json.hpp

/*!
@file
@copyright The code is licensed under the MIT License
           <http://opensource.org/licenses/MIT>,
           Copyright (c) 2013-2015 Niels Lohmann.
@author Niels Lohmann <http://nlohmann.me>
@see https://github.com/nlohmann/json
*/

#ifndef _NLOHMANN_JSON
#define _NLOHMANN_JSON

#include <algorithm>
#include <cmath>
#include <cstdio>
#include <functional>
#include <initializer_list>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <limits>
#include <map>
#include <memory>
#include <sstream>
#include <string>
#include <type_traits>
#include <utility>
#include <vector>

/*!
@brief namespace for Niels Lohmann
@see https://github.com/nlohmann
*/
namespace nlohmann
{


// Helper to determine whether there's a key_type for T.
// http://stackoverflow.com/a/7728728/266378
template<typename T>
struct has_mapped_type
{
  private:
    template<typename C> static char test(typename C::mapped_type*);
    template<typename C> static int  test(...);
  public:
    enum { value = sizeof(test<T>(0)) == sizeof(char) };
};

/*!
@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)
@tparam AllocatorType      type of the allocator to use
                           (@c std::allocator by default)

@note ObjectType trick from http://stackoverflow.com/a/9860911

@see RFC 7159 <http://rfc7159.net/rfc7159>
@see ECMA 404 <http://www.ecma-international.org/publications/standards/Ecma-404.htm>
*/
template <
    template<typename U, typename V, typename... Args> class ObjectType = std::map,
    template<typename U, typename... Args> class ArrayType = std::vector,
    class StringType = std::string,
    class BooleanType = bool,
    class NumberIntegerType = int64_t,
    class NumberFloatType = double,
    template<typename U> class AllocatorType = std::allocator
    >
class basic_json
{
  public:
    /////////////////////
    // container types //
    /////////////////////

    // forward declarations
    class iterator;
    class const_iterator;
    class reverse_iterator;
    class const_reverse_iterator;

    /*!
    @brief the type of elements in a basic_json container
    @ingroup container
    */
    using value_type = basic_json;

    /*!
    @brief the type of an element reference
    @ingroup container
    */
    using reference = value_type&;

    /*!
    @brief the type of an element const reference
    @ingroup container
    */
    using const_reference = const value_type&;

    /*!
    @brief a type to represent differences between iterators
    @ingroup container
    */
    using difference_type = std::ptrdiff_t;

    /*!
    @brief a type to represent container sizes
    @ingroup container
    */
    using size_type = std::size_t;

    /// the allocator type
    using allocator_type = AllocatorType<basic_json>;

    /// the type of an element pointer
    using pointer = typename std::allocator_traits<allocator_type>::pointer;
    /// the type of an element const pointer
    using const_pointer = typename std::allocator_traits<allocator_type>::const_pointer;

    /*!
    @brief an iterator for a basic_json container
    @ingroup container
    */
    using iterator = basic_json::iterator;

    /*!
    @brief a const iterator for a basic_json container
    @ingroup container
    */
    using const_iterator = basic_json::const_iterator;

    /*!
    @brief a reverse iterator for a basic_json container
    @ingroup reversiblecontainer
    */
    using reverse_iterator = basic_json::reverse_iterator;

    /*!
    @brief a const reverse iterator for a basic_json container
    @ingroup reversiblecontainer
    */
    using const_reverse_iterator = basic_json::const_reverse_iterator;


    /// returns the allocator associated with the container
    inline static allocator_type get_allocator()
    {
        return allocator_type();
    }


    ///////////////////////////
    // 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 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,           ///< null value
        object,         ///< object (unordered set of name/value pairs)
        array,          ///< array (ordered collection of values)
        string,         ///< string value
        boolean,        ///< boolean value
        number_integer, ///< number value (integer)
        number_float    ///< number value (floating-point)
    };

