The deque class now fully supports the IList<> and IList interfaces (with the exception of CopyTo() and CopyToArray() which are not implemented yet); implemented a Clear() method; the deque enumerator is now fully functioning (but still missing an out-of-sync check); moved IndexOf() into its own file; wrote several additional unit tests to verify all the new interface methods are working and to keep test coverage at 100%

git-svn-id: file:///srv/devel/repo-conversion/nusu@163 d2e56fa2-650e-0410-a79f-9358c0239efd

Nuclex.Support (Xbox 360).csproj

@@ -73,9 +73,15 @@
     <Compile Include="Source\Collections\Deque.Insertion.cs">
       <DependentUpon>Deque.cs</DependentUpon>
     </Compile>
+    <Compile Include="Source\Collections\Deque.Interfaces.cs">
+      <DependentUpon>Deque.cs</DependentUpon>
+    </Compile>
     <Compile Include="Source\Collections\Deque.Removal.cs">
       <DependentUpon>Deque.cs</DependentUpon>
     </Compile>
+    <Compile Include="Source\Collections\Deque.Search.cs">
+      <DependentUpon>Deque.cs</DependentUpon>
+    </Compile>
     <Compile Include="Source\Collections\Deque.Test.cs">
       <DependentUpon>Deque.cs</DependentUpon>
     </Compile>

Nuclex.Support.csproj

@@ -55,9 +55,15 @@
     <Compile Include="Source\Collections\Deque.Insertion.cs">
       <DependentUpon>Deque.cs</DependentUpon>
     </Compile>
+    <Compile Include="Source\Collections\Deque.Interfaces.cs">
+      <DependentUpon>Deque.cs</DependentUpon>
+    </Compile>
     <Compile Include="Source\Collections\Deque.Removal.cs">
       <DependentUpon>Deque.cs</DependentUpon>
     </Compile>
+    <Compile Include="Source\Collections\Deque.Search.cs">
+      <DependentUpon>Deque.cs</DependentUpon>
+    </Compile>
     <Compile Include="Source\Collections\Deque.Test.cs">
       <DependentUpon>Deque.cs</DependentUpon>
     </Compile>

Source/Collections/Deque.Insertion.cs

@@ -23,14 +23,14 @@ namespace Nuclex.Support.Collections {
     /// <summary>Appends an item to the end of the double-ended queue</summary>
     /// <param name="item">Item that will be appended to the queue</param>
     public void AddLast(ItemType item) {
-      if(this.lastBlockEndIndex < this.blockSize) {
+      if(this.lastBlockCount < this.blockSize) {
-        ++this.lastBlockEndIndex;
+        ++this.lastBlockCount;
       } else { // Need to allocate a new block
         this.blocks.Add(new ItemType[this.blockSize]);
-        this.lastBlockEndIndex = 1;
+        this.lastBlockCount = 1;
       }
 
-      this.blocks[this.blocks.Count - 1][this.lastBlockEndIndex - 1] = item;
+      this.blocks[this.blocks.Count - 1][this.lastBlockCount - 1] = item;
       ++this.count;
     }
 
@@ -137,15 +137,15 @@ namespace Nuclex.Support.Collections {
         int blockLength;
 
         // If the lastmost block is full, we need to add another block
-        if(this.lastBlockEndIndex == this.blockSize) {
+        if(this.lastBlockCount == this.blockSize) {
           this.blocks.Add(new ItemType[this.blockSize]);
           this.blocks[lastBlock + 1][0] = this.blocks[lastBlock][this.blockSize - 1];
-          this.lastBlockEndIndex = 1;
+          this.lastBlockCount = 1;
 
           blockLength = this.blockSize - 1;
         } else {
-          blockLength = this.lastBlockEndIndex;
+          blockLength = this.lastBlockCount;
-          ++this.lastBlockEndIndex;
+          ++this.lastBlockCount;
         }
 
