src/DotNetOpenAuth/Messaging/EmptyList.cs

   1 //-----------------------------------------------------------------------
   2 // <copyright file="EmptyList.cs" company="Andrew Arnott">
   3 //     Copyright (c) Andrew Arnott. All rights reserved.
   4 // </copyright>
   5 //-----------------------------------------------------------------------
   6
   7 namespace DotNetOpenAuth.Messaging {
   8         using System;
   9         using System.Collections.Generic;
  10
  11         /// <summary>
  12         /// An empty, read-only list.
  13         /// </summary>
  14         /// <typeparam name="T">The type the list claims to include.</typeparam>
  15         internal class EmptyList<T> : IList<T> {
  16                 /// <summary>
  17                 /// The singleton instance of the empty list.
  18                 /// </summary>
  19                 internal static readonly EmptyList<T> Instance = new EmptyList<T>();
  20
  21                 /// <summary>
  22                 /// Prevents a default instance of the EmptyList class from being created.
  23                 /// </summary>
  24                 private EmptyList() {
  25                 }
  26
  27                 /// <summary>
  28                 /// Gets the number of elements contained in the <see cref="T:System.Collections.Generic.ICollection`1"/>.
  29                 /// </summary>
  30                 /// <value></value>
  31                 /// <returns>
  32                 /// The number of elements contained in the <see cref="T:System.Collections.Generic.ICollection`1"/>.
  33                 /// </returns>
  34                 public int Count {
  35                         get { return 0; }
  36                 }
  37
  38                 /// <summary>
  39                 /// Gets a value indicating whether the <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.
  40                 /// </summary>
  41                 /// <value></value>
  42                 /// <returns>true if the <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only; otherwise, false.
  43                 /// </returns>
  44                 public bool IsReadOnly {
  45                         get { return true; }
  46                 }
  47
  48                 #region IList<T> Members
  49
  50                 /// <summary>
  51                 /// Gets or sets the <typeparamref name="T"/> at the specified index.
  52                 /// </summary>
  53                 /// <param name="index">The index of the element in the list to change.</param>
  54                 public T this[int index] {
  55                         get {
  56                                 throw new ArgumentOutOfRangeException("index");
  57                         }
  58
  59                         set {
  60                                 throw new ArgumentOutOfRangeException("index");
  61                         }
  62                 }
  63
  64                 /// <summary>
  65                 /// Determines the index of a specific item in the <see cref="T:System.Collections.Generic.IList`1"/>.
  66                 /// </summary>
  67                 /// <param name="item">The object to locate in the <see cref="T:System.Collections.Generic.IList`1"/>.</param>
  68                 /// <returns>
  69                 /// The index of <paramref name="item"/> if found in the list; otherwise, -1.
  70                 /// </returns>
  71                 public int IndexOf(T item) {
  72                         return -1;
  73                 }
  74
  75                 /// <summary>
  76                 /// Inserts an item to the <see cref="T:System.Collections.Generic.IList`1"/> at the specified index.
  77                 /// </summary>
  78                 /// <param name="index">The zero-based index at which <paramref name="item"/> should be inserted.</param>
  79                 /// <param name="item">The object to insert into the <see cref="T:System.Collections.Generic.IList`1"/>.</param>
  80                 /// <exception cref="T:System.ArgumentOutOfRangeException">
  81                 ///     <paramref name="index"/> is not a valid index in the <see cref="T:System.Collections.Generic.IList`1"/>.
  82                 /// </exception>
  83                 /// <exception cref="T:System.NotSupportedException">
  84                 /// The <see cref="T:System.Collections.Generic.IList`1"/> is read-only.
  85                 /// </exception>
  86                 public void Insert(int index, T item) {
  87                         throw new NotSupportedException();
  88                 }
  89
  90                 /// <summary>
  91                 /// Removes the <see cref="T:System.Collections.Generic.IList`1"/> item at the specified index.
  92                 /// </summary>
  93                 /// <param name="index">The zero-based index of the item to remove.</param>
  94                 /// <exception cref="T:System.ArgumentOutOfRangeException">
  95                 ///     <paramref name="index"/> is not a valid index in the <see cref="T:System.Collections.Generic.IList`1"/>.
  96                 /// </exception>
  97                 /// <exception cref="T:System.NotSupportedException">
  98                 /// The <see cref="T:System.Collections.Generic.IList`1"/> is read-only.
