Add ToArraySegments support

Fixes #26

Author: joaoportela

CircularBuffer.Tests/CircularBufferTests.cs

@@ -1,5 +1,6 @@
 using NUnit.Framework;
 using System;
+using System.Linq;
 
 namespace CircularBuffer.Tests
 {
@@ -116,6 +117,32 @@ public void CircularBuffer_ToArrayOverflowedBuffer_CorrectContent()
             Assert.That(buffer.ToArray(), Is.EqualTo(new[] { 5, 6, 7, 8, 9 }));
         }
 
+        [Test]
+        public void CircularBuffer_ToArraySegmentsConstructorDefinedArray_CorrectContent()
+        {
+            var buffer = new CircularBuffer<int>(5, new[] { 0, 1, 2, 3 });
+
+            var arraySegments = buffer.ToArraySegments();
+
+            Assert.That(arraySegments.Count, Is.EqualTo(2)); // length of 2 is part of the contract.
+            Assert.That(arraySegments.SelectMany(x => x), Is.EqualTo(new[] { 0, 1, 2, 3 }));
+        }
+
+        [Test]
+        public void CircularBuffer_ToArraySegmentsOverflowedBuffer_CorrectContent()
+        {
+            var buffer = new CircularBuffer<int>(5);
+
+            for (int i = 0; i < 10; i++)
+            {
+                buffer.PushBack(i);
+            }
+
+            var arraySegments = buffer.ToArraySegments();
+            Assert.That(arraySegments.Count, Is.EqualTo(2)); // length of 2 is part of the contract.
+            Assert.That(arraySegments.SelectMany(x => x), Is.EqualTo(new[] { 5, 6, 7, 8, 9 }));
+        }
+
         [Test]
         public void CircularBuffer_PushFront_CorrectContent()
         {

CircularBuffer/CircularBuffer.cs

@@ -260,7 +260,7 @@ public T[] ToArray()
         {
             T[] newArray = new T[Size];
             int newArrayOffset = 0;
-            var segments = new ArraySegment<T>[2] { ArrayOne(), ArrayTwo() };
+            var segments = ToArraySegments();
             foreach (ArraySegment<T> segment in segments)
             {
                 Array.Copy(segment.Array, segment.Offset, newArray, newArrayOffset, segment.Count);
@@ -269,14 +269,31 @@ public T[] ToArray()
             return newArray;
         }
 
+        /// <summary>
+        /// Get the contents of the buffer as 2 ArraySegments.
+        /// Respects the logical contents of the buffer, where
+        /// each segment and items in each segment are ordered
+        /// according to insertion.
+        ///
+        /// Fast: does not copy the array elements.
+        /// Useful for methods like <c>Send(IList&lt;ArraySegment&lt;Byte&gt;&gt;)</c>.
+        /// 
+        /// <remarks>Segments may be empty.</remarks>
+        /// </summary>
+        /// <returns>An IList with 2 segments corresponding to the buffer content.</returns>
+        public IList<ArraySegment<T>> ToArraySegments()
+        {
+            return new [] { ArrayOne(), ArrayTwo() };
+        }
+
         #region IEnumerable<T> implementation
         /// <summary>
         /// Returns an enumerator that iterates through this buffer.
         /// </summary>
         /// <returns>An enumerator that can be used to iterate this collection.</returns>
         public IEnumerator<T> GetEnumerator()
         {
-            var segments = new ArraySegment<T>[2] { ArrayOne(), ArrayTwo() };
+            var segments = ToArraySegments();
             foreach (ArraySegment<T> segment in segments)
             {
                 for (int i = 0; i < segment.Count; i++)