createDisplay function

Display createDisplay({ int length = 9, int? decimal, String placeholder = '', String? separator = ',', String? decimalPoint = '.', RoundingType roundingType = RoundingType.round, List<String> units = const ['k', 'M', 'G', 'T', 'P'], })

Implementation

Display createDisplay({
  int length = 9,
  int? decimal,
  String placeholder = '',
  String? separator = ',',
  String? decimalPoint = '.',
  RoundingType roundingType = RoundingType.round,
  List<String> units = const ['k', 'M', 'G', 'T', 'P'],
}) => (num? value) {
  decimal ??= length;
  placeholder = placeholder.substring(0, min(length, placeholder.length));

  if (value == null || !value.isFinite) {
    return placeholder;
  }

  final valueStr = num.parse(value.toStringAsPrecision(maxPrecision)).toString();
  final negative = RegExp(r'^-?').stringMatch(valueStr) ?? '';

  var roundingRst = _rounding(
    RegExp(r'\d+').stringMatch(valueStr) ?? '',
    RegExp(r'(?<=\.)\d+$').stringMatch(valueStr) ?? '',
    decimal!,
    roundingType,
  );
  var integer = roundingRst[0];
  var deci = roundingRst[1];
  final localeInt = integer.replaceAllMapped(
    RegExp(r'(\d{1,3})(?=(\d{3})+(?!\d))'),
    (m) => '${m[1]},',
  );

  separator = separator?.substring(0, 1);
  decimalPoint = decimalPoint?.substring(0, 1);

  final currentLen = negative.length + localeInt.length + 1 + deci.length;
  if (separator != null && currentLen <= length) {
    deci = deci.replaceAll(RegExp(r'0+$'), '');
    return '${negative}${localeInt.replaceAll(',', separator!)}${deci == '' ? '' : decimalPoint}${deci}';
  }

  var space = length - negative.length - integer.length;
  if (space >= 0) {
    roundingRst = _rounding(integer, deci, space - 1, roundingType);
    integer = roundingRst[0];
    deci = roundingRst[1].replaceAll(RegExp(r'0+$'), '');
    return '${negative}${integer}${deci == '' ? '' : decimalPoint}${deci}';
  }

  final sections = localeInt.split(',');
  if (sections.length > 1) {
    final mainSection = sections[0];
    final tailSection = sections.sublist(1).join();
    const baseUnits = ['k', 'M', 'G', 'T', 'P'];
    final unitIndex = sections.length - 2;
    final unit = unitIndex < units.length
      ? units[sections.length - 2].substring(0, 1)
      : baseUnits[sections.length - 2];
    space = length - negative.length - mainSection.length - 1;
    if (space >= 0) {
      roundingRst = _rounding(mainSection, tailSection, space - 1, roundingType);
      final main = roundingRst[0];
      final tail = roundingRst[1].replaceAll(RegExp(r'0+$'), '');
      return '${negative}${main}${tail == '' ? '' : decimalPoint}${tail}${unit}';
    }
  }

  print('number_display: length: ${length} is too small for ${value}');
  return value.toString();
};