Created
December 4, 2022 13:39
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A C++ iterator class that uses integer indices rather than pointers
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template<typename T> | |
class buf_idx_iter | |
{ | |
public: | |
using iterator_category = std::random_access_iterator_tag; | |
using value_type = T; | |
using difference_type = std::ptrdiff_t; | |
using pointer = T*; | |
using reference = T&; | |
buf_idx_iter(pointer ptr = nullptr, size_t idx = 0) : m_ptr(ptr), m_idx(idx) {} | |
friend auto operator<=>(const buf_idx_iter& lhs, const buf_idx_iter& rhs) {return lhs.m_idx <=> rhs.m_idx;}; | |
friend bool operator==(const buf_idx_iter& lhs, const buf_idx_iter& rhs) {return lhs.m_idx == rhs.m_idx;}; | |
friend difference_type operator-(const buf_idx_iter& lhs, const buf_idx_iter& rhs) { return lhs.m_idx - rhs.m_idx;} | |
pointer operator->() const { return m_ptr + m_idx; } | |
reference operator*() const { return *(m_ptr + m_idx); } | |
buf_idx_iter& operator++() { ++m_idx; return *this; } | |
buf_idx_iter& operator--() { --m_idx; return *this; } | |
buf_idx_iter operator+(difference_type n) const { return buf_idx_iter(m_ptr, m_idx + n); } | |
buf_idx_iter operator-(difference_type n) const { return buf_idx_iter(m_ptr, m_idx - n); } | |
private: | |
pointer m_ptr; | |
size_t m_idx; | |
}; | |
template <typename V> buf_idx_iter<V> ibegin(std::vector<V>& vec){ return buf_idx_iter<V>(vec.data(), 0); } | |
template <typename V> buf_idx_iter<V> iend(std::vector<V>& vec) { return buf_idx_iter<V>(vec.data(), vec.size()); } |
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