sringbuffer.h

#pragma once
#include <cstddef>
#include <type_traits>
#include <utility>
 
#include "gaia/core/iterator.h"
#include "gaia/mem/data_layout_policy.h"
#include "gaia/mem/mem_utils.h"
 
namespace gaia {
  namespace cnt {
    namespace sringbuffer_detail {
      using difference_type = int32_t;
      using size_type = uint32_t;
    } // namespace sringbuffer_detail
 
    template <typename T, sringbuffer_detail::size_type N>
    struct sringbuffer_iterator {
      using value_type = T;
      using pointer = T*;
      using reference = T&;
      using difference_type = sringbuffer_detail::difference_type;
      using size_type = sringbuffer_detail::size_type;
 
      using iterator = sringbuffer_iterator;
      using iterator_category = core::random_access_iterator_tag;
 
    private:
      pointer m_ptr;
      sringbuffer_detail::size_type m_tail;
      sringbuffer_detail::size_type m_size;
      sringbuffer_detail::size_type m_index;
 
    public:
      sringbuffer_iterator(
          // Buffer address
          pointer ptr,
          // Ringbuffer tail
          sringbuffer_detail::size_type tail,
          // Ringbuffer size
          sringbuffer_detail::size_type size,
          // Current index
          sringbuffer_detail::size_type index): m_ptr(ptr), m_tail(tail), m_size(size), m_index(index) {}
 
      T& operator*() const {
        return m_ptr[(m_tail + m_index) % N];
      }
      T* operator->() const {
        return &m_ptr[(m_tail + m_index) % N];
      }
      iterator operator[](difference_type offset) const {
        return {m_ptr, m_tail, m_size, (size_type)((difference_type)m_index + offset)};
      }
 
      iterator& operator+=(difference_type diff) {
        m_index = (size_type)((difference_type)m_index + diff);
        return *this;
      }
      iterator& operator-=(difference_type diff) {
        m_index = (size_type)((difference_type)m_index - diff);
        return *this;
      }
      iterator& operator++() {
        ++m_index;
        return *this;
      }
      iterator operator++(int) {
        iterator temp(*this);
        ++*this;
        return temp;
      }
      iterator& operator--() {
        --m_index;
        return *this;
      }
      iterator operator--(int) {
        iterator temp(*this);
        --*this;
        return temp;
      }
      iterator operator+(difference_type offset) const {
        return {m_ptr, m_tail, m_size, (size_type)((difference_type)m_index + offset)};
      }
      iterator operator-(difference_type offset) const {
        return {m_ptr, m_tail, m_size, (size_type)((difference_type)m_index - offset)};
      }
      difference_type operator-(const iterator& other) const {
        GAIA_ASSERT(m_ptr == other.m_ptr);
        return (difference_type)m_index - (difference_type)other.m_index;
      }
      GAIA_NODISCARD bool operator==(const iterator& other) const {
        GAIA_ASSERT(m_ptr == other.m_ptr);
        return m_index == other.m_index;
      }
      GAIA_NODISCARD bool operator!=(const iterator& other) const {
        GAIA_ASSERT(m_ptr == other.m_ptr);
        return m_index != other.m_index;
      }
      GAIA_NODISCARD bool operator>(const iterator& other) const {
        GAIA_ASSERT(m_ptr == other.m_ptr);
        return m_index > other.m_index;
      }
      GAIA_NODISCARD bool operator>=(const iterator& other) const {
        GAIA_ASSERT(m_ptr == other.m_ptr);
        return m_index >= other.m_index;
      }
      GAIA_NODISCARD bool operator<(const iterator& other) const {
        GAIA_ASSERT(m_ptr == other.m_ptr);
        return m_index < other.m_index;
      }
      GAIA_NODISCARD bool operator<=(const iterator& other) const {
        GAIA_ASSERT(m_ptr == other.m_ptr);
        return m_index <= other.m_index;
      }
    };
 
    template <typename T, sringbuffer_detail::size_type N>
    class sringbuffer {
    public:
      static_assert(N > 1);
 
      using value_type = T;
      using reference = T&;
      using const_reference = const T&;
      using pointer = T*;
      using const_pointer = const T*;
      using difference_type = sringbuffer_detail::difference_type;
      using size_type = sringbuffer_detail::size_type;
 
