From ec7c4a64a356faab16415626fc1b79e60193c852 Mon Sep 17 00:00:00 2001
From: martin <laz.git@mfriebe.de>
Date: Thu, 9 Jul 2020 14:28:10 +0000
Subject: [PATCH] SynEdit: WrappedView, fix merging nodes

git-svn-id: trunk@63538 -
---
 components/synedit/syneditwrappedview.pp |  62 +++---
 components/synedit/test/testwordwrap.pas | 241 ++++++++++++++++++++++-
 2 files changed, 279 insertions(+), 24 deletions(-)

diff --git a/components/synedit/syneditwrappedview.pp b/components/synedit/syneditwrappedview.pp
index 34ef4cf8cc..73707fbc6d 100644
--- a/components/synedit/syneditwrappedview.pp
+++ b/components/synedit/syneditwrappedview.pp
@@ -787,6 +787,7 @@ procedure TSynWordWrapLineMap.MoveLinesAtStartTo(ADestPage: TSynWordWrapLineMap;
   ASourceEndLine, ATargetStartLine: Integer);
 var
   MinLineCount, TrgO1: Integer;
+  W: TSynWordWrapLineData;
 begin
   assert(ATargetStartLine >= ADestPage.FWrappedExtraSumsCount + ADestPage.FOffsetAtStart, 'TSynWordWrapLineMap.InsertLinesFromPage: ATargetStartLine > ADestPage.FWrappedExtraSumsCount + ADestPage.FOffsetAtStart');
 
@@ -795,15 +796,22 @@ begin
   if (FWrappedExtraSumsCount = 0) then
     exit;
 
+  ASourceEndLine := ASourceEndLine - Offset;
+  if ASourceEndLine < 0 then
+    exit;
+
+  if (ASourceEndLine > 0) and (ASourceEndLine < FWrappedExtraSumsCount) then begin
+    W := FWrappedExtraSums[ASourceEndLine];
+    while (ASourceEndLine > 0) and
+          (FWrappedExtraSums[ASourceEndLine - 1] = W)
+    do
+      dec(ASourceEndLine);
+  end;
+
   if ADestPage.FWrappedExtraSumsCount = 0 then begin
     // Target page is empty
-    ADestPage.FOffsetAtStart := ATargetStartLine + Min(Offset, ASourceEndLine);
+    ADestPage.FOffsetAtStart := ATargetStartLine + Offset;
     assert(ADestPage.FOffsetAtStart >= 0, 'TSynWordWrapLineMap.MoveLinesAtStartTo: ADestPage.FOffsetAtStart >= 0');
-    ASourceEndLine := ASourceEndLine - Offset;
-    if ASourceEndLine < 0 then begin
-      ADestPage.FOffsetAtStart := 0;
-      exit;
-    end;
 
     MinLineCount := Min(ASourceEndLine+1, FWrappedExtraSumsCount);
     ADestPage.GrowCapacity(MinLineCount);
@@ -816,10 +824,6 @@ begin
     exit;
   end;
 
-  ASourceEndLine := ASourceEndLine - Offset;
-  if ASourceEndLine < 0 then
-    exit;
-
   ATargetStartLine  := ATargetStartLine + Offset - ADestPage.FOffsetAtStart;
   MinLineCount := Min(ASourceEndLine+1, FWrappedExtraSumsCount);
   TrgO1 := ADestPage.GetWrappedExtraSumBefore(ADestPage.FWrappedExtraSumsCount);
@@ -845,6 +849,7 @@ procedure TSynWordWrapLineMap.MoveLinesAtEndTo(ADestPage: TSynWordWrapLineMap;
   ASourceStartLine, ALineCount: Integer);
 var
   OldOffset, SrcO1, SrcO2, MinLineCount: Integer;
+  W: TSynWordWrapLineData;
 begin
   assert(ASourceStartLine-FOffsetAtStart+ALineCount >= FWrappedExtraSumsCount, 'TSynWordWrapLineMap.MoveLinesAtEndTo: ASourceStartLine+ACount >= FWrappedExtraSumsCount');
 
