call method

Implementation

@override
String? call(TerminalKeyboardEvent event) {
  final mode = event.state.kittyKeyboardMode;
  final kittySequenceEnabled = mode &
          (_disambiguateEscapeCodes |
              _reportEventTypes |
              _reportAllKeysAsEscapeCodes) !=
      0;
  if (!kittySequenceEnabled) {
    return null;
  }

  if (_isComposedTextEvent(event, mode)) {
    return null;
  }

  // "Additionally, with this mode, events for pressing modifier keys are
  // reported" — the modifier keys themselves are reported only under report
  // all keys, never under disambiguate alone.
  final specialCode = _specialKeyCode(event.key);
  if (specialCode != null) {
    if (_isModifierKey(event.key) &&
        mode & _reportAllKeysAsEscapeCodes == 0) {
      return null;
    }
    if (!_reportsRelease(event, mode)) {
      return null;
    }
    return _sequence(specialCode, event);
  }

  // "Additionally, all non text keypad keys will be reported as separate
  // keys" — a keypad key that types a character (a digit with Num Lock on,
  // or any operator) follows the same rules as other text keys. The key
  // decides this rather than the event text, which releases never carry.
  final numpadCode = _numpadKeyCode(event.key);
  if (numpadCode != null) {
    // Keypad Enter keeps the legacy carriage return like the main Enter key.
    // kitty and Ghostty send CSI 57414 u here, but clients that only push
    // "disambiguate" (Cursor's agent CLI among them) do not decode it and
    // insert U+E046 instead of submitting.
    if (event.key == TerminalKey.numpadEnter &&
        mode & _reportAllKeysAsEscapeCodes == 0 &&
        !(event.ctrl || event.alt || event.shift || event.superKey)) {
      return switch (event.type) {
        TerminalKeyEventType.release => null,
        _ => '\r',
      };
    }
    if (event.key != TerminalKey.numpadEnter &&
        !_shouldEncodeCharacter(event, mode)) {
      return null;
    }
    if (!_reportsRelease(event, mode)) {
      return null;
    }
    return _sequence(numpadCode, event);
  }

  final functionalSequence = _functionalSequence(event, mode);
  if (functionalSequence != null) {
    return functionalSequence;
  }

  final controlCode = _controlKeyCode(event.key);
  if (controlCode != null && _shouldUseLegacyControlCode(event, mode)) {
    return String.fromCharCode(controlCode);
  }

  if (_shouldEncodeControlKey(event, mode)) {
    if (controlCode != null) {
      return _sequence(controlCode, event);
    }
  }

  final characterCode = _characterKeyCode(event);
  if (characterCode == null) {
    return null;
  }
  if (!_shouldEncodeCharacter(event, mode)) {
    return null;
  }

  var payload = characterCode.toString();
  final reportsAlternateKeys = mode & _reportAlternateKeys != 0;
  final alternateCode = _alternateCharacterCode(event, characterCode);
  if (reportsAlternateKeys && alternateCode != null) {
    payload = '$payload:$alternateCode';
  }

  return _sequence(payload, event);
}