aged_unordered_container.h

#pragma once
 
#include <xrpl/beast/clock/abstract_clock.h>
#include <xrpl/beast/container/aged_container.h>
#include <xrpl/beast/container/detail/aged_associative_container.h>
#include <xrpl/beast/container/detail/aged_container_iterator.h>
#include <xrpl/beast/container/detail/empty_base_optimization.h>
 
#include <boost/intrusive/list.hpp>
#include <boost/intrusive/unordered_set.hpp>
 
#include <algorithm>
#include <cmath>
#include <functional>
#include <initializer_list>
#include <iterator>
#include <memory>
#include <type_traits>
#include <utility>
 
/*
 
TODO
 
- Add constructor variations that take a bucket count
 
- Review for noexcept and exception guarantees
 
- Call the safe version of is_permutation that takes 4 iterators
 
*/
 
#ifndef BEAST_NO_CXX14_IS_PERMUTATION
#define BEAST_NO_CXX14_IS_PERMUTATION 1
#endif
 
namespace beast {
namespace detail {
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock = std::chrono::steady_clock,
    class Hash = std::hash<Key>,
    class KeyEqual = std::equal_to<Key>,
    class Allocator =
        std::allocator<typename std::conditional<IsMap, std::pair<Key const, T>, Key>::type>>
class aged_unordered_container
{
public:
    using clock_type = abstract_clock<Clock>;
    using time_point = typename clock_type::time_point;
    using duration = typename clock_type::duration;
    using key_type = Key;
    using mapped_type = T;
    using value_type = typename std::conditional<IsMap, std::pair<Key const, T>, Key>::type;
    using size_type = std::size_t;
    using difference_type = std::ptrdiff_t;
 
    // Introspection (for unit tests)
    using is_unordered = std::true_type;
    using is_multi = std::integral_constant<bool, IsMulti>;
    using is_map = std::integral_constant<bool, IsMap>;
 
private:
    static Key const&
    extract(value_type const& value)
    {
        return aged_associative_container_extract_t<IsMap>()(value);
    }
 
    // VFALCO TODO hoist to remove template argument dependencies
    struct element : boost::intrusive::unordered_set_base_hook<
                         boost::intrusive::link_mode<boost::intrusive::normal_link>>,
                     boost::intrusive::list_base_hook<
                         boost::intrusive::link_mode<boost::intrusive::normal_link>>
    {
        // Stash types here so the iterator doesn't
        // need to see the container declaration.
        struct stashed
        {
            explicit stashed() = default;
 
            using value_type = typename aged_unordered_container::value_type;
            using time_point = typename aged_unordered_container::time_point;
        };
 
        element(time_point const& when_, value_type const& value_) : value(value_), when(when_)
        {
        }
 
        element(time_point const& when_, value_type&& value_)
            : value(std::move(value_)), when(when_)
        {
        }
 
        template <
            class... Args,
            class =
                typename std::enable_if<std::is_constructible<value_type, Args...>::value>::type>
        element(time_point const& when_, Args&&... args)
            : value(std::forward<Args>(args)...), when(when_)
        {
        }
 
        value_type value;
        time_point when;
    };
 
    // VFALCO TODO hoist to remove template argument dependencies
    class ValueHash : public Hash
    {
    public:
        using argument_type = element;
        using result_type = size_t;
 
        ValueHash()
        {
        }
 
        ValueHash(Hash const& h) : Hash(h)
        {
        }
 
        std::size_t
        operator()(element const& e) const
        {
            return Hash::operator()(extract(e.value));
        }
 
        Hash&
        hash_function()
        {
            return *this;
        }
 
        Hash const&
        hash_function() const
        {
            return *this;
        }
    };
 
    // Compares value_type against element, used in find/insert_check
    // VFALCO TODO hoist to remove template argument dependencies
    class KeyValueEqual : public KeyEqual
    {
    public:
        using first_argument_type = Key;
        using second_argument_type = element;
        using result_type = bool;
 
        KeyValueEqual()
        {
        }
 
        KeyValueEqual(KeyEqual const& keyEqual) : KeyEqual(keyEqual)
        {
        }
 
        bool
        operator()(Key const& k, element const& e) const
        {
            return KeyEqual::operator()(k, extract(e.value));
        }
 
        bool
        operator()(element const& e, Key const& k) const
        {
            return KeyEqual::operator()(extract(e.value), k);
        }
 
        bool
        operator()(element const& lhs, element const& rhs) const
        {
            return KeyEqual::operator()(extract(lhs.value), extract(rhs.value));
        }
 
        KeyEqual&
        key_eq()
        {
            return *this;
        }
 
        KeyEqual const&
        key_eq() const
        {
            return *this;
        }
    };
 
    using list_type = typename boost::intrusive::
        make_list<element, boost::intrusive::constant_time_size<false>>::type;
 
    using cont_type = typename std::conditional<
        IsMulti,
        typename boost::intrusive::make_unordered_multiset<
            element,
            boost::intrusive::constant_time_size<true>,
            boost::intrusive::hash<ValueHash>,
            boost::intrusive::equal<KeyValueEqual>,
            boost::intrusive::cache_begin<true>>::type,
        typename boost::intrusive::make_unordered_set<
            element,
            boost::intrusive::constant_time_size<true>,
            boost::intrusive::hash<ValueHash>,
            boost::intrusive::equal<KeyValueEqual>,
            boost::intrusive::cache_begin<true>>::type>::type;
 
    using bucket_type = typename cont_type::bucket_type;
    using bucket_traits = typename cont_type::bucket_traits;
 
    using ElementAllocator =
        typename std::allocator_traits<Allocator>::template rebind_alloc<element>;
 
    using ElementAllocatorTraits = std::allocator_traits<ElementAllocator>;
 
    using BucketAllocator =
        typename std::allocator_traits<Allocator>::template rebind_alloc<element>;
 
    using BucketAllocatorTraits = std::allocator_traits<BucketAllocator>;
 
    class config_t : private ValueHash,
                     private KeyValueEqual,
                     private beast::detail::empty_base_optimization<ElementAllocator>
    {
    public:
        explicit config_t(clock_type& clock_) : clock(clock_)
        {
        }
 
        config_t(clock_type& clock_, Hash const& hash) : ValueHash(hash), clock(clock_)
        {
        }
 
        config_t(clock_type& clock_, KeyEqual const& keyEqual)
            : KeyValueEqual(keyEqual), clock(clock_)
        {
        }
 
        config_t(clock_type& clock_, Allocator const& alloc_)
            : beast::detail::empty_base_optimization<ElementAllocator>(alloc_), clock(clock_)
        {
        }
 
        config_t(clock_type& clock_, Hash const& hash, KeyEqual const& keyEqual)
            : ValueHash(hash), KeyValueEqual(keyEqual), clock(clock_)
        {
        }
 
