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//
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Copyright (c) 2008-2024 NVIDIA Corporation. All rights reserved.

#ifndef NV_NSFOUNDATION_NSHASHSET_H
#define NV_NSFOUNDATION_NSHASHSET_H

#include "NsHashInternals.h"

// TODO: make this doxy-format

// This header defines two hash sets. Hash sets
// * support custom initial table sizes (rounded up internally to power-of-2)
// * support custom static allocator objects
// * auto-resize, based on a load factor (i.e. a 64-entry .75 load factor hash will resize
//                                        when the 49th element is inserted)
// * are based on open hashing
//
// Sets have STL-like copying semantics, and properly initialize and destruct copies of objects
//
// There are two forms of set: coalesced and uncoalesced. Coalesced sets keep the entries in the
// initial segment of an array, so are fast to iterate over; however deletion is approximately
// twice as expensive.
//
// HashSet<T>:
//      bool        insert(const T& k)                      amortized O(1) (exponential resize policy)
//      bool        contains(const T& k)    const;          O(1)
//      bool        erase(const T& k);                      O(1)
//      uint32_t        size()                  const;          constant
//      void        reserve(uint32_t size);                 O(MAX(size, currentOccupancy))
//      void        clear();                                O(currentOccupancy) (with zero constant for objects without
// destructors)
//      Iterator    getIterator();
//
// Use of iterators:
//
// for(HashSet::Iterator iter = test.getIterator(); !iter.done(); ++iter)
//          myFunction(*iter);
//
// CoalescedHashSet<T> does not support getIterator, but instead supports
//      const Key *getEntries();
//
// insertion into a set already containing the element fails returning false, as does
// erasure of an element not in the set
//

namespace nvidia
{
namespace shdfnd
{
template <class Key, class HashFn = Hash<Key>, class Allocator = NonTrackingAllocator>
class HashSet : public internal::HashSetBase<Key, HashFn, Allocator, false>
{
  public:
    typedef internal::HashSetBase<Key, HashFn, Allocator, false> HashSetBase;
    typedef typename HashSetBase::Iterator Iterator;

    HashSet(uint32_t initialTableSize = 64, float loadFactor = 0.75f) : HashSetBase(initialTableSize, loadFactor)
    {
    }
    HashSet(uint32_t initialTableSize, float loadFactor, const Allocator& alloc)
    : HashSetBase(initialTableSize, loadFactor, alloc)
    {
    }
    HashSet(const Allocator& alloc) : HashSetBase(64, 0.75f, alloc)
    {
    }
    Iterator getIterator()
    {
        return Iterator(HashSetBase::mBase);
    }
};

template <class Key, class HashFn = Hash<Key>, class Allocator = NonTrackingAllocator>
class CoalescedHashSet : public internal::HashSetBase<Key, HashFn, Allocator, true>
{
  public:
    typedef typename internal::HashSetBase<Key, HashFn, Allocator, true> HashSetBase;

    CoalescedHashSet(uint32_t initialTableSize = 64, float loadFactor = 0.75f)
    : HashSetBase(initialTableSize, loadFactor)
    {
    }

    CoalescedHashSet(uint32_t initialTableSize, float loadFactor, const Allocator& alloc)
    : HashSetBase(initialTableSize, loadFactor, alloc)
    {
    }
    CoalescedHashSet(const Allocator& alloc) : HashSetBase(64, 0.75f, alloc)
    {
    }

    const Key* getEntries() const
    {
        return HashSetBase::mBase.getEntries();
    }
};

} // namespace shdfnd
} // namespace nvidia

#endif // #ifndef NV_NSFOUNDATION_NSHASHSET_H