         // If the insertion point is not in the lastmost block

Source/Collections/Deque.Interfaces.cs

@@ -0,0 +1,126 @@
+using System;
+using System.Collections.Generic;
+using System.Collections;
+
+namespace Nuclex.Support.Collections {
+
+  partial class Deque<ItemType> {
+
+    #region IEnumerable members
+
+    /// <summary>Obtains a new enumerator for the contents of the deque</summary>
+    /// <returns>The new enumerator</returns>
+    IEnumerator IEnumerable.GetEnumerator() {
+      return new Enumerator(this);
+    }
+
+    #endregion
+
+    #region IList Members
+
+    /// <summary>Adds an item to the deque</summary>
+    /// <param name="value">Item that will be added to the deque</param>
+    /// <returns>The index at which the new item was added</returns>
+    int IList.Add(object value) {
+      verifyCompatibleObject(value);
+
+      AddLast((ItemType)value);
+      return this.count - 1;
+    }
+
+    /// <summary>Checks whether the deque contains the specified item</summary>
+    /// <param name="value">Item the deque will be scanned for</param>
+    /// <returns>True if the deque contained the specified item</returns>
+    bool IList.Contains(object value) {
+      return isCompatibleObject(value) && Contains((ItemType)value);
+    }
+
+    /// <summary>Determines the index of the item in the deque</summary>
+    /// <param name="value">Item whose index will be determined</param>
+    /// <returns>The index of the specified item in the deque</returns>
+    int IList.IndexOf(object value) {
+      if(isCompatibleObject(value)) {
+        return IndexOf((ItemType)value);
+      } else {
+        return -1;
+      }
+    }
+
+    /// <summary>Inserts an item into the deque at the specified location</summary>
+    /// <param name="index">Index at which the item will be inserted</param>
+    /// <param name="value">Item that will be inserted</param>
+    void IList.Insert(int index, object value) {
+      verifyCompatibleObject(value);
+      Insert(index, (ItemType)value);
+    }
+
+    /// <summary>Whether the deque has a fixed size</summary>
+    bool IList.IsFixedSize {
+      get { return false; }
+    }
+
+    /// <summary>Whether the deque is read-only</summary>
+    bool IList.IsReadOnly {
+      get { throw new NotImplementedException(); }
+    }
+
+    /// <summary>Removes the specified item from the deque</summary>
+    /// <param name="value">Item that will be removed from the deque</param>
+    void IList.Remove(object value) {
+      if(isCompatibleObject(value)) {
+        Remove((ItemType)value);
+      }
+    }
+
+    /// <summary>Accesses an item in the deque by its index</summary>
+    /// <param name="index">Index of the item that will be accessed</param>
+    /// <returns>The item at the specified index</returns>
+    object IList.this[int index] {
+      get { return this[index]; }
+      set {
+        verifyCompatibleObject(value);
+        this[index] = (ItemType)value;
+      }
+    }
+
+    #endregion
+
+    #region ICollection<ItemType> Members
+
+    /// <summary>Adds an item into the deque</summary>
+    /// <param name="item">Item that will be added to the deque</param>
+    void ICollection<ItemType>.Add(ItemType item) {
+      AddLast(item);
+    }
+
+    /// <summary>Whether the collection is read-only</summary>
+    bool ICollection<ItemType>.IsReadOnly {
+      get { return false; }
+    }
+
+    #endregion
+
+    #region ICollection Members
+
+    /// <summary>Copies the contents of the deque into an array</summary>
+    /// <param name="array">Array the contents of the deque will be copied into</param>
+    /// <param name="index">Index at which writing into the array will begin</param>
+    void ICollection.CopyTo(Array array, int index) {
+      throw new NotImplementedException();
+    }
+
+    /// <summary>Whether the deque is thread-synchronized</summary>
+    bool ICollection.IsSynchronized {
+      get { return false; }
+    }
+
+    /// <summary>Synchronization root of the instance</summary>
+    object ICollection.SyncRoot {
+      get { return this; }
+    }
+
+    #endregion
+
+  }
+
+} // namespace Nuclex.Support.Collections

Source/Collections/Deque.Removal.cs

@@ -6,6 +6,49 @@ namespace Nuclex.Support.Collections {
 
   partial class Deque<ItemType> {
 
+    /// <summary>Removes all items from the deque</summary>
+    public void Clear() {
+      if(this.blocks.Count > 1) { // Are there multiple blocks?
+
+        // Clear the items in the first block to avoid holding on to references
+        // in memory unreachable to the user
+        for(int index = this.firstBlockStartIndex; index < this.blockSize; ++index) {
+          this.blocks[0][index] = default(ItemType);
+        }
+
+        // Remove any other blocks
+        this.blocks.RemoveRange(1, this.blocks.Count - 1);
+
+      } else { // Nope, only a single block exists
+
+        // Clear the items in the block to release any reference we may be keeping alive
+        for(
+          int index = this.firstBlockStartIndex; index < this.lastBlockCount; ++index
+        ) {
+          this.blocks[0][index] = default(ItemType);
+        }
+
+      }
+
+      // Reset the counters to restart the deque from scratch
+      this.firstBlockStartIndex = 0;
+      this.lastBlockCount = 0;
+      this.count = 0;
+    }
+
+    /// <summary>Removes the specified item from the deque</summary>
+    /// <param name="item">Item that will be removed from the deque</param>
+    /// <returns>True if the item was found and removed</returns>
+    public bool Remove(ItemType item) {
+      int index = IndexOf(item);
+      if(index == -1) {
+        return false;
+      }
+
+      RemoveAt(index);
+      return true;
+    }
+
     /// <summary>Removes the first item in the double-ended queue</summary>
     public void RemoveFirst() {
       if(this.count == 0) {
@@ -16,6 +59,8 @@ namespace Nuclex.Support.Collections {
       // in unreachable spaces of its memory.
       this.blocks[0][this.firstBlockStartIndex] = default(ItemType);
 
