Edit File: type_traits
// C++0x type_traits -*- C++ -*- // Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file include/type_traits * This is a Standard C++ Library header. */ #ifndef _GLIBCXX_TYPE_TRAITS #define _GLIBCXX_TYPE_TRAITS 1 #pragma GCC system_header #ifndef __GXX_EXPERIMENTAL_CXX0X__ # include <c++0x_warning.h> #else #if defined(_GLIBCXX_INCLUDE_AS_TR1) # error C++0x header cannot be included from TR1 header #endif #include <cstddef> #if defined(_GLIBCXX_INCLUDE_AS_CXX0X) # include <tr1_impl/type_traits> #else # define _GLIBCXX_INCLUDE_AS_CXX0X # define _GLIBCXX_BEGIN_NAMESPACE_TR1 # define _GLIBCXX_END_NAMESPACE_TR1 # define _GLIBCXX_TR1 # include <tr1_impl/type_traits> # undef _GLIBCXX_TR1 # undef _GLIBCXX_END_NAMESPACE_TR1 # undef _GLIBCXX_BEGIN_NAMESPACE_TR1 # undef _GLIBCXX_INCLUDE_AS_CXX0X #endif namespace std { /** @addtogroup metaprogramming * @{ */ // Primary classification traits. /// is_lvalue_reference template<typename> struct is_lvalue_reference : public false_type { }; template<typename _Tp> struct is_lvalue_reference<_Tp&> : public true_type { }; /// is_rvalue_reference template<typename> struct is_rvalue_reference : public false_type { }; template<typename _Tp> struct is_rvalue_reference<_Tp&&> : public true_type { }; // Secondary classification traits. /// is_reference template<typename _Tp> struct is_reference : public integral_constant<bool, (is_lvalue_reference<_Tp>::value || is_rvalue_reference<_Tp>::value)> { }; // Reference transformations. /// remove_reference template<typename _Tp> struct remove_reference { typedef _Tp type; }; template<typename _Tp> struct remove_reference<_Tp&> { typedef _Tp type; }; template<typename _Tp> struct remove_reference<_Tp&&> { typedef _Tp type; }; template<typename _Tp, bool = !is_reference<_Tp>::value && !is_void<_Tp>::value, bool = is_rvalue_reference<_Tp>::value> struct __add_lvalue_reference_helper { typedef _Tp type; }; template<typename _Tp> struct __add_lvalue_reference_helper<_Tp, true, false> { typedef _Tp& type; }; template<typename _Tp> struct __add_lvalue_reference_helper<_Tp, false, true> { typedef typename remove_reference<_Tp>::type& type; }; /// add_lvalue_reference template<typename _Tp> struct add_lvalue_reference : public __add_lvalue_reference_helper<_Tp> { }; template<typename _Tp, bool = !is_reference<_Tp>::value && !is_void<_Tp>::value> struct __add_rvalue_reference_helper { typedef _Tp type; }; template<typename _Tp> struct __add_rvalue_reference_helper<_Tp, true> { typedef _Tp&& type; }; /// add_rvalue_reference template<typename _Tp> struct add_rvalue_reference : public __add_rvalue_reference_helper<_Tp> { }; // Scalar properties and transformations. template<typename _Tp, bool = is_integral<_Tp>::value, bool = is_floating_point<_Tp>::value> struct __is_signed_helper : public false_type { }; template<typename _Tp> struct __is_signed_helper<_Tp, false, true> : public true_type { }; template<typename _Tp> struct __is_signed_helper<_Tp, true, false> : public integral_constant<bool, _Tp(-1) < _Tp(0)> { }; /// is_signed template<typename _Tp> struct is_signed : public integral_constant<bool, __is_signed_helper<_Tp>::value> { }; /// is_unsigned template<typename _Tp> struct is_unsigned : public integral_constant<bool, (is_arithmetic<_Tp>::value && !is_signed<_Tp>::value)> { }; // Member introspection. /// is_pod template<typename _Tp> struct is_pod : public integral_constant<bool, __is_pod(_Tp)> { }; /// has_trivial_default_constructor template<typename _Tp> struct has_trivial_default_constructor : public integral_constant<bool, __has_trivial_constructor(_Tp)> { }; /// has_trivial_copy_constructor template<typename _Tp> struct has_trivial_copy_constructor : public integral_constant<bool, __has_trivial_copy(_Tp)> { }; /// has_trivial_assign template<typename _Tp> struct has_trivial_assign : public integral_constant<bool, __has_trivial_assign(_Tp)> { }; /// has_trivial_destructor template<typename _Tp> struct has_trivial_destructor : public integral_constant<bool, __has_trivial_destructor(_Tp)> { }; /// has_nothrow_default_constructor template<typename _Tp> struct has_nothrow_default_constructor : public integral_constant<bool, __has_nothrow_constructor(_Tp)> { }; /// has_nothrow_copy_constructor template<typename _Tp> struct has_nothrow_copy_constructor : public integral_constant<bool, __has_nothrow_copy(_Tp)> { }; /// has_nothrow_assign template<typename _Tp> struct has_nothrow_assign : public integral_constant<bool, __has_nothrow_assign(_Tp)> { }; /// is_base_of template<typename _Base, typename _Derived> struct is_base_of : public integral_constant<bool, __is_base_of(_Base, _Derived)> { }; // Relationships between types. template<typename _From, typename _To> struct __is_convertible_simple : public __sfinae_types { private: