1 files changed, 24 insertions, 15 deletions

diff --git a/src/Text/Impl/StandaloneUndo/UndoHistoryImpl.cs b/src/Text/Impl/StandaloneUndo/UndoHistoryImpl.cs
index 9f5bac5..47fec01 100644
--- a/src/Text/Impl/StandaloneUndo/UndoHistoryImpl.cs
+++ b/src/Text/Impl/StandaloneUndo/UndoHistoryImpl.cs
@@ -8,13 +8,11 @@
 using System;
 using System.Collections.Generic;
 using System.Globalization;
-using System.Collections.ObjectModel;
-using System.ComponentModel.Composition;
 using Microsoft.VisualStudio.Utilities;
 
 namespace Microsoft.VisualStudio.Text.Operations.Standalone
 {
-    internal class UndoHistoryImpl : ITextUndoHistory
+    internal class UndoHistoryImpl : ITextUndoHistory2
     {
         public event EventHandler<TextUndoRedoEventArgs> UndoRedoHappened;
         public event EventHandler<TextUndoTransactionCompletedEventArgs> UndoTransactionCompleted;
@@ -25,7 +23,7 @@ namespace Microsoft.VisualStudio.Text.Operations.Standalone
         private Stack<ITextUndoTransaction> undoStack;
         private Stack<ITextUndoTransaction> redoStack;
         private DelegatedUndoPrimitiveImpl activeUndoOperationPrimitive;
-        private TextUndoHistoryState state;
+        internal TextUndoHistoryState state;
         private PropertyCollection properties;
 
         #endregion
@@ -188,6 +186,13 @@ namespace Microsoft.VisualStudio.Text.Operations.Standalone
             get { return this.state; }
         }
 
+        public ITextUndoTransaction CreateInvisibleTransaction(string description)
+        {
+            // Standalone undo doesn't support invisible transactions so simply return
+            // a normal transaction.
+            return this.CreateTransaction(description);
+        }
+
         /// <summary>
         /// Creates a new transaction, nests it in the previously current transaction, and marks it current.
         /// If there is a redo stack, it gets cleared.
@@ -198,9 +203,9 @@ namespace Microsoft.VisualStudio.Text.Operations.Standalone
         /// <returns></returns>
         public ITextUndoTransaction CreateTransaction(string description)
         {
-            if (String.IsNullOrEmpty(description))
+            if (string.IsNullOrEmpty(description))
             {
-                throw new ArgumentNullException("description", String.Format(CultureInfo.CurrentUICulture, "Strings.ArgumentCannotBeNull", "CreateTransaction", "description"));
+                throw new ArgumentNullException(nameof(description));
             }
 
             // If there is a pending transaction that has already been completed, we should not be permitted
@@ -244,12 +249,12 @@ namespace Microsoft.VisualStudio.Text.Operations.Standalone
         {
             if (count <= 0)
             {
-                throw new ArgumentException(String.Format(CultureInfo.CurrentUICulture, "Strings.RedoAndUndoAcceptOnlyPositiveCounts", "Undo", count), "count");
+                throw new ArgumentOutOfRangeException(nameof(count));
             }
 
             if (!IsThereEnoughVisibleTransactions(this.undoStack, count))
             {
-                throw new InvalidOperationException(String.Format(CultureInfo.CurrentUICulture, "Strings.CannotUndoMoreTransactionsThanExist", "undo", count));
+                throw new InvalidOperationException("Cannot undo more transactions than exist");
             }
 
             TextUndoHistoryState originalState = this.state;
@@ -321,12 +326,12 @@ namespace Microsoft.VisualStudio.Text.Operations.Standalone
         {
             if (count <= 0)
             {
-                throw new ArgumentException(String.Format(CultureInfo.CurrentUICulture, "Strings.RedoAndUndoAcceptOnlyPositiveCounts", "Redo", count), "count");
+                throw new ArgumentOutOfRangeException(nameof(count));
             }
 
             if (!IsThereEnoughVisibleTransactions(this.redoStack, count))
             {
-                throw new InvalidOperationException(String.Format(CultureInfo.CurrentUICulture, "Strings.CannotUndoMoreTransactionsThanExist", "redo", count));
+                throw new InvalidOperationException("Cannot redo more transactions than exist");
             }
 
             TextUndoHistoryState originalState = this.state;
@@ -424,15 +429,19 @@ namespace Microsoft.VisualStudio.Text.Operations.Standalone
                 throw new InvalidOperationException("Strings.EndTransactionOutOfOrder");
             }
 
+            // Note that the VS undo history actually "pops" the nested undo stack on the Complete/Cancel
+            // (instead of in the Dispose). This shouldn't affect anything but we should consider adapting
+            // this code to follow the model in VS undo.
+            this.currentTransaction = (UndoTransactionImpl)(transaction.Parent);
+
             // only add completed transactions to their parents (or the stack)
-            if (this.currentTransaction.State == UndoTransactionState.Completed)
+            if (transaction.State == UndoTransactionState.Completed)
             {
-                if (this.currentTransaction.Parent == null) // stack bottomed out!
+                if (transaction.Parent == null) // stack bottomed out!
                 {
-                    MergeOrPushToUndoStack(this.currentTransaction);
+                    MergeOrPushToUndoStack((UndoTransactionImpl)transaction);
                 }
             }
-            this.currentTransaction = this.currentTransaction.Parent as UndoTransactionImpl;
         }
 
         /// <summary>
@@ -471,7 +480,7 @@ namespace Microsoft.VisualStudio.Text.Operations.Standalone
                 transactionAdded = transaction;
                 transactionResult = TextUndoTransactionCompletionResult.TransactionAdded;
             }
-            RaiseUndoTransactionCompleted(transactionAdded, transactionResult);            
+            RaiseUndoTransactionCompleted(transactionAdded, transactionResult);
         }
 
         public bool ValidTransactionForMarkers(ITextUndoTransaction transaction)