+      // Cut off the item from the first block. If the block became empty and it's
+      // not the last remaining block, remove it as well.
       ++this.firstBlockStartIndex;
       if(this.firstBlockStartIndex >= this.blockSize) { // Block became empty
         if(this.count > 1) { // Still more blocks in queue, remove block
@@ -23,7 +68,7 @@ namespace Nuclex.Support.Collections {
           this.firstBlockStartIndex = 0;
         } else { // Last block - do not remove
           this.firstBlockStartIndex = 0;
-          this.lastBlockEndIndex = 0;
+          this.lastBlockCount = 0;
         }
       }
       --this.count;
@@ -38,16 +83,18 @@ namespace Nuclex.Support.Collections {
       // This is necessary to make sure the deque doesn't hold dead objects alive
       // in unreachable spaces of its memory.
       int lastBlock = this.blocks.Count - 1;
-      this.blocks[lastBlock][this.lastBlockEndIndex - 1] = default(ItemType);
+      this.blocks[lastBlock][this.lastBlockCount - 1] = default(ItemType);
 
-      --this.lastBlockEndIndex;
+      // Cut off the last item in the last block. If the block became empty and it's
-      if(this.lastBlockEndIndex == 0) { // Block became empty
+      // not the last remaining block, remove it as well.
+      --this.lastBlockCount;
+      if(this.lastBlockCount == 0) { // Block became empty
         if(this.count > 1) {
           this.blocks.RemoveAt(lastBlock);
-          this.lastBlockEndIndex = this.blockSize;
+          this.lastBlockCount = this.blockSize;
         } else { // Last block - do not remove
           this.firstBlockStartIndex = 0;
-          this.lastBlockEndIndex = 0;
+          this.lastBlockCount = 0;
         }
       }
       --this.count;
@@ -159,15 +206,15 @@ namespace Nuclex.Support.Collections {
         Array.Copy(
           this.blocks[lastBlock], startIndex + 1,
           this.blocks[lastBlock], startIndex,
-          this.lastBlockEndIndex - startIndex - 1
+          this.lastBlockCount - startIndex - 1
         );
 
-        if(this.lastBlockEndIndex == 1) {
+        if(this.lastBlockCount == 1) {
           this.blocks.RemoveAt(lastBlock);
-          this.lastBlockEndIndex = this.blockSize;
+          this.lastBlockCount = this.blockSize;
         } else {
-          this.blocks[lastBlock][this.lastBlockEndIndex - 1] = default(ItemType);
+          this.blocks[lastBlock][this.lastBlockCount - 1] = default(ItemType);
-          --this.lastBlockEndIndex;
+          --this.lastBlockCount;
         }
 
         --this.count;

Source/Collections/Deque.Search.cs

@@ -0,0 +1,66 @@
+using System;
+using System.Collections.Generic;
+using System.Collections;
+
+namespace Nuclex.Support.Collections {
+
+  partial class Deque<ItemType> {
+
+    /// <summary>
+    ///   Determines the index of the first occurence of the specified item in the deque
+    /// </summary>
+    /// <param name="item">Item that will be located in the deque</param>
+    /// <returns>The index of the item or -1 if it wasn't found</returns>
+    public int IndexOf(ItemType item) {
+      if(this.blocks.Count == 1) { // Only one block to scan?
+        int length = this.lastBlockCount - this.firstBlockStartIndex;
+        int index = Array.IndexOf<ItemType>(
+          this.blocks[0], item, this.firstBlockStartIndex, length
+        );
+
+        // If we found something, we need to adjust its index so the first item in
+        // the deque always appears at index 0 to the user
+        if(index != -1) {
+          return (index - this.firstBlockStartIndex);
+        } else {
+          return -1;
+        }
+      } else { // At least two blocks exist
+
+        // Scan the first block for the item and if found, return the index
+        int length = this.blockSize - this.firstBlockStartIndex;
+        int index = Array.IndexOf<ItemType>(
+          this.blocks[0], item, this.firstBlockStartIndex, length
+        );
+
+        // If we found something, we need to adjust its index
+        if(index != -1) {
+          return (index - this.firstBlockStartIndex);
+        }
+
+        int lastBlock = this.blocks.Count - 1;
+        for(int tempIndex = 1; tempIndex < lastBlock; ++tempIndex) {
+          index = Array.IndexOf<ItemType>(
+            this.blocks[tempIndex], item, 0, this.blockSize
+          );
+          if(index != -1) {
+            return (index - this.firstBlockStartIndex + tempIndex * this.blockSize);
+          }
+        }
+
+        // Nothing found, continue the search in the 
+        index = Array.IndexOf<ItemType>(
+          this.blocks[lastBlock], item, 0, this.lastBlockCount
+        );
+        if(index == -1) {
+          return -1;
+        } else {
+          return (index - this.firstBlockStartIndex + lastBlock * this.blockSize);
+        }
+
+      }
+    }
+
+  }
+
+} // namespace Nuclex.Support.Collections

