Advent Of Code 2020 Day 4 in dart

aoc2020_4.dart

void main() {
  final List<Object> solutions = [
    SolutionA(),
    SolutionB()
  ];
  solutions.forEach((s) => print(s.toString()));
}

// Full inputs at https://adventofcode.com/2020/day/4/input
var inputAdvent4 = """pid:087499704 hgt:74in ecl:grn iyr:2012 eyr:2030 byr:1980
hcl:#623a2f

eyr:2029 ecl:blu cid:129 byr:1989
iyr:2014 pid:896056539 hcl:#a97842 hgt:165cm

hcl:#888785
hgt:164cm byr:2001 iyr:2015 cid:88
pid:545766238 ecl:hzl
eyr:2022

iyr:2010 hgt:158cm hcl:#b6652a ecl:blu byr:1944 eyr:2021 pid:093154719

eyr:1972 cid:100
hcl:#18171d ecl:amb hgt:170 pid:186cm iyr:2018 byr:1926

iyr:2019
hcl:#602927 eyr:1967 hgt:170cm
ecl:grn pid:012533040 byr:1946

hcl:dab227 iyr:2012
ecl:brn hgt:182cm pid:021572410 eyr:2020 byr:1992 cid:277

hgt:59cm ecl:zzz
eyr:2038 hcl:74454a iyr:2023
pid:3556412378 byr:2007""";

List<Passport> _parseInputs(String inputs) => inputs
    .split("\n\n")
    .where((e) => e.isNotEmpty)
    .map<Passport>((e) => Passport.fromString(e))
    .toList();
var _passports = _parseInputs(inputAdvent4);

class Passport {
  Map<String, String> _data = {};
  static final passportFields = const <String>{
    'byr', // (Birth Year)
    'iyr', // (Issue Year)
    'eyr', // (Expiration Year)
    'hgt', // (Height)
    'hcl', // (Hair Color)
    'ecl', // (Eye Color)
    'pid', // (Passport ID)
    'cid', // (Country ID)
  };
  Passport.fromString(String input) {
    // replace new lines with spaces
    input.replaceAll(RegExp(r'\n'), ' ').split(' ').forEach((e) {
      var p = e.split(':');
      if (passportFields.contains(p[0])) {
        var key = p[0];
        this._data[key] = p[1];
      }
    });
  }

  bool isSet(String key) => _data.containsKey(key) && _data[key].isNotEmpty;

  bool hasAllFields(Set<String> requiredFields) =>
      requiredFields.every((f) => isSet(f));

  bool allFieldsValid(Map<String, Function(String)> validations) =>
      validations.keys.every((k) {
        if (!isSet(k)) {
          return false;
        }
        var v = _data[k];
        var valid = validations[k](v);
        return valid;
      });
}

abstract class AdventSolution {
  final int day;
  final String name;
  AdventSolution(this.day, this.name);

  String get solution => getSolution();

  // implement in subclass
  String getSolution();

  @override
  String toString() {
    return "Advent Of Code, "
        "Day $day "
        "${name.isNotEmpty ? name : ''} "
        "solution: $solution";
  }
}

abstract class _Day4Solution extends AdventSolution {
  _Day4Solution(name) : super(4, name);
}

class SolutionA extends _Day4Solution {
  SolutionA() : super("A");

  String getSolution() {
    var requiredFields = <String>{...Passport.passportFields.toList()};
    requiredFields.remove('cid');
    return _passports
        .map<bool>((p) => p.hasAllFields(requiredFields))
        .where((element) => element)
        .toList()
        .length
        .toString();
  }
}

class SolutionB extends _Day4Solution {
  SolutionB() : super("B");

  String getSolution() {
    var validations = <String, Function(String)>{
      // four digits; at least 1920 and at most 2002.
      'byr': (v) {
        var iv = int.parse(v);
        return v.length == 4 && iv >= 1920 && iv <= 2002;
      },

      // four digits; at least 2010 and at most 2020.
      'iyr': (v) {
        var iv = int.parse(v);
        return v.length == 4 && iv >= 2010 && iv <= 2020;
      },

      // four digits; at least 2020 and at most 2030.
      'eyr': (v) {
        var iv = int.parse(v);
        return v.length == 4 && iv >= 2020 && iv <= 2030;
      },

      // a number followed by either cm or in:
      // If cm, the number must be at least 150 and at most 193.
      // If in, the number must be at least 59 and at most 76.
      'hgt': (v) {
        if (v.contains('cm')) {
          var p = v.split('cm'), pv = p.length > 0 ? int.parse(p[0]) : 0;
          return pv >= 150 && pv <= 193;
        } else if (v.contains('in')) {
          var p = v.split('in'), pv = p.length > 0 ? int.parse(p[0]) : 0;
          return pv >= 59 && pv <= 76;
        } else {
          return false;
        }
      },

      // a # followed by exactly six characters 0-9 or a-f
      'hcl': (v) {
        return RegExp(r'#[a-f|0-9]{6}').hasMatch(v);
      },

      // exactly one of: amb blu brn gry grn hzl oth.
      'ecl': (v) {
        var valid = ['amb', 'blu', 'brn', 'gry', 'grn', 'hzl', 'oth'];
        return valid.contains(v);
      },

      // a nine-digit number, including leading zeroes.
      'pid': (v) {
        return v.length == 9 && int.tryParse(v) != null;
      },
    };
    return _passports
        .map<bool>((p) => p.allFieldsValid(validations))
        .where((v) => v)
        .toList()
        .length
        .toString();
  }
}