parse static method

BinarySize? parse(String size, { BinarySizeConventionStandard? fallbackStandard, })

Parse a text into a BinarySize object When unit contains 'i', it will be considered as IEC standard When unit contains no 'i', we will use fallbackStandard to determine the standard fallbackStandard in default is BinarySizeSiStandard

Implementation

static BinarySize? parse(String size, {BinarySizeConventionStandard? fallbackStandard}) {
  BinarySize? result;

  fallbackStandard ??= BinarySizeSiStandard();

  var exp = RegExp(r'(\d+).?(\d*)\s*(B|Ki?B|Mi?B|Gi?B|Ti?B|Pi?B|Ei?B)', caseSensitive: false);

  if (exp.hasMatch(size)) {
    result = BinarySize();

    var match = exp.firstMatch(size);

    if (match == null) return null;

    var integer = match.group(1) ?? '';
    var left = match.group(2) ?? '';
    var unit = match.group(3) ?? '';

    var isIec = unit.toLowerCase().contains('i');

    result.standard = isIec ? BinarySizeIecStandard() : fallbackStandard;

    var diff = result.standard.getLevelBase();

    var scale = BigInt.from(1);

    switch (unit.toUpperCase().replaceAll('IB', 'B')) {
      case 'B':
        break;
      case 'KB':
        scale = diff;
        break;
      case 'MB':
        scale = diff * diff;
        break;
      case 'GB':
        scale = diff * diff * diff;
        break;
      case 'TB':
        scale = diff * diff * diff * diff;
        break;
      case 'PB':
        scale = diff * diff * diff * diff * diff;
        break;
      case 'EB':
        scale = diff * diff * diff * diff * diff * diff;
        break;
      default:
        break;
    }

    var p = 0;

    for (var i = integer.length - 1; i >= 0; --i, ++p) {
      var addon = BigInt.from(int.parse(integer[i]) * pow(10, p)) * scale;
      result.bytesCount += addon;
    }

    p = -1;

    for (var i = 0; i < left.length; ++i, --p) {
      var addon = BigInt.from(int.parse(left[i]) * pow(10, p)) * scale;
      result.bytesCount += addon;
    }

    if (unit.contains('b')) result.bytesCount = BigInt.from(result.bytesCount / BigInt.from(8));
  }

  return result;
}