Source/Collections/Deque.Test.cs

@@ -21,6 +21,7 @@ License along with this library
 #if UNITTEST
 
 using System;
+using System.Collections;
 using System.Collections.Generic;
 
 using NUnit.Framework;
@@ -103,10 +104,7 @@ namespace Nuclex.Support.Collections {
     [Test]
     public void TestInsert() {
       for(int testedIndex = 0; testedIndex <= 96; ++testedIndex) {
-        Deque<int> intDeque = new Deque<int>(16);
+        Deque<int> intDeque = createDeque(96);
-        for(int item = 0; item < 96; ++item) {
-          intDeque.AddLast(item);
-        }
 
         intDeque.Insert(testedIndex, 12345);
 
@@ -129,14 +127,7 @@ namespace Nuclex.Support.Collections {
     [Test]
     public void TestInsertNonNormalized() {
       for(int testedIndex = 0; testedIndex <= 96; ++testedIndex) {
-        Deque<int> intDeque = new Deque<int>(16);
+        Deque<int> intDeque = createNonNormalizedDeque(96);
-        for(int item = 4; item < 96; ++item) {
-          intDeque.AddLast(item);
-        }
-        intDeque.AddFirst(3);
-        intDeque.AddFirst(2);
-        intDeque.AddFirst(1);
-        intDeque.AddFirst(0);
 
         intDeque.Insert(testedIndex, 12345);
 
@@ -301,10 +292,7 @@ namespace Nuclex.Support.Collections {
     /// </summary>
     [Test]
     public void TestIndexAssignment() {
-      Deque<int> intDeque = new Deque<int>(16);
+      Deque<int> intDeque = createDeque(32);
-      for(int item = 0; item < 32; ++item) {
-        intDeque.AddLast(item);
-      }
       intDeque[16] = 12345;
       intDeque[17] = 54321;
 
