128 lines
2.8 KiB
C++
128 lines
2.8 KiB
C++
#pragma once
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#include <ciso646> // not
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#include <cstddef> // ptrdiff_t
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#include <limits> // numeric_limits
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#include <ostream> // ostream
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namespace nlohmann
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{
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namespace detail
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{
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/*
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@brief an iterator for primitive JSON types
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This class models an iterator for primitive JSON types (boolean, number,
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string). It's only purpose is to allow the iterator/const_iterator classes
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to "iterate" over primitive values. Internally, the iterator is modeled by
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a `difference_type` variable. Value begin_value (`0`) models the begin,
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end_value (`1`) models past the end.
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*/
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class primitive_iterator_t
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{
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public:
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using difference_type = std::ptrdiff_t;
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constexpr difference_type get_value() const noexcept
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{
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return m_it;
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}
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/// set iterator to a defined beginning
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void set_begin() noexcept
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{
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m_it = begin_value;
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}
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/// set iterator to a defined past the end
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void set_end() noexcept
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{
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m_it = end_value;
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}
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/// return whether the iterator can be dereferenced
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constexpr bool is_begin() const noexcept
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{
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return m_it == begin_value;
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}
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/// return whether the iterator is at end
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constexpr bool is_end() const noexcept
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{
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return m_it == end_value;
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}
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friend constexpr bool operator==(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
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{
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return lhs.m_it == rhs.m_it;
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}
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friend constexpr bool operator<(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
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{
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return lhs.m_it < rhs.m_it;
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}
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primitive_iterator_t operator+(difference_type i)
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{
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auto result = *this;
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result += i;
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return result;
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}
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friend constexpr difference_type operator-(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
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{
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return lhs.m_it - rhs.m_it;
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}
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friend std::ostream& operator<<(std::ostream& os, primitive_iterator_t it)
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{
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return os << it.m_it;
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}
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primitive_iterator_t& operator++()
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{
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++m_it;
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return *this;
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}
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primitive_iterator_t const operator++(int)
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{
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auto result = *this;
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m_it++;
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return result;
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}
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primitive_iterator_t& operator--()
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{
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--m_it;
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return *this;
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}
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primitive_iterator_t const operator--(int)
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{
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auto result = *this;
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m_it--;
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return result;
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}
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primitive_iterator_t& operator+=(difference_type n)
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{
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m_it += n;
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return *this;
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}
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primitive_iterator_t& operator-=(difference_type n)
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{
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m_it -= n;
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return *this;
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}
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private:
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static constexpr difference_type begin_value = 0;
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static constexpr difference_type end_value = begin_value + 1;
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/// iterator as signed integer type
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difference_type m_it = (std::numeric_limits<std::ptrdiff_t>::min)();
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};
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}
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}
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