValues, allowing

		/// them to be compared by their keys. An IEqualityComparer on keys is

		/// required.

		/// </summary>

		private class KeyAndValuesEqualityComparer : IEqualityComparer<KeyAndValues>

		{

			#region Private



			#region keyEqualityComparer (Private)

			/// <summary>

			/// Key equality comparer

			/// </summary>

			private readonly IEqualityComparer<TKey> keyEqualityComparer;

			#endregion



			#endregion



			#region Constructors

			/// <summary>

			/// Create key and values equality comparer

			/// </summary>

			/// <param name="keyEqualityComparer">Key equality comparer</param>

			public KeyAndValuesEqualityComparer(

				IEqualityComparer<TKey> keyEqualityComparer)

			{

				this.keyEqualityComparer = keyEqualityComparer;

			}

			#endregion



			#region IEqualityComparer<MultiDictionary<TKey,TValue>.KeyAndValues> Members

			/// <summary>

			/// Equals

			/// </summary>

			/// <param name="x">X value</param>

			/// <param name="y">Y value</param>

			/// <returns>True if x and y match.</returns>

			public bool Equals(KeyAndValues x, KeyAndValues y)

			{

				return keyEqualityComparer.Equals(x.Key, y.Key);

			}



			/// <summary>

			/// Get hash code

			/// </summary>

			/// <param name="obj">Object to generate hash code for</param>

			/// <returns>Hash code</returns>

			public int GetHashCode(KeyAndValues obj)

			{

				return obj.Key == null

				       	? 0x1786E23C

				       	: keyEqualityComparer.GetHashCode(obj.Key);

			}

			#endregion

		}

		#endregion



		#region GetHashCode (Static)

		/// <summary>

		/// Gets the hash code for an object using a comparer. Correctly handles

		/// null.

		/// </summary>

		/// <param name="item">Item to get hash code for. Can be null.</param>

		/// <param name="equalityComparer">The comparer to use.</param>

		/// <returns>The hash code for the item.</returns>

		public static int GetHashCode<T>(T item,

			IEqualityComparer<T> equalityComparer)

		{

			if (item == null)

			{

				return 0x1786E23C;

			}

			else

			{

				return equalityComparer.GetHashCode(item);

			}

		}

		#endregion



		#region IsCloneableType (Static)

		/// <summary>

		/// Determine if a type is cloneable: either a value type or implementing

		/// ICloneable.

		/// </summary>

		/// <param name="type">Type to check.</param>

		/// <param name="isValue">Returns if the type is a value type, and does not

		/// implement ICloneable.</param>

		/// <returns>True if the type is cloneable.</returns>

		public static bool IsCloneableType(Type type, out bool isValue)

		{

			isValue = false;



			if (typeof(ICloneable<MultiDictionary<TKey, TValue>>).

				IsAssignableFrom(type))

			{

				return true;

			}

			else if (type.IsValueType)

			{

				isValue = true;

				return true;

			}

			else

			{

				return false;

			}

		}

		#endregion



		#region KeyComparer (Public)

		/// <summary>

		/// Returns the IEqualityComparer&lt;T&gt; used to compare keys in this

		/// dictionary.

		/// </summary>

		/// <value>If the dictionary was created using a comparer, that comparer

		/// is returned. Otherwise the default comparer for TKey

		/// (EqualityComparer&lt;TKey&gt;.Default) is returned.</value>

		/// <typeparam name="TKey">TKey</typeparam>

		/// <typeparam name="TValue">TValue</typeparam>

		public IEqualityComparer<TKey> KeyComparer

		{

			get

			{

				return keyEqualityComparer;

			}

		}

		#endregion



		#region ValueComparer (Public)

		/// <summary>

		/// Returns the IEqualityComparer&lt;T&gt; used to compare values in this

		/// dictionary.

		/// </summary>

		/// <value>If the dictionary was created using a comparer, that comparer

		/// is returned. Otherwise the default comparer for TValue

		/// (EqualityComparer&lt;TValue&gt;.Default) is returned.</value>

		/// <typeparam name="TKey">TKey</typeparam>

		/// <typeparam name="TValue">TValue</typeparam>

		public IEqualityComparer<TValue> ValueComparer

		{

			get

			{

				return valueEqualityComparer;

			}

		}

		#endregion



		#region Count (Public)

		/// <summary>

		/// Gets the number of key-value pairs in the dictionary. Each value

		/// associated with a given key is counted. If duplicate values are

		/// permitted, each duplicate value is included in the count.

		/// </summary>

		/// <value>The number of key-value pairs in the dictionary.</value>

		/// <typeparam name="TKey">TKey</typeparam>

		/// <typeparam name="TValue">TValue</typeparam>

		public override sealed int Count

		{

			get

			{

				return hash.ElementCount;

			}

		}

		#endregion



		#region Private



		#region keyEqualityComparer (Private)

		/// <summary>

		/// The comparer for comparing keys

		/// </summary>

		/// <typeparam name="TKey">TKey</typeparam>

		/// <typeparam name="TValue">TValue</typeparam>

		private readonly IEqualityComparer<TKey> keyEqualityComparer;

		#endregion



		#region valueEqualityComparer (Private)

		/// <summary>

		/// The comparer for comparing values;

		/// </summary>

		/// <typeparam name="TKey">TKey</typeparam>

		/// <typeparam name="TValue">TValue</typeparam>

		private readonly IEqualityComparer<TValue> valueEqualityComparer;

		#endregion



		#region equalityComparer (Private)

		/// <summary>

		/// The comparer for compaing keys and values.

		/// </summary>

		/// <typeparam name="TKey">TKey</typeparam>

		/// <typeparam name="TValue">TValue</typeparam>

		private readonly IEqualityComparer<KeyAndValues> equalityComparer;

		#endregion



		#region allowDuplicateValues (Private)

		/// <summary>

		/// Whether duplicate values for the same key are allowed.

		/// </summary>

		/// <typeparam name="TKey">TKey</typeparam>

		/// <typeparam name="TValue">TValue</typeparam>

		private readonly bool allowDuplicateValues;

		#endregion



		#region hash (Private)

		/// <summary>

		/// The hash that holds the keys and values.

