json_pointer.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 <algorithm> // all_of
#include <cctype> // isdigit
#include <cerrno> // errno, ERANGE
#include <cstdlib> // strtoull
#ifndef JSON_NO_IO
    #include <iosfwd> // ostream
#endif  // JSON_NO_IO
#include <limits> // max
#include <numeric> // accumulate
#include <string> // string
#include <utility> // move
#include <vector> // vector
 
#include <nlohmann/detail/exceptions.hpp>
#include <nlohmann/detail/macro_scope.hpp>
#include <nlohmann/detail/string_concat.hpp>
#include <nlohmann/detail/string_escape.hpp>
#include <nlohmann/detail/value_t.hpp>
 
NLOHMANN_JSON_NAMESPACE_BEGIN
 
/// @brief JSON Pointer defines a string syntax for identifying a specific value within a JSON document
/// @sa https://json.nlohmann.me/api/json_pointer/
template<typename RefStringType>
class json_pointer
{
 // allow basic_json to access private members
    NLOHMANN_BASIC_JSON_TPL_DECLARATION
 friend class basic_json;
 
 template<typename>
 friend class json_pointer;
 
 template<typename T>
 struct string_t_helper
    {
 using type = T;
    };
 
    NLOHMANN_BASIC_JSON_TPL_DECLARATION
 struct string_t_helper<NLOHMANN_BASIC_JSON_TPL>
    {
 using type = StringType;
    };
 
 public:
 // for backwards compatibility accept BasicJsonType
 using string_t = typename string_t_helper<RefStringType>::type;
 
    /// @brief create JSON pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/json_pointer/
 explicit json_pointer(const string_t& s = "")
        : reference_tokens(split(s))
    {}
 
    /// @brief return a string representation of the JSON pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/to_string/
    string_t to_string() const
 {
 return std::accumulate(reference_tokens.begin(), reference_tokens.end(),
                               string_t{},
                               [](const string_t& a, const string_t& b)
        {
            return detail::concat(a, '/', detail::escape(b));
        });
    }
 
    /// @brief return a string representation of the JSON pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_string/
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, to_string())
    operator string_t() const
 {
 return to_string();
    }
 
#ifndef JSON_NO_IO
    /// @brief write string representation of the JSON pointer to stream
    /// @sa https://json.nlohmann.me/api/basic_json/operator_ltlt/
 friend std::ostream& operator<<(std::ostream& o, const json_pointer& ptr)
    {
        o << ptr.to_string();
 return o;
    }
#endif
 
    /// @brief append another JSON pointer at the end of this JSON pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_slasheq/
    json_pointer& operator/=(const json_pointer& ptr)
    {
        reference_tokens.insert(reference_tokens.end(),
                                ptr.reference_tokens.begin(),
                                ptr.reference_tokens.end());
 return *this;
    }
 
    /// @brief append an unescaped reference token at the end of this JSON pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_slasheq/
    json_pointer& operator/=(string_t token)
    {
 push_back(std::move(token));
 return *this;
    }
 
    /// @brief append an array index at the end of this JSON pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_slasheq/
    json_pointer& operator/=(std::size_t array_idx)
    {
 return *this /= std::to_string(array_idx);
    }
 
    /// @brief create a new JSON pointer by appending the right JSON pointer at the end of the left JSON pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_slash/
 friend json_pointer operator/(const json_pointer& lhs,
 const json_pointer& rhs)
    {
 return json_pointer(lhs) /= rhs;
    }
 
    /// @brief create a new JSON pointer by appending the unescaped token at the end of the JSON pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_slash/
 friend json_pointer operator/(const json_pointer& lhs, string_t token) // NOLINT(performance-unnecessary-value-param)
    {
 return json_pointer(lhs) /= std::move(token);
    }
 
    /// @brief create a new JSON pointer by appending the array-index-token at the end of the JSON pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_slash/
 friend json_pointer operator/(const json_pointer& lhs, std::size_t array_idx)
    {
 return json_pointer(lhs) /= array_idx;
    }
 