@@ -875,8 +880,22 @@ begin
   else
     ASourceStartLine := ASourceStartLine - Offset;
 
+
+  if (ASourceStartLine > 0) and (ASourceStartLine < FWrappedExtraSumsCount) then begin
+    SrcO2 := ASourceStartLine;
+    W := FWrappedExtraSums[ASourceStartLine - 1];
+    while (ASourceStartLine < FWrappedExtraSumsCount) and
+          (FWrappedExtraSums[ASourceStartLine] = W)
+    do
+      inc(ASourceStartLine);
+    ALineCount := ALineCount + SrcO2 - ASourceStartLine;
+    ADestPage.FOffsetAtStart := ADestPage.FOffsetAtStart + ASourceStartLine - SrcO2;
+    if ALineCount <= 0 then
+      exit;
+  end;
+
+
   SrcO1 := GetWrappedExtraSumBefore(Min(ASourceStartLine,              FWrappedExtraSumsCount));
-  SrcO2 := GetWrappedExtraSumBefore(Min(ASourceStartLine + ALineCount, FWrappedExtraSumsCount));
   MinLineCount := Max(0, Min(ALineCount, FWrappedExtraSumsCount - ASourceStartLine));
 
   if ADestPage.FWrappedExtraSumsCount = 0 then begin
@@ -894,6 +913,7 @@ begin
     exit;
   end;
 
+  SrcO2 := GetWrappedExtraSumBefore(Min(ASourceStartLine + ALineCount, FWrappedExtraSumsCount));
   ADestPage.GrowCapacity(ADestPage.FWrappedExtraSumsCount + ALineCount + OldOffset);
   WrapInfoMoveUpAndAdjustFromTo(
     @ADestPage.FWrappedExtraSums[0],
@@ -1122,12 +1142,10 @@ begin
       assert(NextLineOffs > RealEndLine, 'TSynWordWrapIndexPage.MaybeJoinWithSibling: NextLineOffs > RealEndLine');
       NextLineDist := NextLineOffs - RealEndLine + NextPage.RealStartLine;
       c := NextPage.RealCount;
-      if (c <> 0) and (
-           (c > Tree.PageJoinSize) or
-           (NextLineDist > Tree.PageJoinDistance) or
-           (NextPage.FirstInvalidLine >= 0) or
-           (not NextPage.CanExtendStartTo(-NextLineOffs + RealStartLine, True))
-         )
+      if ( (c <> 0) and (NextLineDist > Tree.PageJoinDistance) ) or
+         (c > Tree.PageJoinSize) or
+         (NextPage.FirstInvalidLine >= 0) or
+         (not NextPage.CanExtendStartTo(-NextLineOffs + RealStartLine, True))
       then
         NextLineOffs := 0;
     end
@@ -1142,12 +1160,10 @@ begin
       assert(PrevLineOffs > PrevPage.RealEndLine, 'TSynWordWrapIndexPage.MaybeJoinWithSibling: -PrevLineOffs > PrevPage.RealEndLine');
       PrevLineDist := PrevLineOffs + RealStartLine - PrevPage.RealEndLine;
       c := PrevPage.RealCount;
-      if (c <> 0) and (
-          (c > Tree.PageJoinSize) or
-          (PrevLineDist> Tree.PageJoinDistance) or
-          (PrevPage.FirstInvalidLine >= 0) or
-          (not PrevPage.CanExtendEndTo(PrevLineOffs + RealEndLine, True))
-         )
+      if ( (c <> 0) and (PrevLineDist> Tree.PageJoinDistance) ) or
+         (c > Tree.PageJoinSize) or
+         (PrevPage.FirstInvalidLine >= 0) or
+         (not PrevPage.CanExtendEndTo(PrevLineOffs + RealEndLine, True))
       then
         PrevLineOffs := 0;
     end
diff --git a/components/synedit/test/testwordwrap.pas b/components/synedit/test/testwordwrap.pas
index 08d4b9976e..e7809d7f2c 100644
--- a/components/synedit/test/testwordwrap.pas
+++ b/components/synedit/test/testwordwrap.pas
@@ -322,7 +322,7 @@ end;
 procedure TTestWordWrap.InitLine(ALine: TSynWordWrapLineMap;
   const AWrapValues: TExpWraps);
 begin
-  ALine.DeleteLinesAtOffset(0, ALine.RealCount + ALine.Offset);
+  ALine.DeleteLinesAtOffset(0, max(ALine.RealCount + ALine.Offset, ALine.LastInvalidLine+1));
   if AWrapValues.len > 0 then begin
     ALine.InsertLinesAtOffset(0, AWrapValues.len);
     ValidateWraps(ALine, AWrapValues);
@@ -982,6 +982,70 @@ begin
   //ALine1.InsertLinesFromPage(ALine2, 0, 6, 3);
   AssertLineForWraps(ATestName, ALine1, w.init([1, 1, 3, 3, 1,   1, 1, 5, 6,   1,1]));
 
