primitive_iterator.hpp

//     __ _____ _____ _____
//  __|  |   __|     |   | |  JSON for Modern C++
// |  |  |__   |  |  | | | |  version 3.12.0
// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2025 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include <cstddef> // ptrdiff_t
#include <limits> // numeric_limits
 
#include <nlohmann/detail/macro_scope.hpp>
 
NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
{
 
/*
@brief an iterator for primitive JSON types
 
This class models an iterator for primitive JSON types (boolean, number,
string). Its only purpose is to allow the iterator/const_iterator classes
to "iterate" over primitive values. Internally, the iterator is modeled by
a `difference_type` variable. Value begin_value (`0`) models the begin and
end_value (`1`) models past the end.
*/
class primitive_iterator_t
{
 private:
 using difference_type = std::ptrdiff_t;
 static constexpr difference_type begin_value = 0;
 static constexpr difference_type end_value = begin_value + 1;
 
  JSON_PRIVATE_UNLESS_TESTED:
    /// iterator as signed integer type
    difference_type m_it = (std::numeric_limits<std::ptrdiff_t>::min)();
 
 public:
 constexpr difference_type get_value() const noexcept
    {
 return m_it;
    }
 
    /// set iterator to a defined beginning
 void set_begin() noexcept
    {
        m_it = begin_value;
    }
 
    /// set iterator to a defined past the end
 void set_end() noexcept
    {
        m_it = end_value;
    }
 
    /// return whether the iterator can be dereferenced
 constexpr bool is_begin() const noexcept
    {
 return m_it == begin_value;
    }
 
    /// return whether the iterator is at end
 constexpr bool is_end() const noexcept
    {
 return m_it == end_value;
    }
 
 friend constexpr bool operator==(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
    {
 return lhs.m_it == rhs.m_it;
    }
 
 friend constexpr bool operator<(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
    {
 return lhs.m_it < rhs.m_it;
    }
 
    primitive_iterator_t operator+(difference_type n) noexcept
    {
 auto result = *this;
        result += n;
 return result;
    }
 
 friend constexpr difference_type operator-(primitive_iterator_t lhs, primitive_iterator_t rhs) noexcept
    {
 return lhs.m_it - rhs.m_it;
    }
 
    primitive_iterator_t& operator++() noexcept
    {
        ++m_it;
 return *this;
    }
 
    primitive_iterator_t operator++(int)& noexcept // NOLINT(cert-dcl21-cpp)
    {
 auto result = *this;
        ++m_it;
 return result;
    }
 
    primitive_iterator_t& operator--() noexcept
    {
        --m_it;
 return *this;
    }
 
    primitive_iterator_t operator--(int)& noexcept // NOLINT(cert-dcl21-cpp)
    {
 auto result = *this;
        --m_it;
 return result;
    }
 
    primitive_iterator_t& operator+=(difference_type n) noexcept
    {
        m_it += n;
 return *this;
    }
 
    primitive_iterator_t& operator-=(difference_type n) noexcept
    {
        m_it -= n;
 return *this;
    }
};
 
}  // namespace detail
NLOHMANN_JSON_NAMESPACE_END