Introduce new merge functionality, including Pull, merge options, and

merging branches.

This includes a refactoring of the merge logic to support the new
scenarios. New functionality includes:

- Deprecate Network.Fetchheads, Repository.MergeHeads as these should be
  internal only.

- Introduce ability to pull the configured upstream branch for the current
  branch

- Introduce ability to merge a branch into the current branch.

- Introduce options to control merge behavior. The current exposed options
  include whether to commit the merge commit and the allowed merge types.

1 files changed, 54 insertions, 0 deletions

diff --git a/LibGit2Sharp/MergeOptions.cs b/LibGit2Sharp/MergeOptions.cs
new file mode 100644
index 00000000..49096dbd
--- /dev/null
+++ b/LibGit2Sharp/MergeOptions.cs
@@ -0,0 +1,54 @@
+
+namespace LibGit2Sharp
+{
+    /// <summary>
+    /// Options controlling Merge behavior.
+    /// </summary>
+    public class MergeOptions
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="MergeOptions"/> class.
+        /// By default, a fast-forward merge will be performed if possible, and
+        /// if a merge commit is created, then it will be commited.
+        /// </summary>
+        public MergeOptions()
+        {
+            CommitOnSuccess = true;
+        }
+
+        /// <summary>
+        /// Commit the merge if the merge is successful and this is a non-fast-forward merge.
+        /// If this is a fast-forward merge, then there is no merge commit and this option
+        /// will not affect the merge.
+        /// </summary>
+        public virtual bool CommitOnSuccess { get; set; }
+
+        /// <summary>
+        /// The type of merge to perform.
+        /// </summary>
+        public virtual FastForwardStrategy FastForwardStrategy { get; set; }
+    }
+
+    /// <summary>
+    /// Strategy used for merging.
+    /// </summary>
+    public enum FastForwardStrategy
+    {
+        /// <summary>
+        /// Default fast-forward strategy. This will perform a fast-forward merge
+        /// if possible, otherwise will perform a non-fast-forward merge that
+        /// results in a merge commit.
+        /// </summary>
+        Default = 0,
+
+        /// <summary>
+        /// Do not fast-forward. Always creates a merge commit.
+        /// </summary>
+        NoFastFoward = 1, /* GIT_MERGE_NO_FASTFORWARD */
+
+        /// <summary>
+        /// Only perform fast-forward merges.
+        /// </summary>
+        FastForwardOnly = 2, /* GIT_MERGE_FASTFORWARD_ONLY */
+    }
+}