+///////////////////////////////////////
+  (* split node at none wrapping lines - ensure the none-wrap "WrappedExtraSums" are stripped *)
+  ATestName := 'Insert at start: empty lines in the middle -> dest 2';
+  InitLine(ALine1, w.init([4, 5]));
+  InitLine(ALine2, w.init([2, 1, 1, 1, 1, 3]));
+  ALine2.MoveLinesAtEndTo(ALine1, 3, 3);
+  AssertLineForWraps('', ALine1, w.init([1, 1, 3, 4, 5,   1,1]));
+
+  ATestName := 'Insert at start: empty lines in the middle -> dest 1';
+  InitLine(ALine1, w.init([4]));
+  InitLine(ALine2, w.init([2, 1, 1, 1, 1, 3]));
+  ALine2.MoveLinesAtEndTo(ALine1, 3, 3);
+  AssertLineForWraps('', ALine1, w.init([1, 1, 3, 4,   1,1]));
+
+  ATestName := 'Insert at start: empty lines in the middle -> empty dest';
+  InitLine(ALine1, w.init([]));
+  InitLine(ALine2, w.init([2, 1, 1, 1, 1, 3]));
+  ALine2.MoveLinesAtEndTo(ALine1, 3, 3);
+  AssertLineForWraps('', ALine1, w.init([1, 1, 3,   1,1]));
+
+  ATestName := 'Insert at start: empty lines in the middle -> dest 2 - with dest offset';
+  InitLine(ALine1, w.init([1, 1, 4, 5]));
+  InitLine(ALine2, w.init([2, 1, 1, 1, 1, 3]));
+  ALine2.MoveLinesAtEndTo(ALine1, 3, 3);
+  AssertLineForWraps('', ALine1, w.init([1, 1, 3, 1, 1, 4, 5,   1,1]));
+
+  ATestName := 'Insert at start: empty lines in the middle -> dest 2 - with source offset';
+  InitLine(ALine1, w.init([4, 5]));
+  InitLine(ALine2, w.init([1, 1, 2, 1, 1, 1, 1, 3]));
+  ALine2.MoveLinesAtEndTo(ALine1, 5, 3);
+  AssertLineForWraps('', ALine1, w.init([1, 1, 3, 4, 5,   1,1]));
+
+
+
+  ATestName := 'Insert at end : empty lines in the middle -> dest 2';
+  InitLine(ALine1, w.init([4, 5]));
+  InitLine(ALine2, w.init([2, 1, 1, 1, 1, 3]));
+  ALine2.MoveLinesAtStartTo(ALine1, 3, 2);
+  AssertLineForWraps('', ALine1, w.init([4, 5, 2, 1, 1,   1,1]));
+
+  ATestName := 'Insert at end : empty lines in the middle -> dest 1';
+  InitLine(ALine1, w.init([4]));
+  InitLine(ALine2, w.init([2, 1, 1, 1, 1, 3]));
+  ALine2.MoveLinesAtStartTo(ALine1, 3, 1);
+  AssertLineForWraps('', ALine1, w.init([4, 2, 1, 1,   1,1]));
+
+  ATestName := 'Insert at end : empty lines in the middle -> emyty dest';
+  InitLine(ALine1, w.init([]));
+  InitLine(ALine2, w.init([2, 1, 1, 1, 1, 3]));
+  ALine2.MoveLinesAtStartTo(ALine1, 3, 0);
+  AssertLineForWraps('', ALine1, w.init([2, 1, 1,   1,1]));
+
+  ATestName := 'Insert at end : empty lines in the middle -> dest 2 - with dest offset';
+  InitLine(ALine1, w.init([1, 1, 4, 5]));
+  InitLine(ALine2, w.init([2, 1, 1, 1, 1, 3]));
+  ALine2.MoveLinesAtStartTo(ALine1, 3, 4);
+  AssertLineForWraps('', ALine1, w.init([1, 1, 4, 5, 2, 1, 1,   1,1]));
+
+  ATestName := 'Insert at end : empty lines in the middle -> dest 2 - with source offset';
+  InitLine(ALine1, w.init([4, 5]));
+  InitLine(ALine2, w.init([1, 1, 2, 1, 1, 1, 1, 2]));
+  ALine2.MoveLinesAtStartTo(ALine1, 5, 2);
+  AssertLineForWraps('', ALine1, w.init([4, 5, 1, 1, 2, 1, 1,   1,1]));
+
 end;
 
