91 lines
1.8 KiB
C++
91 lines
1.8 KiB
C++
// SPDX-License-Identifier: BSD-2-Clause
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// author: Max Kellermann <max.kellermann@gmail.com>
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#ifndef DEREFERENCE_ITERATOR_HXX
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#define DEREFERENCE_ITERATOR_HXX
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#include <iterator>
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#include <type_traits>
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/**
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* An iterator wrapper that dereferences the values returned by the
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* original iterator.
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*/
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template<typename IT,
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typename VT=typename std::remove_pointer<typename IT::value_type>::type>
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class DereferenceIterator {
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using Traits = std::iterator_traits<IT>;
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IT original;
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public:
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using iterator_category = typename Traits::iterator_category;
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using difference_type = typename Traits::difference_type;
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using value_type = VT;
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using pointer = VT *;
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using reference = VT &;
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DereferenceIterator() = default;
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constexpr DereferenceIterator(const IT _original) noexcept
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:original(_original) {}
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reference operator*() const noexcept {
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return static_cast<reference>(**original);
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}
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pointer operator->() const noexcept {
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return static_cast<pointer>(&**original);
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}
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auto &operator++() noexcept {
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++original;
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return *this;
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}
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auto operator++(int) noexcept {
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auto old = *this;
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original++;
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return old;
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}
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auto &operator+=(difference_type n) noexcept {
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original += n;
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return *this;
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}
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auto &operator+(difference_type n) noexcept {
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return original + n;
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}
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auto &operator--() noexcept {
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original = --original;
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return *this;
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}
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auto operator--(int) noexcept {
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auto old = *this;
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original--;
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return old;
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}
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auto &operator-=(difference_type n) noexcept {
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original -= n;
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return *this;
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}
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auto &operator-(difference_type n) noexcept {
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return original - n;
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}
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bool operator==(const DereferenceIterator<IT,VT> &other) const noexcept {
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return original == other.original;
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}
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bool operator!=(const DereferenceIterator<IT,VT> &other) const noexcept {
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return original != other.original;
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}
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};
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#endif
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