SignalImpl.hpp

//
// TGUI - Texus' Graphical User Interface
// Copyright (C) 2012-2019 Bruno Van de Velde (vdv_b@tgui.eu)
//
// This software is provided 'as-is', without any express or implied warranty.
// In no event will the authors be held liable for any damages arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it freely,
// subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented;
// you must not claim that you wrote the original software.
// If you use this software in a product, an acknowledgment
// in the product documentation would be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such,
// and must not be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//


#ifndef TGUI_SIGNAL_IMPL_HPP
#define TGUI_SIGNAL_IMPL_HPP

#include <TGUI/Signal.hpp>


namespace tgui
{
 namespace internal_signal
 {
 #ifdef TGUI_USE_CPP17
 using std::void_t;
 #else
 // void_t only exists in c++17 so we use our own implementation to support c++14 compilers
 template<typename...>
 using void_t = void;
 #endif

 // Type to pass a list of template types
 template <typename...>
 struct TypeSet;

 // The dereference function turns the void* elements in the parameters list back into its original type right before calling the signal handler
 #ifdef TGUI_USE_CPP17
 template <typename Type>
 decltype(auto) dereference(const void* obj)
 {
 if constexpr (std::is_same_v<Type, std::string>) // Signal handlers are allowed to have std::string parameters while the signal sends sf::String
 return static_cast<std::string>(*static_cast<const sf::String*>(obj));
 else if constexpr (std::is_same_v<Type, sf::Vector2f>) // Signal handlers are allowed to have sf::Vector2f parameters while the signal sends tgui::Vector2f
 return static_cast<sf::Vector2f>(*static_cast<const Vector2f*>(obj));
 else
 return *static_cast<const std::decay_t<Type>*>(obj);
 }
 #else
 template <typename Type, typename std::enable_if<std::is_same<Type, std::string>::value>::type* = nullptr>
 decltype(auto) dereference(const void* obj)
 {
 // Signal handlers are allowed to have std::string parameters while the signal sends sf::String
 return static_cast<std::string>(*static_cast<const sf::String*>(obj));
 }

 template <typename Type, typename std::enable_if<std::is_same<Type, sf::Vector2f>::value>::type* = nullptr>
 decltype(auto) dereference(const void* obj)
 {
 // Signal handlers are allowed to have sf::Vector2f parameters while the signal sends tgui::Vector2f
 return static_cast<sf::Vector2f>(*static_cast<const Vector2f*>(obj));
 }

 template <typename Type, typename std::enable_if<!std::is_same<Type, std::string>::value && !std::is_same<Type, sf::Vector2f>::value>::type* = nullptr>
 decltype(auto) dereference(const void* obj)
 {
 return *static_cast<const typename std::decay<Type>::type*>(obj);
 }
 #endif

 #ifndef TGUI_USE_CPP17
 // std::invoke only exists in c++17 so we use our own implementation to support c++14 compilers
 // Visual Studio compiler did not like it when the function was called "invoke"
 template <typename Func, typename... Args, typename std::enable_if<std::is_member_pointer<typename std::decay<Func>::type>::value>::type* = nullptr>
 void invokeFunc(Func&& func, Args&&... args)
 {
 std::mem_fn(func)(std::forward<Args>(args)...);
 }

 template <typename Func, typename... Args, typename std::enable_if<!std::is_member_pointer<typename std::decay<Func>::type>::value>::type* = nullptr>
 void invokeFunc(Func&& func, Args&&... args)
 {
 std::forward<Func>(func)(std::forward<Args>(args)...);
 }
 #endif

 // The binder will figure out the unbound parameters and bind them if they correspond to what the signal sends
 template <typename... Args>
 struct binder;

 template <typename Arg, typename... AllArgs, typename BoundArg, typename... BoundArgs>
 struct binder<TypeSet<Arg, AllArgs...>, TypeSet<BoundArg, BoundArgs...>>
 : binder<TypeSet<AllArgs...>, TypeSet<BoundArgs...>>
 {
 };

 template <typename... UnboundArgs>
 struct binder<TypeSet<std::shared_ptr<Widget>, std::string, UnboundArgs...>, TypeSet<>>
 {
 template <typename Func, typename... BoundArgs>
 static decltype(auto) bind(Signal& signal, Func&& func, BoundArgs&&... args)
 {
 return bindImpl(std::index_sequence_for<UnboundArgs...>{}, signal, std::forward<Func>(func), std::forward<BoundArgs>(args)...);
 }

 private:

