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Diffstat (limited to 'Runtime/Utilities/type_traits.h')
| -rw-r--r-- | Runtime/Utilities/type_traits.h | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/Runtime/Utilities/type_traits.h b/Runtime/Utilities/type_traits.h new file mode 100644 index 0000000..edffc34 --- /dev/null +++ b/Runtime/Utilities/type_traits.h @@ -0,0 +1,250 @@ +// Copyright (c) 2006, Google Inc. +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +// ---- +// Author: Matt Austern +// +// Define a small subset of tr1 type traits. The traits we define are: +// is_integral +// is_floating_point +// is_pointer +// is_reference +// is_pod +// has_trivial_constructor +// has_trivial_copy +// has_trivial_assign +// has_trivial_destructor +// remove_const +// remove_volatile +// remove_cv +// remove_reference +// remove_pointer +// is_convertible +// We can add more type traits as required. + +#ifndef BASE_TYPE_TRAITS_H_ +#define BASE_TYPE_TRAITS_H_ + +//#include <google/sparsehash/sparseconfig.h> +#include <utility> // For pair + +namespace dense_hash_map_traits +{ + +// integral_constant, defined in tr1, is a wrapper for an integer +// value. We don't really need this generality; we could get away +// with hardcoding the integer type to bool. We use the fully +// general integer_constant for compatibility with tr1. + +template<class T, T v> +struct integral_constant { + static const T value = v; + typedef T value_type; + typedef integral_constant<T, v> type; +}; + +template <class T, T v> const T integral_constant<T, v>::value; + +// Abbreviations: true_type and false_type are structs that represent +// boolean true and false values. +typedef integral_constant<bool, true> true_type; +typedef integral_constant<bool, false> false_type; + +// Types small_ and big_ are guaranteed such that sizeof(small_) < +// sizeof(big_) +typedef char small_; + +struct big_ { + char dummy[2]; +}; + +// is_integral is false except for the built-in integer types. +template <class T> struct is_integral : false_type { }; +template<> struct is_integral<bool> : true_type { }; +template<> struct is_integral<char> : true_type { }; +template<> struct is_integral<unsigned char> : true_type { }; +template<> struct is_integral<signed char> : true_type { }; +#if defined(_MSC_VER) +// wchar_t is not by default a distinct type from unsigned short in +// Microsoft C. +// See http://msdn2.microsoft.com/en-us/library/dh8che7s(VS.80).aspx +template<> struct is_integral<__wchar_t> : true_type { }; +#else +template<> struct is_integral<wchar_t> : true_type { }; +#endif +template<> struct is_integral<short> : true_type { }; +template<> struct is_integral<unsigned short> : true_type { }; +template<> struct is_integral<int> : true_type { }; +template<> struct is_integral<unsigned int> : true_type { }; +template<> struct is_integral<long> : true_type { }; +template<> struct is_integral<unsigned long> : true_type { }; +#ifdef HAVE_LONG_LONG +template<> struct is_integral<long long> : true_type { }; +template<> struct is_integral<unsigned long long> : true_type { }; +#endif + + +// is_floating_point is false except for the built-in floating-point types. +template <class T> struct is_floating_point : false_type { }; +template<> struct is_floating_point<float> : true_type { }; +template<> struct is_floating_point<double> : true_type { }; +template<> struct is_floating_point<long double> : true_type { }; + + +// is_pointer is false except for pointer types. +template <class T> struct is_pointer : false_type { }; +template <class T> struct is_pointer<T*> : true_type { }; + + +// is_reference is false except for reference types. +template<typename T> struct is_reference : false_type {}; +template<typename T> struct is_reference<T&> : true_type {}; + + +// We can't get is_pod right without compiler help, so fail conservatively. +// We will assume it's false except for arithmetic types and pointers, +// and const versions thereof. Note that std::pair is not a POD. +template <class T> struct is_pod + : integral_constant<bool, (is_integral<T>::value || + is_floating_point<T>::value || + is_pointer<T>::value)> { }; +template <class T> struct is_pod<const T> : is_pod<T> { }; + + +// We can't get has_trivial_constructor right without compiler help, so +// fail conservatively. We will assume it's false except for: (1) types +// for which is_pod is true. (2) std::pair of types with trivial +// constructors. (3) array of a type with a trivial constructor. +// (4) const versions thereof. +template <class T> struct has_trivial_constructor : is_pod<T> { }; +template <class T, class U> struct