		/// </summary>

		/// <typeparam name="TKey">TKey</typeparam>

		/// <typeparam name="TValue">TValue</typeparam>

		private Hash<KeyAndValues> hash;

		#endregion



		#endregion



		#region Constructors

		/// <summary>

		/// Create a new MultiDictionary. The default ordering of keys and values

		/// are used. If duplicate values are allowed, multiple copies of the same

		/// value can be associated with the same key. For example, the key "foo"

		/// could have "a", "a", and "b" associated with it. If duplicate values

		/// are not allowed, only one copies of a given value can be associated

		/// with the same key, although different keys can have the same value.

		/// For example, the key "foo" could have "a" and "b" associated with it,

		/// which key "bar" has values "b" and "c" associated with it.

		/// </summary>

		/// <remarks>The default ordering of keys and values will be used, as

		/// defined by TKey and TValue's implementation of IComparable&lt;T&gt;

		/// (or IComparable if IComparable&lt;T&gt; is not implemented). If a

		/// different ordering should be used, other constructors allow a custom

		/// Comparer or IComparer to be passed to changed the ordering.</remarks>

		/// <param name="allowDuplicateValues">Can the same value be associated

		/// with a key multiple times?</param>

		/// <exception cref="InvalidOperationException">TKey or TValue does not

		/// implement either IComparable&lt;T&gt; or IComparable.</exception>

		public MultiDictionary(bool allowDuplicateValues)

			: this(allowDuplicateValues,

				EqualityComparer<TKey>.Default,

				EqualityComparer<TValue>.Default)

		{

		}



		/// <summary>

		/// Create a new MultiDictionary. If duplicate values are allowed,

		/// multiple copies of the same value can be associated with the same key.

		/// For example, the key "foo" could have "a", "a", and "b" associated

		/// with it. If duplicate values are not allowed, only one copies of a

		/// given value can be associated with the same key, although different

		/// keys can have the same value. For example, the key "foo" could have

		/// "a" and "b" associated with it, which key "bar" has values "b" and "c"

		/// associated with it.

		/// </summary>

		/// <param name="allowDuplicateValues">

		/// Can the same value be associated with a key multiple times?</param>

		/// <param name="keyEqualityComparer">

		/// An IEqualityComparer&lt;TKey&gt; instance that will be used to compare

		/// keys.</param>

		/// <exception cref="InvalidOperationException">TValue does not implement

		/// either IComparable&lt;TValue&gt; or IComparable.</exception>

		public MultiDictionary(bool allowDuplicateValues,

			IEqualityComparer<TKey> keyEqualityComparer)

			: this(allowDuplicateValues, keyEqualityComparer,

				EqualityComparer<TValue>.Default)

		{

		}



		/// <summary>

		/// Create a new MultiDictionary. If duplicate values are allowed,

		/// multiple copies of the same value can be associated with the same key.

		/// For example, the key "foo" could have "a", "a", and "b" associated

		/// with it. If duplicate values are not allowed, only one copies of a

		/// given value can be associated with the same key, although different

		/// keys can have the same value. For example, the key "foo" could have

		/// "a" and "b" associated with it, which key "bar" has values "b" and "c"

		/// associated with it.

		/// </summary>

		/// <param name="allowDuplicateValues">Can the same value be associated

		/// with a key multiple times?</param>

		/// <param name="keyEqualityComparer">An IEqualityComparer&lt;TKey&gt;

		/// instance that will be used to compare keys.</param>

		/// <param name="valueEqualityComparer">An IEqualityComparer&lt;TValue&gt;

		/// instance that will be used to compare values.</param>

		public MultiDictionary(bool allowDuplicateValues,

			IEqualityComparer<TKey> keyEqualityComparer,

			IEqualityComparer<TValue> valueEqualityComparer)

		{

			if (keyEqualityComparer == null)

			{

				throw new ArgumentNullException("keyEqualityComparer");

			}

			if (valueEqualityComparer == null)

			{

				throw new ArgumentNullException("valueEqualityComparer");

			}



			this.allowDuplicateValues = allowDuplicateValues;

			this.keyEqualityComparer = keyEqualityComparer;

			this.valueEqualityComparer = valueEqualityComparer;

			equalityComparer =

				new KeyAndValuesEqualityComparer(keyEqualityComparer);

			hash = new Hash<KeyAndValues>(equalityComparer);

		}



		/// <summary>

		/// Create a new MultiDictionary. Private constructor, for use by Clone().

		/// </summary>

		/// <param name="allowDuplicateValues">Allow duplicate values</param>

		/// <param name="equalityComparer">Equality comparer</param>

		/// <param name="hash">hash</param>

		/// <param name="keyEqualityComparer">Key equality comparer</param>

		/// <param name="valueEqualityComparer">Value equality comparer</param>

		private MultiDictionary(bool allowDuplicateValues,

			IEqualityComparer<TKey> keyEqualityComparer,

			IEqualityComparer<TValue> valueEqualityComparer,

			IEqualityComparer<KeyAndValues> equalityComparer,

			Hash<KeyAndValues> hash)

		{

			if (keyEqualityComparer == null)

			{

				throw new ArgumentNullException("keyEqualityComparer");

			}

			if (valueEqualityComparer == null)

			{

				throw new ArgumentNullException("valueEqualityComparer");

			}



			this.allowDuplicateValues = allowDuplicateValues;

			this.keyEqualityComparer = keyEqualityComparer;

			this.valueEqualityComparer = valueEqualityComparer;

			this.equalityComparer = equalityComparer;

			this.hash = hash;

		}

		#endregion



		#region ICloneable<MultiDictionary<TKey,TValue>> Members

		/// <summary>

		/// Makes a shallow clone of this dictionary; i.e., if keys or values of

		/// the dictionary are reference types, then they are not cloned. If TKey

		/// or TValue is a value type, then each element is copied as if by simple

		/// assignment.