 template <typename Func, typename... BoundArgs, std::size_t... Indices>
 static decltype(auto) bindImpl(std::index_sequence<Indices...>, Signal& signal, Func&& func, BoundArgs&&... args)
 {
 const std::size_t offset = (sizeof...(UnboundArgs) > 0) ? signal.validateTypes({typeid(UnboundArgs)...}) : 0;
 #if defined TGUI_USE_CPP17
 return [=](const std::shared_ptr<Widget>& widget, const std::string& signalName) {
 std::invoke(func, // An error "variable 'func' has function type" here means you passed a reference instead of a function pointer to 'connect'
 args...,
 widget,
 signalName,
 internal_signal::dereference<UnboundArgs>(internal_signal::parameters[offset + Indices])...);
 #else
 return [=,o=offset](const std::shared_ptr<Widget>& widget, const std::string& signalName) { // MinGW TDM GCC 5.1 won't compile code without "o=offset" hack
 invokeFunc(func, // An error "variable 'func' has function type" here means you passed a reference instead of a function pointer to 'connect'
 args...,
 widget,
 signalName,
 internal_signal::dereference<UnboundArgs>(internal_signal::parameters[o + Indices])...);
 #endif
 };
 }
 };

 template <typename... UnboundArgs>
 struct binder<TypeSet<UnboundArgs...>, TypeSet<>>
 {
 template <typename Func, typename... BoundArgs>
 static decltype(auto) bind(Signal& signal, Func&& func, BoundArgs&&... args)
 {
 return bindImpl(std::index_sequence_for<UnboundArgs...>{}, signal, std::forward<Func>(func), std::forward<BoundArgs>(args)...);
 }

 private:

 template <typename Func, typename... BoundArgs, std::size_t... Indices>
 static decltype(auto) bindImpl(std::index_sequence<Indices...>, Signal& signal, Func&& func, BoundArgs&&... args)
 {
 const std::size_t offset = (sizeof...(UnboundArgs) > 0) ? signal.validateTypes({typeid(UnboundArgs)...}) : 0;
 #if defined TGUI_USE_CPP17
 return [=]{
 std::invoke(func, // An error "variable 'func' has function type" here means you passed a reference instead of a function pointer to 'connect'
 args...,
 internal_signal::dereference<UnboundArgs>(internal_signal::parameters[offset + Indices])...);
 #else
 return [=,o=offset]{ // MinGW TDM GCC 5.1 won't compile code without "o=offset" hack
 invokeFunc(func, // An error "variable 'func' has function type" here means you passed a reference instead of a function pointer to 'connect'
 args...,
 internal_signal::dereference<UnboundArgs>(internal_signal::parameters[o + Indices])...);
 #endif
 };
 }
 };


 #ifdef TGUI_USE_CPP17
 // Error case (function signature did not match anything)
 template <typename Enable, typename Func, typename... BoundArgs>
 struct func_traits;

 // Free function
 template <typename... Args, typename... BoundArgs>
 struct func_traits<void, void(*)(Args...), BoundArgs...> : binder<TypeSet<std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename... Args, typename... BoundArgs>
 struct func_traits<void, void(*)(Args...) noexcept, BoundArgs...> : binder<TypeSet<std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};

 // Non-const member function
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...), BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) noexcept, BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile, BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile noexcept, BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) &, BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) & noexcept, BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile &, BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile & noexcept, BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) &&, BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) && noexcept, BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile &&, BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile && noexcept, BoundArgs...> : binder<TypeSet<Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};

 // Const member function
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) const, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) const noexcept, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile const, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile const noexcept, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) const &, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) const & noexcept, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile const &, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile const & noexcept, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) const &&, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) const && noexcept, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile const &&, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) volatile const && noexcept, BoundArgs...> : binder<TypeSet<const Class*, std::decay_t<Args>...>, TypeSet<BoundArgs...>> {};

 // std::function or lambda
 template <typename Func, typename... BoundArgs>
 struct func_traits<void_t<decltype(&Func::operator())>, Func, BoundArgs...> : public func_traits<void, decltype(&Func::operator()), Func*, BoundArgs...> {};
 #else
 // Error case (function signature did not match anything)
 template <typename Enable, typename Func, typename... BoundArgs>
 struct func_traits;

 // std::function or lambda
 template <typename Func, typename... BoundArgs>
 struct func_traits<void_t<decltype(&Func::operator())>, Func, BoundArgs...>
 : public func_traits<void, decltype(&Func::operator()), Func*, BoundArgs...>
 {
 };

 // Non-const member function
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...), BoundArgs...>
 : binder<TypeSet<Class*, typename std::decay<Args>::type...>, TypeSet<BoundArgs...>>
 {
 };

 // Const member function
 template <typename Class, typename... Args, typename... BoundArgs>
 struct func_traits<void, void(Class::*)(Args...) const, BoundArgs...>
 : binder<TypeSet<const Class*, typename std::decay<Args>::type...>, TypeSet<BoundArgs...>>
 {
 };

