223 lines
10 KiB
C++
223 lines
10 KiB
C++
#pragma once
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/* #include "log.hpp" */
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#include "util.hpp"
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#include <vector>
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#include <iterator>
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#include <algorithm>
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#include <concepts>
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namespace gz {
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/**
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* @brief A fixed size buffer that can store data continuously without needing to move data or reallocate memory
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* @details
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* A buffer with size n will store the n newest elements that were inserted. If the number of inserted elements is < n, the buffers size will also be < n.
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*
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* The buffer can be @ref RingBuffer::resize() "resized", which potentially leads to a reallocation of memory.
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*
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* @subsection ringbuffer_iteration Iteration
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* The RingBuffer has its own bidirectional iterator. The normal direction is from newest to oldest element.
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* @code
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* RingBuffer<int> rb(4);
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* for (int i = 0; i < 7; i++) { rb.push_back(i); }
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* for (auto it = rb.begin(); it != rb.end(); it++) {
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* std::cout << *it << " ";
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* }
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* @endcode
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* will produce @code 6 5 4 3 @endcode
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*
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* If the buffer is empty, all iterators point to the separator element (end() == rend() == begin() == rbegin()).
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*
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* @subsection ringbuffer_technical_details Technical Details
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* A buffer with size n will store its objects in a std::vector with size n+1, where the additional element serves as a separator between the newest and the oldest element.
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* It is technically the real oldest element and could be accessed using end() or rend(), which will always point to this element (meaning end() == rend()), giving you a n+1 sized buffer.
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* However, this element will be default initialized until n+1 elements have been inserted into the buffer, so it is not advisable to use this extra element.
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*
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* The RingBuffer satisfies concept std::ranges::bidirectional_range and RingBuffer::Iterator satisfies std::bidirectional_iterator
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*
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* The writeIndex will always point to the element that was last written.
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*
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*/
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template<std::swappable T>
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class RingBuffer {
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public:
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RingBuffer(size_t size=10);
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/**
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* @brief Bidirectonal iterator for the RingBuffer
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* @todo make a const and non-const version, since const here is all over the place
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*/
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struct Iterator {
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public:
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Iterator(const RingBuffer<T>& b, size_t index) : b(b), ptr(const_cast<T*>(&b.buffer.at(index))) {}
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Iterator(const Iterator& other) : b(other.b), ptr(other.ptr) {}
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// Needed for std::input_iterator
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using value_type = T;
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T& operator*() const { return *ptr; }
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Iterator& operator=(const Iterator& other) {
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b = other.b;
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ptr = other.ptr;
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return this;
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}
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Iterator& operator++() {
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if (ptr == &*b.buffer.begin()) { ptr = const_cast<T*>(&*b.buffer.rbegin()); }
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else { ptr--; }
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return *this;
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}
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Iterator operator++(int) {
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auto copy = *this;
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if (ptr == &*b.buffer.begin()) { ptr = const_cast<T*>(&*b.buffer.rbegin()); }
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else { ptr--; }
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return copy;
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}
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friend int operator-(Iterator lhs, Iterator rhs) {
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return lhs.getCurrentIndex() - rhs.getCurrentIndex();
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}
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// Needed for std::forward_iterator
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/// @warning Default constructor has to be defined for std::forward_iterator but can not be used, since reference to RingBuffer<T> can not be initialized! Your compiler should (hopefully) not allow it.
