backspace method

void backspace()

Remove the selection or last char if the selection is empty (backspace key)

Implementation

void backspace() {
  if (readOnly) return;
  if (_undoController?.isUndoRedoInProgress ?? false) return;

  final selectionBefore = _selection;
  final sel = _selection;
  String deletedText;

  if (sel.start < sel.end) {
    _flushBuffer();

    if (deleteFoldRangeOnDeletingFirstLine) {
      final startLine = _rope.getLineAtOffset(sel.start);
      final endLine = _rope.getLineAtOffset(sel.end);

      if (startLine == endLine ||
          (startLine + 1 == endLine &&
              sel.end == _rope.getLineStartOffset(endLine))) {
        final lineStart = _rope.getLineStartOffset(startLine);
        final lineText = _rope.getLineText(startLine);
        final lineEnd = lineStart + lineText.length;
        final selectsWholeLine = sel.start <= lineStart && sel.end >= lineEnd;

        if (selectsWholeLine) {
          FoldRange? foldToDelete;
          if (_isFirstLineOfFoldedRange(startLine)) {
            foldToDelete = foldings[startLine];
          } else {
            for (final fold in foldings.values) {
              if (fold != null && fold.isFolded) {
                if (startLine > fold.startIndex &&
                    startLine <= fold.endIndex) {
                  for (final child in fold.originallyFoldedChildren) {
                    if (child.startIndex == startLine) {
                      foldToDelete = child;
                      break;
                    }
                  }
                  if (foldToDelete != null) break;
                }
              }
            }
          }

          if (foldToDelete != null) {
            final foldStart = _rope.getLineStartOffset(
              foldToDelete.startIndex,
            );
            final foldEndLine = foldToDelete.endIndex;
            final foldEndLineText = _rope.getLineText(foldEndLine);
            final foldEnd =
                _rope.getLineStartOffset(foldEndLine) +
                foldEndLineText.length;

            deletedText = _rope.substring(foldStart, foldEnd);
            _rope.delete(foldStart, foldEnd);
            _currentVersion++;
            _selection = TextSelection.collapsed(offset: foldStart);
            dirtyLine = _rope.getLineAtOffset(
              foldStart.clamp(0, _rope.length),
            );
            lineStructureChanged = true;
            foldings.remove(foldToDelete.startIndex);

            for (final fold in foldings.values) {
              if (fold != null) {
                fold.originallyFoldedChildren.remove(foldToDelete);
              }
            }

            _recordDeletion(
              foldStart,
              deletedText,
              selectionBefore,
              _selection,
            );
            _syncToConnection();
            notifyListeners();
            return;
          }
        }
      }
    }

    deletedText = _rope.substring(sel.start, sel.end);
    _rope.delete(sel.start, sel.end);
    _currentVersion++;
    _selection = TextSelection.collapsed(offset: sel.start);
    dirtyLine = _rope.getLineAtOffset(sel.start);

    _recordDeletion(sel.start, deletedText, selectionBefore, _selection);
    _syncToConnection();
    notifyListeners();
    return;
  }

  if (sel.start <= 0) return;

  final deleteOffset = sel.start - 1;

  String charToDelete;
  if (_bufferLineIndex != null && _bufferDirty) {
    final bufferEnd = _bufferLineRopeStart + _bufferLineText!.length;
    if (deleteOffset >= _bufferLineRopeStart && deleteOffset < bufferEnd) {
      charToDelete = _bufferLineText![deleteOffset - _bufferLineRopeStart];
    } else {
      charToDelete = _rope.charAt(deleteOffset);
    }
  } else {
    charToDelete = _rope.charAt(deleteOffset);
  }

  if (charToDelete == '\n') {
    _flushBuffer();
    _rope.delete(deleteOffset, sel.start);
    _currentVersion++;
    _selection = TextSelection.collapsed(offset: deleteOffset);
    dirtyLine = _rope.getLineAtOffset(deleteOffset);
    lineStructureChanged = true;

    _recordDeletion(deleteOffset, '\n', selectionBefore, _selection);
    _syncToConnection();
    notifyListeners();
    return;
  }

  if (_bufferLineIndex != null && _bufferDirty) {
    final bufferEnd = _bufferLineRopeStart + _bufferLineText!.length;

    if (deleteOffset >= _bufferLineRopeStart && deleteOffset < bufferEnd) {
      final localOffset = deleteOffset - _bufferLineRopeStart;
      deletedText = _bufferLineText![localOffset];
      _bufferLineText =
          _bufferLineText!.substring(0, localOffset) +
          _bufferLineText!.substring(localOffset + 1);
      _selection = TextSelection.collapsed(offset: deleteOffset);
      _currentVersion++;

      bufferNeedsRepaint = true;

      _recordDeletion(deleteOffset, deletedText, selectionBefore, _selection);
      _scheduleSyncToConnection();
      _scheduleFlush();
      notifyListeners();
      return;
    }
    _flushBuffer();
  }

  final lineIndex = _rope.getLineAtOffset(deleteOffset);
  _initBuffer(lineIndex);

  final localOffset = deleteOffset - _bufferLineRopeStart;
  if (localOffset >= 0 && localOffset < _bufferLineText!.length) {
    deletedText = _bufferLineText![localOffset];
    _bufferLineText =
        _bufferLineText!.substring(0, localOffset) +
        _bufferLineText!.substring(localOffset + 1);
    _bufferDirty = true;
    _selection = TextSelection.collapsed(offset: deleteOffset);
    _currentVersion++;
    dirtyLine = lineIndex;

    bufferNeedsRepaint = true;

    _recordDeletion(deleteOffset, deletedText, selectionBefore, _selection);
    _scheduleSyncToConnection();
    _scheduleFlush();
    notifyListeners();
  }
}