boost/function/function_base.hpp
// Boost.Function library // Copyright Douglas Gregor 2001-2006 // Copyright Emil Dotchevski 2007 // Use, modification and distribution is subject to the Boost Software License, Version 1.0. // (See accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) // For more information, see http://www.boost.org #ifndef BOOST_FUNCTION_BASE_HEADER #define BOOST_FUNCTION_BASE_HEADER #include <boost/function/function_fwd.hpp> #include <boost/function_equal.hpp> #include <boost/core/typeinfo.hpp> #include <boost/core/ref.hpp> #include <boost/assert.hpp> #include <boost/config.hpp> #include <boost/config/workaround.hpp> #include <stdexcept> #include <string> #include <memory> #include <new> #include <type_traits> #if defined(BOOST_MSVC) # pragma warning( push ) # pragma warning( disable : 4793 ) // complaint about native code generation # pragma warning( disable : 4127 ) // "conditional expression is constant" #endif // retained because used in a test #define BOOST_FUNCTION_TARGET_FIX(x) #define BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor,Type) \ typename std::enable_if< !std::is_integral<Functor>::value, Type>::type namespace boost { namespace detail { namespace function { class X; /** * A buffer used to store small function objects in * boost::function. It is a union containing function pointers, * object pointers, and a structure that resembles a bound * member function pointer. */ union function_buffer_members { // For pointers to function objects typedef void* obj_ptr_t; mutable obj_ptr_t obj_ptr; // For pointers to std::type_info objects struct type_t { // (get_functor_type_tag, check_functor_type_tag). const boost::core::typeinfo* type; // Whether the type is const-qualified. bool const_qualified; // Whether the type is volatile-qualified. bool volatile_qualified; } type; // For function pointers of all kinds typedef void (*func_ptr_t)(); mutable func_ptr_t func_ptr; #if defined(BOOST_MSVC) && BOOST_MSVC >= 1929 # pragma warning(push) # pragma warning(disable: 5243) #endif // For bound member pointers struct bound_memfunc_ptr_t { void (X::*memfunc_ptr)(int); void* obj_ptr; } bound_memfunc_ptr; #if defined(BOOST_MSVC) && BOOST_MSVC >= 1929 # pragma warning(pop) #endif // For references to function objects. We explicitly keep // track of the cv-qualifiers on the object referenced. struct obj_ref_t { mutable void* obj_ptr; bool is_const_qualified; bool is_volatile_qualified; } obj_ref; }; union BOOST_SYMBOL_VISIBLE function_buffer { // Type-specific union members mutable function_buffer_members members; // To relax aliasing constraints mutable char data[sizeof(function_buffer_members)]; }; // The operation type to perform on the given functor/function pointer enum functor_manager_operation_type { clone_functor_tag, move_functor_tag, destroy_functor_tag, check_functor_type_tag, get_functor_type_tag }; // Tags used to decide between different types of functions struct function_ptr_tag {}; struct function_obj_tag {}; struct member_ptr_tag {}; struct function_obj_ref_tag {}; template<typename F> class get_function_tag { typedef typename std::conditional<std::is_pointer<F>::value, function_ptr_tag, function_obj_tag>::type ptr_or_obj_tag; typedef typename std::conditional<std::is_member_pointer<F>::value, member_ptr_tag, ptr_or_obj_tag>::type ptr_or_obj_or_mem_tag; typedef typename std::conditional<is_reference_wrapper<F>::value, function_obj_ref_tag, ptr_or_obj_or_mem_tag>::type or_ref_tag; public: typedef or_ref_tag type; }; // The trivial manager does nothing but return the same pointer (if we // are cloning) or return the null pointer (if we are deleting). template<typename F> struct reference_manager { static inline void manage(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op) { switch (op) { case clone_functor_tag: out_buffer.members.obj_ref = in_buffer.members.obj_ref; return; case move_functor_tag: out_buffer.members.obj_ref = in_buffer.members.obj_ref; in_buffer.members.obj_ref.obj_ptr = 0; return; case destroy_functor_tag: out_buffer.members.obj_ref.obj_ptr = 0; return; case check_functor_type_tag: { // Check whether we have