json/src/json.hpp

#ifndef _NLOHMANN_JSON
#define _NLOHMANN_JSON

#include <algorithm>
#include <cassert>
#include <functional>
#include <initializer_list>
#include <iostream>
#include <iterator>
#include <limits>
#include <map>
#include <memory>
#include <string>
#include <type_traits>
#include <utility>
#include <vector>

/*!
- ObjectType trick from http://stackoverflow.com/a/9860911
*/
/*
template<typename C, typename=void>
struct container_resizable : std::false_type {};
template<typename C>
struct container_resizable<C, decltype(C().resize(0))> : std::true_type {};
*/

/*!
@see https://github.com/nlohmann
*/
namespace nlohmann
{

/*!
@brief JSON

@tparam ObjectType         type for JSON objects
                           (@c std::map by default)
@tparam ArrayType          type for JSON arrays
                           (@c std::vector by default)
@tparam StringType         type for JSON strings and object keys
                           (@c std::string by default)
@tparam BooleanType        type for JSON booleans
                           (@c bool by default)
@tparam NumberIntegerType  type for JSON integer numbers
                           (@c int64_t by default)
@tparam NumberFloatType    type for JSON floating point numbers
                           (@c double by default)
*/
template <
    template<typename U, typename V, typename... Args> class ObjectType = std::map,
    //template<typename... Args> class ArrayType = std::vector,
    template<typename U, typename... Args> class ArrayType = std::vector,
    class StringType = std::string,
    class BooleanType = bool,
    class NumberIntegerType = int64_t,
    class NumberFloatType = double
    >
class basic_json
{
  public:
    /////////////////////
    // container types //
    /////////////////////

    class iterator;
    class const_iterator;

    /// the type of elements in a basic_json container
    using value_type = basic_json;
    /// the type of an element reference
    using reference = basic_json&;
    /// the type of an element const reference
    using const_reference = const basic_json&;
    /// the type of an element pointer
    using pointer = basic_json*;
    /// the type of an element const pointer
    using const_pointer = const basic_json*;
    /// a type to represent differences between iterators
    using difference_type = std::ptrdiff_t;
    /// a type to represent container sizes
    using size_type = std::size_t;
    /// an iterator for a basic_json container
    using iterator = basic_json::iterator;
    /// a const iterator for a basic_json container
    using const_iterator = basic_json::const_iterator;


    ///////////////////////////
    // JSON value data types //
    ///////////////////////////

    /// a type for an object
    using object_t = ObjectType<StringType, basic_json>;
    /// a type for an array
    using array_t = ArrayType<basic_json>;
    /// a type for a string
    using string_t = StringType;
    /// a type for a boolean
    using boolean_t = BooleanType;
    /// a type for a number (integer)
    using number_integer_t = NumberIntegerType;
    /// a type for a number (floating point)
    using number_float_t = NumberFloatType;
    /// a type for list initialization
    using list_init_t = std::initializer_list<basic_json>;


    ////////////////////////
    // JSON value storage //
    ////////////////////////

    /// a JSON value
    union json_value
    {
        /// object (stored with pointer to save storage)
        object_t* object;
        /// array (stored with pointer to save storage)
        array_t* array;
        /// string (stored with pointer to save storage)
        string_t* string;
        /// bolean
        boolean_t boolean;
        /// number (integer)
        number_integer_t number_integer;
        /// number (floating point)
        number_float_t number_float;

        /// default constructor (for null values)
        json_value() = default;
        /// constructor for objects
        json_value(object_t* v) : object(v) {}
        /// constructor for arrays
        json_value(array_t* v) : array(v) {}
        /// constructor for strings
        json_value(string_t* v) : string(v) {}
        /// constructor for booleans
        json_value(boolean_t v) : boolean(v) {}
        /// constructor for numbers (integer)
        json_value(number_integer_t v) : number_integer(v) {}
        /// constructor for numbers (floating point)
        json_value(number_float_t v) : number_float(v) {}
    };


    /////////////////////////////////
    // JSON value type enumeration //
    /////////////////////////////////

    /// JSON value type enumeration
    enum class value_t : uint8_t
    {
        /// null value
        null,
        /// object (unordered set of name/value pairs)
        object,
        /// array (ordered collection of values)
        array,
        /// string value
        string,
        /// boolean value
        boolean,
        /// number value (integer)
        number_integer,
        /// number value (floating point)
        number_float
    };


    //////////////////
    // constructors //
    //////////////////

    /// create an empty value with a given type
    inline basic_json(const value_t value)
        : m_type(value)
    {
        switch (m_type)
        {
            case (value_t::null):
            {
                break;
            }

            case (value_t::object):
            {
                m_value.object = new object_t();
                break;
            }

            case (value_t::array):
            {
                m_value.array = new array_t();
                break;
            }

            case (value_t::string):
            {
                m_value.string = new string_t();
                break;
            }

            case (value_t::boolean):
            {
                m_value.boolean = boolean_t();
                break;
            }

            case (value_t::number_integer):
            {
                m_value.number_integer = number_integer_t();
                break;
            }

            case (value_t::number_float):
            {
                m_value.number_float = number_float_t();
                break;
            }
        }
    }

    /// create a null object (implicitly)
    inline basic_json() noexcept
        : m_type(value_t::null)
    {}

    /// create a null object (explicitly)
    inline basic_json(std::nullptr_t) noexcept
        : m_type(value_t::null)
    {}

    /// create an object (explicit)
    inline basic_json(const object_t& value)
        : m_type(value_t::object), m_value(new object_t(value))
    {}

    /// create an object (implicit)
    template <class V, typename
              std::enable_if<
                  std::is_constructible<string_t, typename V::key_type>::value and
                  std::is_constructible<basic_json, typename V::mapped_type>::value, int>::type
              = 0>
    inline basic_json(const V& value)
        : m_type(value_t::object), m_value(new object_t(value.begin(), value.end()))
    {}