has_trivial_constructor<std::pair<T, U> > + : integral_constant<bool, + (has_trivial_constructor<T>::value && + has_trivial_constructor<U>::value)> { }; +template <class A, int N> struct has_trivial_constructor<A[N]> + : has_trivial_constructor<A> { }; +template <class T> struct has_trivial_constructor<const T> + : has_trivial_constructor<T> { }; + +// We can't get has_trivial_copy right without compiler help, so fail +// conservatively. We will assume it's false except for: (1) types +// for which is_pod is true. (2) std::pair of types with trivial copy +// constructors. (3) array of a type with a trivial copy constructor. +// (4) const versions thereof. +template <class T> struct has_trivial_copy : is_pod<T> { }; +template <class T, class U> struct has_trivial_copy<std::pair<T, U> > + : integral_constant<bool, + (has_trivial_copy<T>::value && + has_trivial_copy<U>::value)> { }; +template <class A, int N> struct has_trivial_copy<A[N]> + : has_trivial_copy<A> { }; +template <class T> struct has_trivial_copy<const T> : has_trivial_copy<T> { }; + +// We can't get has_trivial_assign right without compiler help, so fail +// conservatively. We will assume it's false except for: (1) types +// for which is_pod is true. (2) std::pair of types with trivial copy +// constructors. (3) array of a type with a trivial assign constructor. +template <class T> struct has_trivial_assign : is_pod<T> { }; +template <class T, class U> struct has_trivial_assign<std::pair<T, U> > + : integral_constant<bool, + (has_trivial_assign<T>::value && + has_trivial_assign<U>::value)> { }; +template <class A, int N> struct has_trivial_assign<A[N]> + : has_trivial_assign<A> { }; + +// We can't get has_trivial_destructor right without compiler help, so +// fail conservatively. We will assume it's false except for: (1) types +// for which is_pod is true. (2) std::pair of types with trivial +// destructors. (3) array of a type with a trivial destructor. +// (4) const versions thereof. +template <class T> struct has_trivial_destructor : is_pod<T> { }; +template <class T, class U> struct has_trivial_destructor<std::pair<T, U> > + : integral_constant<bool, + (has_trivial_destructor<T>::value && + has_trivial_destructor<U>::value)> { }; +template <class A, int N> struct has_trivial_destructor<A[N]> + : has_trivial_destructor<A> { }; +template <class T> struct has_trivial_destructor<const T> + : has_trivial_destructor<T> { }; + +// Specified by TR1 [4.7.1] +template<typename T> struct remove_const { typedef T type; }; +template<typename T> struct remove_const<T const> { typedef T type; }; +template<typename T> struct remove_volatile { typedef T type; }; +template<typename T> struct remove_volatile<T volatile> { typedef T type; }; +template<typename T> struct remove_cv { + typedef typename remove_const<typename remove_volatile<T>::type>::type type; +}; + + +// Specified by TR1 [4.7.2] +template<typename T> struct remove_reference { typedef T type; }; +template<typename T> struct remove_reference<T&> { typedef T type; }; + +// Specified by TR1 [4.7.4] Pointer modifications. +template<typename T> struct remove_pointer { typedef T type; }; +template<typename T> struct remove_pointer<T*> { typedef T type; }; +template<typename T> struct remove_pointer<T* const> { typedef T type; }; +template<typename T> struct remove_pointer<T* volatile> { typedef T type; }; +template<typename T> struct remove_pointer<T* const volatile> { + typedef T type; }; + +// Specified by TR1 [4.6] Relationships between types +#ifndef _MSC_VER +namespace internal_type_traits { + +// This class is an implementation detail for is_convertible, and you +// don't need to know how it works to use is_convertible. For those +// who care: we declare two different functions, one whose argument is +// of type To and one with a variadic argument list. We give them +// return types of different size, so we can use sizeof to trick the +// compiler into telling us which function it would have chosen if we +// had called it with an argument of type From. See Alexandrescu's +// _Modern C++ Design_ for more details on this sort of trick. + +template <typename From, typename To> +struct ConvertHelper { + static small_ Test(To); + static big_ Test(...); + static From Create(); +}; +} // namespace internal + +// Inherits from true_type if From is convertible to To, false_type otherwise. +template <typename From, typename To> +struct is_convertible + : integral_constant<bool, + sizeof(internal_type_traits::ConvertHelper<From, To>::Test( + internal_type_traits::ConvertHelper<From, To>::Create())) + == sizeof(small_)> { +}; +#endif + +} +#endif // BASE_TYPE_TRAITS_H_ |