Dart - Iterator

// Dart Iterator

void main(List<String> args) {
  Iterable<int> iter = [1, 2, 3];
  for (var i in iter) {
    print(i);
  }

  print(iter.runtimeType);
  // Unlike a list, you cannot access an element via an iterable object
  // using the square brackets []. Instead, you use the elementAt() method:

  print(iter.elementAt(1));

  List<int> asList = iter as List<int>;
  // Iterable 이 추상 클래스라고 했으므로 이를 List 클래스로 형변환도 가능하다.
  print(asList[0]);

  print("");
  List<int> nums = [1, 2, 3];
  var it = nums.iterator;
  while (it.moveNext()) {
    print(it.current);
  }
}

// 결과
1
2
3
List<int>
2
1
1
2
3
4
5

 

// Dart iterator example
//
// Use Iterator<E> interface for getting items one at a time from an object

void main(List<String> args) {
  var sentence = Sentence('Dart is great.');
  while (sentence.moveNext()) {
    print(sentence.current);
  }
}

class Sentence implements Iterator {
  int _wordIndex = -1;
  List<String> _words = [];

  Sentence(String str) {
    _words = str.split(' ');
  }

  @override
  get current {
    if (_wordIndex >= 0 && _wordIndex <= _words.length) {
      return _words[_wordIndex];
    }
  }

  @override
  bool moveNext() {
    if (_wordIndex < _words.length - 1) {
      _wordIndex++;
      return true;
    }
    return false;
  }
}

// 결과
Dart
is
great.