        config_t(clock_type& clock_, Hash const& hash, Allocator const& alloc_)
            : ValueHash(hash)
            , beast::detail::empty_base_optimization<ElementAllocator>(alloc_)
            , clock(clock_)
        {
        }
 
        config_t(clock_type& clock_, KeyEqual const& keyEqual, Allocator const& alloc_)
            : KeyValueEqual(keyEqual)
            , beast::detail::empty_base_optimization<ElementAllocator>(alloc_)
            , clock(clock_)
        {
        }
 
        config_t(
            clock_type& clock_,
            Hash const& hash,
            KeyEqual const& keyEqual,
            Allocator const& alloc_)
            : ValueHash(hash)
            , KeyValueEqual(keyEqual)
            , beast::detail::empty_base_optimization<ElementAllocator>(alloc_)
            , clock(clock_)
        {
        }
 
        config_t(config_t const& other)
            : ValueHash(other.hash_function())
            , KeyValueEqual(other.key_eq())
            , beast::detail::empty_base_optimization<ElementAllocator>(
                  ElementAllocatorTraits::select_on_container_copy_construction(other.alloc()))
            , clock(other.clock)
        {
        }
 
        config_t(config_t const& other, Allocator const& alloc)
            : ValueHash(other.hash_function())
            , KeyValueEqual(other.key_eq())
            , beast::detail::empty_base_optimization<ElementAllocator>(alloc)
            , clock(other.clock)
        {
        }
 
        config_t(config_t&& other)
            : ValueHash(std::move(other.hash_function()))
            , KeyValueEqual(std::move(other.key_eq()))
            , beast::detail::empty_base_optimization<ElementAllocator>(std::move(other.alloc()))
            , clock(other.clock)
        {
        }
 
        config_t(
            config_t&& other,  // NOLINT(cppcoreguidelines-rvalue-reference-param-not-moved)
            Allocator const& alloc)
            : ValueHash(std::move(other.hash_function()))
            , KeyValueEqual(std::move(other.key_eq()))
            , beast::detail::empty_base_optimization<ElementAllocator>(alloc)
            , clock(other.clock)
        {
        }
 
        config_t&
        operator=(config_t const& other)
        {
            hash_function() = other.hash_function();
            key_eq() = other.key_eq();
            alloc() = other.alloc();
            clock = other.clock;
            return *this;
        }
 
        config_t&
        operator=(config_t&& other)
        {
            hash_function() = std::move(other.hash_function());
            key_eq() = std::move(other.key_eq());
            alloc() = std::move(other.alloc());
            clock = other.clock;
            return *this;
        }
 
        ValueHash&
        value_hash()
        {
            return *this;
        }
 
        ValueHash const&
        value_hash() const
        {
            return *this;
        }
 
        Hash&
        hash_function()
        {
            return ValueHash::hash_function();
        }
 
        Hash const&
        hash_function() const
        {
            return ValueHash::hash_function();
        }
 
        KeyValueEqual&
        key_value_equal()
        {
            return *this;
        }
 
        KeyValueEqual const&
        key_value_equal() const
        {
            return *this;
        }
 
        KeyEqual&
        key_eq()
        {
            return key_value_equal().key_eq();
        }
 
        KeyEqual const&
        key_eq() const
        {
            return key_value_equal().key_eq();
        }
 
        ElementAllocator&
        alloc()
        {
            return beast::detail::empty_base_optimization<ElementAllocator>::member();
        }
 
        ElementAllocator const&
        alloc() const
        {
            return beast::detail::empty_base_optimization<ElementAllocator>::member();
        }
 
        std::reference_wrapper<clock_type> clock;
    };
 
    class Buckets
    {
    public:
        using vec_type = std::vector<
            bucket_type,
            typename std::allocator_traits<Allocator>::template rebind_alloc<bucket_type>>;
 
        Buckets() : m_max_load_factor(1.f), m_vec()
        {
            m_vec.resize(cont_type::suggested_upper_bucket_count(0));
        }
 
        Buckets(Allocator const& alloc) : m_max_load_factor(1.f), m_vec(alloc)
        {
            m_vec.resize(cont_type::suggested_upper_bucket_count(0));
        }
 
        operator bucket_traits()
        {
            return bucket_traits(&m_vec[0], m_vec.size());
        }
 
        void
        clear()
        {
            m_vec.clear();
        }
 
        size_type
        max_bucket_count() const
        {
            return m_vec.max_size();
        }
 
        float&
        max_load_factor()
        {
            return m_max_load_factor;
        }
 
        float const&
        max_load_factor() const
        {
            return m_max_load_factor;
        }
 
        // count is the number of buckets
        template <class Container>
        void
        rehash(size_type count, Container& c)
        {
            size_type const size(m_vec.size());
            if (count == size)
                return;
            if (count > m_vec.capacity())
            {
                // Need two vectors otherwise we
                // will destroy non-empty buckets.
                vec_type vec(m_vec.get_allocator());
                std::swap(m_vec, vec);
                m_vec.resize(count);
                c.rehash(bucket_traits(&m_vec[0], m_vec.size()));
                return;
            }
            // Rehash in place.
            if (count > size)
            {
                // This should not reallocate since
                // we checked capacity earlier.
                m_vec.resize(count);
                c.rehash(bucket_traits(&m_vec[0], count));
                return;
            }
            // Resize must happen after rehash otherwise
            // we might destroy non-empty buckets.
            c.rehash(bucket_traits(&m_vec[0], count));
            m_vec.resize(count);
        }
 
        // Resize the buckets to accommodate at least n items.
        template <class Container>
        void
        resize(size_type n, Container& c)
        {
            size_type const suggested(cont_type::suggested_upper_bucket_count(n));
            rehash(suggested, c);
        }
 
    private:
        float m_max_load_factor;
        vec_type m_vec;
    };
 
    template <class... Args>
    element*
    new_element(Args&&... args)
    {
        struct Deleter
        {
            std::reference_wrapper<ElementAllocator> a_;
            Deleter(ElementAllocator& a) : a_(a)
            {
            }
 
            void
            operator()(element* p)
            {
                ElementAllocatorTraits::deallocate(a_.get(), p, 1);
            }
        };
 
        std::unique_ptr<element, Deleter> p(
            ElementAllocatorTraits::allocate(m_config.alloc(), 1), Deleter(m_config.alloc()));
        ElementAllocatorTraits::construct(
            m_config.alloc(), p.get(), clock().now(), std::forward<Args>(args)...);
        return p.release();
    }
 
    void
    delete_element(element const* p)
    {
        ElementAllocatorTraits::destroy(m_config.alloc(), p);
        ElementAllocatorTraits::deallocate(m_config.alloc(), const_cast<element*>(p), 1);
    }
 
    void
    unlink_and_delete_element(element const* p)
    {
        chronological.list.erase(chronological.list.iterator_to(*p));
        m_cont.erase(m_cont.iterator_to(*p));
        delete_element(p);
    }
 
public:
    using hasher = Hash;
    using key_equal = KeyEqual;
    using allocator_type = Allocator;
    using reference = value_type&;
    using const_reference = value_type const&;
    using pointer = typename std::allocator_traits<Allocator>::pointer;
    using const_pointer = typename std::allocator_traits<Allocator>::const_pointer;
 
