From 2fa2988f755500952b523a48ba51b1c5ea606ad5 Mon Sep 17 00:00:00 2001
From: "kin%netscape.com" <kin%netscape.com>
Date: Sat, 21 Nov 1998 01:02:55 +0000
Subject: [PATCH] First pass implementations of Do, Undo, and Redo.

---
 editor/txmgr/src/nsTransactionManager.cpp | 101 +++++++++++++++++++++-
 editor/txmgr/src/nsTransactionManager.h   |  29 ++++++-
 2 files changed, 125 insertions(+), 5 deletions(-)

diff --git a/editor/txmgr/src/nsTransactionManager.cpp b/editor/txmgr/src/nsTransactionManager.cpp
index 0734c85d7c1..b84440688c8 100644
--- a/editor/txmgr/src/nsTransactionManager.cpp
+++ b/editor/txmgr/src/nsTransactionManager.cpp
@@ -22,7 +22,8 @@
 static NS_DEFINE_IID(kISupportsIID, NS_ISUPPORTS_IID);
 static NS_DEFINE_IID(kITransactionManagerIID, NS_ITRANSACTIONMANAGER_IID);
 
-nsTransactionManager::nsTransactionManager()
+nsTransactionManager::nsTransactionManager(PRInt32 aMaxLevelsOfUndo)
+  : mMaxLevelsOfUndo(aMaxLevelsOfUndo), mRF(), mUndoStack(mRF), mRedoStack(mRF)
 {
 }
 
@@ -56,19 +57,98 @@ nsTransactionManager::QueryInterface(REFNSIID aIID, void** aInstancePtr)
 nsresult
 nsTransactionManager::Do(nsITransaction *aTransaction)
 {
-  return NS_OK;
+  nsresult result = NS_OK;
+
+  if (!aTransaction)
+    return NS_ERROR_NULL_POINTER;
+
+  // XXX: LOCK the transaction manager
+
+  result = aTransaction->Do();
+
+  if (! NS_SUCCEEDED(result)) {
+    // XXX: UNLOCK the transaction manager
+    return result;
+  }
+
+  // XXX: Check if we can coalesce this transaction with the one
+  //      at the top of the undo stack. If we can, merge this one
+  //      into the one currently on the stack.
+
+  // XXX: Check to see if we've hit the max level of undo. If so,
+  //      pop the bottom transaction of the undo stack and release it!
+
+  NS_ADDREF(aTransaction);
+  mUndoStack.Push(aTransaction);
+
+  result = PruneRedoStack();
+
+  if (! NS_SUCCEEDED(result)) {
+    // XXX: What do we do in the case where a prune fails?
+    //      Remove the transaction from the stack, and release it?
+  }
+
+  // XXX: UNLOCK the transaction manager
+
+  return result;
 }
 
 nsresult
 nsTransactionManager::Undo()
 {
-  return NS_OK;
+  nsresult result    = NS_OK;
+  nsITransaction *tx = 0;
+
+  // XXX: LOCK the transaction manager
+
+  // Peek at the top of the undo stack. Don't remove the transaction
+  // until it has successfully completed.
+  tx = (nsITransaction *)(--mUndoStack.End());
+
+  // Bail if there's nothing on the stack.
+  if (!tx) {
+    // XXX: UNLOCK the transaction manager
+    return NS_OK;
+  }
+
+  result = tx->Undo();
+
+  if (NS_SUCCEEDED(result)) {
+    mRedoStack.Push(mUndoStack.Pop());
+  }
+
+  // XXX: UNLOCK the transaction manager
+
+  return result;
 }
 
 nsresult
 nsTransactionManager::Redo()
 {
-  return NS_OK;
+  nsresult result    = NS_OK;
+  nsITransaction *tx = 0;
+
+  // XXX: LOCK the transaction manager
+
+  // Peek at the top of the redo stack. Don't remove the transaction
+  // until it has successfully completed.
+  tx = (nsITransaction *)(--mRedoStack.End());
+
+  // Bail if there's nothing on the stack.
+  if (!tx) {
+    // XXX: UNLOCK the transaction manager
+    return NS_OK;
+  }
+
+  result = tx->Redo();
+
+  if (NS_SUCCEEDED(result)) {
+    mUndoStack.Push(mRedoStack.Pop());
+  }
+
+  // XXX: UNLOCK the transaction manager
+
+  return result;
 }
 
 nsresult
@@ -77,6 +157,8 @@ nsTransactionManager::GetNumberOfUndoItems(PRInt32 *aNumItems)
   if (aNumItems)
     *aNumItems = 0;
 
+  *aNumItems = mUndoStack.GetSize();
+
   return NS_OK;
 }
 
@@ -86,6 +168,8 @@ nsTransactionManager::GetNumberOfRedoItems(PRInt32 *aNumItems)
   if (aNumItems)
     *aNumItems = 0;
 
+  *aNumItems = mRedoStack.GetSize();
+
   return NS_OK;
 }
 
@@ -107,3 +191,12 @@ nsTransactionManager::RemoveListener(nsITransactionListener *aListener)
   return NS_OK;
 }
 
+nsresult
+nsTransactionManager::PruneRedoStack()
+{
+  // XXX: The order in which you release things off this stack matters!
+  //      We may not be able to use Erase().
+  mRedoStack.Erase();
+  return NS_OK;
+}
+
diff --git a/editor/txmgr/src/nsTransactionManager.h b/editor/txmgr/src/nsTransactionManager.h
index 0bbb2441939..472ffcd507a 100644
--- a/editor/txmgr/src/nsTransactionManager.h
+++ b/editor/txmgr/src/nsTransactionManager.h
@@ -20,17 +20,41 @@
 #define nsTransactionManager_h__
 
 #include "nsITransactionManager.h"
+#include "nsDeque.h"
+
+class nsTransactionReleaseFunctor : public nsDequeFunctor
+{
+public:
+
+  nsTransactionReleaseFunctor()  {}
+
+  ~nsTransactionReleaseFunctor() {}
+
+  virtual void *operator()(void *aObject)
+  {
+    nsITransaction *t = (nsITransaction *)aObject;
+    NS_IF_RELEASE(t);
+    return 0;
+  }
+};
 
 /** implementation of a transaction manager object.
  *
  */
 class nsTransactionManager : public nsITransactionManager
 {
+private:
+
+  PRInt32 mMaxLevelsOfUndo;
+  nsTransactionReleaseFunctor mRF;
+  nsDeque mUndoStack;
+  nsDeque mRedoStack;
+
 public:
 
   /** The default constructor.
    */
-  nsTransactionManager();
+  nsTransactionManager(PRInt32 aMaxLevelsOfUndo=-1);
 
   /** The default destructor.
    */
@@ -48,6 +72,9 @@ public:
   virtual nsresult Write(nsIOutputStream *aOutputStream);
   virtual nsresult AddListener(nsITransactionListener *aListener);
   virtual nsresult RemoveListener(nsITransactionListener *aListener);
+
+  /* nsTransactionManager specific methods. */
+  virtual nsresult PruneRedoStack();
 };
 
 #endif // nsTransactionManager_h__