    /*!
    @brief comparison operator for JSON value types

    Returns an ordering that is similar to Python:
    - order: null < boolean < number < object < array < string
    - furthermore, each type is not smaller than itself
    */
    friend bool operator<(const value_t lhs, const value_t rhs)
    {
        // no type is smaller than itself
        if (lhs == rhs)
        {
            return false;
        }

        switch (lhs)
        {
            case (value_t::null):
            {
                // nulls are smaller than all other types
                return true;
            }

            case (value_t::boolean):
            {
                // only nulls are smaller than booleans
                return (rhs != value_t::null);
            }

            case (value_t::number_float):
            case (value_t::number_integer):
            {
                switch (rhs)
                {
                    // numbers are smaller than objects, arrays, and string
                    case (value_t::object):
                    case (value_t::array):
                    case (value_t::string):
                    {
                        return true;
                    }

                    default:
                    {
                        return false;
                    }
                }
            }

            case (value_t::object):
            {
                switch (rhs)
                {
                    // objects are smaller than arrays and string
                    case (value_t::array):
                    case (value_t::string):
                    {
                        return true;
                    }

                    default:
                    {
                        return false;
                    }
                }
            }

            case (value_t::array):
            {
                // arrays are smaller than strings
                return (rhs == value_t::string);
            }

            default:
            {
                // a string is not smaller than any other types
                return false;
            }
        }
    }


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

    /*!
    @brief create an empty value with a given type
    @param value  the type to create an value of

    @exception std::bad_alloc  if allocation for object, array, or string fails.
    */
    inline basic_json(const value_t value)
        : m_type(value)
    {
        switch (m_type)
        {
            case (value_t::null):
            {
                break;
            }

            case (value_t::object):
            {
                AllocatorType<object_t> alloc;
                m_value.object = alloc.allocate(1);
                alloc.construct(m_value.object);
                break;
            }

            case (value_t::array):
            {
                AllocatorType<array_t> alloc;
                m_value.array = alloc.allocate(1);
                alloc.construct(m_value.array);
                break;
            }

            case (value_t::string):
            {
                AllocatorType<string_t> alloc;
                m_value.string = alloc.allocate(1);
                alloc.construct(m_value.string, "");
                break;
            }

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

            case (value_t::number_integer):
            {
                m_value.number_integer = number_integer_t(0);
                break;
            }

            case (value_t::number_float):
            {
                m_value.number_float = number_float_t(0.0);
                break;
            }
        }
    }

    /*!
    @brief create a null object (implicitly)
    @ingroup container
    */
    inline basic_json() noexcept = default;

    /// 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)
    {
        AllocatorType<object_t> alloc;
        m_value.object = alloc.allocate(1);
        alloc.construct(m_value.object, value);
    }

    /// create an object (implicit)
    template <class V, typename
              std::enable_if<
                  std::is_constructible<typename object_t::key_type, 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)
    {
        AllocatorType<object_t> alloc;
        m_value.object = alloc.allocate(1);
        using std::begin;
        using std::end;
        alloc.construct(m_value.object, begin(value), end(value));
    }

    /// create an array (explicit)
    inline basic_json(const array_t& value)
        : m_type(value_t::array)
    {
        AllocatorType<array_t> alloc;
        m_value.array = alloc.allocate(1);
        alloc.construct(m_value.array, 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
                  not std::is_same<V, basic_json::reverse_iterator>::value and
                  not std::is_same<V, basic_json::const_reverse_iterator>::value and
                  not std::is_same<V, typename array_t::iterator>::value and
                  not std::is_same<V, typename array_t::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)
    {
        AllocatorType<array_t> alloc;
        m_value.array = alloc.allocate(1);
        using std::begin;
        using std::end;
        alloc.construct(m_value.array, begin(value), end(value));
    }

    /// create a string (explicit)
    inline basic_json(const string_t& value)
        : m_type(value_t::string)
    {
        AllocatorType<string_t> alloc;
        m_value.string = alloc.allocate(1);
        alloc.construct(m_value.string, value);
    }

    /// create a string (explicit)
    inline basic_json(const typename string_t::value_type* value)
        : m_type(value_t::string)
    {
        AllocatorType<string_t> alloc;
        m_value.string = alloc.allocate(1);
        alloc.construct(m_value.string, 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))
    {}

    /// create a container (array or object) from an initializer list
    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 from initializer list");
            }
        }

        if (is_object)
        {
            // the initializer list is a list of pairs -> create object
            m_type = value_t::object;
            AllocatorType<object_t> alloc;
            m_value.object = alloc.allocate(1);
            alloc.construct(m_value.object);