    // A set iterator (IsMap==false) is always const
    // because the elements of a set are immutable.
    using iterator = beast::detail::aged_container_iterator<!IsMap, typename cont_type::iterator>;
    using const_iterator =
        beast::detail::aged_container_iterator<true, typename cont_type::iterator>;
 
    using local_iterator =
        beast::detail::aged_container_iterator<!IsMap, typename cont_type::local_iterator>;
    using const_local_iterator =
        beast::detail::aged_container_iterator<true, typename cont_type::local_iterator>;
 
    //--------------------------------------------------------------------------
    //
    // Chronological ordered iterators
    //
    // "Memberspace"
    // http://accu.org/index.php/journals/1527
    //
    //--------------------------------------------------------------------------
 
    class chronological_t
    {
    public:
        // A set iterator (IsMap==false) is always const
        // because the elements of a set are immutable.
        using iterator =
            beast::detail::aged_container_iterator<!IsMap, typename list_type::iterator>;
        using const_iterator =
            beast::detail::aged_container_iterator<true, typename list_type::iterator>;
        using reverse_iterator =
            beast::detail::aged_container_iterator<!IsMap, typename list_type::reverse_iterator>;
        using const_reverse_iterator =
            beast::detail::aged_container_iterator<true, typename list_type::reverse_iterator>;
 
        iterator
        begin()
        {
            return iterator(list.begin());
        }
 
        const_iterator
        begin() const
        {
            return const_iterator(list.begin());
        }
 
        const_iterator
        cbegin() const
        {
            return const_iterator(list.begin());
        }
 
        iterator
        end()
        {
            return iterator(list.end());
        }
 
        const_iterator
        end() const
        {
            return const_iterator(list.end());
        }
 
        const_iterator
        cend() const
        {
            return const_iterator(list.end());
        }
 
        reverse_iterator
        rbegin()
        {
            return reverse_iterator(list.rbegin());
        }
 
        const_reverse_iterator
        rbegin() const
        {
            return const_reverse_iterator(list.rbegin());
        }
 
        const_reverse_iterator
        crbegin() const
        {
            return const_reverse_iterator(list.rbegin());
        }
 
        reverse_iterator
        rend()
        {
            return reverse_iterator(list.rend());
        }
 
        const_reverse_iterator
        rend() const
        {
            return const_reverse_iterator(list.rend());
        }
 
        const_reverse_iterator
        crend() const
        {
            return const_reverse_iterator(list.rend());
        }
 
        iterator
        iterator_to(value_type& value)
        {
            static_assert(std::is_standard_layout<element>::value, "must be standard layout");
            return list.iterator_to(*reinterpret_cast<element*>(
                reinterpret_cast<uint8_t*>(&value) -
                ((std::size_t)std::addressof(((element*)0)->member))));
        }
 
        const_iterator
        iterator_to(value_type const& value) const
        {
            static_assert(std::is_standard_layout<element>::value, "must be standard layout");
            return list.iterator_to(*reinterpret_cast<element const*>(
                reinterpret_cast<uint8_t const*>(&value) -
                ((std::size_t)std::addressof(((element*)0)->member))));
        }
 
    private:
        chronological_t()
        {
        }
 
        chronological_t(chronological_t const&) = delete;
        chronological_t(chronological_t&&) = delete;
 
        friend class aged_unordered_container;
        list_type mutable list;
    } chronological;
 
    //--------------------------------------------------------------------------
    //
    // Construction
    //
    //--------------------------------------------------------------------------
 
    aged_unordered_container() = delete;
 
    explicit aged_unordered_container(clock_type& clock);
 
    aged_unordered_container(clock_type& clock, Hash const& hash);
 
    aged_unordered_container(clock_type& clock, KeyEqual const& key_eq);
 
    aged_unordered_container(clock_type& clock, Allocator const& alloc);
 
    aged_unordered_container(clock_type& clock, Hash const& hash, KeyEqual const& key_eq);
 
    aged_unordered_container(clock_type& clock, Hash const& hash, Allocator const& alloc);
 
    aged_unordered_container(clock_type& clock, KeyEqual const& key_eq, Allocator const& alloc);
 
    aged_unordered_container(
        clock_type& clock,
        Hash const& hash,
        KeyEqual const& key_eq,
        Allocator const& alloc);
 
    template <class InputIt>
    aged_unordered_container(InputIt first, InputIt last, clock_type& clock);
 
    template <class InputIt>
    aged_unordered_container(InputIt first, InputIt last, clock_type& clock, Hash const& hash);
 
    template <class InputIt>
    aged_unordered_container(
        InputIt first,
        InputIt last,
        clock_type& clock,
        KeyEqual const& key_eq);
 
    template <class InputIt>
    aged_unordered_container(
        InputIt first,
        InputIt last,
        clock_type& clock,
        Allocator const& alloc);
 
    template <class InputIt>
    aged_unordered_container(
        InputIt first,
        InputIt last,
        clock_type& clock,
        Hash const& hash,
        KeyEqual const& key_eq);
 
    template <class InputIt>
    aged_unordered_container(
        InputIt first,
        InputIt last,
        clock_type& clock,
        Hash const& hash,
        Allocator const& alloc);
 
    template <class InputIt>
    aged_unordered_container(
        InputIt first,
        InputIt last,
        clock_type& clock,
        KeyEqual const& key_eq,
        Allocator const& alloc);
 
    template <class InputIt>
    aged_unordered_container(
        InputIt first,
        InputIt last,
        clock_type& clock,
        Hash const& hash,
        KeyEqual const& key_eq,
        Allocator const& alloc);
 
    aged_unordered_container(aged_unordered_container const& other);
 
    aged_unordered_container(aged_unordered_container const& other, Allocator const& alloc);
 
    aged_unordered_container(aged_unordered_container&& other);
 
    aged_unordered_container(
        // NOLINTNEXTLINE(cppcoreguidelines-rvalue-reference-param-not-moved)
        aged_unordered_container&& other,
        Allocator const& alloc);
 
    aged_unordered_container(std::initializer_list<value_type> init, clock_type& clock);
 
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        Hash const& hash);
 
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        KeyEqual const& key_eq);
 
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        Allocator const& alloc);
 
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        Hash const& hash,
        KeyEqual const& key_eq);
 
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        Hash const& hash,
        Allocator const& alloc);
 
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        KeyEqual const& key_eq,
        Allocator const& alloc);
 
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        Hash const& hash,
        KeyEqual const& key_eq,
        Allocator const& alloc);
 