@@ -351,7 +339,290 @@ namespace Nuclex.Support.Collections {
     /// </summary>
     [Test, TestCase(0), TestCase(16), TestCase(32), TestCase(48)]
     public void TestIndexOfNonNormalized(int count) {
+      Deque<int> intDeque = createNonNormalizedDeque(count);
+
+      for(int item = 0; item < count; ++item) {
+        Assert.AreEqual(item, intDeque.IndexOf(item));
+      }
+      Assert.AreEqual(-1, intDeque.IndexOf(count));
+    }
+
+    /// <summary>Verifies that the deque's enumerator works</summary>
+    [Test]
+    public void TestEnumerator() {
+      Deque<int> intDeque = createNonNormalizedDeque(40);
+
+      for(int testRun = 0; testRun < 2; ++testRun) {
+        using(IEnumerator<int> enumerator = intDeque.GetEnumerator()) {
+          for(int index = 0; index < intDeque.Count; ++index) {
+            Assert.IsTrue(enumerator.MoveNext());
+            Assert.AreEqual(index, enumerator.Current);
+          }
+
+          Assert.IsFalse(enumerator.MoveNext());
+
+          enumerator.Reset();
+        }
+      }
+    }
+
+    /// <summary>Verifies that the deque's enumerator works</summary>
+    [Test]
+    public void TestObjectEnumerator() {
+      Deque<int> intDeque = createNonNormalizedDeque(40);
+
+      for(int testRun = 0; testRun < 2; ++testRun) {
+        IEnumerator enumerator = ((IEnumerable)intDeque).GetEnumerator();
+        for(int index = 0; index < intDeque.Count; ++index) {
+          Assert.IsTrue(enumerator.MoveNext());
+          Assert.AreEqual(index, enumerator.Current);
+        }
+
+        Assert.IsFalse(enumerator.MoveNext());
+
+        enumerator.Reset();
+      }
+    }
+
+    /// <summary>
+    ///   Verifies that an exception is thrown if the enumerator is accessed in
+    ///   an invalid position
+    /// </summary>
+    [Test]
+    public void TestThrowOnInvalidEnumeratorPosition() {
+      Deque<int> intDeque = createNonNormalizedDeque(40);
+
+      using(IEnumerator<int> enumerator = intDeque.GetEnumerator()) {
+        Assert.Throws<InvalidOperationException>(
+          delegate() { Console.WriteLine(enumerator.Current); }
+        );
+
+        while(enumerator.MoveNext()) { }
+
+        Assert.Throws<InvalidOperationException>(
+          delegate() { Console.WriteLine(enumerator.Current); }
+        );
+      }
+    }
+
+    /// <summary>Tests whether a small deque can be cleared</summary>
+    [Test]
+    public void TestClearSmallDeque() {
+      Deque<int> intDeque = createDeque(12);
+      intDeque.Clear();
+      Assert.AreEqual(0, intDeque.Count);
+    }
+
+    /// <summary>Tests whether a large deque can be cleared</summary>
+    [Test]
+    public void TestClearLargeDeque() {
+      Deque<int> intDeque = createDeque(40);
+      intDeque.Clear();
+      Assert.AreEqual(0, intDeque.Count);
+    }
+
+    /// <summary>Verifies that the non-typesafe Add() method is working</summary>
+    [Test]
+    public void TestAddObject() {
+      Deque<int> intDeque = new Deque<int>();
+      Assert.AreEqual(0, ((IList)intDeque).Add(123));
+      Assert.AreEqual(1, intDeque.Count);
+    }
+
+    /// <summary>
+    ///   Tests whether an exception is thrown if the non-typesafe Add() method is
+    ///   used to add an incompatible object into the deque
+    /// </summary>
+    [Test]
+    public void TestThrowOnAddIncompatibleObject() {
+      Deque<int> intDeque = new Deque<int>();
+      Assert.Throws<ArgumentException>(
+        delegate() { ((IList)intDeque).Add("Hello World"); }
+      );
+    }
+
+    /// <summary>Verifies that the Add() method is working</summary>
+    [Test]
+    public void TestAdd() {
+      Deque<int> intDeque = new Deque<int>();
+      ((IList<int>)intDeque).Add(123);
+      Assert.AreEqual(1, intDeque.Count);
+    }
+
+    /// <summary>Tests whether the Contains() method is working</summary>
+    [Test]
+    public void TestContains() {
+      Deque<int> intDeque = createDeque(16);
+      Assert.IsTrue(intDeque.Contains(14));
+      Assert.IsFalse(intDeque.Contains(16));
+    }
+
+    /// <summary>Tests the non-typesafe Contains() method</summary>
+    [Test]
+    public void TestContainsObject() {
+      Deque<int> intDeque = createDeque(16);
+      Assert.IsTrue(((IList)intDeque).Contains(14));
+      Assert.IsFalse(((IList)intDeque).Contains(16));
+      Assert.IsFalse(((IList)intDeque).Contains("Hello World"));
+    }
+
+    /// <summary>Tests the non-typesafe Contains() method</summary>
+    [Test]
+    public void TestIndexOfObject() {
+      Deque<int> intDeque = createDeque(16);
+      Assert.AreEqual(14, ((IList)intDeque).IndexOf(14));
+      Assert.AreEqual(-1, ((IList)intDeque).IndexOf(16));
+      Assert.AreEqual(-1, ((IList)intDeque).IndexOf("Hello World"));
+    }
+
+    /// <summary>Tests wether the non-typesafe Insert() method is working</summary>
+    [Test]
+    public void TestInsertObject() {
+      for(int testedIndex = 0; testedIndex <= 96; ++testedIndex) {
+        Deque<int> intDeque = createDeque(96);
+