		/// </summary>

		/// <remarks>Cloning the dictionary takes time O(N), where N is the number

		/// of key-value pairs in the dictionary.</remarks>

		/// <returns>The cloned dictionary.</returns>

		public MultiDictionary<TKey, TValue> Clone()

		{

			return new MultiDictionary<TKey, TValue>(

				allowDuplicateValues, keyEqualityComparer,

				valueEqualityComparer, equalityComparer,

				hash.Clone(KeyAndValues.Copy));

		}

		#endregion



		#region Add (Public)

		/// <summary>

		/// <para>Adds a new value to be associated with a key. If duplicate

		/// values are permitted, this method always adds a new key-value pair

		/// to the dictionary.</para>

		/// <para>If duplicate values are not permitted, and <paramref name="key"/>

		/// already has a value equal to <paramref name="value"/> associated with

		/// it, then that value is replaced with <paramref name="value"/>,

		/// and the number of values associate with <paramref name="key"/> is

		/// unchanged.</para>

		/// </summary>

		/// <param name="key">Key</param>

		/// <param name="value">Value</param>

		public override sealed void Add(TKey key, TValue value)

		{

			KeyAndValues keyValues = new KeyAndValues(key);

			KeyAndValues existing;



			if (hash.Find(keyValues, false, out existing))

			{

				// There already is an item in the hash table equal to this key.

				// Add the new value, taking into account duplicates if needed.

				int existingCount = existing.Count;

				if (!allowDuplicateValues)

				{

					int valueHash = GetHashCode(value, valueEqualityComparer);

					for (int i = 0; i < existingCount; ++i)

					{

						if (GetHashCode(existing.Values[i], valueEqualityComparer) ==

						    valueHash &&

						    valueEqualityComparer.Equals(existing.Values[i], value))

						{

							// Found an equal existing value. Replace it and we're done.

							existing.Values[i] = value;

							return;

						}

					}

				}



				// Add a new value to an existing key.

				if (existingCount == existing.Values.Length)

				{

					// Grow the array to make room.

					TValue[] newValues = new TValue[existingCount * 2];

					Array.Copy(existing.Values, newValues, existingCount);

					existing.Values = newValues;

				}

				existing.Values[existingCount] = value;

				existing.Count = existingCount + 1;



				// Update the hash table.

				hash.Find(existing, true, out keyValues);

				return;

			}

			else

			{

				// No item with this key. Add it.

				keyValues.Count = 1;

				keyValues.Values = new TValue[1]

				{

					value

				};

				hash.Insert(keyValues, true, out existing);

				return;

			}

		}

		#endregion



		#region Remove (Public)

		/// <summary>

		/// Removes a given value from the values associated with a key. If the

		/// last value is removed from a key, the key is removed also.

		/// </summary>

		/// <param name="key">A key to remove a value from.</param>

		/// <param name="value">The value to remove.</param>

		/// <returns>True if <paramref name="value"/> was associated with

		/// <paramref name="key"/> (and was therefore removed). False if

		/// <paramref name="value"/> was not associated with

		/// <paramref name="key"/>.</returns>

		public override sealed bool Remove(TKey key, TValue value)

		{

			KeyAndValues keyValues = new KeyAndValues(key);

			KeyAndValues existing;



			if (hash.Find(keyValues, false, out existing))

			{

				// There is an item in the hash table equal to this key.

				// Find the value.

				int existingCount = existing.Count;

				int valueHash = GetHashCode(value, valueEqualityComparer);

				int indexFound = -1;

				for (int i = 0; i < existingCount; ++i)

				{

					if (GetHashCode(existing.Values[i], valueEqualityComparer) ==

					    valueHash &&

					    valueEqualityComparer.Equals(existing.Values[i], value))

					{

						// Found an equal existing value

						indexFound = i;

					}

				}



				if (existingCount == 1)

				{

					// Removing the last value. Remove the key.

					hash.Delete(existing, out keyValues);

					return true;

				}

				else if (indexFound >= 0)

				{

					// Found a value. Remove it.

					if (indexFound < existingCount - 1)

					{

						Array.Copy(existing.Values, indexFound + 1, existing.Values,

							indexFound, existingCount - indexFound - 1);

					}

					existing.Count = existingCount - 1;



					// Update the hash.

					hash.Find(existing, true, out keyValues);

					return true;

				}

				else

				{

					// Value was not found.

					return false;

				}

			}

			else

			{

				return false; // key not found.

			}

		}



		/// <summary>

		/// Removes a key and all associated values from the dictionary. If the

		/// key is not present in the dictionary, it is unchanged and false is

		/// returned.

		/// </summary>

		/// <param name="key">The key to remove.</param>

		/// <returns>True if the key was present and was removed. Returns 

		/// false if the key was not present.</returns>

		public override sealed bool Remove(TKey key)

		{

			KeyAndValues dummy;

			return hash.Delete(new KeyAndValues(key), out dummy);

		}

		#endregion



		#region Clear (Public)

		/// <summary>

		/// Removes all keys and values from the dictionary.

		/// </summary>

		public override sealed void Clear()

		{

			hash.StopEnumerations(); // Invalidate any enumerations.



			// The simplest and fastest way is simply to throw away the old hash

			// and create a new one.

			hash = new Hash<KeyAndValues>(equalityComparer);

		}

		#endregion



		#region Contains (Public)

		/// <summary>

		/// Checks to see if <paramref name="value"/> is associated with

		/// <paramref name="key"/> in the dictionary.

		/// </summary>

		/// <param name="key">The key to check.</param>

		/// <param name="value">The value to check.</param>

		/// <returns>True if <paramref name="value"/> is associated with

		/// <paramref name="key"/>.</returns>

		public override sealed bool Contains(TKey key, TValue value)

		{

			KeyAndValues find = new KeyAndValues(key);

			KeyAndValues item;

			if (hash.Find(find, false, out item))

			{

				int existingCount = item.Count;

				int valueHash = GetHashCode(value, valueEqualityComparer);

				for (int i = 0; i < existingCount; ++i)

				{

					if (GetHashCode(item.Values[i], valueEqualityComparer) ==

					    valueHash &&

					    valueEqualityComparer.Equals(item.Values[i], value))

					{

						// Found an equal existing value. 

						return true;

					}

				}

			}



			return false;

		}

		#endregion



		#region ContainsKey (Public)

		/// <summary>

		/// Checks to see if the key is present in the dictionary and has

		/// at least one value associated with it.

		/// </summary>

		/// <param name="key">The key to check.</param>

		/// <returns>True if <paramref name="key"/> is present and has at least

		/// one value associated with it. Returns false otherwise.</returns>

		public override sealed bool ContainsKey(TKey key)

		{

			KeyAndValues find = new KeyAndValues(key);

			KeyAndValues temp;

			return hash.Find(find, false, out temp);

		}

		#endregion



		#region CloneContents (Public)

		/// <summary>

		/// Makes a deep clone of this dictionary. A new dictionary is created

		/// with a clone of each entry of this dictionary, by calling

		/// ICloneable.Clone on each element. If TKey or TValue is a value type,

		/// then each element is copied as if by simple assignment.

