textDiagnosticNavigationIndex function

int? textDiagnosticNavigationIndex({ required List<TextDiagnosticRange> diagnostics, required int cursorOffset, int? activeIndex, bool forward = true, bool wrap = true, })

Implementation

int? textDiagnosticNavigationIndex({
  required List<TextDiagnosticRange> diagnostics,
  required int cursorOffset,
  int? activeIndex,
  bool forward = true,
  bool wrap = true,
}) {
  if (diagnostics.isEmpty) {
    return null;
  }

  final normalizedOffset = cursorOffset < 0 ? 0 : cursorOffset;
  final currentIndex =
      activeIndex ??
      textDiagnosticContainingIndex(
        diagnostics: diagnostics,
        offset: normalizedOffset,
      );

  if (forward) {
    if (currentIndex != null) {
      final nextIndex = currentIndex + 1;
      if (nextIndex < diagnostics.length) {
        return nextIndex;
      }
      return wrap ? 0 : null;
    }

    for (var index = 0; index < diagnostics.length; index++) {
      if (diagnostics[index].startOffset > normalizedOffset) {
        return index;
      }
    }
    return wrap ? 0 : null;
  }

  if (currentIndex != null) {
    final previousIndex = currentIndex - 1;
    if (previousIndex >= 0) {
      return previousIndex;
    }
    return wrap ? diagnostics.length - 1 : null;
  }

  for (var index = diagnostics.length - 1; index >= 0; index--) {
    if (diagnostics[index].startOffset < normalizedOffset) {
      return index;
    }
  }
  return wrap ? diagnostics.length - 1 : null;
}