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Diffstat (limited to 'src/DotNetOpenAuth.Messaging/Messaging/EmptyDictionary.cs')
| -rw-r--r-- | src/DotNetOpenAuth.Messaging/Messaging/EmptyDictionary.cs | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/src/DotNetOpenAuth.Messaging/Messaging/EmptyDictionary.cs b/src/DotNetOpenAuth.Messaging/Messaging/EmptyDictionary.cs new file mode 100644 index 0000000..9db5169 --- /dev/null +++ b/src/DotNetOpenAuth.Messaging/Messaging/EmptyDictionary.cs @@ -0,0 +1,250 @@ +//----------------------------------------------------------------------- +// <copyright file="EmptyDictionary.cs" company="Andrew Arnott"> +// Copyright (c) Andrew Arnott. All rights reserved. +// </copyright> +//----------------------------------------------------------------------- + +namespace DotNetOpenAuth.Messaging { + using System; + using System.Collections.Generic; + using System.Diagnostics.CodeAnalysis; + using System.Linq; + + /// <summary> + /// An empty dictionary. Useful for avoiding memory allocations in creating new dictionaries to represent empty ones. + /// </summary> + /// <typeparam name="TKey">The type of the key.</typeparam> + /// <typeparam name="TValue">The type of the value.</typeparam> + [Serializable] + internal class EmptyDictionary<TKey, TValue> : IDictionary<TKey, TValue> { + /// <summary> + /// The singleton instance of the empty dictionary. + /// </summary> + internal static readonly EmptyDictionary<TKey, TValue> Instance = new EmptyDictionary<TKey, TValue>(); + + /// <summary> + /// Prevents a default instance of the EmptyDictionary class from being created. + /// </summary> + private EmptyDictionary() { + } + + /// <summary> + /// Gets an <see cref="T:System.Collections.Generic.ICollection`1"/> containing the values in the <see cref="T:System.Collections.Generic.IDictionary`2"/>. + /// </summary> + /// <value></value> + /// <returns> + /// An <see cref="T:System.Collections.Generic.ICollection`1"/> containing the values in the object that implements <see cref="T:System.Collections.Generic.IDictionary`2"/>. + /// </returns> + public ICollection<TValue> Values { + get { return EmptyList<TValue>.Instance; } + } + + /// <summary> + /// Gets the number of elements contained in the <see cref="T:System.Collections.Generic.ICollection`1"/>. + /// </summary> + /// <value></value> + /// <returns> + /// The number of elements contained in the <see cref="T:System.Collections.Generic.ICollection`1"/>. + /// </returns> + public int Count { + get { return 0; } + } + + /// <summary> + /// Gets a value indicating whether the <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only. + /// </summary> + /// <value></value> + /// <returns>true if the <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only; otherwise, false. + /// </returns> + public bool IsReadOnly { + get { return true; } + } + + /// <summary> + /// Gets an <see cref="T:System.Collections.Generic.ICollection`1"/> containing the keys of the <see cref="T:System.Collections.Generic.IDictionary`2"/>. + /// </summary> + /// <value></value> + /// <returns> + /// An <see cref="T:System.Collections.Generic.ICollection`1"/> containing the keys of the object that implements <see cref="T:System.Collections.Generic.IDictionary`2"/>. + /// </returns> + public ICollection<TKey> Keys { + get { return EmptyList<TKey>.Instance; } + } + + /// <summary> + /// Gets or sets the value with the specified key. + /// </summary> + /// <param name="key">The key being read or written.</param> + public TValue this[TKey key] { + get { throw new KeyNotFoundException(); } + set { throw new NotSupportedException(); } + } + + /// <summary> + /// Adds an element with the provided key and value to the <see cref="T:System.Collections.Generic.IDictionary`2"/>. + /// </summary> + /// <param name="key">The object to use as the key of the element to add.</param> + /// <param name="value">The object to use as the value of the element to add.</param> + /// <exception cref="T:System.ArgumentNullException"> + /// <paramref name="key"/> is null. + /// </exception> + /// <exception cref="T:System.ArgumentException"> + /// An element with the same key already exists in the <see cref="T:System.Collections.Generic.IDictionary`2"/>. + /// </exception> + /// <exception cref="T:System.NotSupportedException"> + /// The <see cref="T:System.Collections.Generic.IDictionary`2"/> is read-only. + /// </exception> + public void Add(TKey key, TValue value) { + throw new NotSupportedException(); + } + + /// <summary> + /// Determines whether the <see cref="T:System.Collections.Generic.IDictionary`2"/> contains an element with the specified key. + /// </summary> + /// <param name="key">The key to locate in the <see cref="T:System.Collections.Generic.IDictionary`2"/>.</param> + /// <returns> + /// true if the <see cref="T:System.Collections.Generic.IDictionary`2"/> contains an element with the key; otherwise, false. + /// </returns> + /// <exception cref="T:System.ArgumentNullException"> + /// <paramref name="key"/> is null. + /// </exception> + public bool ContainsKey(TKey key) { + return false; + } + + /// <summary> + /// Removes the element with the specified key from the <see cref="T:System.Collections.Generic.IDictionary`2"/>. + /// </summary> + /// <param name="key">The key of the element to remove.</param> + /// <returns> + /// true if the element is successfully removed; otherwise, false. This method also returns false if <paramref name="key"/> was not found in the original <see cref="T:System.Collections.Generic.IDictionary`2"/>. + /// </returns> + /// <exception cref="T:System.ArgumentNullException"> + /// <paramref name="key"/> is null. + /// </exception> + /// <exception cref="T:System.NotSupportedException"> + /// The <see cref="T:System.Collections.Generic.IDictionary`2"/> is read-only. + /// </exception> + public bool Remove(TKey key) { + return false; + } + + /// <summary> + /// Gets the value associated with the specified key. + /// </summary> + /// <param name="key">The key whose value to get.