227 lines
9.8 KiB
C++
227 lines
9.8 KiB
C++
/*!
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* \file cont/deque.h
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* \brief
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* A statically allocated deque based on a ring buffer.
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*
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* \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
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*
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* <dl class=\"section copyright\"><dt>License</dt><dd>
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* The MIT License (MIT)
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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* </dd></dl>
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*/
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#ifndef TBX_CONT_DEQUE_H_
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#define TBX_CONT_DEQUE_H_
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#include <core/core.h>
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#include <core/ring_iterator.h>
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#include <cont/range.h>
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#include <array>
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#include <atomic>
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namespace tbx {
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/*!
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* \class deque
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* \brief
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* A statically allocated deque based on a ring buffer
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*
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* The deque uses two ring_iterators one for the front and one for the rear. The iterators
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* are pointing to the next available spot, not on the last inserted spot. This way at the
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* initialization the iterators wont "pretend" to point to a valid item .
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*
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* We use a ring buffer of size \c N+1. We start the front iterator at the last location of the buffer
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* and the rear on the first. This way when the queue is full the iterators are pointing to the same location.
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*
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* \tparam Data_t The char-like queued item type. Usually \c char
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* \tparam N The size of deque
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* \tparam SemiAtomic True for semi-atomic operation. In that case the \c ring_iterator is also atomic.
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* \note
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* SemiAtomic means it is safe to access different ends from different threads. For example one thread can
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* push only from front and another can pop from back to implement a queue.
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*/
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template <typename Data_t, size_t N, bool SemiAtomic =false>
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class deque {
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public:
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// meta-identity type
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using type = deque<Data_t, N>;
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using buffer_t = std::array<Data_t, N+1>; // We need N+1 spaces ring buffer for N spaces deque
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using iterator_t = ring_iterator<Data_t*, N+1, SemiAtomic>;
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using range_t = range<iterator_t>;
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// STL
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using value_type = Data_t;
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using reference = Data_t&;
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using const_reference = const Data_t&;
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using pointer = Data_t*;
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using const_pointer = const Data_t*;
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using iterator = iterator_t;
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using const_iterator = const iterator_t;
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using reverse_iterator = std::reverse_iterator<iterator>;
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using const_reverse_iterator = std::reverse_iterator<const_iterator>;
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//! \name Constructor / Destructor
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//! @{
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public:
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//! Default constructor
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constexpr deque () noexcept :
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data_{},
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f{data_.data(), N},
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r{data_.data()} {
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if constexpr (SemiAtomic)
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std::atomic_thread_fence(std::memory_order_release);
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}
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//! fill contructor
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constexpr deque(const Data_t& value) noexcept {
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data_.fill(value);
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f = iterator(data_.data(), N);
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r = iterator(data_.data(), N);
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if constexpr (SemiAtomic)
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std::atomic_thread_fence(std::memory_order_release);
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}
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//! Initializer list contructor
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template <typename ...It>
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constexpr deque(It&& ...it) noexcept :
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data_{{std::forward<It>(it)...}},
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f(data_.data(), N),
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r(data_.data(), sizeof...(It)) {
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if constexpr (SemiAtomic)
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std::atomic_thread_fence(std::memory_order_release);
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}
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deque(const deque&) = delete; //!< No copies
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deque& operator= (const deque&) = delete; //!< No copy assignments
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~deque () = default; //!< default destructor
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//! @}
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//! \name Iterators
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//! @{
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public:
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constexpr iterator begin() noexcept { iterator ret = f; return ++ret; }
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constexpr const_iterator begin() const noexcept { iterator ret = f; return ++ret; }
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constexpr const_iterator cbegin() const noexcept { iterator ret = f; return ++ret; }
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constexpr iterator end() noexcept { return r; }
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constexpr const_iterator end() const noexcept { return r; }
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constexpr const_iterator cend() const noexcept { return r; }
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constexpr reverse_iterator rbegin() noexcept { return r; }
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constexpr const_reverse_iterator rbegin() const noexcept { return r; }
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constexpr const_reverse_iterator crbegin() const noexcept { return r; }
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constexpr reverse_iterator rend() noexcept { reverse_iterator ret = f; return ++ret; }
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constexpr const_reverse_iterator rend() const noexcept { reverse_iterator ret = f; return ++ret; }
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constexpr const_reverse_iterator crend() const noexcept { reverse_iterator ret = f; return ++ret; }
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//! @}
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//! \name Capacity
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//! @{
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public:
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//! \return The size of the deque. The items currently in queue.
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constexpr size_t size() noexcept {
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return r - (f +1);
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}
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constexpr size_t size() const noexcept {
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return r - (f +1);
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}
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//! \return The maximum size of the deque. The items the queue can hold.
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constexpr size_t max_size() noexcept { return N; }
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//! \return The capacity of the deque. The items the queue can hold.
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constexpr size_t capacity() noexcept { return N; }
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//! \return True if the deque is empty
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constexpr bool empty() noexcept { return size() == 0 ? true : false; }
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//! \return True if the deque is full
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constexpr bool full() noexcept { return size() == N ? true : false; }
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//! @}
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//! \name Member access
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//! @{
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public:
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//! \brief Clears-empty the deque and return it to init state, without
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//! really deleting the contents.
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constexpr void clear() noexcept {
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f = iterator_t(data_.data(), N);
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r = iterator_t(data_.data());
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if constexpr (SemiAtomic)
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std::atomic_thread_fence(std::memory_order_release);
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}
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//! \brief Push an item in the front of the deque
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//! \param it The item to push
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constexpr void push_front (const Data_t& it) noexcept {
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if (full()) return;
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*f = it;
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--f; // keep this separate for thread safety
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}
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//! \brief Push an item in the back of the deque
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//! \param it The item to push
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constexpr void push_back (const Data_t& it) noexcept {
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if (full()) return;
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*r = it;
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++r; // keep this separate for thread safety
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}
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//! \brief Extract an item from the front of the deque and remove it from the deque
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//! \param it The item to push
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constexpr Data_t pop_front () noexcept {
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if (empty()) return Data_t{};
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return *++f;
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}
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//! \brief Extract an item from the back of the deque and remove it from the deque
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//! \param it The item to push
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constexpr Data_t pop_back () noexcept {
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if (empty()) return Data_t{};
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return *--r;
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}
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//! \brief Get a reference to the item in the front of the deque without extracting it.
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//! \return Reference to the item
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constexpr Data_t& front() noexcept { iterator_t it = f; return *++it; }
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constexpr const Data_t& front() const noexcept { iterator_t it = f; return *++it; }
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//! \brief Get a reference to the item in the front of the deque without extracting it.
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//! \return Reference to the item
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constexpr Data_t& back() noexcept { iterator_t it = r; return *--it; }
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constexpr const Data_t& back() const noexcept { iterator_t it = r; return *--it; }
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//! \brief Get a pointer to the begin of the items on the deque
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//! \return
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constexpr Data_t* data() noexcept { return &front(); }
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constexpr const Data_t* data() const noexcept { return &front(); }
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//! \brief Get a range for the data in queue
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//! \return A begin-end iterator pair struct
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constexpr range_t contents () noexcept { iterator_t b = f; return {++b, r}; }
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constexpr const range_t contents () const noexcept { iterator_t b = f; return {++b, r}; }
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//! @}
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private:
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buffer_t data_{}; //!< The statically allocated buffer
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iterator_t f{data_.data(), N}; //!< A ring iterator for the front (points to the next available location)
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iterator_t r{data_.data()}; //!< A ring iterator for the rear (points to the next available location).
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};
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}
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#endif /* TBX_CONT_ADEQUE_H_ */
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