Fixes issue #13; Added right-centric versions of TakeLeftThenRight*Me…

…rgeConflictResolver types

DiffLib/TakeRightThenLeftIfLeftDiffersFromRight.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+using JetBrains.Annotations;
+
+namespace DiffLib
+{
+    /// <summary>
+    /// This implementation of <see cref="IMergeConflictResolver{T}"/> resolves a conflict by taking the left side and then taking the right side. In the case
+    /// where both cases are identical, only the left side is taken.
+    /// </summary>
+    /// <typeparam name="T">
+    /// The type of elements in the collections being merged.
+    /// </typeparam>
+    public class TakeRightThenLeftIfLeftDiffersFromRight<T> : IMergeConflictResolver<T>
+    {
+        private readonly IEqualityComparer<T> _EqualityComparer;
+
+        /// <summary>
+        /// Constructs a new instance of <see cref="DiffLib.TakeLeftThenRightIfRightDiffersFromLeft{T}"/> using the specified <paramref name="equalityComparer"/>.
+        /// </summary>
+        /// <param name="equalityComparer">
+        /// The <see cref="IEqualityComparer{T}"/> to use when determining if elements of the left side of a conflict matches those on the right side. If
+        /// <c>null</c> then <see cref="EqualityComparer{T}.Default"/> is used.
+        /// </param>
+        public TakeRightThenLeftIfLeftDiffersFromRight([CanBeNull] IEqualityComparer<T> equalityComparer = null)
+        {
+            _EqualityComparer = equalityComparer ?? EqualityComparer<T>.Default;
+        }
+
+        /// <inheritdoc />
+        [NotNull, ItemCanBeNull]
+        public IEnumerable<T> Resolve([NotNull] IList<T> commonBase, [NotNull] IList<T> left, [NotNull] IList<T> right)
+        {
+            foreach (var item in right)
+                yield return item;
+
+            if (left.SequenceEqual(right, _EqualityComparer))
+                yield break;
+
+            foreach (var item in left)
+                yield return item;
+        }
+    }
+}

DiffLib/TakeRightThenLeftMergeConflictResolver.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Collections.Generic;
+
+using JetBrains.Annotations;
+
+namespace DiffLib
+{
+    /// <summary>
+    /// This implementation of <see cref="IMergeConflictResolver{T}"/> takes the left side then takes the right side.
+    /// </summary>
+    /// <typeparam name="T">
+    /// The type of elements in the collections being merged.
+    /// </typeparam>
+    public class TakeRightThenLeftMergeConflictResolver<T> : IMergeConflictResolver<T>
+    {
+        /// <inheritdoc />
+        [NotNull, ItemCanBeNull]
+        public IEnumerable<T> Resolve([NotNull] IList<T> commonBase, [NotNull] IList<T> left, [NotNull] IList<T> right)
+        {
+            foreach (var item in right)
+                yield return item;
+
+            foreach (var item in left)
+                yield return item;
+        }
+    }
+}