Added read-only collection wrappers for IDictionary<>, IList<> and ICollection<> since the classes provided by the .NET framework in System.Collections.ObjectModel are incomplete and inconsistent (eg. System.Collections.ObjectModel.ReadOnlyCollection wraps an IList<>!); minor improvements to documentation; added ReverseComparer for inverting the results of an existing IComparer<> or simply comparing values in inverted order

git-svn-id: file:///srv/devel/repo-conversion/nusu@80 d2e56fa2-650e-0410-a79f-9358c0239efd

Source/Collections/ReadOnlyCollection.cs

@@ -0,0 +1,120 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace Nuclex.Support.Collections {
+
+  /// <summary>Wraps a Collection and prevents users from modifying it</summary>
+  /// <typeparam name="ItemType">Type of items to manage in the Collection</typeparam>
+  public class ReadOnlyCollection<ItemType> :
+    ICollection<ItemType>,
+    ICollection {
+
+    /// <summary>Initializes a new read-only Collection wrapper</summary>
+    /// <param name="collection">Collection that will be wrapped</param>
+    public ReadOnlyCollection(ICollection<ItemType> collection) {
+      this.typedCollection = collection;
+      this.objectCollection = (collection as ICollection);
+    }
+
+    /// <summary>Determines whether the List contains the specified item</summary>
+    /// <param name="item">Item that will be checked for</param>
+    /// <returns>True if the specified item is contained in the List</returns>
+    public bool Contains(ItemType item) {
+      return this.typedCollection.Contains(item);
+    }
+
+    /// <summary>Copies the contents of the List into an array</summary>
+    /// <param name="array">Array the List will be copied into</param>
+    /// <param name="arrayIndex">
+    ///   Starting index at which to begin filling the destination array
+    /// </param>
+    public void CopyTo(ItemType[] array, int arrayIndex) {
+      this.typedCollection.CopyTo(array, arrayIndex);
+    }
+
+    /// <summary>The number of items current contained in the List</summary>
+    public int Count {
+      get { return this.typedCollection.Count; }
+    }
+
+    /// <summary>Whether the List is write-protected</summary>
+    public bool IsReadOnly {
+      get { return true; }
+    }
+
+    /// <summary>Returns a new enumerator over the contents of the List</summary>
+    /// <returns>The new List contents enumerator</returns>
+    public IEnumerator<ItemType> GetEnumerator() {
+      return this.typedCollection.GetEnumerator();
+    }
+
+    #region ICollection<> implementation
+
+    /// <summary>Adds an item to the end of the List</summary>
+    /// <param name="item">Item that will be added to the List</param>
+    void ICollection<ItemType>.Add(ItemType item) {
+      throw new NotSupportedException(
+        "Adding items is not supported by the read-only List"
+      );
+    }
+
+    /// <summary>Removes all items from the List</summary>
+    void ICollection<ItemType>.Clear() {
+      throw new NotSupportedException(
+        "Clearing is not supported by the read-only List"
+      );
+    }
+
+    /// <summary>Removes the specified item from the List</summary>
+    /// <param name="item">Item that will be removed from the List</param>
+    /// <returns>True of the specified item was found in the List and removed</returns>
+    bool ICollection<ItemType>.Remove(ItemType item) {
+      throw new NotSupportedException(
+        "Removing items is not supported by the read-only List"
+      );
+    }
+
+    #endregion
+
+    #region IEnumerable implementation
+
+    /// <summary>Returns a new enumerator over the contents of the List</summary>
+    /// <returns>The new List contents enumerator</returns>
+    IEnumerator IEnumerable.GetEnumerator() {
+      return this.objectCollection.GetEnumerator();
+    }
+
+    #endregion
+
+    #region ICollection implementation
+
+    /// <summary>Copies the contents of the List into an array</summary>
+    /// <param name="array">Array the List will be copied into</param>
+    /// <param name="index">
+    ///   Starting index at which to begin filling the destination array
+    /// </param>
+    void ICollection.CopyTo(Array array, int index) {
+      throw new NotImplementedException();
+    }
+
+    /// <summary>Whether the List is synchronized for multi-threaded usage</summary>
+    bool ICollection.IsSynchronized {
+      get { throw new NotImplementedException(); }
+    }
+
+    /// <summary>Synchronization root on which the List locks</summary>
+    object ICollection.SyncRoot {
+      get { throw new NotImplementedException(); }
+    }
+
+    #endregion
+
+    /// <summary>The wrapped Collection under its type-safe interface</summary>
+    private ICollection<ItemType> typedCollection;
+    /// <summary>The wrapped Collection under its object interface</summary>
+    private ICollection objectCollection;
+
+  }
+
+} // namespace Nuclex.Support.Collections