    /// @brief returns the parent of this JSON pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/parent_pointer/
    json_pointer parent_pointer() const
 {
 if (empty())
        {
 return *this;
        }
 
        json_pointer res = *this;
        res.pop_back();
 return res;
    }
 
    /// @brief remove last reference token
    /// @sa https://json.nlohmann.me/api/json_pointer/pop_back/
 void pop_back()
    {
 if (JSON_HEDLEY_UNLIKELY(empty()))
        {
            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
        }
 
        reference_tokens.pop_back();
    }
 
    /// @brief return last reference token
    /// @sa https://json.nlohmann.me/api/json_pointer/back/
 const string_t& back() const
 {
 if (JSON_HEDLEY_UNLIKELY(empty()))
        {
            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
        }
 
 return reference_tokens.back();
    }
 
    /// @brief append an unescaped token at the end of the reference pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/push_back/
 void push_back(const string_t& token)
    {
        reference_tokens.push_back(token);
    }
 
    /// @brief append an unescaped token at the end of the reference pointer
    /// @sa https://json.nlohmann.me/api/json_pointer/push_back/
 void push_back(string_t&& token)
    {
        reference_tokens.push_back(std::move(token));
    }
 
    /// @brief return whether pointer points to the root document
    /// @sa https://json.nlohmann.me/api/json_pointer/empty/
 bool empty() const noexcept
    {
 return reference_tokens.empty();
    }
 
 private:
    /*!
    @param[in] s  reference token to be converted into an array index
 
    @return integer representation of @a s
 
    @throw parse_error.106  if an array index begins with '0'
    @throw parse_error.109  if an array index begins not with a digit
    @throw out_of_range.404 if string @a s could not be converted to an integer
    @throw out_of_range.410 if an array index exceeds size_type
    */
 template<typename BasicJsonType>
 static typename BasicJsonType::size_type array_index(const string_t& s)
    {
 using size_type = typename BasicJsonType::size_type;
 
 // error condition (cf. RFC 6901, Sect. 4)
 if (JSON_HEDLEY_UNLIKELY(s.size() > 1 && s[0] == '0'))
        {
            JSON_THROW(detail::parse_error::create(106, 0, detail::concat("array index '", s, "' must not begin with '0'"), nullptr));
        }
 
 // error condition (cf. RFC 6901, Sect. 4)
 if (JSON_HEDLEY_UNLIKELY(s.size() > 1 && !(s[0] >= '1' && s[0] <= '9')))
        {
            JSON_THROW(detail::parse_error::create(109, 0, detail::concat("array index '", s, "' is not a number"), nullptr));
        }
 
 const char* p = s.c_str();
 char* p_end = nullptr; // NOLINT(misc-const-correctness)
        errno = 0; // strtoull doesn't reset errno
 const unsigned long long res = std::strtoull(p, &p_end, 10); // NOLINT(runtime/int)
 if (p == p_end // invalid input or empty string
                || errno == ERANGE // out of range
                || JSON_HEDLEY_UNLIKELY(static_cast<std::size_t>(p_end - p) != s.size())) // incomplete read
        {
            JSON_THROW(detail::out_of_range::create(404, detail::concat("unresolved reference token '", s, "'"), nullptr));
        }
 
 // only triggered on special platforms (like 32bit), see also
 // https://github.com/nlohmann/json/pull/2203
 if (res >= static_cast<unsigned long long>((std::numeric_limits<size_type>::max)()))  // NOLINT(runtime/int)
        {
            JSON_THROW(detail::out_of_range::create(410, detail::concat("array index ", s, " exceeds size_type"), nullptr));   // LCOV_EXCL_LINE
        }
 
 return static_cast<size_type>(res);
    }
 
  JSON_PRIVATE_UNLESS_TESTED:
    json_pointer top() const
 {
 if (JSON_HEDLEY_UNLIKELY(empty()))
        {
            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
        }
 
        json_pointer result = *this;
        result.reference_tokens = {reference_tokens[0]};
 return result;
    }
 
 private:
    /*!
    @brief create and return a reference to the pointed to value
 
    @complexity Linear in the number of reference tokens.
 