    ~aged_unordered_container();
 
    aged_unordered_container&
    operator=(aged_unordered_container const& other);
 
    aged_unordered_container&
    operator=(aged_unordered_container&& other);
 
    aged_unordered_container&
    operator=(std::initializer_list<value_type> init);
 
    allocator_type
    get_allocator() const
    {
        return m_config.alloc();
    }
 
    clock_type&
    clock()
    {
        return m_config.clock;
    }
 
    clock_type const&
    clock() const
    {
        return m_config.clock;
    }
 
    //--------------------------------------------------------------------------
    //
    // Element access (maps)
    //
    //--------------------------------------------------------------------------
 
    template <
        class K,
        bool maybe_multi = IsMulti,
        bool maybe_map = IsMap,
        class = typename std::enable_if<maybe_map && !maybe_multi>::type>
    typename std::conditional<IsMap, T, void*>::type&
    at(K const& k);
 
    template <
        class K,
        bool maybe_multi = IsMulti,
        bool maybe_map = IsMap,
        class = typename std::enable_if<maybe_map && !maybe_multi>::type>
    typename std::conditional<IsMap, T, void*>::type const&
    at(K const& k) const;
 
    template <
        bool maybe_multi = IsMulti,
        bool maybe_map = IsMap,
        class = typename std::enable_if<maybe_map && !maybe_multi>::type>
    typename std::conditional<IsMap, T, void*>::type&
    operator[](Key const& key);
 
    template <
        bool maybe_multi = IsMulti,
        bool maybe_map = IsMap,
        class = typename std::enable_if<maybe_map && !maybe_multi>::type>
    typename std::conditional<IsMap, T, void*>::type&
    operator[](Key&& key);
 
    //--------------------------------------------------------------------------
    //
    // Iterators
    //
    //--------------------------------------------------------------------------
 
    iterator
    begin()
    {
        return iterator(m_cont.begin());
    }
 
    const_iterator
    begin() const
    {
        return const_iterator(m_cont.begin());
    }
 
    const_iterator
    cbegin() const
    {
        return const_iterator(m_cont.begin());
    }
 
    iterator
    end()
    {
        return iterator(m_cont.end());
    }
 
    const_iterator
    end() const
    {
        return const_iterator(m_cont.end());
    }
 
    const_iterator
    cend() const
    {
        return const_iterator(m_cont.end());
    }
 
    iterator
    iterator_to(value_type& value)
    {
        static_assert(std::is_standard_layout<element>::value, "must be standard layout");
        return m_cont.iterator_to(*reinterpret_cast<element*>(
            reinterpret_cast<uint8_t*>(&value) -
            ((std::size_t)std::addressof(((element*)0)->member))));
    }
 
    const_iterator
    iterator_to(value_type const& value) const
    {
        static_assert(std::is_standard_layout<element>::value, "must be standard layout");
        return m_cont.iterator_to(*reinterpret_cast<element const*>(
            reinterpret_cast<uint8_t const*>(&value) -
            ((std::size_t)std::addressof(((element*)0)->member))));
    }
 
    //--------------------------------------------------------------------------
    //
    // Capacity
    //
    //--------------------------------------------------------------------------
 
    bool
    empty() const noexcept
    {
        return m_cont.empty();
    }
 
    size_type
    size() const noexcept
    {
        return m_cont.size();
    }
 
    size_type
    max_size() const noexcept
    {
        return m_config.max_size();
    }
 
    //--------------------------------------------------------------------------
    //
    // Modifiers
    //
    //--------------------------------------------------------------------------
 
    void
    clear();
 
    // map, set
    template <bool maybe_multi = IsMulti>
    auto
    insert(value_type const& value) ->
        typename std::enable_if<!maybe_multi, std::pair<iterator, bool>>::type;
 
    // multimap, multiset
    template <bool maybe_multi = IsMulti>
    auto
    insert(value_type const& value) -> typename std::enable_if<maybe_multi, iterator>::type;
 
    // map, set
    template <bool maybe_multi = IsMulti, bool maybe_map = IsMap>
    auto
    insert(value_type&& value) ->
        typename std::enable_if<!maybe_multi && !maybe_map, std::pair<iterator, bool>>::type;
 
    // multimap, multiset
    template <bool maybe_multi = IsMulti, bool maybe_map = IsMap>
    auto
    insert(value_type&& value) ->
        typename std::enable_if<maybe_multi && !maybe_map, iterator>::type;
 
    // map, set
    template <bool maybe_multi = IsMulti>
    typename std::enable_if<!maybe_multi, iterator>::type
    insert(const_iterator /*hint*/, value_type const& value)
    {
        // Hint is ignored but we provide the interface so
        // callers may use ordered and unordered interchangeably.
        return insert(value).first;
    }
 
    // multimap, multiset
    template <bool maybe_multi = IsMulti>
    typename std::enable_if<maybe_multi, iterator>::type
    insert(const_iterator /*hint*/, value_type const& value)
    {
        // VFALCO TODO The hint could be used to let
        //             the client order equal ranges
        return insert(value);
    }
 
    // map, set
    template <bool maybe_multi = IsMulti>
    typename std::enable_if<!maybe_multi, iterator>::type
    insert(const_iterator /*hint*/, value_type&& value)
    {
        // Hint is ignored but we provide the interface so
        // callers may use ordered and unordered interchangeably.
        return insert(std::move(value)).first;
    }
 
    // multimap, multiset
    template <bool maybe_multi = IsMulti>
    typename std::enable_if<maybe_multi, iterator>::type
    insert(const_iterator /*hint*/, value_type&& value)
    {
        // VFALCO TODO The hint could be used to let
        //             the client order equal ranges
        return insert(std::move(value));
    }
 
    // map, multimap
    template <class P, bool maybe_map = IsMap>
    typename std::enable_if<
        maybe_map && std::is_constructible<value_type, P&&>::value,
        typename std::conditional<IsMulti, iterator, std::pair<iterator, bool>>::type>::type
    insert(P&& value)
    {
        return emplace(std::forward<P>(value));
    }
 
    // map, multimap
    template <class P, bool maybe_map = IsMap>
    typename std::enable_if<
        maybe_map && std::is_constructible<value_type, P&&>::value,
        typename std::conditional<IsMulti, iterator, std::pair<iterator, bool>>::type>::type
    insert(const_iterator hint, P&& value)
    {
        return emplace_hint(hint, std::forward<P>(value));
    }
 
    template <class InputIt>
    void
    insert(InputIt first, InputIt last)
    {
        insert(first, last, typename std::iterator_traits<InputIt>::iterator_category());
    }
 
    void
    insert(std::initializer_list<value_type> init)
    {
        insert(init.begin(), init.end());
    }
 
    // set, map
    template <bool maybe_multi = IsMulti, class... Args>
    auto
    emplace(Args&&... args) ->
        typename std::enable_if<!maybe_multi, std::pair<iterator, bool>>::type;
 
    // multiset, multimap
    template <bool maybe_multi = IsMulti, class... Args>
    auto
    emplace(Args&&... args) -> typename std::enable_if<maybe_multi, iterator>::type;
 