            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;
            AllocatorType<array_t> alloc;
            m_value.array = alloc.allocate(1);
            alloc.construct(m_value.array, std::move(l));
        }
    }

    /// explicitly create an array from an initializer list
    inline static basic_json array(list_init_t l = list_init_t())
    {
        return basic_json(l, false, value_t::array);
    }

    /// explicitly create an object from an initializer list
    inline static basic_json object(list_init_t l = list_init_t())
    {
        return basic_json(l, false, value_t::object);
    }

    /// construct an array with count copies of given value
    inline basic_json(size_type count, const basic_json& other)
        : m_type(value_t::array)
    {
        AllocatorType<array_t> alloc;
        m_value.array = alloc.allocate(1);
        alloc.construct(m_value.array, count, other);
    }

    /// construct a JSON container given an iterator range
    template <class T, typename
              std::enable_if<
                  std::is_same<T, basic_json::iterator>::value or
                  std::is_same<T, basic_json::const_iterator>::value
                  , int>::type
              = 0>
    inline basic_json(T first, T last)
    {
        // make sure iterator fits the current value
        if (first.m_object != last.m_object or
                first.m_object->m_type != last.m_object->m_type)
        {
            throw std::runtime_error("iterators are not compatible");
        }

        // set the type
        m_type = first.m_object->m_type;

        // check if iterator range is complete for non-compound values
        switch (m_type)
        {
            case value_t::number_integer:
            case value_t::number_float:
            case value_t::boolean:
            case value_t::string:
            {
                if (first.m_it.generic_iterator != 0 or last.m_it.generic_iterator != 1)
                {
                    throw std::out_of_range("iterators out of range");
                }
                break;
            }

            default:
            {
                break;
            }
        }

        switch (m_type)
        {
            case value_t::number_integer:
            {
                m_value.number_integer = first.m_object->m_value.number_integer;
                break;
            }

            case value_t::number_float:
            {
                m_value.number_float = first.m_object->m_value.number_float;
                break;
            }

            case value_t::boolean:
            {
                m_value.boolean = first.m_object->m_value.boolean;
                break;
            }

            case value_t::string:
            {
                AllocatorType<string_t> alloc;
                m_value.string = alloc.allocate(1);
                alloc.construct(m_value.string, *first.m_object->m_value.string);
                break;
            }

            case value_t::object:
            {
                AllocatorType<object_t> alloc;
                m_value.object = alloc.allocate(1);
                alloc.construct(m_value.object, first.m_it.object_iterator, last.m_it.object_iterator);
                break;
            }

            case value_t::array:
            {
                AllocatorType<array_t> alloc;
                m_value.array = alloc.allocate(1);
                alloc.construct(m_value.array, first.m_it.array_iterator, last.m_it.array_iterator);
                break;
            }

            default:
            {
                throw std::runtime_error("cannot use construct with iterators from " + first.m_object->type_name());
            }
        }
    }

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

    /*!
    @brief copy constructor

    @exception std::bad_alloc  if allocation for object, array, or string fails.

    @ingroup container
    */
    inline basic_json(const basic_json& other)
        : m_type(other.m_type)
    {
        switch (m_type)
        {
            case (value_t::null):
            {
                break;
            }

            case (value_t::object):
            {
                AllocatorType<object_t> alloc;
                m_value.object = alloc.allocate(1);
                alloc.construct(m_value.object, *other.m_value.object);
                break;
            }

            case (value_t::array):
            {
                AllocatorType<array_t> alloc;
                m_value.array = alloc.allocate(1);
                alloc.construct(m_value.array, *other.m_value.array);
                break;
            }

            case (value_t::string):
            {
                AllocatorType<string_t> alloc;
                m_value.string = alloc.allocate(1);
                alloc.construct(m_value.string, *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))
    {
        // invalidate payload
        other.m_type = value_t::null;
        other.m_value = {};
    }

    /*!
    @brief copy assignment
    @ingroup container
    */
    inline reference& operator=(basic_json other) noexcept (
        std::is_nothrow_move_constructible<value_t>::value and
        std::is_nothrow_move_assignable<value_t>::value and
        std::is_nothrow_move_constructible<json_value>::value and
        std::is_nothrow_move_assignable<json_value>::value
    )
    {
        std::swap(m_type, other.m_type);
        std::swap(m_value, other.m_value);
        return *this;
    }