    @throw parse_error.109 if array index is not a number
    @throw type_error.313 if value cannot be unflattened
    */
 template<typename BasicJsonType>
    BasicJsonType& get_and_create(BasicJsonType& j) const
 {
 auto* result = &j;
 
 // in case no reference tokens exist, return a reference to the JSON value
 // j which will be overwritten by a primitive value
 for (const auto& reference_token : reference_tokens)
        {
 switch (result->type())
            {
 case detail::value_t::null:
                {
 if (reference_token == "0")
                    {
 // start a new array if the reference token is 0
                        result = &result->operator[](0);
                    }
 else
                    {
 // start a new object otherwise
                        result = &result->operator[](reference_token);
                    }
 break;
                }
 
 case detail::value_t::object:
                {
 // create an entry in the object
                    result = &result->operator[](reference_token);
 break;
                }
 
 case detail::value_t::array:
                {
 // create an entry in the array
                    result = &result->operator[](array_index<BasicJsonType>(reference_token));
 break;
                }
 
 /*
                The following code is only reached if there exists a reference
                token _and_ the current value is primitive. In this case, we have
                an error situation, because primitive values may only occur as
                a single value; that is, with an empty list of reference tokens.
                */
 case detail::value_t::string:
 case detail::value_t::boolean:
 case detail::value_t::number_integer:
 case detail::value_t::number_unsigned:
 case detail::value_t::number_float:
 case detail::value_t::binary:
 case detail::value_t::discarded:
 default:
                    JSON_THROW(detail::type_error::create(313, "invalid value to unflatten", &j));
            }
        }
 
 return *result;
    }
 
    /*!
    @brief return a reference to the pointed to value
 
    @note This version does not throw if a value is not present, but tries to
          create nested values instead. For instance, calling this function
          with pointer `"/this/that"` on a null value is equivalent to calling
          `operator[]("this").operator[]("that")` on that value, effectively
          changing the null value to an object.
 
    @param[in] ptr  a JSON value
 
    @return reference to the JSON value pointed to by the JSON pointer
 
    @complexity Linear in the length of the JSON pointer.
 
    @throw parse_error.106   if an array index begins with '0'
    @throw parse_error.109   if an array index was not a number
    @throw out_of_range.404  if the JSON pointer can not be resolved
    */
 template<typename BasicJsonType>
    BasicJsonType& get_unchecked(BasicJsonType* ptr) const
 {
 for (const auto& reference_token : reference_tokens)
        {
 // convert null values to arrays or objects before continuing
 if (ptr->is_null())
            {
 // check if the reference token is a number
 const bool nums =
                    std::all_of(reference_token.begin(), reference_token.end(),
                                [](const unsigned char x)
                {
                    return std::isdigit(x);
                });
 
 // change value to an array for numbers or "-" or to object otherwise
                *ptr = (nums || reference_token == "-")
                       ? detail::value_t::array
                       : detail::value_t::object;
            }
 
 switch (ptr->type())
            {
 case detail::value_t::object:
                {
 // use unchecked object access
                    ptr = &ptr->operator[](reference_token);
 break;
                }
 
 case detail::value_t::array:
                {
 if (reference_token == "-")
                    {
 // explicitly treat "-" as index beyond the end
                        ptr = &ptr->operator[](ptr->m_data.m_value.array->size());
                    }
 else
                    {
 // convert array index to number; unchecked access
                        ptr = &ptr->operator[](array_index<BasicJsonType>(reference_token));
                    }
 break;
                }
 
 case detail::value_t::null:
 case detail::value_t::string:
 case detail::value_t::boolean:
 case detail::value_t::number_integer:
 case detail::value_t::number_unsigned:
 case detail::value_t::number_float:
 case detail::value_t::binary:
 case detail::value_t::discarded:
 default:
                    JSON_THROW(detail::out_of_range::create(404, detail::concat("unresolved reference token '", reference_token, "'"), ptr));
            }
        }
 
 return *ptr;
    }
 
    /*!
    @throw parse_error.106   if an array index begins with '0'
    @throw parse_error.109   if an array index was not a number
    @throw out_of_range.402  if the array index '-' is used
    @throw out_of_range.404  if the JSON pointer can not be resolved
    */
 template<typename BasicJsonType>
    BasicJsonType& get_checked(BasicJsonType* ptr) const
 {
 for (const auto& reference_token : reference_tokens)
        {
 switch (ptr->type())
            {
 case detail::value_t::object:
                {
 // note: at performs range check
                    ptr = &ptr->at(reference_token);
 break;
                }
 
 case detail::value_t::array:
                {
 if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                    {
 // "-" always fails the range check
                        JSON_THROW(detail::out_of_range::create(402, detail::concat(
 "array index '-' (", std::to_string(ptr->m_data.m_value.array->size()),
 ") is out of range"), ptr));
                    }
 