  99                 /// </exception>
 100                 public void RemoveAt(int index) {
 101                         throw new ArgumentOutOfRangeException("index");
 102                 }
 103
 104                 #endregion
 105
 106                 #region ICollection<T> Members
 107
 108                 /// <summary>
 109                 /// Adds an item to the <see cref="T:System.Collections.Generic.ICollection`1"/>.
 110                 /// </summary>
 111                 /// <param name="item">The object to add to the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param>
 112                 /// <exception cref="T:System.NotSupportedException">
 113                 /// The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.
 114                 /// </exception>
 115                 public void Add(T item) {
 116                         throw new NotSupportedException();
 117                 }
 118
 119                 /// <summary>
 120                 /// Removes all items from the <see cref="T:System.Collections.Generic.ICollection`1"/>.
 121                 /// </summary>
 122                 /// <exception cref="T:System.NotSupportedException">
 123                 /// The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.
 124                 /// </exception>
 125                 public void Clear() {
 126                         throw new NotSupportedException();
 127                 }
 128
 129                 /// <summary>
 130                 /// Determines whether the <see cref="T:System.Collections.Generic.ICollection`1"/> contains a specific value.
 131                 /// </summary>
 132                 /// <param name="item">The object to locate in the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param>
 133                 /// <returns>
 134                 /// true if <paramref name="item"/> is found in the <see cref="T:System.Collections.Generic.ICollection`1"/>; otherwise, false.
 135                 /// </returns>
 136                 public bool Contains(T item) {
 137                         return false;
 138                 }
 139
 140                 /// <summary>
 141                 /// 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.
 142                 /// </summary>
 143                 /// <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>
 144                 /// <param name="arrayIndex">The zero-based index in <paramref name="array"/> at which copying begins.</param>
 145                 /// <exception cref="T:System.ArgumentNullException">
 146                 ///     <paramref name="array"/> is null.
 147                 /// </exception>
 148                 /// <exception cref="T:System.ArgumentOutOfRangeException">
 149                 ///     <paramref name="arrayIndex"/> is less than 0.
 150                 /// </exception>
 151                 /// <exception cref="T:System.ArgumentException">
 152                 ///     <paramref name="array"/> is multidimensional.
 153                 /// -or-
 154                 /// <paramref name="arrayIndex"/> is equal to or greater than the length of <paramref name="array"/>.
 155                 /// -or-
 156                 /// 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"/>.
 157                 /// -or-
 158                 /// Type <paramref name="T"/> cannot be cast automatically to the type of the destination <paramref name="array"/>.
 159                 /// </exception>
 160                 public void CopyTo(T[] array, int arrayIndex) {
 161                 }
 162
 163                 /// <summary>
 164                 /// Removes the first occurrence of a specific object from the <see cref="T:System.Collections.Generic.ICollection`1"/>.
 165                 /// </summary>
 166                 /// <param name="item">The object to remove from the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param>
 167                 /// <returns>
 168                 /// 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"/>.
 169                 /// </returns>
 170                 /// <exception cref="T:System.NotSupportedException">
 171                 /// The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.
 172                 /// </exception>
 173                 public bool Remove(T item) {
 174                         return false;
 175                 }
 176
 177                 #endregion
 178
 179                 #region IEnumerable<T> Members
 180
 181                 /// <summary>
 182                 /// Returns an enumerator that iterates through the collection.
 183                 /// </summary>
 184                 /// <returns>
 185                 /// A <see cref="T:System.Collections.Generic.IEnumerator`1"/> that can be used to iterate through the collection.
 186                 /// </returns>
 187                 public IEnumerator<T> GetEnumerator() {
 188                         return System.Linq.Enumerable.Empty<T>().GetEnumerator();
 189                 }
 190
 191                 #endregion
 192
 193                 #region IEnumerable Members
 194
 195                 /// <summary>
 196                 /// Returns an enumerator that iterates through a collection.
 197                 /// </summary>
 198                 /// <returns>
 199                 /// An <see cref="T:System.Collections.IEnumerator"/> object that can be used to iterate through the collection.
 200                 /// </returns>
 201                 System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() {
 202                         return EmptyEnumerator.Instance;
 203                 }
 204
 205                 #endregion
 206         }
 207 }