		/// </summary>

		/// <remarks><para>If TKey or TValue is a reference type, it must implement

		/// ICloneable. Otherwise, an InvalidOperationException is thrown.</para>

		/// <para>Cloning the dictionary takes time O(N log N), where N is the

		/// number of key-value pairs in the dictionary.</para></remarks>

		/// <returns>The cloned dictionary.</returns>

		/// <exception cref="InvalidOperationException">TKey or TValue is a

		/// reference type that does not implement ICloneable.</exception>

		public MultiDictionary<TKey, TValue> CloneContents()

		{

			bool keyIsValueType, valueIsValueType;



			// Make sure that TKey and TValue can be cloned.

			if (!IsCloneableType(typeof(TKey), out keyIsValueType))

			{

				NonCloneableType(typeof(TKey));

			}



			if (!IsCloneableType(typeof(TValue), out valueIsValueType))

			{

				NonCloneableType(typeof(TValue));

			}



			// It's tempting to do a more efficient cloning, utilizing the

			// hash.Clone() method. However, we can't know that

			// the cloned version of the key has the same hash value.

			MultiDictionary<TKey, TValue> newDict =

				new MultiDictionary<TKey, TValue>(

					allowDuplicateValues, keyEqualityComparer, valueEqualityComparer);



			foreach (KeyAndValues item in hash)

			{

				// Clone the key and values parts. Value types can be cloned

				// by just copying them, otherwise, ICloneable is used.

				TKey keyClone;

				TValue[] valuesClone;



				if (keyIsValueType)

				{

					keyClone = item.Key;

				}

				else

				{

					if (item.Key == null)

					{

						// Really null, because we know TKey isn't a value type.

						keyClone = default(TKey);

					}

					else

					{

						keyClone = ((ICloneable<TKey>)item.Key).Clone();

					}

				}



				valuesClone = new TValue[item.Count];

				if (valueIsValueType)

				{

					Array.Copy(item.Values, valuesClone, item.Count);

				}

				else

				{

					for (int i = 0; i < item.Count; ++i)

					{

						if (item.Values[i] == null)

						{

							// Really null, because we know TKey isn't a value type.

							valuesClone[i] = default(TValue);

						}

						else

						{

							valuesClone[i] = ((ICloneable<TValue>)item.Values[i]).Clone();

						}

					}

				}



				newDict.AddMany(keyClone, valuesClone);

			}



			return newDict;

		}

		#endregion



		#region Methods (Private)



		#region EqualValues

		/// <summary>

		/// Determine if two values are equal.

		/// </summary>

		/// <param name="value1">First value to compare.</param>

		/// <param name="value2">Second value to compare.</param>

		/// <returns>True if the values are equal.</returns>

		protected override sealed bool EqualValues(TValue value1, TValue value2)

		{

			return valueEqualityComparer.Equals(value1, value2);

		}

		#endregion



		#region EnumerateKeys

		/// <summary>

		/// Enumerate all the keys in the dictionary. 

		/// </summary>

		/// <returns>

		/// An IEnumerator&lt;TKey&gt; that enumerates all of the keys in the

		/// dictionary that have at least one value associated with them.

		/// </returns>

		protected override sealed IEnumerator<TKey> EnumerateKeys()

		{

			foreach (KeyAndValues item in hash)

			{

				yield return item.Key;

			}

		}

		#endregion



		#region EnumerateValues

		/// <summary>

		///  Enumerate the values in the a KeyAndValues structure. Can't return

		/// the array directly because:

		///   a) The array might be larger than the count.

		///   b) We can't allow clients to down-cast to the array and modify it.

		///   c) We have to abort enumeration if the hash changes.

		/// </summary>

		/// <param name="keyAndValues">Item with the values to enumerate..</param>

		/// <returns>An enumerable that enumerates the items in the KeyAndValues

		/// structure.</returns>

		private IEnumerator<TValue> EnumerateValues(KeyAndValues keyAndValues)

		{

			int count = keyAndValues.Count;

			int stamp = hash.GetEnumerationStamp();



			for (int i = 0; i < count; ++i)

			{

				yield return keyAndValues.Values[i];

				hash.CheckEnumerationStamp(stamp);

			}

		}

		#endregion



		#region TryEnumerateValuesForKey

		/// <summary>

		/// Determines if this dictionary contains a key equal to

		/// <paramref name="key"/>. If so, all the values associated with that key

		/// are returned through the values parameter.

		/// </summary>

		/// <param name="key">The key to search for.</param>

		/// <param name="values">Returns all values associated with key, if true

		/// was returned.</param>

		/// <returns>True if the dictionary contains key. False if the dictionary

		/// does not contain key.</returns>

		protected override sealed bool TryEnumerateValuesForKey(

			TKey key, out IEnumerator<TValue> values)

		{

			KeyAndValues find = new KeyAndValues(key);

			KeyAndValues item;

			if (hash.Find(find, false, out item))

			{

				values = EnumerateValues(item);

				return true;

			}

			else

			{

				values = null;

				return false;

			}

		}

		#endregion



		#region CountValues

		/// <summary>

		/// Gets the number of values associated with a given key.

		/// </summary>

		/// <param name="key">The key to count values of.</param>

		/// <returns>The number of values associated with <paramref name="key"/>.

		/// If <paramref name="key"/> is not present in the dictionary, zero is

		/// returned.</returns>

		protected override sealed int CountValues(TKey key)

		{

			KeyAndValues find = new KeyAndValues(key);

			KeyAndValues item;

			if (hash.Find(find, false, out item))

			{

				return item.Count;

			}

			else

			{

				return 0;

			}

		}

		#endregion



		#region NonCloneableType

		/// <summary>

		/// Throw an InvalidOperationException indicating that this type is not

		/// cloneable.

		/// </summary>

		/// <param name="t">Type to test.</param>

		private void NonCloneableType(Type t)

		{

			throw new InvalidOperationException(

				"Type " + t.FullName + " does not implement ICloneable.");

		}

		#endregion



		#endregion

	}



	/// <summary>

	/// Multi dictionary tests, needs to be an extra class because

	/// MultiDictionary is generic.