    /// create an array (explicit)
    inline basic_json(const array_t& value)
        : m_type(value_t::array), m_value(new array_t(value))
    {}

    /// create an array (implicit)
    template <class V, typename
              std::enable_if<
                  not std::is_same<V, basic_json::iterator>::value and
                  not std::is_same<V, basic_json::const_iterator>::value and
                  std::is_constructible<basic_json, typename V::value_type>::value, int>::type
              = 0>
    inline basic_json(const V& value)
        : m_type(value_t::array), m_value(new array_t(value.begin(), value.end()))
    {}

    /// create a string (explicit)
    inline basic_json(const string_t& value)
        : m_type(value_t::string), m_value(new string_t(value))
    {}

    /// create a string (explicit)
    inline basic_json(const typename string_t::value_type* value)
        : m_type(value_t::string), m_value(new string_t(value))
    {}

    /// create a string (implicit)
    template <class V, typename
              std::enable_if<
                  std::is_constructible<string_t, V>::value, int>::type
              = 0>
    inline basic_json(const V& value)
        : basic_json(string_t(value))
    {}

    /// create a boolean (explicit)
    inline basic_json(boolean_t value)
        : m_type(value_t::boolean), m_value(value)
    {}

    /// create an integer number (explicit)
    inline basic_json(const number_integer_t& value)
        : m_type(value_t::number_integer), m_value(value)
    {}

    /// create an integer number (implicit)
    template<typename T, typename
             std::enable_if<
                 std::is_constructible<number_integer_t, T>::value and
                 std::numeric_limits<T>::is_integer, T>::type
             = 0>
    inline basic_json(const T value) noexcept
        : m_type(value_t::number_integer), m_value(number_integer_t(value))
    {}

    /// create a floating point number (explicit)
    inline basic_json(const number_float_t& value)
        : m_type(value_t::number_float), m_value(value)
    {}

    /// create a floating point number (implicit)
    template<typename T, typename = typename
             std::enable_if<
                 std::is_constructible<number_float_t, T>::value and
                 std::is_floating_point<T>::value>::type
             >
    inline basic_json(const T value) noexcept
        : m_type(value_t::number_float), m_value(number_float_t(value))
    {}

    inline basic_json(list_init_t l, bool type_deduction = true, value_t manual_type = value_t::array)
    {
        // the initializer list could describe an object
        bool is_object = true;

        // check if each element is an array with two elements whose first element
        // is a string
        for (const auto& element : l)
        {
            if ((element.m_final and element.m_type == value_t::array)
                    or (element.m_type != value_t::array or element.size() != 2
                        or element[0].m_type != value_t::string))
            {
                // we found an element that makes it impossible to use the
                // initializer list as object
                is_object = false;
                break;
            }
        }

        // adjust type if type deduction is not wanted
        if (not type_deduction)
        {
            // mark this object's type as final
            m_final = true;

            // if array is wanted, do not create an object though possible
            if (manual_type == value_t::array)
            {
                is_object = false;
            }

            // if object is wanted but impossible, throw an exception
            if (manual_type == value_t::object and not is_object)
            {
                throw std::logic_error("cannot create JSON object");
            }
        }

        if (is_object)
        {
            // the initializer list is a list of pairs -> create object
            m_type = value_t::object;
            m_value = new object_t();
            for (auto& element : l)
            {
                m_value.object->emplace(std::move(*(element[0].m_value.string)), std::move(element[1]));
            }
        }
        else
        {
            // the initializer list describes an array -> create array
            m_type = value_t::array;
            m_value = new array_t(std::move(l));
        }
    }

    inline static basic_json array(list_init_t l = list_init_t())
    {
        return basic_json(l, false, value_t::array);
    }

    inline static basic_json object(list_init_t l = list_init_t())
    {
        // if more than one element is in the initializer list, wrap it
        if (l.size() > 1)
        {
            return basic_json({l}, false, value_t::object);
        }
        else
        {
            return basic_json(l, false, value_t::object);
        }
    }

    ///////////////////////////////////////
    // other constructors and destructor //
    ///////////////////////////////////////

    /// copy constructor
    inline basic_json(const basic_json& other)
        : m_type(other.m_type)
    {
        switch (m_type)
        {
            case (value_t::null):
            {
                break;
            }
            case (value_t::object):
            {
                m_value.object = new object_t(*other.m_value.object);
                break;
            }
            case (value_t::array):
            {
                m_value.array = new array_t(*other.m_value.array);
                break;
            }
            case (value_t::string):
            {
                m_value.string = new string_t(*other.m_value.string);
                break;
            }
            case (value_t::boolean):
            {
                m_value.boolean = other.m_value.boolean;
                break;
            }
            case (value_t::number_integer):
            {
                m_value.number_integer = other.m_value.number_integer;
                break;
            }
            case (value_t::number_float):
            {
                m_value.number_float = other.m_value.number_float;
                break;
            }
        }
    }

    /// move constructor
    inline basic_json(basic_json&& other) noexcept
        : m_type(std::move(other.m_type)),
          m_value(std::move(other.m_value))
    {
        // invaludate payload
        other.m_type = value_t::null;
        other.m_value = {};
    }

    /// copy assignment
    inline reference operator=(basic_json other) noexcept
    {
        std::swap(m_type, other.m_type);
        std::swap(m_value, other.m_value);
        return *this;
    }

    /// destructor
    inline ~basic_json() noexcept
    {
        switch (m_type)
        {
            case (value_t::object):
            {
                delete m_value.object;
                m_value.object = nullptr;
                break;
            }
            case (value_t::array):
            {
                delete m_value.array;
                m_value.array = nullptr;
                break;
            }
            case (value_t::string):
            {
                delete m_value.string;
                m_value.string = nullptr;
                break;
            }
            case (value_t::null):
            case (value_t::boolean):
            case (value_t::number_integer):
            case (value_t::number_float):
            {
                break;
            }
        }
    }


  public:
    ///////////////////////
    // object inspection //
    ///////////////////////

    /*!
    Serialization function for JSON objects. The function tries to mimick Python's
    @p json.dumps() function, and currently supports its @p indent parameter.

