unique method

Iterable<E> unique([ bool comparator(E a, E b)? ])

Returns a new lazy Iterable with unique elements from this collection.

If comparator is provided, it uses the custom logic to determine if two elements are equal. If comparator is null, it falls back to the default equality operator (==).

The comparator should return true if a and b are considered duplicates.

Implementation

Iterable<E> unique([bool Function(E a, E b)? comparator]) {
  final List<E> result = [];

  for (final element in this) {
    if (comparator == null) {
      // Fallback to standard equality and hashCode check
      if (!result.contains(element)) {
        result.add(element);
      }
    } else {
      // Use custom comparison logic
      bool isDuplicate = false;
      for (final existing in result) {
        if (comparator(existing, element)) {
          isDuplicate = true;
          break;
        }
      }
      if (!isDuplicate) {
        result.add(element);
      }
    }
  }

  return result;
}