 // note: at performs range check
                    ptr = &ptr->at(array_index<BasicJsonType>(reference_token));
 break;
                }
 
 case detail::value_t::null:
 case detail::value_t::string:
 case detail::value_t::boolean:
 case detail::value_t::number_integer:
 case detail::value_t::number_unsigned:
 case detail::value_t::number_float:
 case detail::value_t::binary:
 case detail::value_t::discarded:
 default:
                    JSON_THROW(detail::out_of_range::create(404, detail::concat("unresolved reference token '", reference_token, "'"), ptr));
            }
        }
 
 return *ptr;
    }
 
    /*!
    @brief return a const reference to the pointed to value
 
    @param[in] ptr  a JSON value
 
    @return const reference to the JSON value pointed to by the JSON
    pointer
 
    @throw parse_error.106   if an array index begins with '0'
    @throw parse_error.109   if an array index was not a number
    @throw out_of_range.402  if the array index '-' is used
    @throw out_of_range.404  if the JSON pointer can not be resolved
    */
 template<typename BasicJsonType>
 const BasicJsonType& get_unchecked(const BasicJsonType* ptr) const
 {
 for (const auto& reference_token : reference_tokens)
        {
 switch (ptr->type())
            {
 case detail::value_t::object:
                {
 // use unchecked object access
                    ptr = &ptr->operator[](reference_token);
 break;
                }
 
 case detail::value_t::array:
                {
 if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                    {
 // "-" cannot be used for const access
                        JSON_THROW(detail::out_of_range::create(402, detail::concat("array index '-' (", std::to_string(ptr->m_data.m_value.array->size()), ") is out of range"), ptr));
                    }
 
 // use unchecked array access
                    ptr = &ptr->operator[](array_index<BasicJsonType>(reference_token));
 break;
                }
 
 case detail::value_t::null:
 case detail::value_t::string:
 case detail::value_t::boolean:
 case detail::value_t::number_integer:
 case detail::value_t::number_unsigned:
 case detail::value_t::number_float:
 case detail::value_t::binary:
 case detail::value_t::discarded:
 default:
                    JSON_THROW(detail::out_of_range::create(404, detail::concat("unresolved reference token '", reference_token, "'"), ptr));
            }
        }
 
 return *ptr;
    }
 
    /*!
    @throw parse_error.106   if an array index begins with '0'
    @throw parse_error.109   if an array index was not a number
    @throw out_of_range.402  if the array index '-' is used
    @throw out_of_range.404  if the JSON pointer can not be resolved
    */
 template<typename BasicJsonType>
 const BasicJsonType& get_checked(const BasicJsonType* ptr) const
 {
 for (const auto& reference_token : reference_tokens)
        {
 switch (ptr->type())
            {
 case detail::value_t::object:
                {
 // note: at performs range check
                    ptr = &ptr->at(reference_token);
 break;
                }
 
 case detail::value_t::array:
                {
 if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                    {
 // "-" always fails the range check
                        JSON_THROW(detail::out_of_range::create(402, detail::concat(
 "array index '-' (", std::to_string(ptr->m_data.m_value.array->size()),
 ") is out of range"), ptr));
                    }
 
 // note: at performs range check
                    ptr = &ptr->at(array_index<BasicJsonType>(reference_token));
 break;
                }
 
 case detail::value_t::null:
 case detail::value_t::string:
 case detail::value_t::boolean:
 case detail::value_t::number_integer:
 case detail::value_t::number_unsigned:
 case detail::value_t::number_float:
 case detail::value_t::binary:
 case detail::value_t::discarded:
 default:
                    JSON_THROW(detail::out_of_range::create(404, detail::concat("unresolved reference token '", reference_token, "'"), ptr));
            }
        }
 
 return *ptr;
    }
 
    /*!
    @throw parse_error.106   if an array index begins with '0'
    @throw parse_error.109   if an array index was not a number
    */
 template<typename BasicJsonType>
 bool contains(const BasicJsonType* ptr) const
 {
 for (const auto& reference_token : reference_tokens)
        {
 switch (ptr->type())
            {
 case detail::value_t::object:
                {
 if (!ptr->contains(reference_token))
                    {
 // we did not find the key in the object
 return false;
                    }
 