    // set, map
    template <bool maybe_multi = IsMulti, class... Args>
    auto
    emplace_hint(const_iterator /*hint*/, Args&&... args) ->
        typename std::enable_if<!maybe_multi, std::pair<iterator, bool>>::type;
 
    // multiset, multimap
    template <bool maybe_multi = IsMulti, class... Args>
    typename std::enable_if<maybe_multi, iterator>::type
    emplace_hint(const_iterator /*hint*/, Args&&... args)
    {
        // VFALCO TODO The hint could be used for multi, to let
        //             the client order equal ranges
        return emplace<maybe_multi>(std::forward<Args>(args)...);
    }
 
    template <bool is_const, class Iterator>
    beast::detail::aged_container_iterator<false, Iterator>
    erase(beast::detail::aged_container_iterator<is_const, Iterator> pos);
 
    template <bool is_const, class Iterator>
    beast::detail::aged_container_iterator<false, Iterator>
    erase(
        beast::detail::aged_container_iterator<is_const, Iterator> first,
        beast::detail::aged_container_iterator<is_const, Iterator> last);
 
    template <class K>
    auto
    erase(K const& k) -> size_type;
 
    void
    swap(aged_unordered_container& other) noexcept;
 
    template <bool is_const, class Iterator>
    void
    touch(beast::detail::aged_container_iterator<is_const, Iterator> pos)
    {
        touch(pos, clock().now());
    }
 
    template <class K>
    auto
    touch(K const& k) -> size_type;
 
    //--------------------------------------------------------------------------
    //
    // Lookup
    //
    //--------------------------------------------------------------------------
 
    // VFALCO TODO Respect is_transparent (c++14)
    template <class K>
    size_type
    count(K const& k) const
    {
        return m_cont.count(
            k, std::cref(m_config.hash_function()), std::cref(m_config.key_value_equal()));
    }
 
    // VFALCO TODO Respect is_transparent (c++14)
    template <class K>
    iterator
    find(K const& k)
    {
        return iterator(m_cont.find(
            k, std::cref(m_config.hash_function()), std::cref(m_config.key_value_equal())));
    }
 
    // VFALCO TODO Respect is_transparent (c++14)
    template <class K>
    const_iterator
    find(K const& k) const
    {
        return const_iterator(m_cont.find(
            k, std::cref(m_config.hash_function()), std::cref(m_config.key_value_equal())));
    }
 
    // VFALCO TODO Respect is_transparent (c++14)
    template <class K>
    std::pair<iterator, iterator>
    equal_range(K const& k)
    {
        auto const r(m_cont.equal_range(
            k, std::cref(m_config.hash_function()), std::cref(m_config.key_value_equal())));
        return std::make_pair(iterator(r.first), iterator(r.second));
    }
 
    // VFALCO TODO Respect is_transparent (c++14)
    template <class K>
    std::pair<const_iterator, const_iterator>
    equal_range(K const& k) const
    {
        auto const r(m_cont.equal_range(
            k, std::cref(m_config.hash_function()), std::cref(m_config.key_value_equal())));
        return std::make_pair(const_iterator(r.first), const_iterator(r.second));
    }
 
    //--------------------------------------------------------------------------
    //
    // Bucket interface
    //
    //--------------------------------------------------------------------------
 
    local_iterator
    begin(size_type n)
    {
        return local_iterator(m_cont.begin(n));
    }
 
    const_local_iterator
    begin(size_type n) const
    {
        return const_local_iterator(m_cont.begin(n));
    }
 
    const_local_iterator
    cbegin(size_type n) const
    {
        return const_local_iterator(m_cont.begin(n));
    }
 
    local_iterator
    end(size_type n)
    {
        return local_iterator(m_cont.end(n));
    }
 
    const_local_iterator
    end(size_type n) const
    {
        return const_local_iterator(m_cont.end(n));
    }
 
    const_local_iterator
    cend(size_type n) const
    {
        return const_local_iterator(m_cont.end(n));
    }
 
    size_type
    bucket_count() const
    {
        return m_cont.bucket_count();
    }
 
    size_type
    max_bucket_count() const
    {
        return m_buck.max_bucket_count();
    }
 
    size_type
    bucket_size(size_type n) const
    {
        return m_cont.bucket_size(n);
    }
 
    size_type
    bucket(Key const& k) const
    {
        XRPL_ASSERT(
            bucket_count() != 0,
            "beast::detail::aged_unordered_container::bucket : nonzero bucket "
            "count");
        return m_cont.bucket(k, std::cref(m_config.hash_function()));
    }
 
    //--------------------------------------------------------------------------
    //
    // Hash policy
    //
    //--------------------------------------------------------------------------
 
    float
    load_factor() const
    {
        return size() / static_cast<float>(m_cont.bucket_count());
    }
 
    float
    max_load_factor() const
    {
        return m_buck.max_load_factor();
    }
 
    void
    max_load_factor(float ml)
    {
        m_buck.max_load_factor() = std::max(ml, m_buck.max_load_factor());
    }
 
    void
    rehash(size_type count)
    {
        count = std::max(count, size_type(size() / max_load_factor()));
        m_buck.rehash(count, m_cont);
    }
 
    void
    reserve(size_type count)
    {
        rehash(std::ceil(count / max_load_factor()));
    }
 
    //--------------------------------------------------------------------------
    //
    // Observers
    //
    //--------------------------------------------------------------------------
 
    hasher const&
    hash_function() const
    {
        return m_config.hash_function();
    }
 
    key_equal const&
    key_eq() const
    {
        return m_config.key_eq();
    }
 
    //--------------------------------------------------------------------------
    //
    // Comparison
    //
    //--------------------------------------------------------------------------
 
    // This differs from the standard in that the comparison
    // is only done on the key portion of the value type, ignoring
    // the mapped type.
    //
    template <
        bool OtherIsMap,
        class OtherKey,
        class OtherT,
        class OtherDuration,
        class OtherHash,
        class OtherAllocator,
        bool maybe_multi = IsMulti>
    typename std::enable_if<!maybe_multi, bool>::type
    operator==(aged_unordered_container<
               false,
               OtherIsMap,
               OtherKey,
               OtherT,
               OtherDuration,
               OtherHash,
               KeyEqual,
               OtherAllocator> const& other) const;
 
    template <
        bool OtherIsMap,
        class OtherKey,
        class OtherT,
        class OtherDuration,
        class OtherHash,
        class OtherAllocator,
        bool maybe_multi = IsMulti>
    typename std::enable_if<maybe_multi, bool>::type
    operator==(aged_unordered_container<
               true,
               OtherIsMap,
               OtherKey,
               OtherT,
               OtherDuration,
               OtherHash,
               KeyEqual,
               OtherAllocator> const& other) const;
 
    template <
        bool OtherIsMulti,
        bool OtherIsMap,
        class OtherKey,
        class OtherT,
        class OtherDuration,
        class OtherHash,
        class OtherAllocator>
    bool
    operator!=(aged_unordered_container<
               OtherIsMulti,
               OtherIsMap,
               OtherKey,
               OtherT,
               OtherDuration,
               OtherHash,
               KeyEqual,
               OtherAllocator> const& other) const
    {
        return !(this->operator==(other));
    }
 
private:
    bool
    would_exceed(size_type additional) const
    {
        return size() + additional > bucket_count() * max_load_factor();
    }
 
    void
    maybe_rehash(size_type additional)
    {
        if (would_exceed(additional))
            m_buck.resize(size() + additional, m_cont);
        XRPL_ASSERT(
            load_factor() <= max_load_factor(),
            "beast::detail::aged_unordered_container::maybe_rehash : maximum "
            "load factor");
    }
 