	/// </summary>

	internal class MultiDictionaryTests

	{

		#region Helpers



		#region CheckMultiDictionaryContents

		/// <summary>

		/// Check the contents of a Multi-Dictionary non-destructively.

		/// Keys and Values must be in order.

		/// </summary>

		/// <param name="dict">Dictionary</param>

		/// <param name="keys">Keys</param>

		/// <param name="values">Values</param>

		/// <param name="nonKey">Non key</param>

		/// <param name="nonValue">Non value</param>

		internal static void CheckMultiDictionaryContents<TKey, TValue>(

			MultiDictionary<TKey, TValue> dict, TKey[] keys, TValue[][] values,

			TKey nonKey, TValue nonValue)

		{

			//Optimize performance of this test helper method, it is still to slow

			int iKey, iValue;

			ICollection<TValue> getValues;



			// Check Count.

			Assert.Equal(keys.Length, dict.Count);



			// Check indexer, ContainsKey, Contains, TryGetValue for each key.

			for (iKey = 0; iKey < keys.Length; ++iKey)

			{

				Assert.True(dict.ContainsKey(keys[iKey]));

				Assert.True(dict.Contains(

					new KeyValuePair<TKey, ICollection<TValue>>(

					keys[iKey], values[iKey])));



				bool b = ((IDictionary<TKey, ICollection<TValue>>)dict).TryGetValue(

					keys[iKey], out getValues);

				Assert.True(b);

				iValue = 0;

				CollectionBaseTests.CheckEnumerableElementsAnyOrder(

					getValues, values[iKey]);



				iValue = 0;

				foreach (TValue val in values[iKey])

				{

					Assert.True(dict.Contains(keys[iKey], val));

					++iValue;

				} // foreach

				Assert.True(iValue == values[iKey].Length);



				iValue = 0;

				getValues = dict[keys[iKey]];

				CollectionBaseTests.CheckEnumerableElementsAnyOrder(

					getValues, values[iKey]);

			} // for (iKey)



			// Check Keys collection.

			CollectionBaseTests.CompareCollections(

				dict.Keys, keys, false);



			// Check Values collection

			int a = 0;

			TValue[] vals = new TValue[dict.Values.Count];

			for (iKey = 0; iKey < keys.Length; ++iKey)

			{

				for (iValue = 0; iValue < values[iKey].Length; ++iValue)

				{

					vals[a++] = values[iKey][iValue];

				} // for (iValue)

			} // for (iKey)

			Assert.Equal(dict.Values.Count, a);

			CollectionBaseTests.CompareCollections(

				dict.Values, vals, false);



			// Check KeyValuePairs collection.

			a = 0;

			KeyValuePair<TKey, TValue>[] pairs =

				new KeyValuePair<TKey, TValue>[dict.Values.Count];

			for (iKey = 0; iKey < keys.Length; ++iKey)

			{

				for (iValue = 0; iValue < values[iKey].Length; ++iValue)

				{

					pairs[a++] = new KeyValuePair<TKey, TValue>(

						keys[iKey], values[iKey][iValue]);

				} // for (iValue)

			} // for (iKey)

			CollectionBaseTests.CompareCollections(

				dict.KeyValuePairs, pairs, false);



			// Tests Contains, ContainsKey, TryGetValue for wrong values.

			Assert.False(dict.ContainsKey(nonKey));

			Assert.False(((IDictionary<TKey, ICollection<TValue>>)dict).

				TryGetValue(nonKey, out getValues));

			for (iKey = 0; iKey < keys.Length; ++iKey)

			{

				Assert.False(dict.Contains(keys[iKey], nonValue));

				Assert.False(dict.Contains(

					new KeyValuePair<TKey, ICollection<TValue>>(

					keys[iKey], new TValue[1] { nonValue })));

			}

		}

		#endregion



		#region FirstLetterComparer

		/// <summary>

		/// First letter comparer

		/// </summary>

		private class FirstLetterComparer : IEqualityComparer<string>

		{

			#region IEqualityComparer<string> Members

			/// <summary>

			/// Equals

			/// </summary>

			/// <param name="x">X value</param>

			/// <param name="y">Y value</param>

			/// <returns>True if both x and y match</returns>

			public bool Equals(string x, string y)

			{

				if (x == null)

				{

					return y == null;

				}

				else if (x.Length == 0)

				{

					return (y != null && y.Length == 0);

				}

				else

				{

					if (y == null ||

					    y.Length == 0)

					{

						return false;

					}

					else

					{

						return x[0] == y[0];

					}

				}

			}



			/// <summary>

			/// Get hash code

			/// </summary>

			/// <param name="obj">Object</param>

			/// <returns>Int</returns>

			public int GetHashCode(string obj)

			{

				if (obj == null)

				{

					return 0x12383;

				}

				else if (obj.Length == 0)

				{

					return 17;

				}

				else

				{

					return obj[0].GetHashCode();

				}

			}

			#endregion

		}

		#endregion



		#region CompareClones

		/// <summary>

		/// Compare clones

		/// </summary>

		/// <param name="d1">D 1</param>

		/// <param name="d2">D 2</param>

		private void CompareClones<K, V>(

			MultiDictionary<K, V> d1, MultiDictionary<K, V> d2)

		{

			IEnumerable<KeyValuePair<K, V>> e1 = d1.KeyValuePairs;

			IEnumerable<KeyValuePair<K, V>> e2 = d2.KeyValuePairs;

			KeyValuePair<K, V>[]

				pairs1 = ArrayHelper.ToArray(e1),

				pairs2 = ArrayHelper.ToArray(e2);

			bool[] found = new bool[pairs2.Length];



			// Check that the arrays are equal, but not reference equals

			// (e.g., have been cloned).

