Svelto.ECS/com.sebaslab.svelto.ecs/Core/Filters/EntityFilterIterator.cs

namespace Svelto.ECS
{
    public ref struct EntityFilterIterator
    {
        internal EntityFilterIterator(EntityFilterCollection  filter)
        {
            _filter     = filter;
            _indexGroup = -1;
            _current    = default;
        }

        public bool MoveNext()
        {
            while (++_indexGroup < _filter.groupCount)
            {
                _current = _filter.GetGroup(_indexGroup);

                if (_current.count > 0) break;
            }

            return _indexGroup < _filter.groupCount;
        }

        public void Reset()
        {
            _indexGroup = -1;
        }

        public RefCurrent Current => new RefCurrent(_current);

        int                                 _indexGroup;
        readonly EntityFilterCollection     _filter;
        EntityFilterCollection.GroupFilters _current;

        public readonly ref struct RefCurrent
        {
            internal RefCurrent(EntityFilterCollection.GroupFilters filter)
            {
                _filter = filter;
            }

            public void Deconstruct(out EntityFilterIndices indices, out ExclusiveGroupStruct group)
            {
                indices = _filter.indices;
                group   = _filter.group;
            }

            readonly EntityFilterCollection.GroupFilters _filter;
        }
    }
}