the same type. We can add // cv-qualifiers, but we can't take them away. if (*out_buffer.members.type.type == BOOST_CORE_TYPEID(F) && (!in_buffer.members.obj_ref.is_const_qualified || out_buffer.members.type.const_qualified) && (!in_buffer.members.obj_ref.is_volatile_qualified || out_buffer.members.type.volatile_qualified)) out_buffer.members.obj_ptr = in_buffer.members.obj_ref.obj_ptr; else out_buffer.members.obj_ptr = 0; } return; case get_functor_type_tag: out_buffer.members.type.type = &BOOST_CORE_TYPEID(F); out_buffer.members.type.const_qualified = in_buffer.members.obj_ref.is_const_qualified; out_buffer.members.type.volatile_qualified = in_buffer.members.obj_ref.is_volatile_qualified; return; } } }; /** * Determine if boost::function can use the small-object * optimization with the function object type F. */ template<typename F> struct function_allows_small_object_optimization { BOOST_STATIC_CONSTANT (bool, value = ((sizeof(F) <= sizeof(function_buffer) && (std::alignment_of<function_buffer>::value % std::alignment_of<F>::value == 0)))); }; template <typename F,typename A> struct functor_wrapper: public F, public A { functor_wrapper( F f, A a ): F(f), A(a) { } functor_wrapper(const functor_wrapper& f) : F(static_cast<const F&>(f)), A(static_cast<const A&>(f)) { } }; /** * The functor_manager class contains a static function "manage" which * can clone or destroy the given function/function object pointer. */ template<typename Functor> struct functor_manager_common { typedef Functor functor_type; // Function pointers static inline void manage_ptr(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op) { if (op == clone_functor_tag) out_buffer.members.func_ptr = in_buffer.members.func_ptr; else if (op == move_functor_tag) { out_buffer.members.func_ptr = in_buffer.members.func_ptr; in_buffer.members.func_ptr = 0; } else if (op == destroy_functor_tag) out_buffer.members.func_ptr = 0; else if (op == check_functor_type_tag) { if (*out_buffer.members.type.type == BOOST_CORE_TYPEID(Functor)) out_buffer.members.obj_ptr = &in_buffer.members.func_ptr; else out_buffer.members.obj_ptr = 0; } else /* op == get_functor_type_tag */ { out_buffer.members.type.type = &BOOST_CORE_TYPEID(Functor); out_buffer.members.type.const_qualified = false; out_buffer.members.type.volatile_qualified = false; } } // Function objects that fit in the small-object buffer. static inline void manage_small(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op) { if (op == clone_functor_tag) { const functor_type* in_functor = reinterpret_cast<const functor_type*>(in_buffer.data); new (reinterpret_cast<void*>(out_buffer.data)) functor_type(*in_functor); } else if (op == move_functor_tag) { functor_type* f = reinterpret_cast<functor_type*>(in_buffer.data); new (reinterpret_cast<void*>(out_buffer.data)) functor_type(std::move(*f)); f->~Functor(); } else if (op == destroy_functor_tag) { // Some compilers (Borland, vc6, ...) are unhappy with ~functor_type. functor_type* f = reinterpret_cast<functor_type*>(out_buffer.data); (void)f; // suppress warning about the value of f not being used (MSVC) f->~Functor(); } else if (op == check_functor_type_tag) { if (*out_buffer.members.type.type == BOOST_CORE_TYPEID(Functor)) out_buffer.members.obj_ptr = in_buffer.data; else out_buffer.members.obj_ptr = 0; } else /* op == get_functor_type_tag */ { out_buffer.members.type.type = &BOOST_CORE_TYPEID(Functor); out_buffer.members.type.const_qualified = false; out_buffer.members.type.volatile_qualified = false; } } }; template<typename Functor> struct functor_manager { private: typedef Functor functor_type; // Function pointers static inline void manager(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op, function_ptr_tag) { functor_manager_common<Functor>::manage_ptr(in_buffer,out_buffer,op); } // Function objects that fit in the small-object buffer. static inline void manager(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op, std::true_type) { functor_manager_common<Functor>::manage_small(in_buffer,out_buffer,op); } // Function objects that require heap allocation static inline void