+        ((IList)intDeque).Insert(testedIndex, 12345);
+
+        Assert.AreEqual(97, intDeque.Count);
+
+        for(int index = 0; index < testedIndex; ++index) {
+          Assert.AreEqual(index, intDeque[index]);
+        }
+        Assert.AreEqual(12345, intDeque[testedIndex]);
+        for(int index = testedIndex + 1; index < 97; ++index) {
+          Assert.AreEqual(index - 1, intDeque[index]);
+        }
+      }
+    }
+
+    /// <summary>
+    ///   Verifies that an exception is thrown if an incompatible object is inserted
+    ///   into the deque
+    /// </summary>
+    [Test]
+    public void TestThrowOnInsertIncompatibleObject() {
+      Deque<int> intDeque = createDeque(12);
+      Assert.Throws<ArgumentException>(
+        delegate() { ((IList)intDeque).Insert(8, "Hello World"); }
+      );
+    }
+
+    /// <summary>Validates that the IsFixedObject property is set to false</summary>
+    [Test]
+    public void TestIsFixedObject() {
+      Deque<int> intDeque = new Deque<int>();
+      Assert.IsFalse(((IList)intDeque).IsFixedSize);
+    }
+
+    /// <summary>Validates that the IsSynchronized property is set to false</summary>
+    [Test]
+    public void TestIsSynchronized() {
+      Deque<int> intDeque = new Deque<int>();
+      Assert.IsFalse(((IList)intDeque).IsSynchronized);
+    }
+
+    /// <summary>
+    ///   Verifies that items can be assigned by their index using the non-typesafe
+    ///   IList interface
+    /// </summary>
+    [Test]
+    public void TestObjectIndexAssignment() {
+      Deque<int> intDeque = createDeque(32);
+
+      ((IList)intDeque)[16] = 12345;
+      ((IList)intDeque)[17] = 54321;
+
+      Assert.AreEqual(12345, ((IList)intDeque)[16]);
+      Assert.AreEqual(54321, ((IList)intDeque)[17]);
+    }
+
+    /// <summary>
+    ///   Tests whether an exception is thrown if an incompatible object is assigned
+    ///   to the deque
+    /// </summary>
+    [Test]
+    public void TestIncompatibleObjectIndexAssignment() {
+      Deque<int> intDeque = createDeque(2);
+      Assert.Throws<ArgumentException>(
+        delegate() { ((IList)intDeque)[0] = "Hello World"; }
+      );
+    }
+
+    /// <summary>Verifies that the Remove() method is working correctly</summary>
+    [Test]
+    public void TestRemove() {
+      Deque<int> intDeque = createDeque(16);
+      Assert.AreEqual(16, intDeque.Count);
+      Assert.IsTrue(intDeque.Remove(13));
+      Assert.IsFalse(intDeque.Remove(13));
+      Assert.AreEqual(15, intDeque.Count);
+    }
+
+    /// <summary>Tests the non-typesafe remove method</summary>
+    [Test]
+    public void TestRemoveObject() {
+      Deque<int> intDeque = createDeque(10);
+      Assert.IsTrue(intDeque.Contains(8));
+      Assert.AreEqual(10, intDeque.Count);
+      ((IList)intDeque).Remove(8);
+      Assert.IsFalse(intDeque.Contains(8));
+      Assert.AreEqual(9, intDeque.Count);
+    }
+
+    /// <summary>
+    ///   Tests the non-typesafe remove method used to remove an incompatible object
+    /// </summary>
+    [Test]
+    public void TestRemoveIncompatibleObject() {
+      Deque<int> intDeque = createDeque(10);
+      ((IList)intDeque).Remove("Hello World"); // should simply do nothing
+      Assert.AreEqual(10, intDeque.Count);
+    }
+
+    /// <summary>
+    ///   Verifies that the IsSynchronized property and the SyncRoot property are working
+    /// </summary>
+    [Test]
+    public void TestSynchronization() {
+      Deque<int> intDeque = new Deque<int>();
+
+      if(!(intDeque as ICollection).IsSynchronized) {
+        lock((intDeque as ICollection).SyncRoot) {
+          Assert.AreEqual(0, intDeque.Count);
+        }
+      }
+    }
+
+    /// <summary>
+    ///   Validates that the IsReadOnly property of the deque returns false
+    /// </summary>
+    [Test]
+    public void TestIsReadOnly() {
+      Deque<int> intDeque = new Deque<int>();
+      Assert.IsFalse(((IList)intDeque).IsReadOnly);
+      Assert.IsFalse(((ICollection<int>)intDeque).IsReadOnly);
+    }
+
+    /// <summary>Tests the non-typesafe CopyTo() method</summary>
+    [Test]
+    public void TestCopyToObjectArray() {
+      // TODO Write a unit test for the non-typesafe CopyTo() method
+    }
+
+    /// <summary>Tests the CopyTo() method</summary>
+    [Test]
+    public void TestCopyToArray() {
+      // TODO Write a unit test for the typesafe CopyTo() method
+    }
+
+    /// <summary>
+    ///   Creates a deque whose first element does not coincide with a block boundary
+    /// </summary>
+    /// <param name="count">Number of items the deque will be filled with</param>
+    /// <returns>The newly created deque</returns>
+    private static Deque<int> createNonNormalizedDeque(int count) {
       Deque<int> intDeque = new Deque<int>(16);
+
       for(int item = 4; item < count; ++item) {
         intDeque.AddLast(item);
       }
@@ -360,10 +631,21 @@ namespace Nuclex.Support.Collections {
       if(count > 1) { intDeque.AddFirst(1); }
       if(count > 0) { intDeque.AddFirst(0); }
 
