Pitch.fromString constructor

Pitch.fromString(String notation)

Constrói um Pitch a partir de uma string (ex: "C4", "F#5", "Bb3")

Implementation

factory Pitch.fromString(String notation) {
  if (notation.isEmpty) {
    throw ArgumentError('Notation cannot be empty');
  }

  // Extrair a nota base (primeira letra)
  final step = notation[0].toUpperCase();
  if (!'CDEFGAB'.contains(step)) {
    throw ArgumentError('Invalid note step: $step');
  }

  // Encontrar onde começa o número da oitava
  int octaveStart = 1;
  double alter = 0.0;
  AccidentalType? accidentalType;

  // Processar acidentes
  if (notation.length > 1) {
    for (int i = 1; i < notation.length; i++) {
      final char = notation[i];
      if (char == '#') {
        alter += 1.0;
        accidentalType = alter == 1.0 ? AccidentalType.sharp : AccidentalType.doubleSharp;
      } else if (char == 'b') {
        alter -= 1.0;
        accidentalType = alter == -1.0 ? AccidentalType.flat : AccidentalType.doubleFlat;
      } else if (char.contains(RegExp(r'[0-9]'))) {
        octaveStart = i;
        break;
      }
    }
  }

  // Extrair a oitava
  if (octaveStart >= notation.length) {
    throw ArgumentError('Missing octave number in notation: $notation');
  }

  final octaveString = notation.substring(octaveStart);
  final octave = int.tryParse(octaveString);
  if (octave == null) {
    throw ArgumentError('Invalid octave number: $octaveString');
  }

  return Pitch(
    step: step,
    octave: octave,
    alter: alter,
    accidentalType: accidentalType,
  );
}