    @param indent  if indent is nonnegative, then array elements and object members
                   will be pretty-printed with that indent level. An indent level
                   of 0 will only insert newlines. -1 (the default) selects the
                   most compact representation

    @see https://docs.python.org/2/library/json.html#json.dump
    */
    inline string_t dump(int indent = -1) const noexcept
    {
        if (indent >= 0)
        {
            return dump(true, static_cast<unsigned int>(indent));
        }
        else
        {
            return dump(false, 0);
        }
    }

    /// return the type of the object explicitly
    inline value_t type() const noexcept
    {
        return m_type;
    }

    /// return the type of the object implicitly
    operator value_t() const noexcept
    {
        return m_type;
    }


    //////////////////////
    // value conversion //
    //////////////////////

    /// get an object
    template <class T, typename
              std::enable_if<
                  std::is_constructible<string_t, typename T::key_type>::value and
                  std::is_constructible<basic_json, typename T::mapped_type>::value, int>::type
              = 0>
    inline T get() const
    {
        switch (m_type)
        {
            case (value_t::object):
                return T(m_value.object->begin(), m_value.object->end());
            default:
                throw std::logic_error("cannot cast " + type_name() + " to " + typeid(T).name());
        }
    }

    /// get an array
    template <class T, typename
              std::enable_if<
                  not std::is_same<T, string_t>::value and
                  std::is_constructible<basic_json, typename T::value_type>::value, int>::type
              = 0>
    inline T get() const
    {
        switch (m_type)
        {
            case (value_t::array):
                return T(m_value.array->begin(), m_value.array->end());
            default:
                throw std::logic_error("cannot cast " + type_name() + " to " + typeid(T).name());
        }
    }

    /// get a string
    template <typename T, typename
              std::enable_if<
                  std::is_constructible<T, string_t>::value, int>::type
              = 0>
    inline T get() const
    {
        switch (m_type)
        {
            case (value_t::string):
                return *m_value.string;
            default:
                throw std::logic_error("cannot cast " + type_name() + " to " + typeid(T).name());
        }
    }

    /// get a boolean
    template <typename T, typename
              std::enable_if<
                  std::is_same<boolean_t, T>::value, int>::type
              = 0>
    inline T get() const
    {
        switch (m_type)
        {
            case (value_t::boolean):
                return m_value.boolean;
            default:
                throw std::logic_error("cannot cast " + type_name() + " to " + typeid(T).name());
        }
    }

    /// explicitly get a number
    template<typename T, typename
             std::enable_if<
                 not std::is_same<boolean_t, T>::value and
                 std::is_arithmetic<T>::value, int>::type
             = 0>
    inline T get() const
    {
        switch (m_type)
        {
            case (value_t::number_integer):
                return static_cast<T>(m_value.number_integer);
            case (value_t::number_float):
                return static_cast<T>(m_value.number_float);
            default:
                throw std::logic_error("cannot cast " + type_name() + " to " + typeid(T).name());
        }
    }

    /// explicitly get a value
    template<typename T>
    inline operator T() const
    {
        return get<T>();
    }


    ////////////////////
    // element access //
    ////////////////////

    /// access specified element with bounds checking
    inline reference at(size_type pos)
    {
        // at only works for arrays
        if (m_type != value_t::array)
        {
            throw std::runtime_error("cannot use at with " + type_name());
        }

        return m_value.array->at(pos);
    }

    /// access specified element with bounds checking
    inline const_reference at(size_type pos) const
    {
        // at only works for arrays
        if (m_type != value_t::array)
        {
            throw std::runtime_error("cannot use at with " + type_name());
        }

        return m_value.array->at(pos);
    }

    /// access specified element
    inline reference operator[](size_type pos)
    {
        // at only works for arrays
        if (m_type != value_t::array)
        {
            throw std::runtime_error("cannot use [] with " + type_name());
        }

        return m_value.array->operator[](pos);
    }

    /// access specified element
    inline const_reference operator[](size_type pos) const
    {
        // at only works for arrays
        if (m_type != value_t::array)
        {
            throw std::runtime_error("cannot use [] with " + type_name());
        }

        return m_value.array->operator[](pos);
    }

    /// access specified element with bounds checking
    inline reference at(const typename object_t::key_type& key)
    {
        // at only works for objects
        if (m_type != value_t::object)
        {
            throw std::runtime_error("cannot use at with " + type_name());
        }

        return m_value.object->at(key);
    }

    /// access specified element with bounds checking
    inline const_reference at(const typename object_t::key_type& key) const
    {
        // at only works for objects
        if (m_type != value_t::object)
        {
            throw std::runtime_error("cannot use at with " + type_name());
        }

        return m_value.object->at(key);
    }

    /// access specified element
    inline reference operator[](const typename object_t::key_type& key)
    {
        // at only works for objects
        if (m_type != value_t::object)
        {
            throw std::runtime_error("cannot use [] with " + type_name());
        }

        return m_value.object->operator[](key);
    }

    /// access specified element (needed for clang)
    template<typename T, size_t n>
    inline reference operator[](const T (&key)[n])
    {
        // at only works for objects
        if (m_type != value_t::object)
        {
            throw std::runtime_error("cannot use [] with " + type_name());
        }

        return m_value.object->operator[](key);
    }

    /// access specified element
    inline reference operator[](typename object_t::key_type&& key)
    {
        // at only works for objects
        if (m_type != value_t::object)
        {
            throw std::runtime_error("cannot use [] with " + type_name());
        }

        return m_value.object->operator[](std::move(key));
    }


    ///////////////
    // iterators //
    ///////////////

    /// returns an iterator to the beginning of the container
    inline iterator begin() noexcept
    {
        iterator result(this);
        result.set_begin();
        return result;
    }