-      for(int item = 0; item < count; ++item) {
+      return intDeque;
-        Assert.AreEqual(item, intDeque.IndexOf(item));
     }
-      Assert.AreEqual(-1, intDeque.IndexOf(count));
+
+    /// <summary>Creates a deque filled with the specified number of items
+    /// </summary>
+    /// <param name="count">Number of items the deque will be filled with</param>
+    /// <returns>The newly created deque</returns>
+    private static Deque<int> createDeque(int count) {
+      Deque<int> intDeque = new Deque<int>(16);
+
+      for(int item = 0; item < count; ++item) {
+        intDeque.AddLast(item);
+      }
+
+      return intDeque;
     }
 
   }

Source/Collections/Deque.cs

@@ -18,7 +18,111 @@ namespace Nuclex.Support.Collections {
   ///     require items to be copied around and still can be accessed by index.
   ///   </para>
   /// </remarks>
-  public partial class Deque<ItemType> /*: IList<ItemType>, IList*/ {
+  public partial class Deque<ItemType> : IList<ItemType>, IList {
+
+    #region class Enumerator
+
+    /// <summary>Enumerates over the items in a deque</summary>
+    private class Enumerator : IEnumerator<ItemType>, IEnumerator {
+
+      /// <summary>Initializes a new deque enumerator</summary>
+      /// <param name="deque">Deque whose items will be enumerated</param>
+      public Enumerator(Deque<ItemType> deque) {
+        this.deque = deque;
+        this.blockSize = this.deque.blockSize;
+        this.lastBlock = this.deque.blocks.Count - 1;
+        this.lastBlockEndIndex = this.deque.lastBlockCount - 1;
+
+        Reset();
+      }
+
+      /// <summary>Immediately releases all resources owned by the instance</summary>
+      public void Dispose() {
+        this.deque = null;
+        this.currentBlock = null;
+      }
+
+      /// <summary>The item at the enumerator's current position</summary>
+      public ItemType Current {
+        get {
+          if(this.currentBlock == null) {
+            throw new InvalidOperationException("Enumerator is not on a valid position");
+          }
+
+          return this.currentBlock[this.subIndex];
+        }
+      }
+
+      /// <summary>Advances the enumerator to the next item</summary>
+      /// <returns>True if there was a next item</returns>
+      public bool MoveNext() {
+
+        // If we haven't reached the last block yet      
+        if(this.currentBlockIndex < this.lastBlock) {
+
+          // Advance to the next item. If the end of the current block is reached,
+          // go to the next block's first item
+          ++this.subIndex;
+          if(this.subIndex >= this.blockSize) {
+            ++this.currentBlockIndex;
+            this.currentBlock = this.deque.blocks[this.currentBlockIndex];
+            if(this.currentBlockIndex == 0) {
+              this.subIndex = this.deque.firstBlockStartIndex;
+            } else {
+              this.subIndex = 0;
+            }
+          }
+
+          // Item found. If the current block wasn't the last block, an item *has*
+          // to follow since otherwise, no further blocks would exist!
+          return true;
+
+        } else { // We in or beyond the last block
+
+          // Are there any items left to advance to?
+          if(this.subIndex < this.lastBlockEndIndex) {
+            ++this.subIndex;
+            return true;
+          } else { // Nope, we've reached the end of the deque
+            this.currentBlock = null;
+            return false;
+          }
+
+        }
+
+      }
+
+      /// <summary>Resets the enumerator to its initial position</summary>
+      public void Reset() {
+        this.currentBlock = null;
+        this.currentBlockIndex = -1;
+        this.subIndex = this.deque.blockSize - 1;
+      }
+
+      /// <summary>The item at the enumerator's current position</summary>
+      object IEnumerator.Current {
+        get { return Current; }
+      }
+
+      /// <summary>Deque the enumerator belongs to</summary>
+      private Deque<ItemType> deque;
+      /// <summary>Size of the blocks in the deque</summary>
+      private int blockSize;
+      /// <summary>Index of the last block in the deque</summary>
+      private int lastBlock;
+      /// <summary>End index of the items in the deque's last block</summary>
+      private int lastBlockEndIndex;
+
+      /// <summary>Index of the block the enumerator currently is in</summary>
+      private int currentBlockIndex;
+      /// <summary>Reference to the block being enumerated</summary>
+      private ItemType[] currentBlock;
+      /// <summary>Index in the current block</summary>
+      private int subIndex;
+
+    }
+
+    #endregion // class Enumerator
 
     /// <summary>Initializes a new deque</summary>
     public Deque() : this(512) { }
@@ -58,7 +162,7 @@ namespace Nuclex.Support.Collections {
     /// <summary>The first item in the double-ended queue</summary>
     public ItemType First {
       get {
-        if(this.lastBlockEndIndex <= this.firstBlockStartIndex) {
+        if(this.count == 0) {
           throw new InvalidOperationException("The deque is empty");
         }
         return this.blocks[0][this.firstBlockStartIndex];
@@ -68,66 +172,31 @@ namespace Nuclex.Support.Collections {
     /// <summary>The last item in the double-ended queue</summary>
     public ItemType Last {
       get {
-        if(this.lastBlockEndIndex <= this.firstBlockStartIndex) {
+        if(this.count == 0) {
           throw new InvalidOperationException("The deque is empty");
         }
-        return this.blocks[this.blocks.Count - 1][this.lastBlockEndIndex - 1];
+        return this.blocks[this.blocks.Count - 1][this.lastBlockCount - 1];
       }
     }
 
