between method

bool between(T minimum, T maximum, { int sorter(T value, T element)?, bool minimumInclusive = false, bool maximumInclusive = false, })

Returns true if all elements in the iterable are between minimum and maximum.

Consumes the iterable and examines each element. If any element is not between minimum and maximum, this method returns false. Otherwise, this method returns true.

Exclusivity on this method is controlled by the minimumInclusive and maximumInclusive parameters. These parameters default to false.

If sorter is omitted, the method checks EqualityComparer.forType to see if a default sorting function exists. If one is found, it is used. If one is not found, this method throws an ArgumentError.

If this iterable is empty, a StateError is thrown.

Implementation

bool between(
  T minimum,
  T maximum, {
  int Function(T value, T element)? sorter,
  bool minimumInclusive = false,
  bool maximumInclusive = false,
}) {
  sorter ??= EqualityComparer.tryForType<T>()?.sort;
  if (sorter == null) {
    throw ArgumentError.notNull('sorter');
  }

  final iterator = this.iterator;
  if (!iterator.moveNext()) {
    throw StateError('Cannot call "between" on an empty iterable.');
  }

  do {
    final minCompare = sorter(minimum, iterator.current);
    final maxCompare = sorter(maximum, iterator.current);
    if (minCompare > 0 ||
        (!minimumInclusive && minCompare == 0) ||
        maxCompare < 0 ||
        (!maximumInclusive && maxCompare == 0)) {
      return false;
    }
  } while (iterator.moveNext());

  return true;
}