xbazzi / vector.cpp

#include <cstddef> #include <new> #include <utility> #include <algorithm> #include <stdexcept> #include <memory> #include <iostream> #include <string> namespace getcracked { template <typename T> class vector { private: std::size_t m_size{0}; std::size_t m_cap{0}; T* p_arr{nullptr}; // allocate raw memory (uninitialized) static T* allocate(std::size_t n) { if (n == 0) return nullptr; return static_cast<T*>(::operator new(sizeof(T) * n)); } // destroy all elements and free memory void destroy_and_free() noexcept { if (p_arr) { std::destroy_n(p_arr, m_size); ::operator delete(p_arr); } p_arr = nullptr; m_size = 0; m_cap = 0; } // reallocate with move semantics void grow(std::size_t new_cap) { T* new_arr = allocate(new_cap); std::size_t i = 0; try { for (; i < m_size; ++i) std::construct_at(new_arr + i, std::move_if_noexcept(p_arr[i])); } catch (...) { // rollback on exception std::destroy_n(new_arr, i); ::operator delete(new_arr); throw; } std::destroy_n(p_arr, m_size); ::operator delete(p_arr); p_arr = new_arr; m_cap = new_cap; } public: vector() = default; explicit vector(std::size_t count, const T& value = T()) : m_size(count), m_cap(count), p_arr(allocate(count)) { std::uninitialized_fill_n(p_arr, count, value); } // copy constructor vector(const vector& other) : m_size(other.m_size), m_cap(other.m_size), p_arr(allocate(other.m_size)) { std::uninitialized_copy_n(other.p_arr, other.m_size, p_arr); } // move constructor vector(vector&& other) noexcept : m_size(other.m_size), m_cap(other.m_cap), p_arr(other.p_arr) { other.p_arr = nullptr; other.m_size = other.m_cap = 0; } // destructor ~vector() { destroy_and_free(); } // copy assignment vector& operator=(const vector& other) { if (this == &other) return *this; destroy_and_free(); m_size = other.m_size; m_cap = other.m_size; p_arr = allocate(m_cap); std::uninitialized_copy_n(other.p_arr, other.m_size, p_arr); return *this; } // move assignment vector& operator=(vector&& other) noexcept { if (this == &other) return *this; destroy_and_free(); m_size = other.m_size; m_cap = other.m_cap; p_arr = other.p_arr; other.p_arr = nullptr; other.m_size = other.m_cap = 0; return *this; } template <typename U> void push_back(U&& value) { if (m_size == m_cap) grow(m_cap == 0 ? 1 : m_cap * 2); std::construct_at(p_arr + m_size, std::forward<U>(value)); ++m_size; } void pop_back() { if (m_size == 0) return; --m_size; std::destroy_at(p_arr + m_size); } const T& at(std::size_t index) const { if (index >= m_size) throw std::out_of_range("index out of range"); return p_arr[index]; } T& at(std::size_t index) { if (index >= m_size) throw std::out_of_range("index out of range"); return p_arr[index]; } std::size_t size() const noexcept { return m_size; } std::size_t capacity() const noexcept { return m_cap; } void reserve(std::size_t new_cap) { if (new_cap > m_cap) grow(new_cap); } void shrink_to_fit() { if (m_cap > m_size) grow(m_size); } }; } // namespace getcracked