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 //
 
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// Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
 
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//
 
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
 
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
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//
 
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// Official repository: https://github.com/boostorg/url
 
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//
 
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#ifndef BOOST_URL_DETAIL_OVER_ALLOCATOR_HPP
 
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#define BOOST_URL_DETAIL_OVER_ALLOCATOR_HPP
 
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#include <boost/config.hpp>
 
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#include <boost/core/empty_value.hpp>
 
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#include <boost/assert.hpp>
 
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#include <boost/type_traits/is_final.hpp>
 
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#include <boost/type_traits/type_with_alignment.hpp>
 
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#ifdef BOOST_NO_CXX11_ALLOCATOR
 
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# include <boost/core/allocator_traits.hpp>
 
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#endif
 
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#include <cstddef>
 
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#include <memory>
 
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#include <type_traits>
 
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#include <utility>
 
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namespace boost {
 
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namespace urls {
 
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namespace detail {
 
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// This is a workaround for allocator_traits
 
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// implementations which falsely claim C++11
 
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// compatibility.
 
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#ifdef BOOST_NO_CXX11_ALLOCATOR
 
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template<class Alloc>
 
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using allocator_traits =
 
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    boost::allocator_traits<Alloc>;
 
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#else
 
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template<class Alloc>
 
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using allocator_traits = std::allocator_traits<Alloc>;
 
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#endif
 
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template<class T, class Allocator>
 
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class over_allocator
 
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    : private empty_value<Allocator>
 
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{
 
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    template<class U, class OtherAlloc>
 
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    friend class over_allocator;
 
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    std::size_t extra_;
 
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public:
 
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    using is_always_equal = std::false_type;
 
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    using value_type = typename
 
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        allocator_traits<typename allocator_traits<
 
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            Allocator>::template rebind_alloc<T>>::value_type;
 
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    using pointer = typename
 
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        allocator_traits<typename allocator_traits<
 
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            Allocator>::template rebind_alloc<T>>::pointer;
 
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    using const_pointer = typename
 
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        allocator_traits<typename allocator_traits<
 
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            Allocator>::template rebind_alloc<T>>::const_pointer;
 
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    using size_type = typename
 
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        allocator_traits<typename allocator_traits<
 
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            Allocator>::template rebind_alloc<T>>::size_type;
 
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    using difference_type = typename
 
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        allocator_traits<typename allocator_traits<
 
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            Allocator>::template rebind_alloc<T>>::difference_type;
 
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    template<class U>
 
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    struct rebind
 
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    {
 
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        using other = over_allocator<U, Allocator>;
 
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    };
 
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    over_allocator(
 
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        std::size_t extra,
 
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        Allocator const& alloc)
 
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        : empty_value<Allocator>(
 
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            empty_init, alloc)
 
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        , extra_(extra)
 
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    {
 
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    }
 
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    template<class U>
 
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    over_allocator(over_allocator<U, Allocator> const& other) noexcept
 
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        : empty_value<Allocator>(
 
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            empty_init, other.get())
 
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        , extra_(other.extra_)
 
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    {
 
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    }
 
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    pointer
 
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    allocate(size_type n)
 
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    {
 
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        BOOST_ASSERT(n == 1);
 
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        using U = typename boost::type_with_alignment<
 
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            alignof(value_type)>::type;
 
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        auto constexpr S = sizeof(U);
 
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        using A = typename allocator_traits<
 
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            Allocator>::template rebind_alloc<U>;
 
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        A a(this->get());
 
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        return reinterpret_cast<pointer>(
 
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            std::allocator_traits<A>::allocate(a,
 
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                (n * sizeof(value_type) + extra_ + S - 1) / S));
 
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    }
 
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    void
 
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    deallocate(pointer p, size_type n)
 
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    {
 
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        BOOST_ASSERT(n == 1);
 
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        using U = typename boost::type_with_alignment<
 
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            alignof(value_type)>::type;
 
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        auto constexpr S = sizeof(U);
 
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        using A = typename allocator_traits<
 
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            Allocator>::template rebind_alloc<U>;
 
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        A a{this->get()};
 
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        std::allocator_traits<A>::deallocate(a,
 
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            reinterpret_cast<U*>(p),
 
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                (n * sizeof(value_type) + extra_ + S - 1) / S);
 
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    }
 
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#if defined(BOOST_LIBSTDCXX_VERSION) && BOOST_LIBSTDCXX_VERSION < 60000
 
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    template<class U, class... Args>
 
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    void
 
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    construct(U* ptr, Args&&... args)
 
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    {
 
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        ::new((void*)ptr) U(std::forward<Args>(args)...);
 
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    }
 
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    template<class U>
 
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    void
 
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    destroy(U* ptr)
 
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    {
 
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        ptr->~U();
 
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    }
 
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#endif
 
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    template<class U>
 
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    friend
 
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    bool
 
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    operator==(
 
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        over_allocator const& lhs,
 
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        over_allocator<U, Allocator> const& rhs)
 
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    {
 
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        return
 
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            lhs.get() == rhs.get() &&
 
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            lhs.extra_ == rhs.extra_;
 
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    }
 
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    template<class U>
 
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    friend
 
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    bool
 
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    operator!=(
 
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        over_allocator const& lhs,
 
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        over_allocator<U, Allocator> const& rhs)
 
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    {
 
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        return ! (lhs == rhs);
 
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    }
 
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};
 
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} // detail
 
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} // urls
 
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} // boost
 
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#endif