                    ptr = &ptr->operator[](reference_token);
 break;
                }
 
 case detail::value_t::array:
                {
 if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                    {
 // "-" always fails the range check
 return false;
                    }
 if (JSON_HEDLEY_UNLIKELY(reference_token.size() == 1 && !("0" <= reference_token && reference_token <= "9")))
                    {
 // invalid char
 return false;
                    }
 if (JSON_HEDLEY_UNLIKELY(reference_token.size() > 1))
                    {
 if (JSON_HEDLEY_UNLIKELY(!('1' <= reference_token[0] && reference_token[0] <= '9')))
                        {
 // the first char should be between '1' and '9'
 return false;
                        }
 for (std::size_t i = 1; i < reference_token.size(); i++)
                        {
 if (JSON_HEDLEY_UNLIKELY(!('0' <= reference_token[i] && reference_token[i] <= '9')))
                            {
 // other char should be between '0' and '9'
 return false;
                            }
                        }
                    }
 
 const auto idx = array_index<BasicJsonType>(reference_token);
 if (idx >= ptr->size())
                    {
 // index out of range
 return false;
                    }
 
                    ptr = &ptr->operator[](idx);
 break;
                }
 
 case detail::value_t::null:
 case detail::value_t::string:
 case detail::value_t::boolean:
 case detail::value_t::number_integer:
 case detail::value_t::number_unsigned:
 case detail::value_t::number_float:
 case detail::value_t::binary:
 case detail::value_t::discarded:
 default:
                {
 // we do not expect primitive values if there is still a
 // reference token to process
 return false;
                }
            }
        }
 
 // no reference token left means we found a primitive value
 return true;
    }
 
    /*!
    @brief split the string input to reference tokens
 
    @note This function is only called by the json_pointer constructor.
          All exceptions below are documented there.
 
    @throw parse_error.107  if the pointer is not empty or begins with '/'
    @throw parse_error.108  if character '~' is not followed by '0' or '1'
    */
 static std::vector<string_t> split(const string_t& reference_string)
    {
        std::vector<string_t> result;
 
 // special case: empty reference string -> no reference tokens
 if (reference_string.empty())
        {
 return result;
        }
 
 // check if a nonempty reference string begins with slash
 if (JSON_HEDLEY_UNLIKELY(reference_string[0] != '/'))
        {
            JSON_THROW(detail::parse_error::create(107, 1, detail::concat("JSON pointer must be empty or begin with '/' - was: '", reference_string, "'"), nullptr));
        }
 
 // extract the reference tokens:
 // - slash: position of the last read slash (or end of string)
 // - start: position after the previous slash
 for (
 // search for the first slash after the first character
            std::size_t slash = reference_string.find_first_of('/', 1),
 // set the beginning of the first reference token
            start = 1;
 // we can stop if start == 0 (if slash == string_t::npos)
            start != 0;
 // set the beginning of the next reference token
 // (will eventually be 0 if slash == string_t::npos)
            start = (slash == string_t::npos) ? 0 : slash + 1,
 // find next slash
            slash = reference_string.find_first_of('/', start))
        {
 // use the text between the beginning of the reference token
 // (start) and the last slash (slash).
 auto reference_token = reference_string.substr(start, slash - start);
 
 // check reference tokens are properly escaped
 for (std::size_t pos = reference_token.find_first_of('~');
                    pos != string_t::npos;
                    pos = reference_token.find_first_of('~', pos + 1))
            {
                JSON_ASSERT(reference_token[pos] == '~');
 
 // ~ must be followed by 0 or 1
 if (JSON_HEDLEY_UNLIKELY(pos == reference_token.size() - 1 ||
                                         (reference_token[pos + 1] != '0' &&
                                          reference_token[pos + 1] != '1')))
                {
                    JSON_THROW(detail::parse_error::create(108, 0, "escape character '~' must be followed with '0' or '1'", nullptr));
                }
            }
 
 // finally, store the reference token
 detail::unescape(reference_token);
            result.push_back(reference_token);
        }
 
 return result;
    }
 
 private:
    /*!
    @param[in] reference_string  the reference string to the current value
    @param[in] value             the value to consider
    @param[in,out] result        the result object to insert values to
 
