#ifndef ENTT_ENTITY_FWD_HPP
#define ENTT_ENTITY_FWD_HPP

#include <memory>
#include "../core/fwd.hpp"
#include "utility.hpp"

namespace entt {

template<typename Entity, typename = std::allocator<Entity>>
class basic_sparse_set;

template<typename, typename Type, typename = std::allocator<Type>, typename = void>
class basic_storage;

template<typename>
class basic_registry;

template<typename, typename, typename, typename = void>
class basic_view;

template<typename>
struct basic_runtime_view;

template<typename, typename, typename, typename>
class basic_group;

template<typename>
class basic_observer;

template<typename>
class basic_organizer;

template<typename, typename...>
struct basic_handle;

template<typename>
class basic_snapshot;

template<typename>
class basic_snapshot_loader;

template<typename>
class basic_continuous_loader;

/*! @brief Default entity identifier. */
enum class entity : id_type {};

/*! @brief Alias declaration for the most common use case. */
using sparse_set = basic_sparse_set<entity>;

/**
 * @brief Alias declaration for the most common use case.
 * @tparam Args Other template parameters.
 */
template<typename... Args>
using storage = basic_storage<entity, Args...>;

/*! @brief Alias declaration for the most common use case. */
using registry = basic_registry<entity>;

/*! @brief Alias declaration for the most common use case. */
using observer = basic_observer<entity>;

/*! @brief Alias declaration for the most common use case. */
using organizer = basic_organizer<entity>;

/*! @brief Alias declaration for the most common use case. */
using handle = basic_handle<entity>;

/*! @brief Alias declaration for the most common use case. */
using const_handle = basic_handle<const entity>;

/**
 * @brief Alias declaration for the most common use case.
 * @tparam Args Other template parameters.
 */
template<typename... Args>
using handle_view = basic_handle<entity, Args...>;

/**
 * @brief Alias declaration for the most common use case.
 * @tparam Args Other template parameters.
 */
template<typename... Args>
using const_handle_view = basic_handle<const entity, Args...>;

/*! @brief Alias declaration for the most common use case. */
using snapshot = basic_snapshot<entity>;

/*! @brief Alias declaration for the most common use case. */
using snapshot_loader = basic_snapshot_loader<entity>;

/*! @brief Alias declaration for the most common use case. */
using continuous_loader = basic_continuous_loader<entity>;

/**
 * @brief Alias declaration for the most common use case.
 * @tparam Get Types of components iterated by the view.
 * @tparam Exclude Types of components used to filter the view.
 */
template<typename Get, typename Exclude = exclude_t<>>
using view = basic_view<entity, Get, Exclude>;

/*! @brief Alias declaration for the most common use case. */
using runtime_view = basic_runtime_view<sparse_set>;

/**
 * @brief Alias declaration for the most common use case.
 * @tparam Args Other template parameters.
 */
template<typename... Args>
using group = basic_group<entity, Args...>;

} // namespace entt

#endif