			Assert.True(pairs1.Length == pairs2.Length);

			foreach (KeyValuePair<K, V> p1 in pairs1)

			{

				bool f = false;

				for (int i = 0; i < pairs2.Length; ++i)

				{

					if (!found[i] &&

					    Equals(p1.Key, pairs2[i].Key) &&

					    Equals(p1.Value, pairs2[i].Value))

					{

						found[i] = true;

						f = true;

						Assert.True(p1.Key == null ||

						            !ReferenceEquals(p1.Key, pairs2[i].Key));

						Assert.True(p1.Value == null ||

						            !ReferenceEquals(p1.Value, pairs2[i].Value));

						break;

					}

				}

				Assert.True(f);

			}

		}

		#endregion



		#endregion



		#region Clone (LongRunning)

		/// <summary>

		/// Clone. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void Clone()

		{

			IEqualityComparer<string> firstLetterComparer =

				new FirstLetterComparer();



			MultiDictionary<string, string> dict1 =

				new MultiDictionary<string, string>(false,

					StringComparer.InvariantCultureIgnoreCase,

					firstLetterComparer);



			dict1.Add("qubert", "dinosaur");

			dict1.Add("Hello", "AAA");

			dict1.Add("Hi", "aaa");

			dict1.Add("Qubert", "hello");

			dict1.Add("queztel", "hello");

			dict1.Add("Alpha", "omega");

			dict1.Add("alpha", "oz");

			dict1.Add("qubert", "hippy");



			MultiDictionary<string, string> dict2 = dict1.Clone();



			Assert.True(dict1 != dict2);



			dict2.Add("qubert", "hoover");

			dict2.Remove("queztel");

			dict2.Add("hello", "banana");



			CollectionBaseTests.CheckEnumerableElementsAnyOrder(

				dict1.KeyValuePairs, new[]

				{

					new KeyValuePair<string, string>("Alpha", "oz"),

					new KeyValuePair<string, string>("Hello", "AAA"),

					new KeyValuePair<string, string>("Hi", "aaa"),

					new KeyValuePair<string, string>("qubert", "hippy"),

					new KeyValuePair<string, string>("qubert", "dinosaur"),

					new KeyValuePair<string, string>("queztel", "hello")

				});



			CollectionBaseTests.CheckEnumerableElementsAnyOrder(

				dict2.KeyValuePairs, new[]

				{

					new KeyValuePair<string, string>("Alpha", "oz"),

					new KeyValuePair<string, string>("Hello", "banana"),

					new KeyValuePair<string, string>("Hello", "AAA"),

					new KeyValuePair<string, string>("Hi", "aaa"),

					new KeyValuePair<string, string>("qubert", "hoover"),

					new KeyValuePair<string, string>("qubert", "dinosaur")

				});



			dict2 = dict1.Clone();



			Assert.True(dict1 != dict2);



			dict2.Add("qubert", "hoover");

			dict2.Remove("queztel");

			dict2.Add("hello", "banana");



			CollectionBaseTests.CheckEnumerableElementsAnyOrder(

				dict2.KeyValuePairs, new[]

				{

					new KeyValuePair<string, string>("Alpha", "oz"),

					new KeyValuePair<string, string>("Hello", "banana"),

					new KeyValuePair<string, string>("Hello", "AAA"),

					new KeyValuePair<string, string>("Hi", "aaa"),

					new KeyValuePair<string, string>("qubert", "hoover"),

					new KeyValuePair<string, string>("qubert", "dinosaur")

				});



			MultiDictionary<string, int> dict4 =

				new MultiDictionary<string, int>(true);

			MultiDictionary<string, int> dict5;

			dict5 = dict4.Clone();

			Assert.False(dict4 == dict5);

			Assert.True(dict4.Count == 0 && dict5.Count == 0);

			dict4.Add("hello", 1);

			Assert.True(dict4.Count == 1 && dict5.Count == 0);

			dict5.Add("hi", 7);

			dict4.Clear();

			Assert.True(dict4.Count == 0 && dict5.Count == 1);

		}

		#endregion



		#region TestAddElements (LongRunning)

		/// <summary>

		/// Test add elements. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void TestAddElements()

		{

			// Test without duplicate values.

			MultiDictionary<string, double> dict1 =

				new MultiDictionary<string, double>(false);



			dict1.Add("foo", 3.5);

			dict1.Add("foo", -1.2);

			dict1.Add(null, 11.1);

			dict1.Add("foo", 8.8);

			dict1.Add(null, 11.1);

			dict1.Add("bar", 9.8);

			dict1.Add("foo", 8.8);

			dict1.Add("gib", 7.1);

			dict1.Add("S", -9);

			dict1.Add(null, 5.5);



			Assert.Equal("3.5, -1.2, 8.8",

				dict1["foo"].Write());

			Assert.Equal("7.1",

				dict1["gib"].Write());

			Assert.Equal("11.1, 5.5",

				dict1[null].Write());



			// Test with duplicate values.

			dict1 = new MultiDictionary<string, double>(true);



			dict1.Add("foo", 3.5);

			dict1.Add("foo", -1.2);

			dict1.Add(null, 11.1);

			dict1.Add("foo", 8.8);

			dict1.Add(null, 11.1);

			dict1.Add("bar", 9.8);

			dict1.Add("foo", 8.8);

			dict1.Add("gib", 7.1);

			dict1.Add("S", -9);

			dict1.Add(null, 5.5);



			Assert.Equal("3.5, -1.2, 8.8, 8.8",

				dict1["foo"].Write());

			Assert.Equal("7.1",

				dict1["gib"].Write());

			Assert.Equal("11.1, 11.1, 5.5",

				dict1[null].Write());

		}

		#endregion



		#region AddManyOne (LongRunning)

		/// <summary>

		/// Add many One. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void AddManyOne()

		{

			// Test without duplicate values.