    @note Empty objects or arrays are flattened to `null`.
    */
 template<typename BasicJsonType>
 static void flatten(const string_t& reference_string,
 const BasicJsonType& value,
                        BasicJsonType& result)
    {
 switch (value.type())
        {
 case detail::value_t::array:
            {
 if (value.m_data.m_value.array->empty())
                {
 // flatten empty array as null
                    result[reference_string] = nullptr;
                }
 else
                {
 // iterate array and use index as a reference string
 for (std::size_t i = 0; i < value.m_data.m_value.array->size(); ++i)
                    {
                        flatten(detail::concat<string_t>(reference_string, '/', std::to_string(i)),
                                value.m_data.m_value.array->operator[](i), result);
                    }
                }
 break;
            }
 
 case detail::value_t::object:
            {
 if (value.m_data.m_value.object->empty())
                {
 // flatten empty object as null
                    result[reference_string] = nullptr;
                }
 else
                {
 // iterate object and use keys as reference string
 for (const auto& element : *value.m_data.m_value.object)
                    {
                        flatten(detail::concat<string_t>(reference_string, '/', detail::escape(element.first)), element.second, result);
                    }
                }
 break;
            }
 
 case detail::value_t::null:
 case detail::value_t::string:
 case detail::value_t::boolean:
 case detail::value_t::number_integer:
 case detail::value_t::number_unsigned:
 case detail::value_t::number_float:
 case detail::value_t::binary:
 case detail::value_t::discarded:
 default:
            {
 // add a primitive value with its reference string
                result[reference_string] = value;
 break;
            }
        }
    }
 
    /*!
    @param[in] value  flattened JSON
 
    @return unflattened JSON
 
    @throw parse_error.109 if array index is not a number
    @throw type_error.314  if value is not an object
    @throw type_error.315  if object values are not primitive
    @throw type_error.313  if value cannot be unflattened
    */
 template<typename BasicJsonType>
 static BasicJsonType
    unflatten(const BasicJsonType& value)
    {
 if (JSON_HEDLEY_UNLIKELY(!value.is_object()))
        {
            JSON_THROW(detail::type_error::create(314, "only objects can be unflattened", &value));
        }
 
        BasicJsonType result;
 
 // iterate the JSON object values
 for (const auto& element : *value.m_data.m_value.object)
        {
 if (JSON_HEDLEY_UNLIKELY(!element.second.is_primitive()))
            {
                JSON_THROW(detail::type_error::create(315, "values in object must be primitive", &element.second));
            }
 
 // Assign the value to the reference pointed to by JSON pointer. Note
 // that if the JSON pointer is "" (i.e., points to the whole value),
 // function get_and_create returns a reference to the result itself.
 // An assignment will then create a primitive value.
            json_pointer(element.first).get_and_create(result) = element.second;
        }
 
 return result;
    }
 
 // can't use the conversion operator because of ambiguity
    json_pointer<string_t> convert() const&
    {
        json_pointer<string_t> result;
        result.reference_tokens = reference_tokens;
 return result;
    }
 
    json_pointer<string_t> convert()&&
    {
        json_pointer<string_t> result;
        result.reference_tokens = std::move(reference_tokens);
 return result;
    }
 
 public:
#if JSON_HAS_THREE_WAY_COMPARISON
    /// @brief compares two JSON pointers for equality
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_eq/
 template<typename RefStringTypeRhs>
 bool operator==(const json_pointer<RefStringTypeRhs>& rhs) const noexcept
    {
 return reference_tokens == rhs.reference_tokens;
    }
 
    /// @brief compares JSON pointer and string for equality
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_eq/
    JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator==(json_pointer))
 bool operator==(const string_t& rhs) const
 {
 return *this == json_pointer(rhs);
    }
 
    /// @brief 3-way compares two JSON pointers
 template<typename RefStringTypeRhs>
    std::strong_ordering operator<=>(const json_pointer<RefStringTypeRhs>& rhs) const noexcept // *NOPAD*
    {
 return  reference_tokens <=> rhs.reference_tokens; // *NOPAD*
    }
#else
    /// @brief compares two JSON pointers for equality
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_eq/
 template<typename RefStringTypeLhs, typename RefStringTypeRhs>
 // NOLINTNEXTLINE(readability-redundant-declaration)
 friend bool operator==(const json_pointer<RefStringTypeLhs>& lhs,
 const json_pointer<RefStringTypeRhs>& rhs) noexcept;
 
    /// @brief compares JSON pointer and string for equality
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_eq/
 template<typename RefStringTypeLhs, typename StringType>
 // NOLINTNEXTLINE(readability-redundant-declaration)
 friend bool operator==(const json_pointer<RefStringTypeLhs>& lhs,
 const StringType& rhs);
 