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Iterator() : ptr(nullptr) {};
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bool operator==(const Iterator& other) const {
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return this->ptr == other.ptr;
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}
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// Needed for std::bidirectional_iterator
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Iterator& operator--() {
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if (ptr == &*b.buffer.rbegin()) { ptr = const_cast<T*>(&*b.buffer.begin()); }
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else { ptr++; }
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return *this;
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}
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Iterator operator--(int) {
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auto copy = *this;
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if (ptr == &*b.buffer.rbegin()) { ptr = const_cast<T*>(&*b.buffer.begin()); }
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else { ptr++; }
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return copy;
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}
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// Not needed )
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/* friend Iterator operator+(Iterator lhs, int i) { */
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/* return Iterator(lhs.b, &lhs.b.buffer[lhs.getValidIndex(lhs.getCurrentIndex() + i)]); */
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/* } */
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/* friend Iterator operator-(Iterator lhs, int i) { */
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/* return Iterator(lhs.b, &lhs.b.buffer[lhs.getValidIndex(lhs.getCurrentIndex() - i)]); */
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/* } */
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/* friend Iterator operator+(int i, Iterator rhs) { */
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/* return Iterator(rhs.b, &rhs.b.buffer[rhs.getValidIndex(rhs.getCurrentIndex() + i)]); */
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/* } */
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/* Iterator& operator+=(int i) { */
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/* ptr = &b.buffer[getValidIndex(getCurrentIndex() + i)]; */
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/* return this; */
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/* } */
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/* Iterator& operator-=(int i) { */
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/* ptr = &b.buffer[getValidIndex(getCurrentIndex() - i)]; */
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/* return this; */
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/* } */
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/* bool operator!=(const Iterator& other) const { */
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/* return this->ptr != other.ptr; */
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/* } */
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/// Get the index of the vector that ptr points to
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std::string to_string() const {
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return "Element: " + std::to_string(*ptr) + ", Index: " + std::to_string(getCurrentIndex()) + ", Pointer: " + std::to_string(reinterpret_cast<long>(ptr));
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}
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private:
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size_t getCurrentIndex() const {
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return reinterpret_cast<long>(ptr - &*b.buffer.begin());
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}
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T* ptr;
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const RingBuffer<T>& b;
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};
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void push_back(T& t);
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void push_back(T&& t) { push_back(t); };
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void emplace_back(T&& t);
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/**
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* @brief Return an iterator pointing to the newest object
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*/
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const Iterator cbegin() const { return Iterator(*this, writeIndex); }
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/**
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* @brief Return an iterator poiting to the element preceeding the oldest element
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*/
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const Iterator cend() const { return Iterator(*this, util::getIncrementedIndex(writeIndex, buffer.size())); }
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/**
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* @brief Return an iterator pointing to the oldest object
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*/
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const Iterator crbegin() const { return Iterator(*this, util::getIncrementedIndex(writeIndex + 1, buffer.size())); }
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/**
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* @brief Return an iterator pointing to the element following the newest element
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*/
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const Iterator crend() const { return Iterator(*this, util::getIncrementedIndex(writeIndex, buffer.size())); }
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const Iterator begin() { return Iterator(*this, writeIndex); }
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const Iterator end() { return Iterator(*this, util::getIncrementedIndex(writeIndex, buffer.size())); }
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const Iterator rbegin() { return Iterator(*this, util::getIncrementedIndex(writeIndex + 1, buffer.size())); }
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const Iterator rend() { return Iterator(*this, util::getIncrementedIndex(writeIndex, buffer.size())); }
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/**
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* @brief Resize the buffer to contain max size elements
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* @details
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* If the current size is greater than size, the buffer is reduced to the newest elements that fit size. \n
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* If the current size is smaller than size, the buffer size remains but it will be able to grow during element insertion until size is reached.
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*/
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void resize(const size_t size);
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size_t capacity() const { return vectorCapacity - 1; }
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size_t size() const { return buffer.size() - 1; }
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private:
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size_t writeIndex; ///< Points to the element that was last written
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std::vector<T> buffer;
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size_t vectorCapacity;
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};
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template<std::swappable T>
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RingBuffer<T>::RingBuffer(size_t capacity) {
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buffer.reserve(capacity + 1);
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buffer.resize(1);
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vectorCapacity = capacity + 1;
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writeIndex = 0;
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}
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template<std::swappable T>
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void RingBuffer<T>::resize(size_t size) {
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if (size + 1 > buffer.capacity()) { // when growing
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// point writeIndex to separator
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util::incrementIndex(writeIndex, buffer.size());
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// separator element becomes first element -> vector grows while inserting elements
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std::rotate(buffer.begin(), buffer.begin() + writeIndex, buffer.end());
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buffer.reserve(size + 1);
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writeIndex = buffer.size() - 1;
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}
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else if (size + 1 < buffer.size()) { // when shrinking
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// point writeIndex to separator
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util::incrementIndex(writeIndex, buffer.size());
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// separator becomes last element in smaller vector -> resize cuts oldest elements
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std::rotate(buffer.begin(), buffer.begin() + util::getValidIndex(static_cast<int>(writeIndex - size), buffer.size()), buffer.end());
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buffer.resize(size + 1);
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writeIndex = util::getValidIndex(static_cast<int>(buffer.size() - 2), buffer.size());
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}
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vectorCapacity = size + 1;
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}
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template<std::swappable T>
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void RingBuffer<T>::push_back(T& t) {
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util::incrementIndex(writeIndex, vectorCapacity);
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if (buffer.size() < vectorCapacity) {
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buffer.push_back(t);
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}
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else {
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buffer[writeIndex] = t;
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}
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}
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template<std::swappable T>
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void RingBuffer<T>::emplace_back(T&& t) {
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util::incrementIndex(writeIndex, vectorCapacity);
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if (buffer.size() < vectorCapacity) {
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buffer.emplace_back(std::move(t));
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}
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else {
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buffer[writeIndex] = std::move(t);
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}
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}
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}
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