manager(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op, std::false_type) { if (op == clone_functor_tag) { // Clone the functor // GCC 2.95.3 gets the CV qualifiers wrong here, so we // can't do the static_cast that we should do. // jewillco: Changing this to static_cast because GCC 2.95.3 is // obsolete. const functor_type* f = static_cast<const functor_type*>(in_buffer.members.obj_ptr); functor_type* new_f = new functor_type(*f); out_buffer.members.obj_ptr = new_f; } else if (op == move_functor_tag) { out_buffer.members.obj_ptr = in_buffer.members.obj_ptr; in_buffer.members.obj_ptr = 0; } else if (op == destroy_functor_tag) { /* Cast from the void pointer to the functor pointer type */ functor_type* f = static_cast<functor_type*>(out_buffer.members.obj_ptr); delete f; out_buffer.members.obj_ptr = 0; } else if (op == check_functor_type_tag) { if (*out_buffer.members.type.type == BOOST_CORE_TYPEID(Functor)) out_buffer.members.obj_ptr = in_buffer.members.obj_ptr; else out_buffer.members.obj_ptr = 0; } else /* op == get_functor_type_tag */ { out_buffer.members.type.type = &BOOST_CORE_TYPEID(Functor); out_buffer.members.type.const_qualified = false; out_buffer.members.type.volatile_qualified = false; } } // For function objects, we determine whether the function // object can use the small-object optimization buffer or // whether we need to allocate it on the heap. static inline void manager(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op, function_obj_tag) { manager(in_buffer, out_buffer, op, std::integral_constant<bool, (function_allows_small_object_optimization<functor_type>::value)>()); } // For member pointers, we use the small-object optimization buffer. static inline void manager(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op, member_ptr_tag) { manager(in_buffer, out_buffer, op, std::true_type()); } public: /* Dispatch to an appropriate manager based on whether we have a function pointer or a function object pointer. */ static inline void manage(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op) { typedef typename get_function_tag<functor_type>::type tag_type; if (op == get_functor_type_tag) { out_buffer.members.type.type = &BOOST_CORE_TYPEID(functor_type); out_buffer.members.type.const_qualified = false; out_buffer.members.type.volatile_qualified = false; } else { manager(in_buffer, out_buffer, op, tag_type()); } } }; template<typename Functor, typename Allocator> struct functor_manager_a { private: typedef Functor functor_type; // Function pointers static inline void manager(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op, function_ptr_tag) { functor_manager_common<Functor>::manage_ptr(in_buffer,out_buffer,op); } // Function objects that fit in the small-object buffer. static inline void manager(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op, std::true_type) { functor_manager_common<Functor>::manage_small(in_buffer,out_buffer,op); } // Function objects that require heap allocation static inline void manager(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op, std::false_type) { typedef functor_wrapper<Functor,Allocator> functor_wrapper_type; using wrapper_allocator_type = typename std::allocator_traits<Allocator>::template rebind_alloc<functor_wrapper_type>; using wrapper_allocator_pointer_type = typename std::allocator_traits<wrapper_allocator_type>::pointer; if (op == clone_functor_tag) { // Clone the functor // GCC 2.95.3 gets the CV qualifiers wrong here, so we // can't do the static_cast that we should do. const functor_wrapper_type* f = static_cast<const functor_wrapper_type*>(in_buffer.members.obj_ptr); wrapper_allocator_type wrapper_allocator(static_cast<Allocator const &>(*f)); wrapper_allocator_pointer_type copy = wrapper_allocator.allocate(1); std::allocator_traits<wrapper_allocator_type>::construct(wrapper_allocator, copy, *f); // Get back to the original pointer type functor_wrapper_type* new_f = static_cast<functor_wrapper_type*>(copy); out_buffer.members.obj_ptr = new_f; } else if (op == move_functor_tag) { out_buffer.members.obj_ptr = in_buffer.members.obj_ptr; in_buffer.members.obj_ptr = 0; } else if (op == destroy_functor_tag) { /* Cast