    // map, set
    template <bool maybe_multi = IsMulti>
    auto
    insert_unchecked(value_type const& value) ->
        typename std::enable_if<!maybe_multi, std::pair<iterator, bool>>::type;
 
    // multimap, multiset
    template <bool maybe_multi = IsMulti>
    auto
    insert_unchecked(value_type const& value) ->
        typename std::enable_if<maybe_multi, iterator>::type;
 
    template <class InputIt>
    void
    insert_unchecked(InputIt first, InputIt last)
    {
        for (; first != last; ++first)
            insert_unchecked(*first);
    }
 
    template <class InputIt>
    void
    insert(InputIt first, InputIt last, std::input_iterator_tag)
    {
        for (; first != last; ++first)
            insert(*first);
    }
 
    template <class InputIt>
    void
    insert(InputIt first, InputIt last, std::random_access_iterator_tag)
    {
        auto const n(std::distance(first, last));
        maybe_rehash(n);
        insert_unchecked(first, last);
    }
 
    template <bool is_const, class Iterator>
    void
    touch(
        beast::detail::aged_container_iterator<is_const, Iterator> pos,
        typename clock_type::time_point const& now)
    {
        auto& e(*pos.iterator());
        e.when = now;
        chronological.list.erase(chronological.list.iterator_to(e));
        chronological.list.push_back(e);
    }
 
    template <
        bool maybe_propagate = std::allocator_traits<Allocator>::propagate_on_container_swap::value>
    typename std::enable_if<maybe_propagate>::type
    swap_data(aged_unordered_container& other) noexcept
    {
        std::swap(m_config.key_compare(), other.m_config.key_compare());
        std::swap(m_config.alloc(), other.m_config.alloc());
        std::swap(m_config.clock, other.m_config.clock);
    }
 
    template <
        bool maybe_propagate = std::allocator_traits<Allocator>::propagate_on_container_swap::value>
    typename std::enable_if<!maybe_propagate>::type
    swap_data(aged_unordered_container& other) noexcept
    {
        std::swap(m_config.key_compare(), other.m_config.key_compare());
        std::swap(m_config.clock, other.m_config.clock);
    }
 
private:
    config_t m_config;
    Buckets m_buck;
    cont_type mutable m_cont;
};
 
//------------------------------------------------------------------------------
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(clock_type& clock)
    : m_config(clock)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(clock_type& clock, Hash const& hash)
    : m_config(clock, hash)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(clock_type& clock, KeyEqual const& key_eq)
    : m_config(clock, key_eq)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(clock_type& clock, Allocator const& alloc)
    : m_config(clock, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(clock_type& clock, Hash const& hash, KeyEqual const& key_eq)
    : m_config(clock, hash, key_eq)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(clock_type& clock, Hash const& hash, Allocator const& alloc)
    : m_config(clock, hash, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(clock_type& clock, KeyEqual const& key_eq, Allocator const& alloc)
    : m_config(clock, key_eq, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        clock_type& clock,
        Hash const& hash,
        KeyEqual const& key_eq,
        Allocator const& alloc)
    : m_config(clock, hash, key_eq, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class InputIt>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(InputIt first, InputIt last, clock_type& clock)
    : m_config(clock)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(first, last);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class InputIt>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(InputIt first, InputIt last, clock_type& clock, Hash const& hash)
    : m_config(clock, hash)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(first, last);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class InputIt>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(InputIt first, InputIt last, clock_type& clock, KeyEqual const& key_eq)
    : m_config(clock, key_eq)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(first, last);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class InputIt>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(InputIt first, InputIt last, clock_type& clock, Allocator const& alloc)
    : m_config(clock, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(first, last);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class InputIt>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        InputIt first,
        InputIt last,
        clock_type& clock,
        Hash const& hash,
        KeyEqual const& key_eq)
    : m_config(clock, hash, key_eq)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(first, last);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class InputIt>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        InputIt first,
        InputIt last,
        clock_type& clock,
        Hash const& hash,
        Allocator const& alloc)
    : m_config(clock, hash, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(first, last);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class InputIt>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        InputIt first,
        InputIt last,
        clock_type& clock,
        KeyEqual const& key_eq,
        Allocator const& alloc)
    : m_config(clock, key_eq, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(first, last);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class InputIt>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        InputIt first,
        InputIt last,
        clock_type& clock,
        Hash const& hash,
        KeyEqual const& key_eq,
        Allocator const& alloc)
    : m_config(clock, hash, key_eq, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(first, last);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(aged_unordered_container const& other)
    : m_config(other.m_config)
    , m_buck(m_config.alloc())
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(other.cbegin(), other.cend());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(aged_unordered_container const& other, Allocator const& alloc)
    : m_config(other.m_config, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(other.cbegin(), other.cend());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(aged_unordered_container&& other)
    : m_config(std::move(other.m_config))
    , m_buck(std::move(other.m_buck))
    , m_cont(std::move(other.m_cont))
{
    chronological.list = std::move(other.chronological.list);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        // NOLINTNEXTLINE(cppcoreguidelines-rvalue-reference-param-not-moved)
        aged_unordered_container&& other,
        Allocator const& alloc)
    : m_config(std::move(other.m_config), alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(other.cbegin(), other.cend());
    other.clear();
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(std::initializer_list<value_type> init, clock_type& clock)
    : m_config(clock)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(init.begin(), init.end());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        Hash const& hash)
    : m_config(clock, hash)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(init.begin(), init.end());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        KeyEqual const& key_eq)
    : m_config(clock, key_eq)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(init.begin(), init.end());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        Allocator const& alloc)
    : m_config(clock, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(init.begin(), init.end());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        Hash const& hash,
        KeyEqual const& key_eq)
    : m_config(clock, hash, key_eq)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(init.begin(), init.end());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        Hash const& hash,
        Allocator const& alloc)
    : m_config(clock, hash, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(init.begin(), init.end());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        KeyEqual const& key_eq,
        Allocator const& alloc)
    : m_config(clock, key_eq, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(init.begin(), init.end());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    aged_unordered_container(
        std::initializer_list<value_type> init,
        clock_type& clock,
        Hash const& hash,
        KeyEqual const& key_eq,
        Allocator const& alloc)
    : m_config(clock, hash, key_eq, alloc)
    , m_buck(alloc)
    , m_cont(m_buck, std::cref(m_config.value_hash()), std::cref(m_config.key_value_equal()))
{
    insert(init.begin(), init.end());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    ~aged_unordered_container()
{
    clear();
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::operator=(
    aged_unordered_container const& other) -> aged_unordered_container&
{
    if (this != &other)
    {
        size_type const n(other.size());
        clear();
        m_config = other.m_config;
        m_buck = Buckets(m_config.alloc());
        maybe_rehash(n);
        insert_unchecked(other.begin(), other.end());
    }
    return *this;
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::operator=(
    aged_unordered_container&& other) -> aged_unordered_container&
{
    size_type const n(other.size());
    clear();
    m_config = std::move(other.m_config);
    m_buck = Buckets(m_config.alloc());
    maybe_rehash(n);
    insert_unchecked(other.begin(), other.end());
    other.clear();
    return *this;
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::operator=(
    std::initializer_list<value_type> init) -> aged_unordered_container&
{
    clear();
    insert(init);
    return *this;
}
 