static __one __test(_To); static __two __test(...); static _From __makeFrom(); public: static const bool __value = sizeof(__test(__makeFrom())) == 1; }; template<typename _Tp> struct __is_int_or_cref { typedef typename remove_reference<_Tp>::type __rr_Tp; static const bool __value = (is_integral<_Tp>::value || (is_integral<__rr_Tp>::value && is_const<__rr_Tp>::value && !is_volatile<__rr_Tp>::value)); }; template<typename _From, typename _To, bool = (is_void<_From>::value || is_void<_To>::value || is_function<_To>::value || is_array<_To>::value // This special case is here only to avoid warnings. || (is_floating_point<typename remove_reference<_From>::type>::value && __is_int_or_cref<_To>::__value))> struct __is_convertible_helper { // "An imaginary lvalue of type From...". static const bool __value = (__is_convertible_simple<typename add_lvalue_reference<_From>::type, _To>::__value); }; template<typename _From, typename _To> struct __is_convertible_helper<_From, _To, true> { static const bool __value = (is_void<_To>::value || (__is_int_or_cref<_To>::__value && !is_void<_From>::value)); }; // XXX FIXME // The C++0x specifications are different, see N2255. /// is_convertible template<typename _From, typename _To> struct is_convertible : public integral_constant<bool, __is_convertible_helper<_From, _To>::__value> { }; template<std::size_t _Len> struct __aligned_storage_msa { union __type { unsigned char __data[_Len]; struct __attribute__((__aligned__)) { } __align; }; }; /** * @brief Alignment type. * * The value of _Align is a default-alignment which shall be the * most stringent alignment requirement for any C++ object type * whose size is no greater than _Len (3.9). The member typedef * type shall be a POD type suitable for use as uninitialized * storage for any object whose size is at most _Len and whose * alignment is a divisor of _Align. */ template<std::size_t _Len, std::size_t _Align = __alignof__(typename __aligned_storage_msa<_Len>::__type)> struct aligned_storage { union type { unsigned char __data[_Len]; struct __attribute__((__aligned__((_Align)))) { } __align; }; }; // Define a nested type if some predicate holds. // Primary template. /// enable_if template<bool, typename _Tp = void> struct enable_if { }; // Partial specialization for true. template<typename _Tp> struct enable_if<true, _Tp> { typedef _Tp type; }; // A conditional expression, but for types. If true, first, if false, second. // Primary template. /// conditional template<bool _Cond, typename _Iftrue, typename _Iffalse> struct conditional { typedef _Iftrue type; }; // Partial specialization for false. template<typename _Iftrue, typename _Iffalse> struct conditional<false, _Iftrue, _Iffalse> { typedef _Iffalse type; }; // Decay trait for arrays and functions, used for perfect forwarding // in make_pair, make_tuple, etc. template<typename _Up, bool _IsArray = is_array<_Up>::value, bool _IsFunction = is_function<_Up>::value> struct __decay_selector; // NB: DR 705. template<typename _Up> struct __decay_selector<_Up, false, false> { typedef typename remove_cv<_Up>::type __type; }; template<typename _Up> struct __decay_selector<_Up, true, false> { typedef typename remove_extent<_Up>::type* __type; }; template<typename _Up> struct __decay_selector<_Up, false, true> { typedef typename add_pointer<_Up>::type __type; }; /// decay template<typename _Tp> struct decay { private: typedef typename remove_reference<_Tp>::type __remove_type; public: typedef typename __decay_selector<__remove_type>::__type type; }; // Utility for constructing identically cv-qualified types. template<typename _Unqualified, bool _IsConst, bool _IsVol> struct __cv_selector; template<typename _Unqualified> struct __cv_selector<_Unqualified, false, false> { typedef _Unqualified __type; }; template<typename _Unqualified> struct __cv_selector<_Unqualified, false, true> { typedef volatile _Unqualified __type; }; template<typename _Unqualified> struct __cv_selector<_Unqualified, true, false> { typedef const _Unqualified __type; }; template<typename _Unqualified> struct __cv_selector<_Unqualified, true, true> { typedef const volatile _Unqualified __type; }; template<typename _Qualified, typename _Unqualified, bool _IsConst = is_const<_Qualified>::value, bool _IsVol = is_volatile<_Qualified>::value> struct __match_cv_qualifiers { private: typedef __cv_selector<_Unqualified, _IsConst, _IsVol> __match; public: typedef typename __match::__type __type; }; // Utility for finding the unsigned versions of signed integral types. template<typename _Tp> struct __make_unsigned { typedef _Tp __type; }; template<> struct __make_unsigned<char> { typedef unsigned char __type; }; template<> struct __make_unsigned<signed char> { typedef unsigned char __type; }; template<> struct __make_unsigned<short> { typedef