from the void pointer to the functor_wrapper_type */ functor_wrapper_type* victim = static_cast<functor_wrapper_type*>(in_buffer.members.obj_ptr); wrapper_allocator_type wrapper_allocator(static_cast<Allocator const &>(*victim)); std::allocator_traits<wrapper_allocator_type>::destroy(wrapper_allocator, victim); wrapper_allocator.deallocate(victim,1); out_buffer.members.obj_ptr = 0; } else if (op == check_functor_type_tag) { if (*out_buffer.members.type.type == BOOST_CORE_TYPEID(Functor)) out_buffer.members.obj_ptr = in_buffer.members.obj_ptr; else out_buffer.members.obj_ptr = 0; } else /* op == get_functor_type_tag */ { out_buffer.members.type.type = &BOOST_CORE_TYPEID(Functor); out_buffer.members.type.const_qualified = false; out_buffer.members.type.volatile_qualified = false; } } // For function objects, we determine whether the function // object can use the small-object optimization buffer or // whether we need to allocate it on the heap. static inline void manager(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op, function_obj_tag) { manager(in_buffer, out_buffer, op, std::integral_constant<bool, (function_allows_small_object_optimization<functor_type>::value)>()); } public: /* Dispatch to an appropriate manager based on whether we have a function pointer or a function object pointer. */ static inline void manage(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op) { typedef typename get_function_tag<functor_type>::type tag_type; if (op == get_functor_type_tag) { out_buffer.members.type.type = &BOOST_CORE_TYPEID(functor_type); out_buffer.members.type.const_qualified = false; out_buffer.members.type.volatile_qualified = false; } else { manager(in_buffer, out_buffer, op, tag_type()); } } }; // A type that is only used for comparisons against zero struct useless_clear_type {}; /** * Stores the "manager" portion of the vtable for a * boost::function object. */ struct vtable_base { void (*manager)(const function_buffer& in_buffer, function_buffer& out_buffer, functor_manager_operation_type op); }; } // end namespace function } // end namespace detail /** * The function_base class contains the basic elements needed for the * function1, function2, function3, etc. classes. It is common to all * functions (and as such can be used to tell if we have one of the * functionN objects). */ class function_base { public: function_base() : vtable(0) { } /** Determine if the function is empty (i.e., has no target). */ bool empty() const { return !vtable; } /** Retrieve the type of the stored function object, or type_id<void>() if this is empty. */ const boost::core::typeinfo& target_type() const { if (!vtable) return BOOST_CORE_TYPEID(void); detail::function::function_buffer type; get_vtable()->manager(functor, type, detail::function::get_functor_type_tag); return *type.members.type.type; } template<typename Functor> Functor* target() { if (!vtable) return 0; detail::function::function_buffer type_result; type_result.members.type.type = &BOOST_CORE_TYPEID(Functor); type_result.members.type.const_qualified = std::is_const<Functor>::value; type_result.members.type.volatile_qualified = std::is_volatile<Functor>::value; get_vtable()->manager(functor, type_result, detail::function::check_functor_type_tag); return static_cast<Functor*>(type_result.members.obj_ptr); } template<typename Functor> const Functor* target() const { if (!vtable) return 0; detail::function::function_buffer type_result; type_result.members.type.type = &BOOST_CORE_TYPEID(Functor); type_result.members.type.const_qualified = true; type_result.members.type.volatile_qualified = std::is_volatile<Functor>::value; get_vtable()->manager(functor, type_result, detail::function::check_functor_type_tag); // GCC 2.95.3 gets the CV qualifiers wrong here, so we // can't do the static_cast that we should do. return static_cast<const Functor*>(type_result.members.obj_ptr); } template<typename F> typename std::enable_if< !std::is_function<F>::value, bool >::type contains(const F& f) const { if (const F* fp = this->template target<F>()) { return function_equal(*fp, f); } else { return false; } } template<typename Fn> typename