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#ifndef ENTT_SIGNAL_EMITTER_HPP
#define ENTT_SIGNAL_EMITTER_HPP
#include <functional>
#include <type_traits>
#include <utility>
#include "../container/dense_map.hpp"
#include "../core/compressed_pair.hpp"
#include "../core/fwd.hpp"
#include "../core/type_info.hpp"
#include "../core/utility.hpp"
#include "fwd.hpp"
namespace entt {
/**
* @brief General purpose event emitter.
*
* To create an emitter type, derived classes must inherit from the base as:
*
* @code{.cpp}
* struct my_emitter: emitter<my_emitter> {
* // ...
* }
* @endcode
*
* Handlers for the different events are created internally on the fly. It's not
* required to specify in advance the full list of accepted events.<br/>
* Moreover, whenever an event is published, an emitter also passes a reference
* to itself to its listeners.
*
* @tparam Derived Emitter type.
* @tparam Allocator Type of allocator used to manage memory and elements.
*/
template<typename Derived, typename Allocator>
class emitter {
using key_type = id_type;
using mapped_type = std::function<void(void *)>;
using alloc_traits = std::allocator_traits<Allocator>;
using container_allocator = typename alloc_traits::template rebind_alloc<std::pair<const key_type, mapped_type>>;
using container_type = dense_map<key_type, mapped_type, identity, std::equal_to<>, container_allocator>;
public:
/*! @brief Allocator type. */
using allocator_type = Allocator;
/*! @brief Unsigned integer type. */
using size_type = std::size_t;
/*! @brief Default constructor. */
emitter()
: emitter{allocator_type{}} {}
/**
* @brief Constructs an emitter with a given allocator.
* @param allocator The allocator to use.
*/
explicit emitter(const allocator_type &allocator)
: handlers{allocator, allocator} {}
/*! @brief Default copy constructor, deleted on purpose. */
emitter(const emitter &) = delete;
/**
* @brief Move constructor.
* @param other The instance to move from.
*/
emitter(emitter &&other) noexcept
: handlers{std::move(other.handlers)} {}
/**
* @brief Allocator-extended move constructor.
* @param other The instance to move from.
* @param allocator The allocator to use.
*/
emitter(emitter &&other, const allocator_type &allocator)
: handlers{container_type{std::move(other.handlers.first()), allocator}, allocator} {
ENTT_ASSERT(alloc_traits::is_always_equal::value || handlers.second() == other.handlers.second(), "Copying an emitter is not allowed");
}
/*! @brief Default destructor. */
virtual ~emitter() noexcept {
static_assert(std::is_base_of_v<emitter<Derived, Allocator>, Derived>, "Invalid emitter type");
}
/**
* @brief Default copy assignment operator, deleted on purpose.
* @return This emitter.
*/
emitter &operator=(const emitter &) = delete;
/**
* @brief Move assignment operator.
* @param other The instance to move from.
* @return This emitter.
*/
emitter &operator=(emitter &&other) noexcept {
ENTT_ASSERT(alloc_traits::is_always_equal::value || handlers.second() == other.handlers.second(), "Copying an emitter is not allowed");
handlers = std::move(other.handlers);
return *this;
}
/**
* @brief Exchanges the contents with those of a given emitter.
* @param other Emitter to exchange the content with.
*/
void swap(emitter &other) {
using std::swap;
swap(handlers, other.handlers);
}
/**
* @brief Returns the associated allocator.
* @return The associated allocator.
*/
[[nodiscard]] constexpr allocator_type get_allocator() const noexcept {
return handlers.second();
}
/**
* @brief Publishes a given event.
* @tparam Type Type of event to trigger.
* @param value An instance of the given type of event.
*/
template<typename Type>
void publish(Type &&value) {
if(const auto id = type_id<Type>().hash(); handlers.first().contains(id)) {
handlers.first()[id](&value);
}
}
/**
* @brief Registers a listener with the event emitter.
* @tparam Type Type of event to which to connect the listener.
* @param func The listener to register.
*/
template<typename Type>
void on(std::function<void(Type &, Derived &)> func) {
handlers.first().insert_or_assign(type_id<Type>().hash(), [func = std::move(func), this](void *value) {
func(*static_cast<Type *>(value), static_cast<Derived &>(*this));
});
}
/**
* @brief Disconnects a listener from the event emitter.
* @tparam Type Type of event of the listener.
*/
template<typename Type>
void erase() {
handlers.first().erase(type_hash<std::remove_cv_t<std::remove_reference_t<Type>>>::value());
}
/*! @brief Disconnects all the listeners. */
void clear() noexcept {
handlers.first().clear();
}
/**
* @brief Checks if there are listeners registered for the specific event.
* @tparam Type Type of event to test.
* @return True if there are no listeners registered, false otherwise.
*/
template<typename Type>
[[nodiscard]] bool contains() const {
return handlers.first().contains(type_hash<std::remove_cv_t<std::remove_reference_t<Type>>>::value());
}
/**
* @brief Checks if there are listeners registered with the event emitter.
* @return True if there are no listeners registered, false otherwise.
*/
[[nodiscard]] bool empty() const noexcept {
return handlers.first().empty();
}
private:
compressed_pair<container_type, allocator_type> handlers;
};
} // namespace entt
#endif
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