    /// returns a const iterator to the beginning of the container
    inline const_iterator begin() const noexcept
    {
        const_iterator result(this);
        result.set_begin();
        return result;
    }

    /// returns a const iterator to the beginning of the container
    inline const_iterator cbegin() const noexcept
    {
        const_iterator result(this);
        result.set_begin();
        return result;
    }

    /// returns an iterator to the end of the container
    inline iterator end() noexcept
    {
        iterator result(this);
        result.set_end();
        return result;
    }

    /// returns a const iterator to the end of the container
    inline const_iterator end() const noexcept
    {
        const_iterator result(this);
        result.set_end();
        return result;
    }

    /// returns a const iterator to the end of the container
    inline const_iterator cend() const noexcept
    {
        const_iterator result(this);
        result.set_end();
        return result;
    }


    //////////////
    // capacity //
    //////////////

    /// checks whether the container is empty
    inline bool empty() const noexcept
    {
        switch (m_type)
        {
            case (value_t::null):
            {
                return true;
            }
            case (value_t::number_integer):
            case (value_t::number_float):
            case (value_t::boolean):
            case (value_t::string):
            {
                return false;
            }
            case (value_t::array):
            {
                return m_value.array->empty();
            }
            case (value_t::object):
            {
                return m_value.object->empty();
            }
        }
    }

    /// returns the number of elements
    inline size_type size() const noexcept
    {
        switch (m_type)
        {
            case (value_t::null):
            {
                return 0;
            }
            case (value_t::number_integer):
            case (value_t::number_float):
            case (value_t::boolean):
            case (value_t::string):
            {
                return 1;
            }
            case (value_t::array):
            {
                return m_value.array->size();
            }
            case (value_t::object):
            {
                return m_value.object->size();
            }
        }
    }

    /// returns the maximum possible number of elements
    inline size_type max_size() const noexcept
    {
        switch (m_type)
        {
            case (value_t::null):
            {
                return 0;
            }
            case (value_t::number_integer):
            case (value_t::number_float):
            case (value_t::boolean):
            case (value_t::string):
            {
                return 1;
            }
            case (value_t::array):
            {
                return m_value.array->max_size();
            }
            case (value_t::object):
            {
                return m_value.object->max_size();
            }
        }
    }


    ///////////////
    // modifiers //
    ///////////////

    /// clears the contents
    inline void clear() noexcept
    {
        switch (m_type)
        {
            case (value_t::null):
            {
                break;
            }
            case (value_t::number_integer):
            {
                m_value.number_integer = {};
                break;
            }
            case (value_t::number_float):
            {
                m_value.number_float = {};
                break;
            }
            case (value_t::boolean):
            {
                m_value.boolean = {};
                break;
            }
            case (value_t::string):
            {
                m_value.string->clear();
                break;
            }
            case (value_t::array):
            {
                m_value.array->clear();
                break;
            }
            case (value_t::object):
            {
                m_value.object->clear();
                break;
            }
        }
    }

    /// add an object to an array
    inline void push_back(basic_json&& value)
    {
        // push_back only works for null objects or arrays
        if (not(m_type == value_t::null or m_type == value_t::array))
        {
            throw std::runtime_error("cannot add element to " + type_name());
        }

        // transform null object into an array
        if (m_type == value_t::null)
        {
            m_type = value_t::array;
            m_value.array = new array_t;
        }

        // add element to array (move semantics)
        m_value.array->push_back(std::move(value));
        // invalidate object
        value.m_type = value_t::null;
    }

    /// add an object to an array
    inline void push_back(const basic_json& value)
    {
        // push_back only works for null objects or arrays
        if (not(m_type == value_t::null or m_type == value_t::array))
        {
            throw std::runtime_error("cannot add element to " + type_name());
        }

        // transform null object into an array
        if (m_type == value_t::null)
        {
            m_type = value_t::array;
            m_value.array = new array_t;
        }

        // add element to array
        m_value.array->push_back(value);
    }

    /*
    /// add an object to an array
    inline reference operator+=(const basic_json& value)
    {
        push_back(value);
        return *this;
    }
    */

    /// add constructible objects to an array
    template<class T, typename std::enable_if<std::is_constructible<basic_json, T>::value>::type = 0>
    inline void push_back(const T& value)
    {
        assert(false); // not sure if function will ever be called
        push_back(basic_json(value));
    }

    /*
    /// add constructible objects to an array
    template<class T, typename std::enable_if<std::is_constructible<basic_json, T>::value>::type = 0>
    inline reference operator+=(const T& value)
    {
        push_back(basic_json(value));
        return *this;
    }
    */

    /// add an object to an object
    inline void push_back(const typename object_t::value_type& value)
    {
        // push_back only works for null objects or objects
        if (not(m_type == value_t::null or m_type == value_t::object))
        {
            throw std::runtime_error("cannot add element to " + type_name());
        }

        // transform null object into an object
        if (m_type == value_t::null)
        {
            m_type = value_t::object;
            m_value.object = new object_t;
        }

        // add element to array
        m_value.object->insert(value);
    }

    /*
    /// add an object to an object
    inline reference operator+=(const typename object_t::value_type& value)
    {
        push_back(value);
        return operator[](value.first);
    }
    */