unsigned short __type; }; template<> struct __make_unsigned<int> { typedef unsigned int __type; }; template<> struct __make_unsigned<long> { typedef unsigned long __type; }; template<> struct __make_unsigned<long long> { typedef unsigned long long __type; }; // Select between integral and enum: not possible to be both. template<typename _Tp, bool _IsInt = is_integral<_Tp>::value, bool _IsEnum = is_enum<_Tp>::value> struct __make_unsigned_selector; template<typename _Tp> struct __make_unsigned_selector<_Tp, true, false> { private: typedef __make_unsigned<typename remove_cv<_Tp>::type> __unsignedt; typedef typename __unsignedt::__type __unsigned_type; typedef __match_cv_qualifiers<_Tp, __unsigned_type> __cv_unsigned; public: typedef typename __cv_unsigned::__type __type; }; template<typename _Tp> struct __make_unsigned_selector<_Tp, false, true> { private: // With -fshort-enums, an enum may be as small as a char. typedef unsigned char __smallest; static const bool __b0 = sizeof(_Tp) <= sizeof(__smallest); static const bool __b1 = sizeof(_Tp) <= sizeof(unsigned short); static const bool __b2 = sizeof(_Tp) <= sizeof(unsigned int); typedef conditional<__b2, unsigned int, unsigned long> __cond2; typedef typename __cond2::type __cond2_type; typedef conditional<__b1, unsigned short, __cond2_type> __cond1; typedef typename __cond1::type __cond1_type; public: typedef typename conditional<__b0, __smallest, __cond1_type>::type __type; }; // Given an integral/enum type, return the corresponding unsigned // integer type. // Primary template. /// make_unsigned template<typename _Tp> struct make_unsigned { typedef typename __make_unsigned_selector<_Tp>::__type type; }; // Integral, but don't define. template<> struct make_unsigned<bool>; // Utility for finding the signed versions of unsigned integral types. template<typename _Tp> struct __make_signed { typedef _Tp __type; }; template<> struct __make_signed<char> { typedef signed char __type; }; template<> struct __make_signed<unsigned char> { typedef signed char __type; }; template<> struct __make_signed<unsigned short> { typedef signed short __type; }; template<> struct __make_signed<unsigned int> { typedef signed int __type; }; template<> struct __make_signed<unsigned long> { typedef signed long __type; }; template<> struct __make_signed<unsigned long long> { typedef signed long long __type; }; // Select between integral and enum: not possible to be both. template<typename _Tp, bool _IsInt = is_integral<_Tp>::value, bool _IsEnum = is_enum<_Tp>::value> struct __make_signed_selector; template<typename _Tp> struct __make_signed_selector<_Tp, true, false> { private: typedef __make_signed<typename remove_cv<_Tp>::type> __signedt; typedef typename __signedt::__type __signed_type; typedef __match_cv_qualifiers<_Tp, __signed_type> __cv_signed; public: typedef typename __cv_signed::__type __type; }; template<typename _Tp> struct __make_signed_selector<_Tp, false, true> { private: // With -fshort-enums, an enum may be as small as a char. typedef signed char __smallest; static const bool __b0 = sizeof(_Tp) <= sizeof(__smallest); static const bool __b1 = sizeof(_Tp) <= sizeof(signed short); static const bool __b2 = sizeof(_Tp) <= sizeof(signed int); typedef conditional<__b2, signed int, signed long> __cond2; typedef typename __cond2::type __cond2_type; typedef conditional<__b1, signed short, __cond2_type> __cond1; typedef typename __cond1::type __cond1_type; public: typedef typename conditional<__b0, __smallest, __cond1_type>::type __type; }; // Given an integral/enum type, return the corresponding signed // integer type. // Primary template. /// make_signed template<typename _Tp> struct make_signed { typedef typename __make_signed_selector<_Tp>::__type type; }; // Integral, but don't define. template<> struct make_signed<bool>; /// common_type template<typename... _Tp> struct common_type; template<typename _Tp> struct common_type<_Tp> { static_assert(sizeof(_Tp) > 0, "must be complete type"); typedef _Tp type; }; template<typename _Tp, typename _Up> class common_type<_Tp, _Up> { static_assert(sizeof(_Tp) > 0, "must be complete type"); static_assert(sizeof(_Up) > 0, "must be complete type"); static _Tp&& __t(); static _Up&& __u(); // HACK: Prevents optimization of ?: in the decltype // expression when the condition is the literal, "true". // See, PR36628. static bool __true_or_false(); public: typedef decltype(__true_or_false() ? __t() : __u()) type; }; template<typename _Tp, typename _Up, typename... _Vp> struct common_type<_Tp, _Up, _Vp...> { typedef typename common_type<typename common_type<_Tp, _Up>::type, _Vp...>::type type; }; // @} group metaprogramming } #endif // __GXX_EXPERIMENTAL_CXX0X__ #endif // _GLIBCXX_TYPE_TRAITS
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