parse static method

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

Parses a human-readable size string into a BinarySize object.

The string may contain an integer part, an optional fractional part, and a unit suffix. Examples of valid inputs:

• "344 B"
• "1.00 KiB"
• "3.25 GiB"
• "7.5 MB"

Standard detection:

• If the unit contains an i (e.g. KiB, MiB), the IEC standard is used.
• Otherwise, fallbackStandard is used (defaults to BinarySizeSiStandard).

Returns null if the input string does not match the expected format.

final size = BinarySize.parse('3.25 GiB');
print(size?.bytesCount);  // BigInt 3489660928
print(size?.displayText); // "3.25 GiB"

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;
}