      using iterator = sringbuffer_iterator<T, N>;
      using const_iterator = sringbuffer_iterator<const T, N>;
      using iterator_category = core::random_access_iterator_tag;
 
      static constexpr size_type extent = N;
 
      size_type m_tail{};
      size_type m_size{};
      T m_data[N];
 
    private:
      constexpr void copy_live_data(const sringbuffer& other) {
        const auto countFirst = (m_size < N - m_tail) ? m_size : N - m_tail;
        mem::copy_elements<T, false>(
            (uint8_t*)m_data, (const uint8_t*)other.m_data, m_tail + countFirst, m_tail, extent, other.extent);
        if (countFirst < m_size) {
          mem::copy_elements<T, false>(
              (uint8_t*)m_data, (const uint8_t*)other.m_data, m_size - countFirst, 0, extent, other.extent);
        }
      }
 
      constexpr void move_live_data(sringbuffer& other) {
        const auto countFirst = (m_size < N - m_tail) ? m_size : N - m_tail;
        mem::move_elements<T, false>(
            (uint8_t*)m_data, (uint8_t*)other.m_data, m_tail + countFirst, m_tail, extent, other.extent);
        if (countFirst < m_size) {
          mem::move_elements<T, false>(
              (uint8_t*)m_data, (uint8_t*)other.m_data, m_size - countFirst, 0, extent, other.extent);
        }
      }
 
    public:
 
      constexpr sringbuffer() noexcept = default;
 
      template <typename InputIt>
      constexpr sringbuffer(InputIt first, InputIt last) noexcept {
        const auto count = (size_type)core::distance(first, last);
        GAIA_ASSERT(count <= max_size());
        if (count < 1)
          return;
 
        m_size = count;
        m_tail = 0;
 
        if constexpr (std::is_pointer_v<InputIt>) {
          for (size_type i = 0; i < count; ++i)
            m_data[i] = first[i];
        } else if constexpr (std::is_same_v<typename InputIt::iterator_category, core::random_access_iterator_tag>) {
          for (size_type i = 0; i < count; ++i)
            m_data[i] = *(first[i]);
        } else {
          size_type i = 0;
          for (auto it = first; it != last; ++it)
            m_data[i++] = *it;
        }
      }
 
      constexpr sringbuffer(std::initializer_list<T> il) noexcept: sringbuffer(il.begin(), il.end()) {}
 
      constexpr sringbuffer(const sringbuffer& other) noexcept: m_tail(other.m_tail), m_size(other.m_size) {
        copy_live_data(other);
      }
 
      constexpr sringbuffer(sringbuffer&& other) noexcept: m_tail(other.m_tail), m_size(other.m_size) {
        move_live_data(other);
 
        other.m_tail = size_type(0);
        other.m_size = size_type(0);
      }
 
      constexpr sringbuffer& operator=(std::initializer_list<T> il) noexcept {
        *this = sringbuffer(il.begin(), il.end());
        return *this;
      }
 
      constexpr sringbuffer& operator=(const sringbuffer& other) {
        GAIA_ASSERT(core::addressof(other) != this);
 
        m_tail = other.m_tail;
        m_size = other.m_size;
        copy_live_data(other);
 
        return *this;
      }
 
      constexpr sringbuffer& operator=(sringbuffer&& other) noexcept {
        GAIA_ASSERT(core::addressof(other) != this);
 
        m_tail = other.m_tail;
        m_size = other.m_size;
        move_live_data(other);
 
        other.m_tail = size_type(0);
        other.m_size = size_type(0);
 
        return *this;
      }
 
      ~sringbuffer() noexcept = default;
 
      constexpr void push_back(const T& arg) {
        GAIA_ASSERT(m_size < N);
        const auto head = (m_tail + m_size) % N;
        m_data[head] = arg;
        ++m_size;
      }
 
      constexpr void push_back(T&& arg) {
        GAIA_ASSERT(m_size < N);
        const auto head = (m_tail + m_size) % N;
        m_data[head] = GAIA_MOV(arg);
        ++m_size;
      }
 