//------------------------------------------------------------------------------
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class K, bool maybe_multi, bool maybe_map, class>
typename std::conditional<IsMap, T, void*>::type&
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::at(K const& k)
{
    auto const iter(
        m_cont.find(k, std::cref(m_config.hash_function()), std::cref(m_config.key_value_equal())));
    if (iter == m_cont.end())
        throw std::out_of_range("key not found");
    return iter->value.second;
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class K, bool maybe_multi, bool maybe_map, class>
typename std::conditional<IsMap, T, void*>::type const&
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::at(
    K const& k) const
{
    auto const iter(
        m_cont.find(k, std::cref(m_config.hash_function()), std::cref(m_config.key_value_equal())));
    if (iter == m_cont.end())
        throw std::out_of_range("key not found");
    return iter->value.second;
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi, bool maybe_map, class>
typename std::conditional<IsMap, T, void*>::type&
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::operator[](
    Key const& key)
{
    maybe_rehash(1);
    typename cont_type::insert_commit_data d;
    auto const result(m_cont.insert_check(
        key, std::cref(m_config.hash_function()), std::cref(m_config.key_value_equal()), d));
    if (result.second)
    {
        element* const p(new_element(
            std::piecewise_construct, std::forward_as_tuple(key), std::forward_as_tuple()));
        m_cont.insert_commit(*p, d);
        chronological.list.push_back(*p);
        return p->value.second;
    }
    return result.first->value.second;
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi, bool maybe_map, class>
typename std::conditional<IsMap, T, void*>::type&
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::operator[](
    Key&& key)
{
    maybe_rehash(1);
    typename cont_type::insert_commit_data d;
    auto const result(m_cont.insert_check(
        key, std::cref(m_config.hash_function()), std::cref(m_config.key_value_equal()), d));
    if (result.second)
    {
        element* const p(new_element(
            std::piecewise_construct,
            std::forward_as_tuple(std::move(key)),
            std::forward_as_tuple()));
        m_cont.insert_commit(*p, d);
        chronological.list.push_back(*p);
        return p->value.second;
    }
    return result.first->value.second;
}
 
//------------------------------------------------------------------------------
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
void
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::clear()
{
    for (auto iter(chronological.list.begin()); iter != chronological.list.end();)
        unlink_and_delete_element(&*iter++);
    chronological.list.clear();
    m_cont.clear();
    m_buck.clear();
}
 
// map, set
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::insert(
    value_type const& value) ->
    typename std::enable_if<!maybe_multi, std::pair<iterator, bool>>::type
{
    maybe_rehash(1);
    typename cont_type::insert_commit_data d;
    auto const result(m_cont.insert_check(
        extract(value),
        std::cref(m_config.hash_function()),
        std::cref(m_config.key_value_equal()),
        d));
    if (result.second)
    {
        element* const p(new_element(value));
        auto const iter(m_cont.insert_commit(*p, d));
        chronological.list.push_back(*p);
        return std::make_pair(iterator(iter), true);
    }
    return std::make_pair(iterator(result.first), false);
}
 
// multimap, multiset
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::insert(
    value_type const& value) -> typename std::enable_if<maybe_multi, iterator>::type
{
    maybe_rehash(1);
    element* const p(new_element(value));
    chronological.list.push_back(*p);
    auto const iter(m_cont.insert(*p));
    return iterator(iter);
}
 
// map, set
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi, bool maybe_map>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::insert(
    value_type&& value) ->
    typename std::enable_if<!maybe_multi && !maybe_map, std::pair<iterator, bool>>::type
{
    maybe_rehash(1);
    typename cont_type::insert_commit_data d;
    auto const result(m_cont.insert_check(
        extract(value),
        std::cref(m_config.hash_function()),
        std::cref(m_config.key_value_equal()),
        d));
    if (result.second)
    {
        element* const p(new_element(std::move(value)));
        auto const iter(m_cont.insert_commit(*p, d));
        chronological.list.push_back(*p);
        return std::make_pair(iterator(iter), true);
    }
    return std::make_pair(iterator(result.first), false);
}
 
// multimap, multiset
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi, bool maybe_map>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::insert(
    value_type&& value) -> typename std::enable_if<maybe_multi && !maybe_map, iterator>::type
{
    maybe_rehash(1);
    element* const p(new_element(std::move(value)));
    chronological.list.push_back(*p);
    auto const iter(m_cont.insert(*p));
    return iterator(iter);
}
 
#if 1  // Use insert() instead of insert_check() insert_commit()
// set, map
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi, class... Args>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::emplace(
    Args&&... args) -> typename std::enable_if<!maybe_multi, std::pair<iterator, bool>>::type
{
    maybe_rehash(1);
    // VFALCO NOTE Its unfortunate that we need to
    //             construct element here
    element* const p(new_element(std::forward<Args>(args)...));
    auto const result(m_cont.insert(*p));
    if (result.second)
    {
        chronological.list.push_back(*p);
        return std::make_pair(iterator(result.first), true);
    }
    delete_element(p);
    return std::make_pair(iterator(result.first), false);
}
#else   // As original, use insert_check() / insert_commit () pair.
// set, map
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi, class... Args>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::emplace(
    Args&&... args) -> typename std::enable_if<!maybe_multi, std::pair<iterator, bool>>::type
{
    maybe_rehash(1);
    // VFALCO NOTE Its unfortunate that we need to
    //             construct element here
    element* const p(new_element(std::forward<Args>(args)...));
    typename cont_type::insert_commit_data d;
    auto const result(m_cont.insert_check(
        extract(p->value),
        std::cref(m_config.hash_function()),
        std::cref(m_config.key_value_equal()),
        d));
    if (result.second)
    {
        auto const iter(m_cont.insert_commit(*p, d));
        chronological.list.push_back(*p);
        return std::make_pair(iterator(iter), true);
    }
    delete_element(p);
    return std::make_pair(iterator(result.first), false);
}
#endif  // 0
 