-    /// <summary>
+    /// <summary>Determines whether the deque contains the specified item</summary>
-    ///   Determines the index of the first occurence of the specified item in the deque
+    /// <param name="item">Item the deque will be scanned for</param>
-    /// </summary>
+    /// <returns>True if the deque contains the item, false otherwise</returns>
-    /// <param name="item">Item that will be located in the deque</param>
+    public bool Contains(ItemType item) {
-    /// <returns>The index of the item or -1 if it wasn't found</returns>
+      return (IndexOf(item) != -1);
-    public int IndexOf(ItemType item) {
-      if(this.blocks.Count == 1) { // Only one block to scan?
-        int length = this.lastBlockEndIndex - this.firstBlockStartIndex;
-        int index = Array.IndexOf<ItemType>(
-          this.blocks[0], item, this.firstBlockStartIndex, length
-        );
-
-        // If we found something, we need to adjust its index so the first item in
-        // the deque always appears at index 0 to the user
-        if(index != -1) {
-          return (index - this.firstBlockStartIndex);
-        } else {
-          return -1;
-        }
-      } else { // At least two blocks exist
-
-        // Scan the first block for the item and if found, return the index
-        int length = this.blockSize - this.firstBlockStartIndex;
-        int index = Array.IndexOf<ItemType>(
-          this.blocks[0], item, this.firstBlockStartIndex, length
-        );
-
-        // If we found something, we need to adjust its index
-        if(index != -1) {
-          return (index - this.firstBlockStartIndex);
     }
 
-        int lastBlock = this.blocks.Count - 1;
+    /// <summary>Copies the contents of the deque into an array</summary>
-        for(int tempIndex = 1; tempIndex < lastBlock; ++tempIndex) {
+    /// <param name="array">Array the contents of the deque will be copied into</param>
-          index = Array.IndexOf<ItemType>(
+    /// <param name="arrayIndex">Array index the deque contents will begin at</param>
-            this.blocks[tempIndex], item, 0, this.blockSize
+    public void CopyTo(ItemType[] array, int arrayIndex) {
-          );
+      throw new NotImplementedException();
-          if(index != -1) {
-            return (index - this.firstBlockStartIndex + tempIndex * this.blockSize);
-          }
     }
 
-        // Nothing found, continue the search in the 
+    /// <summary>Obtains a new enumerator for the contents of the deque</summary>
-        index = Array.IndexOf<ItemType>(
+    /// <returns>The new enumerator</returns>
-          this.blocks[lastBlock], item, 0, this.lastBlockEndIndex
+    public IEnumerator<ItemType> GetEnumerator() {
-        );
+      return new Enumerator(this);
-        if(index == -1) {
-          return -1;
-        } else {
-          return (index - this.firstBlockStartIndex + lastBlock * this.blockSize);
-        }
-
-      }
     }
 
     /// <summary>Calculates the block index and local sub index of an entry</summary>
@@ -143,6 +212,23 @@ namespace Nuclex.Support.Collections {
       blockIndex = Math.DivRem(index, this.blockSize, out subIndex);
     }
 
+    /// <summary>
+    ///   Determines whether the provided object can be placed in the deque
+    /// </summary>
+    /// <param name="value">Value that will be checked for compatibility</param>
+    /// <returns>True if the value can be placed in the deque</returns>
+    private static bool isCompatibleObject(object value) {
+      return ((value is ItemType) || ((value == null) && !typeof(ItemType).IsValueType));
+    }
+
+    /// <summary>Verifies that the provided object matches the deque's type</summary>
+    /// <param name="value">Value that will be checked for compatibility</param>
+    private static void verifyCompatibleObject(object value) {
+      if(!isCompatibleObject(value)) {
+        throw new ArgumentException("Value does not match the deque's type", "value");
+      }
+    }
+
     /// <summary>Number if items currently stored in the deque</summary>
     private int count;
     /// <summary>Size of a single deque block</summary>
@@ -152,7 +238,7 @@ namespace Nuclex.Support.Collections {
     /// <summary>Starting index of data in the first block</summary>
     private int firstBlockStartIndex;
     /// <summary>End index of data in the last block</summary>
-    private int lastBlockEndIndex;
+    private int lastBlockCount;
 
   }