    /// constructs element in-place at the end of an array
    template <typename T, typename
              std::enable_if<
                  std::is_constructible<basic_json, T>::value, int>::type
              = 0>
    inline void emplace_back(T && arg)
    {
        // push_back only works for null objects or arrays
        if (not(m_type == value_t::null or m_type == value_t::array))
        {
            throw std::runtime_error("cannot add element to " + type_name());
        }

        // transform null object into an array
        if (m_type == value_t::null)
        {
            m_type = value_t::array;
            m_value.array = new array_t;
        }

        // add element to array
        m_value.array->emplace_back(std::forward<T>(arg));
    }

    /// swaps the contents
    inline void swap(reference other) noexcept
    {
        std::swap(m_type, other.m_type);
        std::swap(m_value, other.m_value);
    }

    /// swaps the contents
    inline void swap(array_t& other)
    {
        // swap only works for arrays
        if (m_type != value_t::array)
        {
            throw std::runtime_error("cannot use swap with " + type_name());
        }

        // swap arrays
        std::swap(*(m_value.array), other);
    }

    /// swaps the contents
    inline void swap(object_t& other)
    {
        // swap only works for objects
        if (m_type != value_t::object)
        {
            throw std::runtime_error("cannot use swap with " + type_name());
        }

        // swap arrays
        std::swap(*(m_value.object), other);
    }

    /// swaps the contents
    inline void swap(string_t& other)
    {
        // swap only works for strings
        if (m_type != value_t::string)
        {
            throw std::runtime_error("cannot use swap with " + type_name());
        }

        // swap arrays
        std::swap(*(m_value.string), other);
    }


    //////////////////////////////////////////
    // lexicographical comparison operators //
    //////////////////////////////////////////

    /// comparison: equal
    friend bool operator==(const_reference lhs, const_reference rhs)
    {
        switch (lhs.type())
        {
            case (value_t::array):
            {
                if (rhs.type() == value_t::array)
                {
                    return *lhs.m_value.array == *rhs.m_value.array;
                }
                break;
            }
            case (value_t::object):
            {
                if (rhs.type() == value_t::object)
                {
                    return *lhs.m_value.object == *rhs.m_value.object;
                }
                break;
            }
            case (value_t::null):
            {
                if (rhs.type() == value_t::null)
                {
                    return true;
                }
                break;
            }
            case (value_t::string):
            {
                if (rhs.type() == value_t::string)
                {
                    return *lhs.m_value.string == *rhs.m_value.string;
                }
                break;
            }
            case (value_t::boolean):
            {
                if (rhs.type() == value_t::boolean)
                {
                    return lhs.m_value.boolean == rhs.m_value.boolean;
                }
                break;
            }
            case (value_t::number_integer):
            {
                if (rhs.type() == value_t::number_integer)
                {
                    return lhs.m_value.number_integer == rhs.m_value.number_integer;
                }
                if (rhs.type() == value_t::number_float)
                {
                    return lhs.m_value.number_integer == static_cast<number_integer_t>(rhs.m_value.number_float);
                }
                break;
            }
            case (value_t::number_float):
            {
                if (rhs.type() == value_t::number_integer)
                {
                    return lhs.m_value.number_float == static_cast<number_float_t>(rhs.m_value.number_integer);
                }
                if (rhs.type() == value_t::number_float)
                {
                    return lhs.m_value.number_float == rhs.m_value.number_float;
                }
                break;
            }
        }

        return false;
    }

    /// comparison: not equal
    friend bool operator!=(const_reference lhs, const_reference rhs)
    {
        return not (lhs == rhs);
    }

    /// comparison: less than
    friend bool operator<(const_reference lhs, const_reference rhs)
    {
        switch (lhs.type())
        {
            case (value_t::array):
            {
                if (rhs.type() == value_t::array)
                {
                    return *lhs.m_value.array < *rhs.m_value.array;
                }
                break;
            }
            case (value_t::object):
            {
                if (rhs.type() == value_t::object)
                {
                    return *lhs.m_value.object < *rhs.m_value.object;
                }
                break;
            }
            case (value_t::null):
            {
                if (rhs.type() == value_t::null)
                {
                    return false;
                }
                break;
            }
            case (value_t::string):
            {
                if (rhs.type() == value_t::string)
                {
                    return *lhs.m_value.string < *rhs.m_value.string;
                }
                break;
            }
            case (value_t::boolean):
            {
                if (rhs.type() == value_t::boolean)
                {
                    return lhs.m_value.boolean < rhs.m_value.boolean;
                }
                break;
            }
            case (value_t::number_integer):
            {
                if (rhs.type() == value_t::number_integer)
                {
                    return lhs.m_value.number_integer < rhs.m_value.number_integer;
                }
                if (rhs.type() == value_t::number_float)
                {
                    return lhs.m_value.number_integer < static_cast<number_integer_t>(rhs.m_value.number_float);
                }
                break;
            }
            case (value_t::number_float):
            {
                if (rhs.type() == value_t::number_integer)
                {
                    return lhs.m_value.number_float < static_cast<number_float_t>(rhs.m_value.number_integer);
                }
                if (rhs.type() == value_t::number_float)
                {
                    return lhs.m_value.number_float < rhs.m_value.number_float;
                }
                break;
            }
        }

        return false;
    }

    /// comparison: less than or equal
    friend bool operator<=(const_reference lhs, const_reference rhs)
    {
        return not (rhs < lhs);
    }

    /// comparison: greater than
    friend bool operator>(const_reference lhs, const_reference rhs)
    {
        return not (lhs <= rhs);
    }

    /// comparison: greater than or equal
    friend bool operator>=(const_reference lhs, const_reference rhs)
    {
        return not (lhs < rhs);
    }