</param> + /// <param name="value">When this method returns, the value associated with the specified key, if the key is found; otherwise, the default value for the type of the <paramref name="value"/> parameter. This parameter is passed uninitialized.</param> + /// <returns> + /// true if the object that implements <see cref="T:System.Collections.Generic.IDictionary`2"/> contains an element with the specified key; otherwise, false. + /// </returns> + /// <exception cref="T:System.ArgumentNullException"> + /// <paramref name="key"/> is null. + /// </exception> + public bool TryGetValue(TKey key, out TValue value) { + value = default(TValue); + return false; + } + + #region ICollection<KeyValuePair<TKey,TValue>> Members + + /// <summary> + /// Adds an item to the <see cref="T:System.Collections.Generic.ICollection`1"/>. + /// </summary> + /// <param name="item">The object to add to the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param> + /// <exception cref="T:System.NotSupportedException"> + /// The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only. + /// </exception> + [SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes", Justification = "Code Contracts ccrewrite does this.")] + public void Add(KeyValuePair<TKey, TValue> item) { + throw new NotSupportedException(); + } + + /// <summary> + /// Removes all items from the <see cref="T:System.Collections.Generic.ICollection`1"/>. + /// </summary> + /// <exception cref="T:System.NotSupportedException"> + /// The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only. + /// </exception> + public void Clear() { + throw new NotSupportedException(); + } + + /// <summary> + /// Determines whether the <see cref="T:System.Collections.Generic.ICollection`1"/> contains a specific value. + /// </summary> + /// <param name="item">The object to locate in the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param> + /// <returns> + /// true if <paramref name="item"/> is found in the <see cref="T:System.Collections.Generic.ICollection`1"/>; otherwise, false. + /// </returns> + public bool Contains(KeyValuePair<TKey, TValue> item) { + return false; + } + + /// <summary> + /// Copies the elements of the <see cref="T:System.Collections.Generic.ICollection`1"/> to an <see cref="T:System.Array"/>, starting at a particular <see cref="T:System.Array"/> index. + /// </summary> + /// <param name="array">The one-dimensional <see cref="T:System.Array"/> that is the destination of the elements copied from <see cref="T:System.Collections.Generic.ICollection`1"/>. The <see cref="T:System.Array"/> must have zero-based indexing.</param> + /// <param name="arrayIndex">The zero-based index in <paramref name="array"/> at which copying begins.</param> + /// <exception cref="T:System.ArgumentNullException"> + /// <paramref name="array"/> is null. + /// </exception> + /// <exception cref="T:System.ArgumentOutOfRangeException"> + /// <paramref name="arrayIndex"/> is less than 0. + /// </exception> + /// <exception cref="T:System.ArgumentException"> + /// <paramref name="array"/> is multidimensional. + /// -or- + /// <paramref name="arrayIndex"/> is equal to or greater than the length of <paramref name="array"/>. + /// -or- + /// The number of elements in the source <see cref="T:System.Collections.Generic.ICollection`1"/> is greater than the available space from <paramref name="arrayIndex"/> to the end of the destination <paramref name="array"/>. + /// -or- + /// Type cannot be cast automatically to the type of the destination <paramref name="array"/>. + /// </exception> + public void CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex) { + } + + /// <summary> + /// Removes the first occurrence of a specific object from the <see cref="T:System.Collections.Generic.ICollection`1"/>. + /// </summary> + /// <param name="item">The object to remove from the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param> + /// <returns> + /// true if <paramref name="item"/> was successfully removed from the <see cref="T:System.Collections.Generic.ICollection`1"/>; otherwise, false. This method also returns false if <paramref name="item"/> is not found in the original <see cref="T:System.Collections.Generic.ICollection`1"/>. + /// </returns> + /// <exception cref="T:System.NotSupportedException"> + /// The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only. + /// </exception> + public bool Remove(KeyValuePair<TKey, TValue> item) { + return false; + } + + #endregion + + #region IEnumerable<KeyValuePair<TKey,TValue>> Members + + /// <summary> + /// Returns an enumerator that iterates through the collection. + /// </summary> + /// <returns> + /// A <see cref="T:System.Collections.Generic.IEnumerator`1"/> that can be used to iterate through the collection. + /// </returns> + public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator() { + return Enumerable.Empty<KeyValuePair<TKey, TValue>>().GetEnumerator(); + } + + #endregion + + #region IEnumerable Members + + /// <summary> + /// Returns an enumerator that iterates through a collection. + /// </summary> + /// <returns> + /// An <see cref="T:System.Collections.IEnumerator"/> object that can be used to iterate through the collection. + /// </returns> + System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { + return EmptyEnumerator.Instance; + } + + #endregion + } +} |