 procedure TTestWordWrap.TestWordWrapLineMapMergeInvalidate;
@@ -990,6 +1054,43 @@ var
   ALine1, ALine2: TSynWordWrapLineMap;
   ATestName: String;
   w: TExpWraps;
+
+  procedure DoMoveLinesAtEndTo(const AName: String;
+    const AWrapValues1, AWrapValues2: array of integer; AInvalLine: Integer; const AInvalDest: Boolean;
+    ASourceStartLine, ALineCount: Integer;
+    Exp: array of integer;  ExpInval: Integer
+  );
+  begin
+    InitLine(ALine1, w.init(AWrapValues1));
+    InitLine(ALine2, w.init(AWrapValues2));
+    if AInvalDest then
+      ALine1.InvalidateLines(AInvalLine, AInvalLine)
+    else
+      ALine2.InvalidateLines(AInvalLine, AInvalLine);
+    ALine2.MoveLinesAtEndTo(ALine1, ASourceStartLine, ALineCount);
+    AssertLineForWraps(AName, ALine1, w.init(Exp));
+    AssertEquals(AName+' invalid', ExpInval, ALine1.FirstInvalidLine);
+    AssertEquals(AName+' invalid', ExpInval, ALine1.LastInvalidLine);
+  end;
+
+  procedure DoMoveLinesAtStartTo(const AName: String;
+    const AWrapValues1, AWrapValues2: array of integer; AInvalLine: Integer; const AInvalDest: Boolean;
+    ASourceEndLine, ATargetStartLine: Integer;
+    Exp: array of integer;  ExpInval: Integer
+  );
+  begin
+    InitLine(ALine1, w.init(AWrapValues1));
+    InitLine(ALine2, w.init(AWrapValues2));
+    if AInvalDest then
+      ALine1.InvalidateLines(AInvalLine, AInvalLine)
+    else
+      ALine2.InvalidateLines(AInvalLine, AInvalLine);
+    ALine2.MoveLinesAtStartTo(ALine1, ASourceEndLine, ATargetStartLine);
+    AssertLineForWraps(AName, ALine1, w.init(Exp));
+    AssertEquals(AName+' invalid', ExpInval, ALine1.FirstInvalidLine);
+    AssertEquals(AName+' invalid', ExpInval, ALine1.LastInvalidLine);
+  end;
+
 begin
   ANode1 := TSynWordWrapIndexPage(FTree.FindPageForLine(0, afmCreate).Page);
   ANode2 := TSynWordWrapIndexPage(FTree.FindPageForLine(100, afmCreate).Page);
@@ -1116,6 +1217,144 @@ begin
   AssertLineForWraps(ATestName, ALine2, w.init([1, 1, 1,  1, 1, 3,    1,1,1]));
 