    ///////////////////
    // serialization //
    ///////////////////

    /// serialize to stream
    friend std::ostream& operator<<(std::ostream& o, const basic_json& j)
    {
        o << j.dump();
        return o;
    }

    /// serialize to stream
    friend std::ostream& operator>>(const basic_json& j, std::ostream& o)
    {
        o << j.dump();
        return o;
    }


  private:
    ///////////////////////////
    // convenience functions //
    ///////////////////////////

    /// return the type as string
    inline string_t type_name() const noexcept
    {
        switch (m_type)
        {
            case (value_t::null):
            {
                return "null";
            }
            case (value_t::object):
            {
                return "object";
            }
            case (value_t::array):
            {
                return "array";
            }
            case (value_t::string):
            {
                return "string";
            }
            case (value_t::boolean):
            {
                return "boolean";
            }
            case (value_t::number_integer):
            case (value_t::number_float):
            {
                return "number";
            }
        }
    }

    /*!
    Internal implementation of the serialization function.

    @param prettyPrint    whether the output shall be pretty-printed
    @param indentStep     the indent level
    @param currentIndent  the current indent level (only used internally)
    */
    inline string_t dump(const bool prettyPrint, const unsigned int indentStep,
                         unsigned int currentIndent = 0) const noexcept
    {
        // helper function to return whitespace as indentation
        const auto indent = [prettyPrint, &currentIndent]()
        {
            return prettyPrint ? string_t(currentIndent, ' ') : string_t();
        };

        switch (m_type)
        {
            case (value_t::null):
            {
                return "null";
            }

            case (value_t::object):
            {
                if (m_value.object->empty())
                {
                    return "{}";
                }

                string_t result = "{";

                // increase indentation
                if (prettyPrint)
                {
                    currentIndent += indentStep;
                    result += "\n";
                }

                for (typename object_t::const_iterator i = m_value.object->begin(); i != m_value.object->end(); ++i)
                {
                    if (i != m_value.object->begin())
                    {
                        result += prettyPrint ? ",\n" : ",";
                    }
                    result += indent() + "\"" + i->first + "\":" + (prettyPrint ? " " : "")
                              + i->second.dump(prettyPrint, indentStep, currentIndent);
                }

                // decrease indentation
                if (prettyPrint)
                {
                    currentIndent -= indentStep;
                    result += "\n";
                }

                return result + indent() + "}";
            }

            case (value_t::array):
            {
                if (m_value.array->empty())
                {
                    return "[]";
                }

                string_t result = "[";

                // increase indentation
                if (prettyPrint)
                {
                    currentIndent += indentStep;
                    result += "\n";
                }

                for (typename array_t::const_iterator i = m_value.array->begin(); i != m_value.array->end(); ++i)
                {
                    if (i != m_value.array->begin())
                    {
                        result += prettyPrint ? ",\n" : ",";
                    }
                    result += indent() + i->dump(prettyPrint, indentStep, currentIndent);
                }

                // decrease indentation
                if (prettyPrint)
                {
                    currentIndent -= indentStep;
                    result += "\n";
                }

                return result + indent() + "]";
            }

            case (value_t::string):
            {
                return string_t("\"") + *m_value.string + "\"";
            }

            case (value_t::boolean):
            {
                return m_value.boolean ? "true" : "false";
            }

            case (value_t::number_integer):
            {
                return std::to_string(m_value.number_integer);
            }

            case (value_t::number_float):
            {
                return std::to_string(m_value.number_float);
            }
        }
    }


  private:
    //////////////////////
    // member variables //
    //////////////////////

    /// the type of the current element
    value_t m_type = value_t::null;

    /// whether the type of JSON object may change later
    bool m_final = false;

    /// the value of the current element
    json_value m_value = {};

  public:
    ///////////////
    // iterators //
    ///////////////

    /// a bidirectional iterator for the basic_json class
    class iterator : public std::iterator<std::bidirectional_iterator_tag, basic_json>
    {
      public:
        /// the type of the values when the iterator is dereferenced
        using value_type = basic_json::value_type;
        /// a type to represent differences between iterators
        using difference_type = basic_json::difference_type;
        /// defines a pointer to the type iterated over (value_type)
        using pointer = basic_json::pointer;
        /// defines a reference to the type iterated over (value_type)
        using reference = basic_json::reference;
        /// the category of the iterator
        using iterator_category = std::bidirectional_iterator_tag;

        /// values of a generic iterator type of non-container JSON values
        enum class generic_iterator_value
        {
            /// the iterator was not initialized
            uninitialized,
            /// the iterator points to the only value
            begin,
            /// the iterator points past the only value
            end
        };

        /// an iterator value
        union internal_iterator
        {
            /// iterator for JSON objects
            typename object_t::iterator object_iterator;
            /// iterator for JSON arrays
            typename array_t::iterator array_iterator;
            /// generic iteraotr for all other value types
            generic_iterator_value generic_iterator;

            /// default constructor
            internal_iterator() : generic_iterator(generic_iterator_value::uninitialized) {}
            /// constructor for object iterators
            internal_iterator(typename object_t::iterator v) : object_iterator(v) {}
            /// constructor for array iterators
            internal_iterator(typename array_t::iterator v) : array_iterator(v) {}
            /// constructor for generic iterators
            internal_iterator(generic_iterator_value v) : generic_iterator(v) {}
        };

        /// constructor for a given JSON instance
        inline iterator(pointer object) : m_object(object)
        {
            if (m_object == nullptr)
            {
                throw std::logic_error("cannot create iterator");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    m_it.object_iterator = typename object_t::iterator();
                    break;
                }
                case (basic_json::value_t::array):
                {
                    m_it.array_iterator = typename array_t::iterator();
                    break;
                }
                default:
                {
                    m_it.generic_iterator = generic_iterator_value::uninitialized;
                    break;
                }
            }
        }

