Improve replacement of rectangular selections

  Entities
  ---------
  * correctly size the buffer by using `SCI_GETSELTEXT` to measure the
    selection region instead of the wrapper object's relative positions;
    fixes an off-by-one bug that could lead to an invalid free and a
    fatal exception when using the heap tracer (debug builds only)

  * trim trailing newlines from the replacement text

  Unicode escapes
  ---------------
  * only replace as many characters as are actually within the selection

*Not (yet) implemented:*

  * accurate replacement of Unicode escapes in multiple stream selections
    (via the new `... Multi-select` suite of functions)

  * accurate replacement of discontinuous selections (i.e., via the new
    `Skip Current & Go to Next Multi-select` function). This will
    probably require multiple `TextRange` objects, one for each
    selection, instead of a straightforward call to `SCI_REPLACESEL`

Author: rdipardo

src/LibNppPlugin/NppSimpleObjects.pas

@@ -517,8 +517,11 @@ procedure TSelection.SetStart(const AValue: Sci_Position);
 function TSelection.GetText: WideString;
 var
   Chars: AnsiString;
+  LenSel: Sci_Position;
 begin
-  Chars := StringOfChar(#0, Self.GetLength + 1);
+  LenSel := FEditor.SendMessage(SCI_GETSELTEXT, 0, Nil);
+  if FEditor.ApiLevel >= sciApi_GTE_515 then Inc(LenSel);
+  Chars := StringOfChar(#0, LenSel);
   FEditor.SendMessage(SCI_GETSELTEXT, 0, PAnsiChar(Chars));
   case FEditor.SendMessage(SCI_GETCODEPAGE) of
     SC_CP_UTF8:
@@ -540,6 +543,10 @@ procedure TSelection.SetText(const AValue: WideString);
   else
     Chars := RawByteString(AValue);
   end;
+  if (FEditor.SendMessage(SCI_GETSELECTIONS) > 1) then begin
+    FEditor.SendMessage(SCI_SETSEL, Self.Anchor, Self.GetCurrentPos);
+    Chars := TrimRight(Chars);
+  end;
   NewLength := System.Length(Chars) - 1;
   Reversed := (Self.Anchor > Self.GetCurrentPos);
   FEditor.SendMessage(SCI_REPLACESEL, 0, PAnsiChar(Chars));

src/U_JSEncode.pas

@@ -116,14 +116,15 @@ function DecodeJS(Scope: TEntityReplacementScope = ersSelection): Integer;
   npp: TApplication;
   doc: TActiveDocument;
   Target, Match, MatchNext: TTextRange;
+  ColumnSel: Boolean;
   HiByte, LoByte: Cardinal;
   EmojiChars: array [0..1] of WideChar;
 begin
   Result := 0;
 
   npp := GetApplication();
   doc := npp.ActiveDocument;
-
+  ColumnSel := (doc.SendMessage(SCI_GETSELECTIONMODE) <> SC_SEL_STREAM);
   Target := TTextRange.Create(doc, doc.Selection.StartPos, doc.Selection.EndPos);
   Match := TTextRange.Create(doc);
   try
@@ -161,7 +162,7 @@ function DecodeJS(Scope: TEntityReplacementScope = ersSelection): Integer;
         if (Result < 1) then doc.Selection.StartPos := Match.StartPos;
         Inc(Result);
       end;
-    until Match.Length = 0;
+    until (Match.Length = 0) or (ColumnSel and (Result = doc.SendMessage(SCI_GETSELECTIONS)));
 
     if Result > 0 then doc.Selection.ClearSelection;
   finally