convert.hpp
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r4 | #ifndef OPAQUE_CONVERT_HPP | |||
#define OPAQUE_CONVERT_HPP | ||||
// | ||||
// Copyright (c) 2015, 2016 | ||||
// Kyle Markley. All rights reserved. | ||||
// | ||||
// Redistribution and use in source and binary forms, with or without | ||||
// modification, are permitted provided that the following conditions are met: | ||||
// | ||||
// 1. Redistributions of source code must retain the above copyright notice, | ||||
// this list of conditions and the following disclaimer. | ||||
// 2. 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. | ||||
// 3. Neither the name of the author nor the names of any 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 HOLDER 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. | ||||
// | ||||
#include "type_traits.hpp" | ||||
#include "utility.hpp" | ||||
#include "data.hpp" | ||||
#include <type_traits> | ||||
namespace opaque { | ||||
/// \addtogroup internal | ||||
/// @{ | ||||
// | ||||
// Conversion operations | ||||
// | ||||
// Convert from one type to a compatible type, avoiding creating a new object | ||||
// when possible. The function determines whether the output must be mutable | ||||
// or may be const. | ||||
// | ||||
// The cost model is: | ||||
// 0 = free case | ||||
// 1 = construction from rvalue reference | ||||
// 2 = construction from lvalue reference | ||||
// | ||||
template <typename T, typename U=T, | ||||
bool free = is_cast_free<T, typename std::decay<U>::type>::value> | ||||
struct converter; | ||||
template <typename T, typename U> | ||||
struct converter<T, const U&, true> { | ||||
static constexpr T convert_mutable(const U& u) noexcept( | ||||
noexcept(static_cast< T >(u))) { | ||||
return static_cast< T >(u); } | ||||
static constexpr const T& convert( const U& u) noexcept( | ||||
noexcept(static_cast<const T& >(u))) { | ||||
return static_cast<const T& >(u); } | ||||
static constexpr unsigned mutable_cost() noexcept { return 2; } | ||||
static constexpr unsigned cost() noexcept { return 0; } | ||||
}; | ||||
template <typename T, typename U> | ||||
struct converter<T, U&, true> { | ||||
static constexpr T& convert_mutable( U& u) noexcept( | ||||
noexcept(static_cast< T& >(u))) { | ||||
return static_cast< T& >(u); } | ||||
static constexpr T& convert( U& u) noexcept( | ||||
noexcept(static_cast< T& >(u))) { | ||||
return static_cast< T& >(u); } | ||||
static constexpr unsigned mutable_cost() noexcept { return 0; } | ||||
static constexpr unsigned cost() noexcept { return 0; } | ||||
}; | ||||
template <typename T, typename U> | ||||
struct converter<T, U&&, true> { | ||||
static constexpr T&& convert_mutable( U&& u) noexcept( | ||||
noexcept(static_cast< T&&>(opaque::move(u)))) { | ||||
return static_cast< T&&>(opaque::move(u)); } | ||||
static constexpr T&& convert( U&& u) noexcept( | ||||
noexcept(static_cast< T&&>(opaque::move(u)))) { | ||||
return static_cast< T&&>(opaque::move(u)); } | ||||
static constexpr unsigned mutable_cost() noexcept { return 0; } | ||||
static constexpr unsigned cost() noexcept { return 0; } | ||||
}; | ||||
template <typename T, typename U> | ||||
struct converter<T, U, true> { // same as U&& | ||||
static constexpr T&& convert_mutable( U&& u) noexcept( | ||||
noexcept(static_cast< T&&>(opaque::move(u)))) { | ||||
return static_cast< T&&>(opaque::move(u)); } | ||||
static constexpr T&& convert( U&& u) noexcept( | ||||
noexcept(static_cast< T&&>(opaque::move(u)))) { | ||||
return static_cast< T&&>(opaque::move(u)); } | ||||
static constexpr unsigned mutable_cost() noexcept { return 0; } | ||||
static constexpr unsigned cost() noexcept { return 0; } | ||||
}; | ||||
template <typename T, typename U> | ||||
struct converter<T, const U&, false> { | ||||
template <typename R=T> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert_mutable(const U& u) noexcept( | ||||
noexcept(static_cast<R>(u))) { | ||||
return static_cast<R>(u); } | ||||
template <typename R=T> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert_mutable(const U& u) noexcept( | ||||
noexcept(static_cast<R>(u.value))) { | ||||
return static_cast<R>(u.value); } | ||||
template <typename R=T> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert( const U& u) noexcept( | ||||
noexcept(static_cast<R>(u))) { | ||||
return static_cast<R>(u); } | ||||
template <typename R=const T&> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert( const U& u) noexcept( | ||||
noexcept(static_cast<R>(u.value))) { | ||||
return static_cast<R>(u.value); } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type mutable_cost() noexcept { return 2; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type mutable_cost() noexcept { return 2; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type cost() noexcept { return 2; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type cost() noexcept { return 0; } | ||||
}; | ||||
template <typename T, typename U> | ||||
struct converter<T, U&, false> { | ||||
template <typename R=T> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert_mutable( U& u) noexcept( | ||||
noexcept(static_cast<R>(u))) { | ||||
return static_cast<R>(u); } | ||||
template <typename R=T&> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert_mutable( U& u) noexcept( | ||||
noexcept(static_cast<R>(u.value))) { | ||||
return static_cast<R>(u.value); } | ||||
template <typename R=T> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert( U& u) noexcept( | ||||
noexcept(static_cast<R>(u))) { | ||||