        /// copy assignment
        inline iterator& operator=(const iterator& other) noexcept
        {
            m_object = other.m_object;
            m_it = other.m_it;
            return *this;
        }

        /// set the iterator to the first value
        inline void set_begin() noexcept
        {
            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    m_it.object_iterator = m_object->m_value.object->begin();
                    break;
                }

                case (basic_json::value_t::array):
                {
                    m_it.array_iterator = m_object->m_value.array->begin();
                    break;
                }

                case (basic_json::value_t::null):
                {
                    m_it.generic_iterator = generic_iterator_value::end;
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::begin;
                    break;
                }
            }
        }

        /// set the iterator past the last value
        inline void set_end() noexcept
        {
            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    m_it.object_iterator = m_object->m_value.object->end();
                    break;
                }

                case (basic_json::value_t::array):
                {
                    m_it.array_iterator = m_object->m_value.array->end();
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::end;
                    break;
                }
            }
        }

        /// return a reference to the value pointed to by the iterator
        inline reference operator*() const
        {
            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot get value");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    return m_it.object_iterator->second;
                }

                case (basic_json::value_t::array):
                {
                    return *m_it.array_iterator;
                }

                case (basic_json::value_t::null):
                {
                    throw std::out_of_range("cannot get value");
                }

                default:
                {
                    if (m_it.generic_iterator == generic_iterator_value::begin)
                    {
                        return *m_object;
                    }
                    else
                    {
                        throw std::out_of_range("cannot get value");
                    }
                }
            }
        }

        /// dereference the iterator
        inline pointer operator->() const
        {
            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot get value");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    return &(m_it.object_iterator->second);
                }

                case (basic_json::value_t::array):
                {
                    return &*m_it.array_iterator;
                }

                default:
                {
                    if (m_it.generic_iterator == generic_iterator_value::begin)
                    {
                        return m_object;
                    }
                    else
                    {
                        throw std::out_of_range("cannot get value");
                    }
                }
            }
        }

        /// post-increment (it++)
        inline iterator operator++(int)
        {
            iterator result = *this;

            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot increment iterator");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    m_it.object_iterator++;
                    break;
                }

                case (basic_json::value_t::array):
                {
                    m_it.array_iterator++;
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::end;
                    break;
                }
            }

            return result;
        }

        /// pre-increment (++it)
        inline iterator& operator++()
        {
            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot increment iterator");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    ++m_it.object_iterator;
                    break;
                }

                case (basic_json::value_t::array):
                {
                    ++m_it.array_iterator;
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::end;
                    break;
                }
            }

            return *this;
        }

        /// post-decrement (it--)
        inline iterator operator--(int)
        {
            iterator result = *this;

            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot decrement iterator");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    m_it.object_iterator--;
                    break;
                }

                case (basic_json::value_t::array):
                {
                    m_it.array_iterator--;
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::uninitialized;
                    break;
                }
            }

            return result;
        }

        /// pre-decrement (--it)
        inline iterator& operator--()
        {
            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot decrement iterator");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    --m_it.object_iterator;
                    break;
                }

                case (basic_json::value_t::array):
                {
                    --m_it.array_iterator;
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::uninitialized;
                    break;
                }
            }

            return *this;
        }

        /// comparison: equal
        inline bool operator==(const iterator& other) const
        {
            if (m_object == nullptr
                    or other.m_object == nullptr
                    or m_object != other.m_object
                    or m_object->m_type != other.m_object->m_type)
            {
                return false;
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    return (m_it.object_iterator == other.m_it.object_iterator);
                }

                case (basic_json::value_t::array):
                {
                    return (m_it.array_iterator == other.m_it.array_iterator);
                }

                default:
                {
                    return (m_it.generic_iterator == other.m_it.generic_iterator);
                }
            }
        }

        /// comparison: not equal
        inline bool operator!=(const iterator& other) const
        {
            return not operator==(other);
        }

      private:
        /// associated JSON instance
        pointer m_object = nullptr;
        /// the actual iterator of the associated instance
        internal_iterator m_it;
    };

    /// a const bidirectional iterator for the basic_json class
    class const_iterator : public std::iterator<std::bidirectional_iterator_tag, const basic_json>
    {
      public:
        /// the type of the values when the iterator is dereferenced
        using value_type = basic_json::value_type;
        /// a type to represent differences between iterators
        using difference_type = basic_json::difference_type;
        /// defines a pointer to the type iterated over (value_type)
        using pointer = basic_json::const_pointer;
        /// defines a reference to the type iterated over (value_type)
        using reference = basic_json::const_reference;
        /// the category of the iterator
        using iterator_category = std::bidirectional_iterator_tag;

        /// values of a generic iterator type of non-container JSON values
        enum class generic_iterator_value
        {
            /// the iterator was not initialized
            uninitialized,
            /// the iterator points to the only value
            begin,
            /// the iterator points past the only value
            end
        };

        /// an iterator value
        union internal_const_iterator
        {
            /// iterator for JSON objects
            typename object_t::const_iterator object_iterator;
            /// iterator for JSON arrays
            typename array_t::const_iterator array_iterator;
            /// generic iteraotr for all other value types
            generic_iterator_value generic_iterator;

            /// default constructor
            internal_const_iterator() : generic_iterator(generic_iterator_value::uninitialized) {}
            /// constructor for object iterators
            internal_const_iterator(typename object_t::iterator v) : object_iterator(v) {}
            /// constructor for array iterators
            internal_const_iterator(typename array_t::iterator v) : array_iterator(v) {}
            /// constructor for generic iterators
            internal_const_iterator(generic_iterator_value v) : generic_iterator(v) {}
        };