 
+///////////////////////////////////////
+  (* split node at none wrapping lines - ensure the none-wrap "WrappedExtraSums" are stripped *)
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   1,  True,    3, 3,  {=>}  [1, 1, 3, 4, 5,   1,1],  4);
+
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   1,  False,    3, 3, {=>}   [1, 1, 3, 4, 5,   1,1],  -1);
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   2,  False,    3, 3, {=>}   [1, 1, 3, 4, 5,   1,1],  -1);
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   3,  False,    3, 3, {=>}   [1, 1, 3, 4, 5,   1,1],  0);
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   4,  False,    3, 3, {=>}   [1, 1, 3, 4, 5,   1,1],  1);
+
+
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2 - gap at source end',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   1,  True,    3, 4,  {=>}  [1, 1, 3, 1, 4, 5,   1,1],  5);
+
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2 - gap at source end',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   1,  False,    3, 4,  {=>}  [1, 1, 3, 1, 4, 5,   1,1],  -1);
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2 - gap at source end',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   4,  False,    3, 4,  {=>}  [1, 1, 3, 1, 4, 5,   1,1],  1);
+
+
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 1',
+    [4],  [2, 1, 1, 1, 1, 3],      1,  True,    3, 3,  {=>}  [1, 1, 3, 4,   1,1],  4);
+
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 1',
+    [4],  [2, 1, 1, 1, 1, 3],      1,  False,    3, 3, {=>}   [1, 1, 3, 4,   1,1],  -1);
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 1',
+    [4],  [2, 1, 1, 1, 1, 3],      3,  False,    3, 3, {=>}   [1, 1, 3, 4,   1,1],  0);
+
+
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> empty dest',
+    [],  [2, 1, 1, 1, 1, 3],       1,  True,    3, 3,  {=>}  [1, 1, 3,   1,1],  4);
+
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> empty dest',
+    [],  [2, 1, 1, 1, 1, 3],       1,  False,    3, 3, {=>}   [1, 1, 3,   1,1],  -1);
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> empty dest',
+    [],  [2, 1, 1, 1, 1, 3],       4,  False,    3, 3, {=>}   [1, 1, 3,   1,1],  1);
+
+
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2 - with dest offset',
+    [1,1,4, 5],  [2, 1, 1, 1, 1, 3],   1,  True,    3, 3,  {=>}  [1, 1, 3, 1,1,4, 5,   1,1],  4);
+
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2 - with dest offset',
+    [1,1,4, 5],  [2, 1, 1, 1, 1, 3],   1,  False,   3, 3,  {=>}  [1, 1, 3, 1,1,4, 5,   1,1], -1);
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2 - with dest offset',
+    [1,1,4, 5],  [2, 1, 1, 1, 1, 3],   4,  False,   3, 3,  {=>}  [1, 1, 3, 1,1,4, 5,   1,1],  1);
+
+
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2 - with source offset',
+    [4, 5],  [1,1,2, 1, 1, 1, 1, 3],   1,  True,    5, 3,  {=>}  [1, 1, 3, 4, 5,   1,1],  4);
+
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2 - with source offset',
+    [4, 5],  [1,1,2, 1, 1, 1, 1, 3],   1,  False,    5, 3,  {=>}  [1, 1, 3, 4, 5,   1,1],  -1);
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2 - with source offset',
+    [4, 5],  [1,1,2, 1, 1, 1, 1, 3],   3,  False,    5, 3,  {=>}  [1, 1, 3, 4, 5,   1,1],  -1);
+  DoMoveLinesAtEndTo('Insert at start: empty lines in the middle -> dest 2 - with source offset',
+    [4, 5],  [1,1,2, 1, 1, 1, 1, 3],   6,  False,    5, 3,  {=>}  [1, 1, 3, 4, 5,   1,1],  1);
+
+
+
+
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   1,  True,    3, 2,  {=>}  [4, 5, 2, 1, 1,   1,1],  1);
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   1,  False,    3, 2,  {=>}  [4, 5, 2, 1, 1,   1,1],  3);
