EntityQuery.hpp

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//
//  CeresEngine - A game development framework
//
//  Created by Rogiel Sulzbach.
//  Copyright (c) 2018-2022 Rogiel Sulzbach. All rights reserved.
//
 
#pragma once
 
#include "EntityPredicate.hpp"
 
#include "CeresEngine/Macros.hpp"
 
namespace CeresEngine {
 
    template<typename P> class EntityQuery {
    public:
        using Predicate = P;
 
    private:
        EntityManager& mEntityManager;
 
        Generator<const Entity> mGenerator;
 
    public:
        EntityQuery(EntityManager& entityManager, Predicate&& predicate);
 
        ~EntityQuery() = default;
 
    public:
        [[nodiscard]] auto begin();
 
        [[nodiscard]] auto end() noexcept;
    };
 
    // `ComponentPredicate`.
    template<CComponent... Cs> class EntityManager::QueryExecutor<ComponentPredicate<Cs...>> {
    public:
        using Predicate = ComponentPredicate<Cs...>;
 
    private:
        Predicate mPredicate;
 
    public:
        explicit inline QueryExecutor(Predicate&& predicate);
 
    public:
        [[nodiscard]] Generator<const Entity> operator()(EntityManager& entityManager) const noexcept;
    };
 
    template<CComponent... Cs, typename SecondPredicate> class EntityManager::QueryExecutor<AndPredicate<ComponentPredicate<Cs...>, SecondPredicate>> {
    public:
        using Predicate = AndPredicate<ComponentPredicate<Cs...>, SecondPredicate>;
 
    private:
        Predicate mPredicate;
 
    public:
        explicit inline QueryExecutor(Predicate&& predicate);
 
    public:
        [[nodiscard]] Generator<const Entity> operator()(EntityManager& entityManager) const noexcept;
    };
 
    template<> class EntityManager::QueryExecutor<ParentPredicate> {
    public:
        using Predicate = ParentPredicate;
 
    private:
        Predicate mPredicate;
 
    public:
        explicit QueryExecutor(Predicate&& predicate);
 
    public:
        [[nodiscard]] Generator<const Entity> operator()(EntityManager& entityManager) const noexcept;
    };
 
} // namespace CeresEngine
 
#include "EntityQuery.inl"