archetype_common.h

#pragma once
#include "gaia/config/config.h"
 
#include <cstdint>
 
#include "gaia/cnt/darray.h"
#include "gaia/cnt/map.h"
#include "gaia/core/hashing_policy.h"
 
namespace gaia {
  namespace ecs {
    class Archetype;
 
    using ArchetypeId = uint32_t;
    using ArchetypeDArray = cnt::darray<Archetype*>;
    using ArchetypeIdHash = core::direct_hash_key<uint32_t>;
 
    struct ArchetypeIdHashPair {
      ArchetypeId id;
      ArchetypeIdHash hash;
 
      GAIA_NODISCARD bool operator==(ArchetypeIdHashPair other) const {
        return id == other.id;
      }
      GAIA_NODISCARD bool operator!=(ArchetypeIdHashPair other) const {
        return id != other.id;
      }
    };
 
    static constexpr ArchetypeId ArchetypeIdBad = (ArchetypeId)-1;
    static constexpr ArchetypeIdHashPair ArchetypeIdHashPairBad = {ArchetypeIdBad, {0}};
 
    class ArchetypeIdLookupKey final {
    public:
      using LookupHash = core::direct_hash_key<uint32_t>;
 
    private:
      ArchetypeId m_id;
      ArchetypeIdHash m_hash;
 
    public:
      GAIA_NODISCARD static LookupHash calc(ArchetypeId id) {
        return {static_cast<uint32_t>(core::calculate_hash64(id))};
      }
 
      static constexpr bool IsDirectHashKey = true;
 
      ArchetypeIdLookupKey(): m_id(0), m_hash({0}) {}
      ArchetypeIdLookupKey(ArchetypeIdHashPair pair): m_id(pair.id), m_hash(pair.hash) {}
      explicit ArchetypeIdLookupKey(ArchetypeId id, LookupHash hash): m_id(id), m_hash(hash) {}
 
      GAIA_NODISCARD size_t hash() const {
        return (size_t)m_hash.hash;
      }
 
      GAIA_NODISCARD bool operator==(const ArchetypeIdLookupKey& other) const {
        // Hash doesn't match we don't have a match.
        // Hash collisions are expected to be very unlikely so optimize for this case.
        if GAIA_LIKELY (m_hash != other.m_hash)
          return false;
 
        return m_id == other.m_id;
      }
    };
 
    using ArchetypeMapById = cnt::map<ArchetypeIdLookupKey, Archetype*>;
  } // namespace ecs
} // namespace gaia