//-----------------------------------------------------------------------
//
// Copyright (c) Outercurve Foundation. All rights reserved.
//
//-----------------------------------------------------------------------
namespace DotNetOpenAuth.Messaging {
using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
///
/// An empty dictionary. Useful for avoiding memory allocations in creating new dictionaries to represent empty ones.
///
/// The type of the key.
/// The type of the value.
[Serializable]
internal class EmptyDictionary : IDictionary {
///
/// The singleton instance of the empty dictionary.
///
internal static readonly EmptyDictionary Instance = new EmptyDictionary();
///
/// Prevents a default instance of the EmptyDictionary class from being created.
///
private EmptyDictionary() {
}
///
/// Gets an containing the values in the .
///
///
///
/// An containing the values in the object that implements .
///
public ICollection Values {
get { return EmptyList.Instance; }
}
///
/// Gets the number of elements contained in the .
///
///
///
/// The number of elements contained in the .
///
public int Count {
get { return 0; }
}
///
/// Gets a value indicating whether the is read-only.
///
///
/// true if the is read-only; otherwise, false.
///
public bool IsReadOnly {
get { return true; }
}
///
/// Gets an containing the keys of the .
///
///
///
/// An containing the keys of the object that implements .
///
public ICollection Keys {
get { return EmptyList.Instance; }
}
///
/// Gets or sets the value with the specified key.
///
/// The key being read or written.
/// Nothing. It always throws.
public TValue this[TKey key] {
get { throw new KeyNotFoundException(); }
set { throw new NotSupportedException(); }
}
///
/// Adds an element with the provided key and value to the .
///
/// The object to use as the key of the element to add.
/// The object to use as the value of the element to add.
///
/// is null.
///
///
/// An element with the same key already exists in the .
///
///
/// The is read-only.
///
public void Add(TKey key, TValue value) {
throw new NotSupportedException();
}
///
/// Determines whether the contains an element with the specified key.
///
/// The key to locate in the .
///
/// true if the contains an element with the key; otherwise, false.
///
///
/// is null.
///
public bool ContainsKey(TKey key) {
return false;
}
///
/// Removes the element with the specified key from the .
///
/// The key of the element to remove.
///
/// true if the element is successfully removed; otherwise, false. This method also returns false if was not found in the original .
///
///
/// is null.
///
///
/// The is read-only.
///
public bool Remove(TKey key) {
return false;
}
///
/// Gets the value associated with the specified key.
///
/// The key whose value to get.
/// 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 parameter. This parameter is passed uninitialized.
///
/// true if the object that implements contains an element with the specified key; otherwise, false.
///
///
/// is null.
///
public bool TryGetValue(TKey key, out TValue value) {
value = default(TValue);
return false;
}
#region ICollection> Members
///
/// Adds an item to the .
///
/// The object to add to the .
///
/// The is read-only.
///
[SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes", Justification = "Code Contracts ccrewrite does this.")]
public void Add(KeyValuePair item) {
throw new NotSupportedException();
}
///
/// Removes all items from the .
///
///
/// The is read-only.
///
public void Clear() {
throw new NotSupportedException();
}
///
/// Determines whether the contains a specific value.
///
/// The object to locate in the .
///
/// true if is found in the ; otherwise, false.
///
public bool Contains(KeyValuePair item) {
return false;
}
///
/// Copies the elements of the to an , starting at a particular index.
///
/// The one-dimensional that is the destination of the elements copied from . The must have zero-based indexing.
/// The zero-based index in at which copying begins.
///
/// is null.
///
///
/// is less than 0.
///
///
/// is multidimensional.
/// -or-
/// is equal to or greater than the length of .
/// -or-
/// The number of elements in the source is greater than the available space from to the end of the destination .
/// -or-
/// Type cannot be cast automatically to the type of the destination .
///
public void CopyTo(KeyValuePair[] array, int arrayIndex) {
}
///
/// Removes the first occurrence of a specific object from the .
///
/// The object to remove from the .
///
/// true if was successfully removed from the ; otherwise, false. This method also returns false if is not found in the original .
///
///
/// The is read-only.
///
public bool Remove(KeyValuePair item) {
return false;
}
#endregion
#region IEnumerable> Members
///
/// Returns an enumerator that iterates through the collection.
///
///
/// A that can be used to iterate through the collection.
///
public IEnumerator> GetEnumerator() {
return Enumerable.Empty>().GetEnumerator();
}
#endregion
#region IEnumerable Members
///
/// Returns an enumerator that iterates through a collection.
///
///
/// An object that can be used to iterate through the collection.
///
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() {
return EmptyEnumerator.Instance;
}
#endregion
}
}