[Proposal] Add git_blame_buffer

LibGit2Sharp/BlameHunkCollection.cs

@@ -11,10 +11,13 @@ namespace LibGit2Sharp
     /// <summary>
     /// The result of a blame operation.
     /// </summary>
-    public class BlameHunkCollection : IEnumerable<BlameHunk>
+    public class BlameHunkCollection : IEnumerable<BlameHunk>, IDisposable
     {
         private readonly IRepository repo;
         private readonly List<BlameHunk> hunks = new List<BlameHunk>();
+        private readonly RepositoryHandle repoHandle;
+        private readonly BlameHandle referenceHandle;
+        private readonly bool shouldDisposeHandle;
 
         /// <summary>
         /// For easy mocking
@@ -49,17 +52,29 @@ internal unsafe BlameHunkCollection(Repository repo, RepositoryHandle repoHandle
                 }
             }
 
-            using (var blameHandle = Proxy.git_blame_file(repoHandle, path, rawopts))
+            referenceHandle = Proxy.git_blame_file(repoHandle, path, rawopts);
+            shouldDisposeHandle = true;
+            this.PopulateHunks(this.referenceHandle);
+        }
+
+        private unsafe BlameHunkCollection(IRepository repo, RepositoryHandle repoHandle, BlameHandle reference, byte[] buffer)
+        {
+            this.repo = repo;
+            this.repoHandle = repoHandle;
+            this.referenceHandle = reference;
+            this.shouldDisposeHandle = false;
+
+            using (var blameHandle = Proxy.git_blame_buffer(repoHandle, reference, buffer))
             {
-                var numHunks = NativeMethods.git_blame_get_hunk_count(blameHandle);
-                for (uint i = 0; i < numHunks; ++i)
-                {
-                    var rawHunk = Proxy.git_blame_get_hunk_byindex(blameHandle, i);
-                    hunks.Add(new BlameHunk(this.repo, rawHunk));
-                }
+                this.PopulateHunks(blameHandle);
             }
         }
 
+        public BlameHunkCollection FromBuffer(byte[] buffer)
+        {
+            return new BlameHunkCollection(repo, repoHandle, this.referenceHandle, buffer);
+        }
+
         /// <summary>
         /// Access blame hunks by index.
         /// </summary>
@@ -100,5 +115,23 @@ IEnumerator IEnumerable.GetEnumerator()
         {
             return GetEnumerator();
         }
+
+        private unsafe void PopulateHunks(BlameHandle blameHandle)
+        {
+            var numHunks = NativeMethods.git_blame_get_hunk_count(blameHandle);
+            for (uint i = 0; i < numHunks; ++i)
+            {
+                var rawHunk = Proxy.git_blame_get_hunk_byindex(blameHandle, i);
+                hunks.Add(new BlameHunk(this.repo, rawHunk));
+            }
+        }
+
+        public void Dispose()
+        {
+            if (shouldDisposeHandle)
+            {
+                this.referenceHandle.Dispose();
+            }
+        }
     }
 }

LibGit2Sharp/Core/NativeMethods.cs

@@ -190,6 +190,13 @@ private sealed class NativeShutdownObject : CriticalFinalizerObject
             [MarshalAs(UnmanagedType.CustomMarshaler, MarshalCookie = UniqueId.UniqueIdentifier, MarshalTypeRef = typeof(StrictUtf8Marshaler))] string path,
             git_blame_options options);
 
+        [DllImport(libgit2, CallingConvention = CallingConvention.Cdecl)]
+        internal static extern unsafe int git_blame_buffer(
+            out git_blame* blame,
+            git_blame* reference,
+            IntPtr buffer,
+            UIntPtr len);
+
         [DllImport(libgit2, CallingConvention = CallingConvention.Cdecl)]
         internal static extern unsafe void git_blame_free(git_blame* blame);
 

LibGit2Sharp/Core/Proxy.cs

@@ -35,6 +35,27 @@ internal class Proxy
             return NativeMethods.git_blame_get_hunk_byindex(blame, idx);
         }
 
+        public static unsafe BlameHandle git_blame_buffer(
+            RepositoryHandle repo,
+            BlameHandle reference,
+            byte[] buffer)
+        {
+            git_blame* ptr;
+            int res;
+
+            unsafe
+            {
+                fixed (byte* p = buffer)
+                {
+                    res = NativeMethods.git_blame_buffer(out ptr, reference, (IntPtr)p, (UIntPtr)buffer.Length);
+                }
+            }
+
+            Ensure.ZeroResult(res);
+
+            return new BlameHandle(ptr, true);
+        }
+
         #endregion
 
         #region git_blob_