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   4,  False,    3, 2,  {=>}  [4, 5, 2, 1, 1,   1,1],  -1);
+
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - gap at target end',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   1,  True,    3, 3,  {=>}  [4, 5, 1,  2, 1, 1,   1,1],  1);
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - gap at target end',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   1,  False,    3, 3,  {=>}  [4, 5, 1,  2, 1, 1,   1,1],  4);
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - gap at target end',
+    [4, 5],  [2, 1, 1, 1, 1, 3],   4,  False,    3, 3,  {=>}  [4, 5, 1,  2, 1, 1,   1,1],  -1);
+
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 1',
+    [4],  [2, 1, 1, 1, 1, 3],   1,  True,    3, 1,  {=>}  [4, 2, 1, 1,   1,1],  1);
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 1',
+    [4],  [2, 1, 1, 1, 1, 3],   1,  False,    3, 1,  {=>}  [4, 2, 1, 1,   1,1],  2);
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 1',
+    [4],  [2, 1, 1, 1, 1, 3],   4,  False,    3, 1,  {=>}  [4, 2, 1, 1,   1,1],  -1);
+
+
+// empty dest can not have invalid...
+  //DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> empty dest',
+  //  [],  [2, 1, 1, 1, 1, 3],   1,  True,    3, 0,  {=>}  [2, 1, 1,   1,1],  1);
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> empty dest',
+    [],  [2, 1, 1, 1, 1, 3],   1,  False,    3, 0,  {=>}  [2, 1, 1,   1,1],  1);
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> empty dest',
+    [],  [2, 1, 1, 1, 1, 3],   4,  False,    3, 0,  {=>}  [2, 1, 1,   1,1],  -1);
+
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> empty dest - gap',
+    [],  [2, 1, 1, 1, 1, 3],   1,  True,    3, 2,  {=>}  [1,1, 2, 1, 1,   1,1],  1);
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> empty dest - gap',
+    [],  [2, 1, 1, 1, 1, 3],   1,  False,    3, 2,  {=>}  [1,1, 2, 1, 1,   1,1],  3);
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> empty dest- gap',
+    [],  [2, 1, 1, 1, 1, 3],   4,  False,    3, 2,  {=>}  [1,1, 2, 1, 1,   1,1],  -1);
+
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - with dest offset',
+    [1,1, 4, 5],  [2, 1, 1, 1, 1, 3],   1,  True,    3, 4,  {=>}  [1,1, 4, 5, 2, 1, 1,   1,1],  1);
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - with dest offset',
+    [1,1, 4, 5],  [2, 1, 1, 1, 1, 3],   1,  False,    3, 4,  {=>}  [1,1, 4, 5, 2, 1, 1,   1,1],  5);
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - with dest offset',
+    [1,1, 4, 5],  [2, 1, 1, 1, 1, 3],   4,  False,    3, 4,  {=>}  [1,1, 4, 5, 2, 1, 1,   1,1],  -1);
+
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - with dest offset - gap',
+    [1,1, 4, 5],  [2, 1, 1, 1, 1, 3],   1,  True,    3, 5,  {=>}  [1,1, 4, 5, 1, 2, 1, 1,   1,1],  1);
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - with dest offset - gap',
+    [1,1, 4, 5],  [2, 1, 1, 1, 1, 3],   1,  False,    3, 5,  {=>}  [1,1, 4, 5, 1, 2, 1, 1,   1,1],  6);
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - with dest offset - gap',
+    [1,1, 4, 5],  [2, 1, 1, 1, 1, 3],   4,  False,    3, 5,  {=>}  [1,1, 4, 5, 1, 2, 1, 1,   1,1],  -1);
+
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - with source offset',
+    [4, 5],  [1,1, 2, 1, 1, 1, 1, 3],   1,  True,    5, 2,  {=>}  [4, 5, 1,1, 2, 1, 1,   1,1],  1);
+
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - with source offset',
+    [4, 5],  [1,1, 2, 1, 1, 1, 1, 3],   1,  False,    5, 2,  {=>}  [4, 5, 1,1, 2, 1, 1,   1,1],  3);
+  DoMoveLinesAtStartTo('Insert at start: empty lines in the middle -> dest 2 - with source offset',
+    [4, 5],  [1,1, 2, 1, 1, 1, 1, 3],   6,  False,    5, 2,  {=>}  [4, 5, 1,1, 2, 1, 1,   1,1],  -1);
+
+
 end;