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#ifndef OPAQUE_CONVERT_HPP
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#define OPAQUE_CONVERT_HPP
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//
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// Copyright (c) 2015, 2016
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// Kyle Markley. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// 3. Neither the name of the author nor the names of any contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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#include "type_traits.hpp"
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#include "utility.hpp"
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#include "data.hpp"
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#include <type_traits>
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namespace opaque {
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/// \addtogroup internal
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/// @{
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//
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// Conversion operations
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//
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// Convert from one type to a compatible type, avoiding creating a new object
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// when possible. The function determines whether the output must be mutable
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// or may be const.
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//
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// The cost model is:
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// 0 = free case
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// 1 = construction from rvalue reference
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// 2 = construction from lvalue reference
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//
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template <typename T, typename U=T,
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bool free = is_cast_free<T, typename std::decay<U>::type>::value>
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struct converter;
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template <typename T, typename U>
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struct converter<T, const U&, true> {
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static constexpr T convert_mutable(const U& u) noexcept(
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noexcept(static_cast< T >(u))) {
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return static_cast< T >(u); }
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static constexpr const T& convert( const U& u) noexcept(
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noexcept(static_cast<const T& >(u))) {
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return static_cast<const T& >(u); }
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static constexpr unsigned mutable_cost() noexcept { return 2; }
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static constexpr unsigned cost() noexcept { return 0; }
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};
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template <typename T, typename U>
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struct converter<T, U&, true> {
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static constexpr T& convert_mutable( U& u) noexcept(
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noexcept(static_cast< T& >(u))) {
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return static_cast< T& >(u); }
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static constexpr T& convert( U& u) noexcept(
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noexcept(static_cast< T& >(u))) {
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return static_cast< T& >(u); }
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static constexpr unsigned mutable_cost() noexcept { return 0; }
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static constexpr unsigned cost() noexcept { return 0; }
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};
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template <typename T, typename U>
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struct converter<T, U&&, true> {
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static constexpr T&& convert_mutable( U&& u) noexcept(
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noexcept(static_cast< T&&>(opaque::move(u)))) {
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return static_cast< T&&>(opaque::move(u)); }
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static constexpr T&& convert( U&& u) noexcept(
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noexcept(static_cast< T&&>(opaque::move(u)))) {
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return static_cast< T&&>(opaque::move(u)); }
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static constexpr unsigned mutable_cost() noexcept { return 0; }
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static constexpr unsigned cost() noexcept { return 0; }
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};
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template <typename T, typename U>
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struct converter<T, U, true> { // same as U&&
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static constexpr T&& convert_mutable( U&& u) noexcept(
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noexcept(static_cast< T&&>(opaque::move(u)))) {
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return static_cast< T&&>(opaque::move(u)); }
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static constexpr T&& convert( U&& u) noexcept(
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noexcept(static_cast< T&&>(opaque::move(u)))) {
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return static_cast< T&&>(opaque::move(u)); }
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static constexpr unsigned mutable_cost() noexcept { return 0; }
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static constexpr unsigned cost() noexcept { return 0; }
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};
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template <typename T, typename U>
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struct converter<T, const U&, false> {
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template <typename R=T>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type convert_mutable(const U& u) noexcept(
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noexcept(static_cast<R>(u))) {
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return static_cast<R>(u); }
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template <typename R=T>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type convert_mutable(const U& u) noexcept(
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noexcept(static_cast<R>(u.value))) {
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return static_cast<R>(u.value); }
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template <typename R=T>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type convert( const U& u) noexcept(
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noexcept(static_cast<R>(u))) {
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return static_cast<R>(u); }
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template <typename R=const T&>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type convert( const U& u) noexcept(
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noexcept(static_cast<R>(u.value))) {
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return static_cast<R>(u.value); }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type mutable_cost() noexcept { return 2; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type mutable_cost() noexcept { return 2; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type cost() noexcept { return 2; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type cost() noexcept { return 0; }
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};
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template <typename T, typename U>
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struct converter<T, U&, false> {
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template <typename R=T>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type convert_mutable( U& u) noexcept(
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noexcept(static_cast<R>(u))) {
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return static_cast<R>(u); }
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template <typename R=T&>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type convert_mutable( U& u) noexcept(
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noexcept(static_cast<R>(u.value))) {
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return static_cast<R>(u.value); }
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template <typename R=T>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type convert( U& u) noexcept(
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noexcept(static_cast<R>(u))) {
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return static_cast<R>(u); }
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template <typename R=T&>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type convert( U& u) noexcept(
