100 lines
3.2 KiB
C++
100 lines
3.2 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2012 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef __UTIL_TYPES_TRAITS_HPP
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#define __UTIL_TYPES_TRAITS_HPP
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#include <memory>
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#include <type_traits>
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//-----------------------------------------------------------------------------
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template <typename T> struct is_dereferencable : std::false_type { };
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template <typename T> struct is_dereferencable<T*> : std::true_type { };
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template <typename T> struct is_dereferencable<std::unique_ptr<T>> : std::true_type { };
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template <typename T> struct is_dereferencable<std::shared_ptr<T>> : std::true_type { };
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template <typename T> struct is_dereferencable<std::weak_ptr<T>> : std::true_type { };
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template <typename T> struct dereferenced_type {
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typedef typename std::enable_if<
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std::is_pointer<T>::value,
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std::remove_pointer<T>
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>::type type;
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};
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//-----------------------------------------------------------------------------
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template <typename T> struct dereferenced_type<std::unique_ptr<T>> { typedef T type; };
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template <typename T> struct dereferenced_type<std::shared_ptr<T>> { typedef T type; };
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template <typename T> struct dereferenced_type<std::weak_ptr<T>> { typedef T type; };
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///----------------------------------------------------------------------------
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/// find the unsigned version of a type if one exists
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template <typename T>
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struct try_unsigned
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{
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typedef typename std::make_unsigned<T>::type type;
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};
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template <> struct try_unsigned<double> { typedef double type; };
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template <> struct try_unsigned<float > { typedef float type; };
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///----------------------------------------------------------------------------
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/// find the signed version of a type if one exists
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template <typename T>
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struct try_signed
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{
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typedef typename std::make_signed<T>::type type;
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};
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template <> struct try_signed<double> { typedef double type; };
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template <> struct try_signed<float > { typedef float type; };
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///----------------------------------------------------------------------------
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/// checks if a type can be converted in all cases without modification
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template <typename T, typename U> struct is_lossless_cast : std::enable_if<
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std::is_integral<T>::value &&
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std::is_integral<U>::value &&
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std::is_signed<T>::value == std::is_signed<U>::value &&
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sizeof (T) <= sizeof (U),
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std::true_type
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>::value { };
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//-----------------------------------------------------------------------------
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template <typename T>
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struct func_traits : public func_traits<decltype(&T::operator())>
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{ };
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template <typename C, typename R, typename ...Args>
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struct func_traits<R(C::*)(Args...) const> {
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typedef R return_type;
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};
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template <typename R, typename ...Args>
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struct func_traits<R(Args...)> {
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typedef R return_type;
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};
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#endif
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