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