        /// constructor for a given JSON instance
        inline const_iterator(pointer object) : m_object(object)
        {
            if (m_object == nullptr)
            {
                throw std::logic_error("cannot create iterator");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    m_it.object_iterator = typename object_t::const_iterator();
                    break;
                }
                case (basic_json::value_t::array):
                {
                    m_it.array_iterator = typename array_t::const_iterator();
                    break;
                }
                default:
                {
                    m_it.generic_iterator = generic_iterator_value::uninitialized;
                    break;
                }
            }
        }

        inline const_iterator(const iterator& other) : m_object(other.m_object), m_it(other.m_it)
        {}

        /// copy assignment
        inline const_iterator operator=(const const_iterator& other) noexcept
        {
            m_object = other.m_object;
            m_it = other.m_it;
            return *this;
        }

        /// set the iterator to the first value
        inline void set_begin() noexcept
        {
            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    m_it.object_iterator = m_object->m_value.object->cbegin();
                    break;
                }

                case (basic_json::value_t::array):
                {
                    m_it.array_iterator = m_object->m_value.array->cbegin();
                    break;
                }

                case (basic_json::value_t::null):
                {
                    m_it.generic_iterator = generic_iterator_value::end;
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::begin;
                    break;
                }
            }
        }

        /// set the iterator past the last value
        inline void set_end() noexcept
        {
            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    m_it.object_iterator = m_object->m_value.object->cend();
                    break;
                }

                case (basic_json::value_t::array):
                {
                    m_it.array_iterator = m_object->m_value.array->cend();
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::end;
                    break;
                }
            }
        }

        /// return a reference to the value pointed to by the iterator
        inline reference operator*() const
        {
            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot get value");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    return m_it.object_iterator->second;
                }

                case (basic_json::value_t::array):
                {
                    return *m_it.array_iterator;
                }

                case (basic_json::value_t::null):
                {
                    throw std::out_of_range("cannot get value");
                }

                default:
                {
                    if (m_it.generic_iterator == generic_iterator_value::begin)
                    {
                        return *m_object;
                    }
                    else
                    {
                        throw std::out_of_range("cannot get value");
                    }
                }
            }
        }

        /// dereference the iterator
        inline pointer operator->() const
        {
            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot get value");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    return &(m_it.object_iterator->second);
                }

                case (basic_json::value_t::array):
                {
                    return &*m_it.array_iterator;
                }

                default:
                {
                    if (m_it.generic_iterator == generic_iterator_value::begin)
                    {
                        return m_object;
                    }
                    else
                    {
                        throw std::out_of_range("cannot get value");
                    }
                }
            }
        }

        /// post-increment (it++)
        inline const_iterator operator++(int)
        {
            const_iterator result = *this;

            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot increment iterator");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    m_it.object_iterator++;
                    break;
                }

                case (basic_json::value_t::array):
                {
                    m_it.array_iterator++;
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::end;
                    break;
                }
            }

            return result;
        }

        /// pre-increment (++it)
        inline const_iterator& operator++()
        {
            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot increment iterator");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    ++m_it.object_iterator;
                    break;
                }

                case (basic_json::value_t::array):
                {
                    ++m_it.array_iterator;
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::end;
                    break;
                }
            }

            return *this;
        }

        /// post-decrement (it--)
        inline const_iterator operator--(int)
        {
            iterator result = *this;

            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot decrement iterator");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    m_it.object_iterator--;
                    break;
                }

                case (basic_json::value_t::array):
                {
                    m_it.array_iterator--;
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::uninitialized;
                    break;
                }
            }

            return result;
        }

        /// pre-decrement (--it)
        inline const_iterator& operator--()
        {
            if (m_object == nullptr)
            {
                throw std::out_of_range("cannot decrement iterator");
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    --m_it.object_iterator;
                    break;
                }

                case (basic_json::value_t::array):
                {
                    --m_it.array_iterator;
                    break;
                }

                default:
                {
                    m_it.generic_iterator = generic_iterator_value::uninitialized;
                    break;
                }
            }

            return *this;
        }

        /// comparison: equal
        inline bool operator==(const const_iterator& other) const
        {
            if (m_object == nullptr
                    or other.m_object == nullptr
                    or m_object != other.m_object
                    or m_object->m_type != other.m_object->m_type)
            {
                return false;
            }

            switch (m_object->m_type)
            {
                case (basic_json::value_t::object):
                {
                    return (m_it.object_iterator == other.m_it.object_iterator);
                }

                case (basic_json::value_t::array):
                {
                    return (m_it.array_iterator == other.m_it.array_iterator);
                }

                default:
                {
                    return (m_it.generic_iterator == other.m_it.generic_iterator);
                }
            }
        }

        /// comparison: not equal
        inline bool operator!=(const const_iterator& other) const
        {
            return not operator==(other);
        }

      private:
        /// associated JSON instance
        pointer m_object = nullptr;
        /// the actual iterator of the associated instance
        internal_const_iterator m_it;
    };
};


/////////////
// presets //
/////////////

/// default JSON class
using json = basic_json<>;

}


/////////////////////////
// nonmember functions //
/////////////////////////

// specialization of std::swap, and std::hash
namespace std
{
/// swaps the values of two JSON objects
template <>
inline void swap(nlohmann::json& j1,
                 nlohmann::json& j2) noexcept(
                     is_nothrow_move_constructible<nlohmann::json>::value and
                     is_nothrow_move_assignable<nlohmann::json>::value
                 )
{
    j1.swap(j2);
}

/// hash value for JSON objects
template <>
struct hash<nlohmann::json>
{
    size_t operator()(const nlohmann::json& j) const
    {
        // a naive hashing via the string representation
        return hash<std::string>()(j.dump());
    }
};
}

#endif