 // Free function
 template <typename... Args, typename... BoundArgs>
 struct func_traits<void, void(*)(Args...), BoundArgs...>
 : binder<TypeSet<typename std::decay<Args>::type...>, TypeSet<BoundArgs...>>
 {
 };
 #endif
 }


#ifdef TGUI_USE_CPP17
 template <typename Func, typename... BoundArgs>
 unsigned int SignalWidgetBase::connect(std::string signalName, Func&& handler, const BoundArgs&... args)
 {
 unsigned int id;
 Signal& signal = getSignal(toLower(signalName));

 if constexpr (std::is_convertible_v<Func, std::function<void(const BoundArgs&...)>>
 && std::is_invocable_v<decltype(&handler), BoundArgs...>
 && !std::is_function_v<Func>)
 {
 // Reference to function, all parameters bound
 id = signal.connect([=, f=std::function<void(const BoundArgs&...)>(handler)]{ std::invoke(f, args...); });
 }
 else if constexpr (std::is_convertible_v<Func, std::function<void(const BoundArgs&...)>>)
 {
 // Function with all parameters bound
 id = signal.connect([=]{ std::invoke(handler, args...); });
 }
 else if constexpr (std::is_convertible_v<Func, std::function<void(const BoundArgs&..., const std::shared_ptr<Widget>&, const std::string&)>>
 && std::is_invocable_v<decltype(&handler), BoundArgs..., const std::shared_ptr<Widget>&, const std::string&>
 && !std::is_function_v<Func>)
 {
 // Reference to function with caller arguments, all parameters bound
 id = signal.connect([=, f=std::function<void(const BoundArgs&..., const std::shared_ptr<Widget>& w, const std::string& s)>(handler)](const std::shared_ptr<Widget>& w, const std::string& s){ std::invoke(f, args..., w, s); });
 }
 else if constexpr (std::is_convertible_v<Func, std::function<void(const BoundArgs&..., const std::shared_ptr<Widget>&, const std::string&)>>)
 {
 // Function with caller arguments, all parameters bound
 id = signal.connect([=](const std::shared_ptr<Widget>& w, const std::string& s){ std::invoke(handler, args..., w, s); });
 }
 else
 {
 // Function with unbound arguments
 using binder = internal_signal::func_traits<void, std::decay_t<Func>, BoundArgs...>;
 id = signal.connect(binder::bind(signal, std::forward<Func>(handler), args...));
 }

 m_connectedSignals[id] = toLower(signalName);
 return id;
 }

#else
 template <typename Func, typename... Args, typename std::enable_if<std::is_convertible<Func, std::function<void(const Args&...)>>::value>::type*>
 unsigned int SignalWidgetBase::connect(std::string signalName, Func&& handler, const Args&... args)
 {
 const unsigned int id = getSignal(toLower(signalName)).connect([f=std::function<void(const Args&...)>(handler),args...](){ f(args...); });
 m_connectedSignals[id] = toLower(signalName);
 return id;
 }

 template <typename Func, typename... BoundArgs, typename std::enable_if<std::is_convertible<Func, std::function<void(const BoundArgs&..., std::shared_ptr<Widget>, const std::string&)>>::value>::type*>
 unsigned int SignalWidgetBase::connect(std::string signalName, Func&& handler, BoundArgs&&... args)
 {
 const unsigned int id = getSignal(toLower(signalName)).connect(
 [f=std::function<void(const BoundArgs&..., const std::shared_ptr<Widget>&, const std::string&)>(handler), args...]
 (const std::shared_ptr<Widget>& w, const std::string& s)
 { f(args..., w, s); }
 );

 m_connectedSignals[id] = toLower(signalName);
 return id;
 }

 template <typename Func, typename... BoundArgs, typename std::enable_if<!std::is_convertible<Func, std::function<void(const BoundArgs&...)>>::value
 && !std::is_convertible<Func, std::function<void(const BoundArgs&..., std::shared_ptr<Widget>, const std::string&)>>::value>::type*>
 unsigned int SignalWidgetBase::connect(std::string signalName, Func&& handler, BoundArgs&&... args)
 {
 Signal& signal = getSignal(toLower(signalName));
 using binder = internal_signal::func_traits<void, typename std::decay<Func>::type, BoundArgs...>;
 const unsigned int id = signal.connect(binder::bind(signal, std::forward<Func>(handler), std::forward<BoundArgs>(args)...));
 m_connectedSignals[id] = toLower(signalName);
 return id;
 }
#endif


 template <typename Func, typename... BoundArgs>
 unsigned int SignalWidgetBase::connect(std::initializer_list<std::string> signalNames, Func&& handler, BoundArgs&&... args)
 {
 unsigned int lastId = 0;
 for (auto& signalName : signalNames)
 lastId = connect(std::move(signalName), handler, args...);

 return lastId;
 }
}


#endif // TGUI_SIGNAL_IMPL_HPP