    /*!
    @brief destructor
    @ingroup container
    */
    inline ~basic_json() noexcept
    {
        switch (m_type)
        {
            case (value_t::object):
            {
                AllocatorType<object_t> alloc;
                alloc.destroy(m_value.object);
                alloc.deallocate(m_value.object, 1);
                m_value.object = nullptr;
                break;
            }

            case (value_t::array):
            {
                AllocatorType<array_t> alloc;
                alloc.destroy(m_value.array);
                alloc.deallocate(m_value.array, 1);
                m_value.array = nullptr;
                break;
            }

            case (value_t::string):
            {
                AllocatorType<string_t> alloc;
                alloc.destroy(m_value.string);
                alloc.deallocate(m_value.string, 1);
                m_value.string = nullptr;
                break;
            }

            default:
            {
                // all other types need no specific destructor
                break;
            }
        }
    }


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

    /*!
    @brief serialization

    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  sif 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(const 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 (explicit)
    inline value_t type() const noexcept
    {
        return m_type;
    }

    // return whether value is null
    inline bool is_null() const noexcept
    {
        return m_type == value_t::null;
    }

    // return whether value is boolean
    inline bool is_boolean() const noexcept
    {
        return m_type == value_t::boolean;
    }

    // return whether value is number
    inline bool is_number() const noexcept
    {
        return (m_type == value_t::number_integer) or (m_type == value_t::number_float);
    }

    // return whether value is object
    inline bool is_object() const noexcept
    {
        return m_type == value_t::object;
    }

    // return whether value is array
    inline bool is_array() const noexcept
    {
        return m_type == value_t::array;
    }

    // return whether value is string
    inline bool is_string() const noexcept
    {
        return m_type == value_t::string;
    }

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

  private:
    //////////////////////
    // value conversion //
    //////////////////////

    /// get an object (explicit)
    template <class T, typename
              std::enable_if<
                  std::is_convertible<typename object_t::key_type, typename T::key_type>::value and
                  std::is_convertible<basic_json, typename T::mapped_type>::value
                  , int>::type = 0>
    inline T get_impl(T*) 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 object (explicit)
    inline object_t get_impl(object_t*) const
    {
        switch (m_type)
        {
            case (value_t::object):
            {
                return *(m_value.object);
            }
            default:
            {
                throw std::logic_error("cannot cast " + type_name() + " to object");
            }
        }
    }

    /// get an array (explicit)
    template <class T, typename
              std::enable_if<
                  std::is_convertible<basic_json, typename T::value_type>::value and
                  not std::is_same<basic_json, typename T::value_type>::value and
                  not std::is_arithmetic<T>::value and
                  not std::is_convertible<std::string, T>::value and
                  not has_mapped_type<T>::value
                  , int>::type = 0>
    inline T get_impl(T*) const
    {
        switch (m_type)
        {
            case (value_t::array):
            {
                T to_vector;
                std::transform(m_value.array->begin(), m_value.array->end(),
                               std::inserter(to_vector, to_vector.end()), [](basic_json i)
                {
                    return i.get<typename T::value_type>();
                });
                return to_vector;
            }
            default:
            {
                throw std::logic_error("cannot cast " + type_name() + " to " + typeid(T).name());
            }
        }
    }

    /// get an array (explicit)
    template <class T, typename
              std::enable_if<
                  std::is_convertible<basic_json, T>::value and
                  not std::is_same<basic_json, T>::value
                  , int>::type = 0>
    inline std::vector<T> get_impl(std::vector<T>*) const
    {
        switch (m_type)
        {
            case (value_t::array):
            {
                std::vector<T> to_vector;
                to_vector.reserve(m_value.array->size());
                std::transform(m_value.array->begin(), m_value.array->end(),
                               std::inserter(to_vector, to_vector.end()), [](basic_json i)
                {
                    return i.get<T>();
                });
                return to_vector;
            }
            default:
            {
                throw std::logic_error("cannot cast " + type_name() + " to " + typeid(T).name());
            }
        }
    }

    /// get an array (explicit)
    template <class T, typename
              std::enable_if<
                  std::is_same<basic_json, typename T::value_type>::value and
                  not has_mapped_type<T>::value
                  , int>::type = 0>