sw, out of order undo: allow multiple actions from other views

Previously we assumed that the action to be executed is always exactly
the top of the undo stack minus 1 element.

Extend this, so that in case an other view appends two or more elements
to the undo stack, we still find our undo action. Obviously only do this
if all those undo actions are independent from us.

This requires replacing the swap in svl/ with a move-out + move a range
down + move in construct.

Change-Id: Ic12d32d6eb5e77618d99eddb4fa096802f32d655
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/125076
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

1 files changed, 13 insertions, 5 deletions

diff --git a/svl/source/undo/undo.cxx b/svl/source/undo/undo.cxx
index f84d2cda185a..e820a3cbb9d1 100644
--- a/svl/source/undo/undo.cxx
+++ b/svl/source/undo/undo.cxx
@@ -683,13 +683,21 @@ bool SfxUndoManager::ImplUndo( SfxUndoContext* i_contextOrNull )
         return false;
     }
 
-    if (i_contextOrNull && i_contextOrNull->GetUndoOffset() == 1)
+    if (i_contextOrNull && i_contextOrNull->GetUndoOffset() > 0)
     {
-        if (m_xData->pActUndoArray->nCurUndoAction >= 2)
+        size_t nCurrent = m_xData->pActUndoArray->nCurUndoAction;
+        size_t nOffset = i_contextOrNull->GetUndoOffset();
+        if (nCurrent >= nOffset + 1)
         {
-            std::swap(
-                m_xData->pActUndoArray->maUndoActions[m_xData->pActUndoArray->nCurUndoAction - 1],
-                m_xData->pActUndoArray->maUndoActions[m_xData->pActUndoArray->nCurUndoAction - 2]);
+            // Move out the action we want to execute.
+            MarkedUndoAction aAction
+                = std::move(m_xData->pActUndoArray->maUndoActions[nCurrent - 1 - nOffset]);
+            // Move the actions after aAction down by one.
+            std::move(m_xData->pActUndoArray->maUndoActions.data() + nCurrent - nOffset,
+                      m_xData->pActUndoArray->maUndoActions.data() + nCurrent,
+                      m_xData->pActUndoArray->maUndoActions.data() + nCurrent - nOffset - 1);
+            // Move aAction to the top.
+            m_xData->pActUndoArray->maUndoActions[nCurrent - 1] = std::move(aAction);
         }
     }