1 files changed, 26 insertions, 13 deletions

diff --git a/src/Editor/Text/Def/TextLogic/DifferenceBuffer/IDifferenceBuffer2.cs b/src/Editor/Text/Def/TextLogic/DifferenceBuffer/IDifferenceBuffer2.cs
index ebfecb6..6370508 100644
--- a/src/Editor/Text/Def/TextLogic/DifferenceBuffer/IDifferenceBuffer2.cs
+++ b/src/Editor/Text/Def/TextLogic/DifferenceBuffer/IDifferenceBuffer2.cs
@@ -9,22 +9,35 @@ namespace Microsoft.VisualStudio.Text.Differencing
     public interface IDifferenceBuffer2 : IDifferenceBuffer
     {
         /// <summary>
-        /// The source of the left buffer in the difference. Can be set to null.
+        /// True if the BaseLeftBuffer can never change. If false, the BaseLeftBuffer can change (via setting the InnerLeftDataModel) and
+        /// can be null.
         /// </summary>
-        new ITextBuffer BaseLeftBuffer { get; set; }
+        bool HasFixedBaseLeftBuffer { get; }
 
-        event EventHandler<BufferChangedEventArgs> BaseLeftBufferChanged;
-    }
+        /// <summary>
+        /// Raised whenever the <see cref="IDifferenceBuffer.BaseLeftBuffer"/> is changed to a different buffer.
+        /// </summary>
+        event EventHandler<BaseLeftBufferChangedEventArgs> BaseLeftBufferChanged;
 
-    public class BufferChangedEventArgs : EventArgs
-    {
-        public BufferChangedEventArgs(ITextBuffer oldBuffer, ITextBuffer newBuffer)
-        {
-            this.OldBuffer = oldBuffer;
-            this.NewBuffer = newBuffer;
-        }
+        /// <summary>
+        /// The <see cref="ITextDataModel"/> for the BaseLeftBuffer. This can be created even if <see cref="IDifferenceBuffer.BaseLeftBuffer"/> is null.
+        /// </summary>
+        ITextDataModel LeftDataModel { get; }
+
+        /// <summary>
+        /// The <see cref="ITextDataModel"/> actual ITextDataModel for the BaseLeftBuffer. This value is only meaningful if <see cref="HasFixedBaseLeftBuffer"/> is
+        /// false. Set InnerLeftDataModel to null to set the difference buffer's BaseLeftBuffer to null.
+        /// </summary>
+        ITextDataModel InnerLeftDataModel { get; set; }
 
-        public ITextBuffer OldBuffer { get; }
-        public ITextBuffer NewBuffer { get; }
+        /// <summary>
+        /// The <see cref="ITextDataModel"/> for the right buffer.
+        /// </summary>
+        ITextDataModel RightDataModel { get; }
+
+        /// <summary>
+        /// The <see cref="ITextDataModel"/> for the inline buffer. This can be created even if <see cref="IDifferenceBuffer.BaseLeftBuffer"/> is null.
+        /// </summary>
+        ITextDataModel InlineDataModel { get; }
     }
 }