command.hpp

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#pragma once
 
#include <concepts>
#include <type_traits>
 
namespace helios::ecs {
 
class World;
 
/**
 * @brief Concept that defines the requirements for a command trait.
 * @details A command must be destructible, move or copy constructible,
 * be an object, not polymorphic, and must have an `Execute` with signature
 * `(helios::ecs::World&) -> void`.
 * @tparam T The type to check for the command trait
 */
template <typename T>
concept CommandTrait =
    std::destructible<T> &&
    (std::move_constructible<T> || std::copy_constructible<T>) &&
    std::is_object_v<std::remove_cvref_t<T>> &&
    !std::is_polymorphic_v<std::remove_cvref_t<T>> &&
    requires(T command, helios::ecs::World& world) {
      { command.Execute(world) } -> std::same_as<void>;
    };
 
}  // namespace helios::ecs