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noexcept(static_cast<R>(u.value))) {
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return static_cast<R>(u.value); }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type mutable_cost() noexcept { return 2; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type mutable_cost() noexcept { return 0; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type cost() noexcept { return 2; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type cost() noexcept { return 0; }
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};
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template <typename T, typename U>
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struct converter<T, U&&, false> {
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template <typename R=T>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type convert_mutable( U&& u) noexcept(
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noexcept(static_cast<R>(opaque::move(u)))) {
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return static_cast<R>(opaque::move(u)); }
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template <typename R=T&&>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type convert_mutable( U&& u) noexcept(
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noexcept(static_cast<R>(opaque::move(u.value)))) {
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return static_cast<R>(opaque::move(u.value)); }
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template <typename R=T>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type convert( U&& u) noexcept(
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noexcept(static_cast<R>(opaque::move(u)))) {
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return static_cast<R>(opaque::move(u)); }
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template <typename R=T&&>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type convert( U&& u) noexcept(
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noexcept(static_cast<R>(opaque::move(u.value)))) {
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return static_cast<R>(opaque::move(u.value)); }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type mutable_cost() noexcept { return 1; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type mutable_cost() noexcept { return 0; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type cost() noexcept { return 1; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type cost() noexcept { return 0; }
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};
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template <typename T, typename U>
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struct converter<T, U, false> { // same as U&&
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template <typename R=T>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type convert_mutable( U&& u) noexcept(
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noexcept(static_cast<R>(opaque::move(u)))) {
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return static_cast<R>(opaque::move(u)); }
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template <typename R=T&&>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type convert_mutable( U&& u) noexcept(
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noexcept(static_cast<R>(opaque::move(u.value)))) {
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return static_cast<R>(opaque::move(u.value)); }
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template <typename R=T>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type convert( U&& u) noexcept(
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noexcept(static_cast<R>(opaque::move(u)))) {
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return static_cast<R>(opaque::move(u)); }
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template <typename R=T&&>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type convert( U&& u) noexcept(
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noexcept(static_cast<R>(opaque::move(u.value)))) {
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return static_cast<R>(opaque::move(u.value)); }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type mutable_cost() noexcept { return 1; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type mutable_cost() noexcept { return 0; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if<not std::is_base_of<data<T,U>, U>::value,
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R>::type cost() noexcept { return 1; }
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template <typename R=unsigned>
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static constexpr
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typename std::enable_if< std::is_base_of<data<T,U>, U>::value,
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R>::type cost() noexcept { return 0; }
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};
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///
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/// Convert the argument and ensure the result is mutable
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///
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/// Where possible, the conversion is performed via a no-cost cast (perhaps an
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/// up or down cast), but for unrelated or const types, a new object is
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/// created.
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///
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template <typename T, typename U=T>
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constexpr auto convert_mutable(U&& u)
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noexcept(noexcept(
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converter<typename std::decay<T>::type, U>::convert_mutable(
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opaque::forward<U>(u)))) -> decltype(
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converter<typename std::decay<T>::type, U>::convert_mutable(
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opaque::forward<U>(u))) { return
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converter<typename std::decay<T>::type, U>::convert_mutable(
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opaque::forward<U>(u));
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}
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///
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/// Convert the argument
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///
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/// Where possible, the conversion is performed via a no-cost cast (perhaps an
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/// up or down cast), but for unrelated types, a new object is created.
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///
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template <typename T, typename U=T>
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constexpr auto convert(U&& u)
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noexcept(noexcept(
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converter<typename std::decay<T>::type, U>::convert(
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opaque::forward<U>(u)))) -> decltype(
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converter<typename std::decay<T>::type, U>::convert(
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opaque::forward<U>(u))) { return
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converter<typename std::decay<T>::type, U>::convert(
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opaque::forward<U>(u));
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}
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template <typename T, typename U>
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constexpr unsigned convert_mutable_cost() noexcept {
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return converter<typename std::decay<T>::type, U&&>::mutable_cost();
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}
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template <typename T, typename U>
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constexpr unsigned convert_mutable_cost(U&&) noexcept {
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return converter<typename std::decay<T>::type, U&&>::mutable_cost();
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}
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template <typename T, typename U>
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constexpr unsigned convert_cost() noexcept {
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return converter<typename std::decay<T>::type, U&&>::cost();
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}
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template <typename T, typename U>
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constexpr unsigned convert_cost(U&&) noexcept {
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return converter<typename std::decay<T>::type, U&&>::cost();
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}
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/// @}
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}
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#endif
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