getAlternates method

List<SpeechRecognitionWords> getAlternates(bool aggregateResults)

Return the full speech recognition results which is the concatenation of all the alternates and all their phrases into separate results. The approach is to concatenate the all phrases from the first, or most likely, alternate. The first is assumed to have the most phrases, since there must be a recognition result for a phrase or it wouldn't have alternates. Then all the phrases for each subsequent alternate are concatenated, any phrase that is missing an alternate has that alternate filled in with the previous alternate. This is done so that the result is a complete transcript of all the alternates.

Implementation

List<SpeechRecognitionWords> getAlternates(bool aggregateResults) {
  final phraseCount = _alternates.length;
  var result = <SpeechRecognitionWords>[];
  final maxAlternates = _alternates.values
      .fold(0, (max, list) => max = list.length > max ? list.length : max);
  // print(
  //     'Speech recognition alternates: $maxAlternates, phrases: $phraseCount');

  if (aggregateResults) {
    for (var phraseIndex = 0; phraseIndex < phraseCount; ++phraseIndex) {
      final phraseAlternates = _alternates[phraseIndex] ?? [];
      for (var altIndex = max(1, phraseAlternates.length);
          altIndex < maxAlternates;
          ++altIndex) {
        phraseAlternates.add(phraseAlternates[altIndex - 1]);
      }
    }
    for (var altCount = 0; altCount < maxAlternates; ++altCount) {
      var alternatePhrase = '';
      var alternateConfidence = 1.0;
      for (var phraseIndex = 0; phraseIndex < phraseCount; ++phraseIndex) {
        alternatePhrase +=
            _alternates[phraseIndex]![altCount].recognizedWords;
        alternateConfidence = min(alternateConfidence,
            _alternates[phraseIndex]![altCount].confidence);
      }
      result
          .add(SpeechRecognitionWords(alternatePhrase, alternateConfidence));
    }
  } else {
    for (var phraseIndex = phraseCount - 1; phraseIndex >= 0; --phraseIndex) {
      if ((_alternates[phraseIndex]?[0].recognizedWords.trim() ?? '')
          .isEmpty) {
        continue;
      }
      for (var altIndex = 0;
          altIndex < _alternates[phraseIndex]!.length;
          ++altIndex) {
        result.add(_alternates[phraseIndex]![altIndex]);
      }
      // result.add(SpeechRecognitionWords(
      //     _alternates[phraseIndex]![0].recognizedWords,
      //     _alternates[phraseIndex]![0].confidence));
      break;
    }
  }
  return result;
}