			MultiDictionary<string, double> dict1 =

				new MultiDictionary<string, double>(

					false, StringComparer.InvariantCultureIgnoreCase);



			dict1.AddMany("foo", new[]

			{

				9.8, 1.2, -9, 9.8, -9, 4

			});

			dict1.AddMany("hi", new double[0]);

			dict1.AddMany("FOO", new double[]

			{

				8, -9

			});



			Assert.Equal(1, dict1.Count);

			Assert.True(dict1.ContainsKey("foo"));

			Assert.False(dict1.ContainsKey("hi"));

			CollectionBaseTests.CheckEnumerableElementsAnyOrder(

				dict1.Keys, new[]

				{

					"foo"

				});

			CollectionBaseTests.CheckEnumerableElementsAnyOrder(

				dict1["fOo"], new[]

				{

					-9, 1.2, 4, 8, 9.8

				});

			CollectionBaseTests.CheckEnumerableElementsAnyOrder(

				dict1.KeyValuePairs, new[]

				{

					new KeyValuePair<string, double>("foo", -9),

					new KeyValuePair<string, double>("foo", 1.2),

					new KeyValuePair<string, double>("foo", 4),

					new KeyValuePair<string, double>("foo", 8),

					new KeyValuePair<string, double>("foo", 9.8)

				});



			// Test with duplicate values

			dict1 = new MultiDictionary<string, double>(

				true, StringComparer.InvariantCultureIgnoreCase);



			dict1.AddMany("foo", new[]

			{

				9.8, 1.2, -9, 9.8, -9, 4

			});

			dict1.AddMany("hi", new double[0]);

			dict1.AddMany("a", new double[]

			{

				2, 1, 2

			});

			dict1.AddMany("FOO", new double[]

			{

				8, -9

			});



			Assert.Equal(2, dict1.Count);

			Assert.True(dict1.ContainsKey("foo"));

			Assert.False(dict1.ContainsKey("hi"));

			CollectionBaseTests.CheckEnumerableElementsAnyOrder(

				dict1.Keys, new[]

				{

					"a", "foo"

				});

			CollectionBaseTests.CheckEnumerableElementsAnyOrder(

				dict1["fOo"], new[]

				{

					-9, -9, -9, 1.2, 4, 8, 9.8, 9.8

				});

			CollectionBaseTests.CheckEnumerableElementsAnyOrder(

				dict1.KeyValuePairs, new[]

				{

					new KeyValuePair<string, double>("a", 1),

					new KeyValuePair<string, double>("a", 2),

					new KeyValuePair<string, double>("a", 2),

					new KeyValuePair<string, double>("foo", -9),

					new KeyValuePair<string, double>("foo", -9),

					new KeyValuePair<string, double>("foo", -9),

					new KeyValuePair<string, double>("foo", 1.2),

					new KeyValuePair<string, double>("foo", 4),

					new KeyValuePair<string, double>("foo", 8),

					new KeyValuePair<string, double>("foo", 9.8),

					new KeyValuePair<string, double>("foo", 9.8)

				});

		}

		#endregion



		#region Replace (LongRunning)

		/// <summary>

		/// Replace. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void Replace()

		{

			MultiDictionary<string, int> dict1 =

				new MultiDictionary<string, int>(true);



			dict1.Add("foo", 4);

			dict1.Add("bar", 7);

			dict1.Add("foo", 6);

			dict1.Add("z", 3);

			dict1.Add("bar", 8);

			dict1.Add("z", 3);

			dict1.Add("foo", 1);



			dict1.Replace("foo", 13);

			dict1.Replace("z", 19);

			dict1.Replace("hello", 193);

			dict1.Replace("foo", 123);

			dict1.Add("foo", 123);



			CheckMultiDictionaryContents(dict1,

				new[]

				{

					"bar", "foo", "hello", "z"

				},

				new[]

				{

					new[]

					{

						7, 8

					},

					new[]

					{

						123, 123

					},

					new[]

					{

						193

					},

					new[]

					{

						19

					}

				},

				"sailor", 19921);

		}

		#endregion



		#region ReplaceMany (LongRunning)

		/// <summary>

		/// Replace many. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void ReplaceMany()

		{

			MultiDictionary<string, int> dict1 =

				new MultiDictionary<string, int>(false);



			dict1.Add("foo", 4);

			dict1.Add("bar", 7);

			dict1.Add("foo", 6);

			dict1.Add("z", 3);

			dict1.Add("bar", 8);

			dict1.Add("z", 3);

			dict1.Add("foo", 1);

			dict1.Add("bill", 9);



			dict1.ReplaceMany("bill", new int[0]);

			dict1.ReplaceMany("foo", new[]

			{

				13, 4

			});

			dict1.ReplaceMany("z", new[]

			{

				19

			});

			dict1.ReplaceMany("hello", new[]

			{

				193, -11, 193

			});

			dict1.ReplaceMany("goodbye", new int[0]);

			dict1.ReplaceMany("foo", new[]

			{

				123, 0, 4

			});

			dict1.Add("foo", 29);



			CheckMultiDictionaryContents(dict1,

				new[]

				{

					"bar", "foo", "hello", "z"

				},

				new[]

				{

					new[]

					{

						7, 8

					},

					new[]

					{

						0, 4, 29, 123

					},

					new[]

					{

						-11, 193

					},

					new[]

					{

						19

					}

				},

				"sailor", 19921);

		}

		#endregion



		#region RemoveKey (LongRunning)

		/// <summary>

		/// Remove key. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void RemoveKey()

		{

			MultiDictionary<string, int> dict1 =

				new MultiDictionary<string, int>(true);



			dict1.Add("foo", 4);

			dict1.Add("bar", 7);

			dict1.Add("foo", 6);

			dict1.Add("z", 3);

			dict1.Add("bar", 8);

			dict1.Add("z", 10);

			dict1.Add("z", 3);

			dict1.Add("foo", 4);

			dict1.Add("bill", 9);



			Assert.True(dict1.ContainsKey("bill"));

			Assert.True(dict1.ContainsKey("foo"));

			Assert.True(dict1.ContainsKey("z"));



			Assert.True(dict1.Remove("bill"));

			Assert.False(dict1.Remove("bill"));

			Assert.False(dict1.Remove("smell"));

			Assert.True(dict1.Remove("foo"));



			CheckMultiDictionaryContents(dict1,

				new[]

				{

					"bar", "z"

				},

				new[]

				{

					new[]

					{

						7, 8

					}, new[]

					{

						3, 3, 10

					}

				},

				"sailor", 19921);

		}

		#endregion



		#region RemoveManyKeys (LongRunning)

		/// <summary>

		/// Remove many keys. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void RemoveManyKeys()

		{

			MultiDictionary<string, int> dict1 =

				new MultiDictionary<string, int>(true);



			dict1.Add("foo", 4);

			dict1.Add("bar", 7);

			dict1.Add("foo", 6);

			dict1.Add("z", 3);

			dict1.Add("bar", 8);

			dict1.Add("z", 10);

			dict1.Add("z", 3);

			dict1.Add("foo", 4);

			dict1.Add("bill", 9);



			Assert.True(dict1.ContainsKey("bill"));