return static_cast<R>(u); } | ||||
template <typename R=T&> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert( U& u) noexcept( | ||||
noexcept(static_cast<R>(u.value))) { | ||||
return static_cast<R>(u.value); } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type mutable_cost() noexcept { return 2; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type mutable_cost() noexcept { return 0; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type cost() noexcept { return 2; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type cost() noexcept { return 0; } | ||||
}; | ||||
template <typename T, typename U> | ||||
struct converter<T, U&&, false> { | ||||
template <typename R=T> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert_mutable( U&& u) noexcept( | ||||
noexcept(static_cast<R>(opaque::move(u)))) { | ||||
return static_cast<R>(opaque::move(u)); } | ||||
template <typename R=T&&> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert_mutable( U&& u) noexcept( | ||||
noexcept(static_cast<R>(opaque::move(u.value)))) { | ||||
return static_cast<R>(opaque::move(u.value)); } | ||||
template <typename R=T> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert( U&& u) noexcept( | ||||
noexcept(static_cast<R>(opaque::move(u)))) { | ||||
return static_cast<R>(opaque::move(u)); } | ||||
template <typename R=T&&> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert( U&& u) noexcept( | ||||
noexcept(static_cast<R>(opaque::move(u.value)))) { | ||||
return static_cast<R>(opaque::move(u.value)); } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type mutable_cost() noexcept { return 1; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type mutable_cost() noexcept { return 0; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type cost() noexcept { return 1; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type cost() noexcept { return 0; } | ||||
}; | ||||
template <typename T, typename U> | ||||
struct converter<T, U, false> { // same as U&& | ||||
template <typename R=T> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert_mutable( U&& u) noexcept( | ||||
noexcept(static_cast<R>(opaque::move(u)))) { | ||||
return static_cast<R>(opaque::move(u)); } | ||||
template <typename R=T&&> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert_mutable( U&& u) noexcept( | ||||
noexcept(static_cast<R>(opaque::move(u.value)))) { | ||||
return static_cast<R>(opaque::move(u.value)); } | ||||
template <typename R=T> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert( U&& u) noexcept( | ||||
noexcept(static_cast<R>(opaque::move(u)))) { | ||||
return static_cast<R>(opaque::move(u)); } | ||||
template <typename R=T&&> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type convert( U&& u) noexcept( | ||||
noexcept(static_cast<R>(opaque::move(u.value)))) { | ||||
return static_cast<R>(opaque::move(u.value)); } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type mutable_cost() noexcept { return 1; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type mutable_cost() noexcept { return 0; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if<not std::is_base_of<data<T,U>, U>::value, | ||||
R>::type cost() noexcept { return 1; } | ||||
template <typename R=unsigned> | ||||
static constexpr | ||||
typename std::enable_if< std::is_base_of<data<T,U>, U>::value, | ||||
R>::type cost() noexcept { return 0; } | ||||
}; | ||||
/// | ||||
/// Convert the argument and ensure the result is mutable | ||||
/// | ||||
/// Where possible, the conversion is performed via a no-cost cast (perhaps an | ||||
/// up or down cast), but for unrelated or const types, a new object is | ||||
/// created. | ||||
/// | ||||
template <typename T, typename U=T> | ||||
constexpr auto convert_mutable(U&& u) | ||||
noexcept(noexcept( | ||||
converter<typename std::decay<T>::type, U>::convert_mutable( | ||||
opaque::forward<U>(u)))) -> decltype( | ||||
converter<typename std::decay<T>::type, U>::convert_mutable( | ||||
opaque::forward<U>(u))) { return | ||||
converter<typename std::decay<T>::type, U>::convert_mutable( | ||||
opaque::forward<U>(u)); | ||||
} | ||||
/// | ||||
/// Convert the argument | ||||
/// | ||||
/// Where possible, the conversion is performed via a no-cost cast (perhaps an | ||||
/// up or down cast), but for unrelated types, a new object is created. | ||||
/// | ||||
template <typename T, typename U=T> | ||||
constexpr auto convert(U&& u) | ||||
noexcept(noexcept( | ||||
converter<typename std::decay<T>::type, U>::convert( | ||||
opaque::forward<U>(u)))) -> decltype( | ||||
converter<typename std::decay<T>::type, U>::convert( | ||||
opaque::forward<U>(u))) { return | ||||
converter<typename std::decay<T>::type, U>::convert( | ||||
opaque::forward<U>(u)); | ||||
} | ||||
template <typename T, typename U> | ||||
constexpr unsigned convert_mutable_cost() noexcept { | ||||
return converter<typename std::decay<T>::type, U&&>::mutable_cost(); | ||||
} | ||||
template <typename T, typename U> | ||||
constexpr unsigned convert_mutable_cost(U&&) noexcept { | ||||
return converter<typename std::decay<T>::type, U&&>::mutable_cost(); | ||||
} | ||||
template <typename T, typename U> | ||||
constexpr unsigned convert_cost() noexcept { | ||||
return converter<typename std::decay<T>::type, U&&>::cost(); | ||||
} | ||||
template <typename T, typename U> | ||||
constexpr unsigned convert_cost(U&&) noexcept { | ||||
return converter<typename std::decay<T>::type, U&&>::cost(); | ||||
} | ||||
/// @} | ||||
} | ||||
#endif | ||||