std::enable_if< std::is_function<Fn>::value, bool >::type contains(Fn& f) const { typedef Fn* F; if (const F* fp = this->template target<F>()) { return function_equal(*fp, &f); } else { return false; } } public: // should be protected, but GCC 2.95.3 will fail to allow access detail::function::vtable_base* get_vtable() const { return reinterpret_cast<detail::function::vtable_base*>( reinterpret_cast<std::size_t>(vtable) & ~static_cast<std::size_t>(0x01)); } bool has_trivial_copy_and_destroy() const { return reinterpret_cast<std::size_t>(vtable) & 0x01; } detail::function::vtable_base* vtable; mutable detail::function::function_buffer functor; }; #if defined(BOOST_CLANG) # pragma clang diagnostic push # pragma clang diagnostic ignored "-Wweak-vtables" #endif /** * The bad_function_call exception class is thrown when a boost::function * object is invoked */ class BOOST_SYMBOL_VISIBLE bad_function_call : public std::runtime_error { public: bad_function_call() : std::runtime_error("call to empty boost::function") {} }; #if defined(BOOST_CLANG) # pragma clang diagnostic pop #endif inline bool operator==(const function_base& f, detail::function::useless_clear_type*) { return f.empty(); } inline bool operator!=(const function_base& f, detail::function::useless_clear_type*) { return !f.empty(); } inline bool operator==(detail::function::useless_clear_type*, const function_base& f) { return f.empty(); } inline bool operator!=(detail::function::useless_clear_type*, const function_base& f) { return !f.empty(); } // Comparisons between boost::function objects and arbitrary function // objects. template<typename Functor> BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor, bool) operator==(const function_base& f, Functor g) { if (const Functor* fp = f.template target<Functor>()) return function_equal(*fp, g); else return false; } template<typename Functor> BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor, bool) operator==(Functor g, const function_base& f) { if (const Functor* fp = f.template target<Functor>()) return function_equal(g, *fp); else return false; } template<typename Functor> BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor, bool) operator!=(const function_base& f, Functor g) { if (const Functor* fp = f.template target<Functor>()) return !function_equal(*fp, g); else return true; } template<typename Functor> BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor, bool) operator!=(Functor g, const function_base& f) { if (const Functor* fp = f.template target<Functor>()) return !function_equal(g, *fp); else return true; } template<typename Functor> BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor, bool) operator==(const function_base& f, reference_wrapper<Functor> g) { if (const Functor* fp = f.template target<Functor>()) return fp == g.get_pointer(); else return false; } template<typename Functor> BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor, bool) operator==(reference_wrapper<Functor> g, const function_base& f) { if (const Functor* fp = f.template target<Functor>()) return g.get_pointer() == fp; else return false; } template<typename Functor> BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor, bool) operator!=(const function_base& f, reference_wrapper<Functor> g) { if (const Functor* fp = f.template target<Functor>()) return fp != g.get_pointer(); else return true; } template<typename Functor> BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor, bool) operator!=(reference_wrapper<Functor> g, const function_base& f) { if (const Functor* fp = f.template target<Functor>()) return g.get_pointer() != fp; else return true; } namespace detail { namespace function { inline bool has_empty_target(const function_base* f) { return f->empty(); } #if BOOST_WORKAROUND(BOOST_MSVC, <= 1310) inline bool has_empty_target(const void*) { return false; } #else inline bool has_empty_target(...) { return false; } #endif } // end namespace function } // end namespace detail } // end namespace boost #undef BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL #if defined(BOOST_MSVC) # pragma warning( pop ) #endif #endif // BOOST_FUNCTION_BASE_HEADER