Added index operator for cloning a range

Closing thorsten/ExaArray#5

ExaArray/ExaArray1D.cs

@@ -188,6 +188,23 @@ namespace Exa
             }
         }
 
+        /// <summary>
+        /// Creates a new ExaArray1D from this instance, respecting the given range.
+        /// </summary>
+        /// <remarks>
+        /// When <c>T</c> is a value type, data gets copied as values. When <c>T</c> is a reference type, the pointers
+        /// to the original objects are copied. Thus, this factory method does not create a deep copy.
+        ///
+        /// Performance: O(n)
+        ///
+        /// The indices are inclusive.
+        /// </remarks>
+        /// <param name="indexFrom">The first source element which should be part of the new array.</param>
+        /// <param name="indexTo">The last source element which should be part of the new array.</param>
+        /// <returns>The new instance</returns>
+        /// <exception cref="IndexOutOfRangeException">Throws, when one or both of the indices are out of range.</exception>
+        public ExaArray1D<T> this[ulong indexFrom, ulong indexTo] => ExaArray1D<T>.CreateFrom(this, indexFrom, indexTo);
+
         /// <summary>
         /// Yields an enumerator across all elements.
         /// </summary>

ExaArrayTests/ExaArray1DTests.cs

@@ -539,13 +539,15 @@ namespace ExaArrayTests
                 var exPerf = new ExaArray1D<byte>(Strategy.MAX_PERFORMANCE);
                 exPerf.Extend(3 * MAX); // more than one chunk
                 
-                var next = ExaArray1D<byte>.CreateFrom(exPerf, 0, exPerf.Length - 1);
+                var next1 = ExaArray1D<byte>.CreateFrom(exPerf, 0, exPerf.Length - 1);
                 var next2 = exPerf.Clone();
                 var next3 = exPerf.Clone(0, exPerf.Length - 1);
+                var next4 = exPerf[0, exPerf.Length - 1];
                 
-                Assert.That(next.Length, Is.EqualTo(exPerf.Length));
+                Assert.That(next1.Length, Is.EqualTo(exPerf.Length));
                 Assert.That(next2.Length, Is.EqualTo(exPerf.Length));
                 Assert.That(next3.Length, Is.EqualTo(exPerf.Length));
+                Assert.That(next4.Length, Is.EqualTo(exPerf.Length));
             }
 
             [Test]