libcruft-util/types/traits.hpp

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/*
* This file is part of libgim.
*
* libgim 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 of the License, or (at your option) any later
* version.
*
* libgim 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.
*
* You should have received a copy of the GNU General Public License
* along with libgim. If not, see <http://www.gnu.org/licenses/>.
*
* Copyright 2012 Danny Robson <danny@nerdcruft.net>
*/
#ifndef __UTIL_TYPES_TRAITS_HPP
#define __UTIL_TYPES_TRAITS_HPP
#include <memory>
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#include <type_traits>
//-----------------------------------------------------------------------------
template <typename T> struct is_dereferencable : std::false_type { };
template <typename T> struct is_dereferencable<T*> : std::true_type { };
template <typename T> struct is_dereferencable<std::unique_ptr<T>> : std::true_type { };
template <typename T> struct is_dereferencable<std::shared_ptr<T>> : std::true_type { };
template <typename T> struct is_dereferencable<std::weak_ptr<T>> : std::true_type { };
template <typename T> struct is_dereferencable<std::auto_ptr<T>> : std::true_type { };
template <typename T> struct dereferenced_type {
typedef typename std::enable_if<
std::is_pointer<T>::value,
std::remove_pointer<T>
>::type type;
};
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//-----------------------------------------------------------------------------
template <typename T> struct dereferenced_type<std::unique_ptr<T>> { typedef T type; };
template <typename T> struct dereferenced_type<std::shared_ptr<T>> { typedef T type; };
template <typename T> struct dereferenced_type<std::weak_ptr<T>> { typedef T type; };
template <typename T> struct dereferenced_type<std::auto_ptr<T>> { typedef T type; };
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///----------------------------------------------------------------------------
/// find the unsigned version of a type if one exists
template <typename T>
struct try_unsigned
{
typedef typename std::make_unsigned<T>::type type;
};
template <> struct try_unsigned<double> { typedef double type; };
template <> struct try_unsigned<float > { typedef float type; };
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///----------------------------------------------------------------------------
/// checks if a type can be converted in all cases without modification
template <typename T, typename U> struct is_lossless_cast : std::enable_if<
std::is_integral<T>::value &&
std::is_integral<U>::value &&
std::is_signed<T>::value == std::is_signed<U>::value &&
sizeof (T) <= sizeof (U),
std::true_type
>::value { };
//-----------------------------------------------------------------------------
template <typename T>
struct func_traits : public func_traits<decltype(&T::operator())>
{ };
template <typename C, typename R, typename ...Args>
struct func_traits<R(C::*)(Args...) const> {
typedef R return_type;
};
template <typename R, typename ...Args>
struct func_traits<R(Args...)> {
typedef R return_type;
};
#endif