    /// @brief compares string and JSON pointer for equality
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_eq/
 template<typename RefStringTypeRhs, typename StringType>
 // NOLINTNEXTLINE(readability-redundant-declaration)
 friend bool operator==(const StringType& lhs,
 const json_pointer<RefStringTypeRhs>& rhs);
 
    /// @brief compares two JSON pointers for inequality
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_ne/
 template<typename RefStringTypeLhs, typename RefStringTypeRhs>
 // NOLINTNEXTLINE(readability-redundant-declaration)
 friend bool operator!=(const json_pointer<RefStringTypeLhs>& lhs,
 const json_pointer<RefStringTypeRhs>& rhs) noexcept;
 
    /// @brief compares JSON pointer and string for inequality
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_ne/
 template<typename RefStringTypeLhs, typename StringType>
 // NOLINTNEXTLINE(readability-redundant-declaration)
 friend bool operator!=(const json_pointer<RefStringTypeLhs>& lhs,
 const StringType& rhs);
 
    /// @brief compares string and JSON pointer for inequality
    /// @sa https://json.nlohmann.me/api/json_pointer/operator_ne/
 template<typename RefStringTypeRhs, typename StringType>
 // NOLINTNEXTLINE(readability-redundant-declaration)
 friend bool operator!=(const StringType& lhs,
 const json_pointer<RefStringTypeRhs>& rhs);
 
    /// @brief compares two JSON pointer for less-than
 template<typename RefStringTypeLhs, typename RefStringTypeRhs>
 // NOLINTNEXTLINE(readability-redundant-declaration)
 friend bool operator<(const json_pointer<RefStringTypeLhs>& lhs,
 const json_pointer<RefStringTypeRhs>& rhs) noexcept;
#endif
 
 private:
    /// the reference tokens
    std::vector<string_t> reference_tokens;
};
 
#if !JSON_HAS_THREE_WAY_COMPARISON
// functions cannot be defined inside the class due to ODR violations
template<typename RefStringTypeLhs, typename RefStringTypeRhs>
inline bool operator==(const json_pointer<RefStringTypeLhs>& lhs,
 const json_pointer<RefStringTypeRhs>& rhs) noexcept
{
 return lhs.reference_tokens == rhs.reference_tokens;
}
 
template<typename RefStringTypeLhs,
 typename StringType = typename json_pointer<RefStringTypeLhs>::string_t>
JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator==(json_pointer, json_pointer))
inline bool operator==(const json_pointer<RefStringTypeLhs>& lhs,
                       const StringType& rhs)
{
 return lhs == json_pointer<RefStringTypeLhs>(rhs);
}
 
template<typename RefStringTypeRhs,
 typename StringType = typename json_pointer<RefStringTypeRhs>::string_t>
JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator==(json_pointer, json_pointer))
inline bool operator==(const StringType& lhs,
                       const json_pointer<RefStringTypeRhs>& rhs)
{
 return json_pointer<RefStringTypeRhs>(lhs) == rhs;
}
 
template<typename RefStringTypeLhs, typename RefStringTypeRhs>
inline bool operator!=(const json_pointer<RefStringTypeLhs>& lhs,
 const json_pointer<RefStringTypeRhs>& rhs) noexcept
{
 return !(lhs == rhs);
}
 
template<typename RefStringTypeLhs,
 typename StringType = typename json_pointer<RefStringTypeLhs>::string_t>
JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator!=(json_pointer, json_pointer))
inline bool operator!=(const json_pointer<RefStringTypeLhs>& lhs,
                       const StringType& rhs)
{
 return !(lhs == rhs);
}
 
template<typename RefStringTypeRhs,
 typename StringType = typename json_pointer<RefStringTypeRhs>::string_t>
JSON_HEDLEY_DEPRECATED_FOR(3.11.2, operator!=(json_pointer, json_pointer))
inline bool operator!=(const StringType& lhs,
                       const json_pointer<RefStringTypeRhs>& rhs)
{
 return !(lhs == rhs);
}
 
template<typename RefStringTypeLhs, typename RefStringTypeRhs>
inline bool operator<(const json_pointer<RefStringTypeLhs>& lhs,
 const json_pointer<RefStringTypeRhs>& rhs) noexcept
{
 return lhs.reference_tokens < rhs.reference_tokens;
}
#endif
 
NLOHMANN_JSON_NAMESPACE_END