// multiset, multimap
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi, class... Args>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::emplace(
    Args&&... args) -> typename std::enable_if<maybe_multi, iterator>::type
{
    maybe_rehash(1);
    element* const p(new_element(std::forward<Args>(args)...));
    chronological.list.push_back(*p);
    auto const iter(m_cont.insert(*p));
    return iterator(iter);
}
 
// set, map
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi, class... Args>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::emplace_hint(
    const_iterator /*hint*/,
    Args&&... args) -> typename std::enable_if<!maybe_multi, std::pair<iterator, bool>>::type
{
    maybe_rehash(1);
    // VFALCO NOTE Its unfortunate that we need to
    //             construct element here
    element* const p(new_element(std::forward<Args>(args)...));
    typename cont_type::insert_commit_data d;
    auto const result(m_cont.insert_check(
        extract(p->value),
        std::cref(m_config.hash_function()),
        std::cref(m_config.key_value_equal()),
        d));
    if (result.second)
    {
        auto const iter(m_cont.insert_commit(*p, d));
        chronological.list.push_back(*p);
        return std::make_pair(iterator(iter), true);
    }
    delete_element(p);
    return std::make_pair(iterator(result.first), false);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool is_const, class Iterator>
beast::detail::aged_container_iterator<false, Iterator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::erase(
    beast::detail::aged_container_iterator<is_const, Iterator> pos)
{
    unlink_and_delete_element(&*((pos++).iterator()));
    return beast::detail::aged_container_iterator<false, Iterator>(pos.iterator());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool is_const, class Iterator>
beast::detail::aged_container_iterator<false, Iterator>
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::erase(
    beast::detail::aged_container_iterator<is_const, Iterator> first,
    beast::detail::aged_container_iterator<is_const, Iterator> last)
{
    for (; first != last;)
        unlink_and_delete_element(&*((first++).iterator()));
 
    return beast::detail::aged_container_iterator<false, Iterator>(first.iterator());
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class K>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::erase(
    K const& k) -> size_type
{
    auto iter(
        m_cont.find(k, std::cref(m_config.hash_function()), std::cref(m_config.key_value_equal())));
    if (iter == m_cont.end())
        return 0;
    size_type n(0);
    for (;;)
    {
        auto p(&*iter++);
        bool const done(m_config(*p, extract(iter->value)));
        unlink_and_delete_element(p);
        ++n;
        if (done)
            break;
    }
    return n;
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
void
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::swap(
    aged_unordered_container& other) noexcept
{
    swap_data(other);
    std::swap(chronological, other.chronological);
    std::swap(m_cont, other.m_cont);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <class K>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::touch(
    K const& k) -> size_type
{
    auto const now(clock().now());
    size_type n(0);
    auto const range(equal_range(k));
    for (auto iter : range)
    {
        touch(iter, now);
        ++n;
    }
    return n;
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <
    bool OtherIsMap,
    class OtherKey,
    class OtherT,
    class OtherDuration,
    class OtherHash,
    class OtherAllocator,
    bool maybe_multi>
typename std::enable_if<!maybe_multi, bool>::type
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::operator==(
    aged_unordered_container<
        false,
        OtherIsMap,
        OtherKey,
        OtherT,
        OtherDuration,
        OtherHash,
        KeyEqual,
        OtherAllocator> const& other) const
{
    if (size() != other.size())
        return false;
    for (auto iter(cbegin()), last(cend()), otherLast(other.cend()); iter != last; ++iter)
    {
        auto otherIter(other.find(extract(*iter)));
        if (otherIter == otherLast)
            return false;
    }
    return true;
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <
    bool OtherIsMap,
    class OtherKey,
    class OtherT,
    class OtherDuration,
    class OtherHash,
    class OtherAllocator,
    bool maybe_multi>
typename std::enable_if<maybe_multi, bool>::type
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::operator==(
    aged_unordered_container<
        true,
        OtherIsMap,
        OtherKey,
        OtherT,
        OtherDuration,
        OtherHash,
        KeyEqual,
        OtherAllocator> const& other) const
{
    if (size() != other.size())
        return false;
    for (auto iter(cbegin()), last(cend()); iter != last;)
    {
        auto const& k(extract(*iter));
        auto const eq(equal_range(k));
        auto const oeq(other.equal_range(k));
#if BEAST_NO_CXX14_IS_PERMUTATION
        if (std::distance(eq.first, eq.second) != std::distance(oeq.first, oeq.second) ||
            !std::is_permutation(eq.first, eq.second, oeq.first))
            return false;
#else
        if (!std::is_permutation(eq.first, eq.second, oeq.first, oeq.second))
            return false;
#endif
        iter = eq.second;
    }
    return true;
}
 
//------------------------------------------------------------------------------
 
// map, set
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    insert_unchecked(value_type const& value) ->
    typename std::enable_if<!maybe_multi, std::pair<iterator, bool>>::type
{
    typename cont_type::insert_commit_data d;
    auto const result(m_cont.insert_check(
        extract(value),
        std::cref(m_config.hash_function()),
        std::cref(m_config.key_value_equal()),
        d));
    if (result.second)
    {
        element* const p(new_element(value));
        auto const iter(m_cont.insert_commit(*p, d));
        chronological.list.push_back(*p);
        return std::make_pair(iterator(iter), true);
    }
    return std::make_pair(iterator(result.first), false);
}
 
// multimap, multiset
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
template <bool maybe_multi>
auto
aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>::
    insert_unchecked(value_type const& value) ->
    typename std::enable_if<maybe_multi, iterator>::type
{
    element* const p(new_element(value));
    chronological.list.push_back(*p);
    auto const iter(m_cont.insert(*p));
    return iterator(iter);
}
 
//------------------------------------------------------------------------------
 
}  // namespace detail
 
//------------------------------------------------------------------------------
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
struct is_aged_container<
    beast::detail::
        aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>>
    : std::true_type
{
    explicit is_aged_container() = default;
};
 
// Free functions
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator>
void
swap(
    beast::detail::
        aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>& lhs,
    beast::detail::
        aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>&
            rhs) noexcept
{
    lhs.swap(rhs);
}
 
template <
    bool IsMulti,
    bool IsMap,
    class Key,
    class T,
    class Clock,
    class Hash,
    class KeyEqual,
    class Allocator,
    class Rep,
    class Period>
std::size_t
expire(
    beast::detail::
        aged_unordered_container<IsMulti, IsMap, Key, T, Clock, Hash, KeyEqual, Allocator>& c,
    std::chrono::duration<Rep, Period> const& age) noexcept
{
    std::size_t n(0);
    auto const expired(c.clock().now() - age);
    for (auto iter(c.chronological.cbegin());
         iter != c.chronological.cend() && iter.when() <= expired;)
    {
        iter = c.erase(iter);
        ++n;
    }
    return n;
}
 
}  // namespace beast