      constexpr void pop_front(T& out) {
        GAIA_ASSERT(!empty());
        out = m_data[m_tail];
        m_tail = (m_tail + 1) % N;
        --m_size;
      }
 
      constexpr void pop_front(T&& out) {
        GAIA_ASSERT(!empty());
        out = GAIA_MOV(m_data[m_tail]);
        m_tail = (m_tail + 1) % N;
        --m_size;
      }
 
      constexpr void pop_back(T& out) {
        GAIA_ASSERT(!empty());
        const auto head = (m_tail + m_size - 1) % N;
        out = m_data[head];
        --m_size;
      }
 
      constexpr void pop_back(T&& out) {
        GAIA_ASSERT(!empty());
        const auto head = (m_tail + m_size - 1) % N;
        out = GAIA_MOV(m_data[head]);
        --m_size;
      }
 
      GAIA_NODISCARD constexpr size_type size() const noexcept {
        return m_size;
      }
 
      GAIA_NODISCARD constexpr bool empty() const noexcept {
        return size() == 0;
      }
 
      GAIA_NODISCARD constexpr size_type capacity() const noexcept {
        return N;
      }
 
      GAIA_NODISCARD constexpr size_type max_size() const noexcept {
        return N;
      }
 
      GAIA_NODISCARD constexpr reference front() noexcept {
        GAIA_ASSERT(!empty());
        return m_data[m_tail];
      }
 
      GAIA_NODISCARD constexpr const_reference front() const noexcept {
        GAIA_ASSERT(!empty());
        return m_data[m_tail];
      }
 
      GAIA_NODISCARD constexpr reference back() noexcept {
        GAIA_ASSERT(!empty());
        const auto head = (m_tail + m_size - 1) % N;
        return m_data[head];
      }
 
      GAIA_NODISCARD constexpr const_reference back() const noexcept {
        GAIA_ASSERT(!empty());
        const auto head = (m_tail + m_size - 1) % N;
        return m_data[head];
      }
 
      GAIA_NODISCARD constexpr auto begin() noexcept {
        return iterator((T*)&m_data[0], m_tail, m_size, 0);
      }
 
      GAIA_NODISCARD constexpr auto begin() const noexcept {
        return const_iterator((T*)&m_data[0], m_tail, m_size, 0);
      }
 
      GAIA_NODISCARD constexpr auto cbegin() const noexcept {
        return const_iterator((T*)&m_data[0], m_tail, m_size, 0);
      }
 
      GAIA_NODISCARD constexpr auto end() noexcept {
        return iterator((T*)&m_data[0], m_tail, m_size, m_size);
      }
 
      GAIA_NODISCARD constexpr auto end() const noexcept {
        return const_iterator((T*)&m_data[0], m_tail, m_size, m_size);
      }
 
      GAIA_NODISCARD constexpr auto cend() const noexcept {
        return const_iterator((T*)&m_data[0], m_tail, m_size, m_size);
      }
 
      GAIA_NODISCARD constexpr bool operator==(const sringbuffer& other) const {
        if (m_size != other.m_size)
          return false;
 
        for (size_type i = 0; i < m_size; ++i) {
          if (!(m_data[(m_tail + i) % N] == other.m_data[(other.m_tail + i) % N]))
            return false;
        }
        return true;
      }
 
      GAIA_NODISCARD constexpr bool operator!=(const sringbuffer& other) const {
        return !operator==(other);
      }
    };
 
    namespace detail {
      template <typename T, uint32_t N, uint32_t... I>
      constexpr sringbuffer<std::remove_cv_t<T>, N>
      to_sringbuffer_impl(T (&a)[N], std::index_sequence<I...> /*no_name*/) {
        return {{a[I]...}};
      }
    } // namespace detail
 
    template <typename T, uint32_t N>
    constexpr sringbuffer<std::remove_cv_t<T>, N> to_sringbuffer(T (&a)[N]) {
      return detail::to_sringbuffer_impl(a, std::make_index_sequence<N>{});
    }
 
    template <typename T, typename... U>
    sringbuffer(T, U...) -> sringbuffer<T, 1 + sizeof...(U)>;
 
  } // namespace cnt
 
} // namespace gaia