			Assert.True(dict1.ContainsKey("foo"));

			Assert.True(dict1.ContainsKey("z"));



			Assert.Equal(2, dict1.RemoveMany(

				new[]

				{

					"bill", "smell", "foo", "bill"

				}));



			CheckMultiDictionaryContents(dict1,

				new[]

				{

					"bar", "z"

				},

				new[]

				{

					new[]

					{

						7, 8

					}, new[]

					{

						3, 3, 10

					}

				},

				"sailor", 19921);

		}

		#endregion



		#region Remove (LongRunning)

		/// <summary>

		/// Remove. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void Remove()

		{

			MultiDictionary<string, int> dict1 =

				new MultiDictionary<string, int>(true);



			dict1.Add("foo", 4);

			dict1.Add("bar", 7);

			dict1.Add("foo", 6);

			dict1.Add("z", 3);

			dict1.Add("bar", 8);

			dict1.Add("z", 10);

			dict1.Add("z", 3);

			dict1.Add("foo", 4);

			dict1.Add("bill", 9);

			dict1.Add("foo", 4);



			Assert.True(dict1.Remove("foo", 4));

			Assert.True(dict1.Remove("foo", 4));

			Assert.True(dict1.Remove("z", 10));

			Assert.False(dict1.Remove("z", 10));

			Assert.False(dict1.Remove("foo", 11));

			Assert.False(dict1.Remove(null, 0));

			Assert.True(dict1.Remove("bill", 9));



			CheckMultiDictionaryContents(dict1,

				new[]

				{

					"bar", "foo", "z"

				},

				new[]

				{

					new[]

					{

						7, 8

					},

					new[]

					{

						4, 6

					},

					new[]

					{

						3, 3

					}

				},

				"sailor", 19921);

		}

		#endregion



		#region RemoveManyOne (LongRunning)

		/// <summary>

		/// Remove many One. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void RemoveManyOne()

		{

			MultiDictionary<string, int> dict1 =

				new MultiDictionary<string, int>(true);



			dict1.Add("bill", 7);

			dict1.Add("foo", 4);

			dict1.Add("bar", 7);

			dict1.Add("foo", 6);

			dict1.Add("z", 3);

			dict1.Add("bar", 8);

			dict1.Add("z", 10);

			dict1.Add("z", 3);

			dict1.Add("foo", 4);

			dict1.Add("bill", 9);

			dict1.Add("foo", 4);



			Assert.Equal(2, dict1.RemoveMany("foo", new[]

			{

				4, 11, 4

			}));

			Assert.Equal(1, dict1.RemoveMany("z", new[]

			{

				9, 2, 10

			}));

			Assert.Equal(0, dict1.RemoveMany("z", new[]

			{

				10, 16, 144, 10

			}));

			Assert.Equal(0, dict1.RemoveMany("foo", new int[0]));

			Assert.Equal(0, dict1.RemoveMany(null, new int[2]

			{

				1, 2

			}));

			Assert.Equal(2, dict1.RemoveMany("bill", new[]

			{

				9, 7

			}));



			CheckMultiDictionaryContents(dict1,

				new[]

				{

					"bar", "foo", "z"

				},

				new[]

				{

					new[]

					{

						7, 8

					},

					new[]

					{

						4, 6

					},

					new[]

					{

						3, 3

					}

				},

				"sailor", 19921);

		}

		#endregion



		#region Clear (LongRunning)

		/// <summary>

		/// Clear. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void Clear()

		{

			MultiDictionary<string, int> dict1 =

				new MultiDictionary<string, int>(true);



			dict1.Add("foo", 4);

			dict1.Add("bill", 7);

			dict1.Add("foo", 4);

			dict1.Add("bar", 7);

			dict1.Add("foo", 6);

			dict1.Add("z", 3);

			dict1.Add("bar", 8);

			dict1.Add("z", 10);

			dict1.Add(null, 3);

			dict1.Add("foo", 4);

			dict1.Add("bill", 9);

			dict1.Add("foo", 4);



			dict1.Clear();



			Assert.Equal(0, dict1.Count);

			Assert.False(dict1.ContainsKey("foo"));

			Assert.False(dict1.ContainsKey("z"));

			Assert.False(dict1.ContainsKey(null));

			Assert.Equal(0, dict1.Keys.Count);

			Assert.Equal(0, dict1.Values.Count);

			Assert.Equal(0, dict1.KeyValuePairs.Count);



			CheckMultiDictionaryContents(dict1, new string[0],

				new int[0][], "foo", 4);

		}

		#endregion



		#region Count (LongRunning)

		/// <summary>

		/// Count. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void Count()

		{

			MultiDictionary<string, int> dict1 =

				new MultiDictionary<string, int>(true);



			dict1.Add("foo", 4);

			dict1.Add(null, 7);

			dict1.Add("bar", 11);

			dict1.Add("foo", 7);

			dict1.Add(null, 7);

			dict1.Add("hello", 11);

			dict1.Add("foo", 4);

			Assert.Equal(4, dict1.Count);



			MultiDictionary<string, int> dict2 =

				new MultiDictionary<string, int>(false);



			dict2.Add("foo", 4);

			dict2.Add(null, 7);

			dict2.Add("bar", 11);

			dict2.Add("foo", 7);

			dict2.Add(null, 7);

			dict2.Add("hello", 11);

			dict2.Add("foo", 4);

			Assert.Equal(4, dict2.Count);



			dict2.Remove("foo");

			Assert.Equal(3, dict2.Count);



			dict2.Clear();

			Assert.Equal(0, dict2.Count);

		}

		#endregion



		#region ContainsKey (LongRunning)

		/// <summary>

		/// Contains key. Note: Too slow for a dynamic unit test.

		/// </summary>

		[Test, Category("LongRunning")]

		public static void ContainsKey()

		{

			MultiDictionary<string, int> dict1 =

				new MultiDictionary<string, int>(true);



			dict1.Add("foo", 4);

			dict1.Add(null, 7);

			dict1.Add("bar", 11);

			dict1.Add("foo", 7);

			dict1.Add(null, 7);

			dict1.Add("hello", 11);

			dict1.Add("foo", 4);



			Assert.True(dict1.ContainsKey(null));

			Assert.True(dict1.ContainsKey("foo"));

			Assert.True(dict1…