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diff --git a/ddl/lib/json.hpp b/ddl/lib/json.hpp
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+/*!
+@mainpage
+
+These pages contain the API documentation of JSON for Modern C++, a C++11
+header-only JSON class.
+
+Class @ref nlohmann::basic_json is a good entry point for the documentation.
+
+@copyright The code is licensed under the [MIT
+           License](http://opensource.org/licenses/MIT):
+           <br>
+           Copyright &copy; 2013-2015 Niels Lohmann.
+           <br>
+           Permission is hereby granted, free of charge, to any person
+           obtaining a copy of this software and associated documentation files
+           (the "Software"), to deal in the Software without restriction,
+           including without limitation the rights to use, copy, modify, merge,
+           publish, distribute, sublicense, and/or sell copies of the Software,
+           and to permit persons to whom the Software is furnished to do so,
+           subject to the following conditions:
+           <br>
+           The above copyright notice and this permission notice shall be
+           included in all copies or substantial portions of the Software.
+           <br>
+           THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+           EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+           MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+           NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+           BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+           ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+           CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+           SOFTWARE.
+
+@author [Niels Lohmann](http://nlohmann.me)
+@see https://github.com/nlohmann/json to download the source code
+*/
+
+#ifndef NLOHMANN_JSON_HPP
+#define NLOHMANN_JSON_HPP
+
+#include <algorithm>
+#include <array>
+#include <ciso646>
+#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>
+
+// enable ssize_t on MinGW
+#ifdef __GNUC__
+    #ifdef __MINGW32__
+        #include <sys/types.h>
+    #endif
+#endif
+
+// enable ssize_t for MSVC
+#ifdef _MSC_VER
+    #include <basetsd.h>
+    using ssize_t = SSIZE_T;
+#endif
+
+/*!
+@brief namespace for Niels Lohmann
+@see https://github.com/nlohmann
+*/
+namespace nlohmann
+{
+
+
+/*!
+@brief unnamed namespace with internal helper functions
+*/
+namespace
+{
+/*!
+@brief Helper to determine whether there's a key_type for T.
+@sa 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) };
+};
+
+/// "equality" comparison for floating point numbers
+template<typename T>
+static bool approx(const T a, const T b)
+{
+    return not (a > b or a < b);
+}
+}
+
+/*!
+@brief a class to store JSON values
+
+@tparam ObjectType type for JSON objects (@c std::map by default; will be used
+in @ref object_t)
+@tparam ArrayType type for JSON arrays (@c std::vector by default; will be used
+in @ref array_t)
+@tparam StringType type for JSON strings and object keys (@c std::string by
+default; will be used in @ref string_t)
+@tparam BooleanType type for JSON booleans (@c `bool` by default; will be used
+in @ref boolean_t)
+@tparam NumberIntegerType type for JSON integer numbers (@c `int64_t` by
+default; will be used in @ref number_integer_t)
+@tparam NumberFloatType type for JSON floating-point numbers (@c `double` by
+default; will be used in @ref number_float_t)
+@tparam AllocatorType type of the allocator to use (@c `std::allocator` by
+default)
+
+@requirement The class satisfies the following concept requirements:
+- Basic
+ - [DefaultConstructible](http://en.cppreference.com/w/cpp/concept/DefaultConstructible):
+   JSON values can be default constructed. The result will be a JSON null value.
+ - [MoveConstructible](http://en.cppreference.com/w/cpp/concept/MoveConstructible):
+   A JSON value can be constructed from an rvalue argument.
+ - [CopyConstructible](http://en.cppreference.com/w/cpp/concept/CopyConstructible):
+   A JSON value can be copy-constrcuted from an lvalue expression.
+ - [MoveAssignable](http://en.cppreference.com/w/cpp/concept/MoveAssignable):
+   A JSON value van be assigned from an rvalue argument.
+ - [CopyAssignable](http://en.cppreference.com/w/cpp/concept/CopyAssignable):
+   A JSON value can be copy-assigned from an lvalue expression.
+ - [Destructible](http://en.cppreference.com/w/cpp/concept/Destructible):
+   JSON values can be destructed.
+- Layout
+ - [StandardLayoutType](http://en.cppreference.com/w/cpp/concept/StandardLayoutType):
+   JSON values have
+   [standard layout](http://en.cppreference.com/w/cpp/language/data_members#Standard_layout):
+   All non-static data members are private and standard layout types, the class
+   has no virtual functions or (virtual) base classes.
+- Library-wide
+ - [EqualityComparable](http://en.cppreference.com/w/cpp/concept/EqualityComparable):
+   JSON values can be compared with `==`, see @ref
+   operator==(const_reference,const_reference).
+ - [LessThanComparable](http://en.cppreference.com/w/cpp/concept/LessThanComparable):
+   JSON values can be compared with `<`, see @ref
+   operator<(const_reference,const_reference).
+ - [Swappable](http://en.cppreference.com/w/cpp/concept/Swappable):
+   Any JSON lvalue or rvalue of can be swapped with any lvalue or rvalue of
+   other compatible types, using unqualified function call @ref swap().
+ - [NullablePointer](http://en.cppreference.com/w/cpp/concept/NullablePointer):
+   JSON values can be compared against `std::nullptr_t` objects which are used
+   to model the `null` value.
+- Container
+ - [Container](http://en.cppreference.com/w/cpp/concept/Container):
+   JSON values can be used like STL containers and provide iterator access.
+ - [ReversibleContainer](http://en.cppreference.com/w/cpp/concept/ReversibleContainer);
+   JSON values can be used like STL containers and provide reverse iterator
+   access.
+
+@internal
+@note ObjectType trick from http://stackoverflow.com/a/9860911
+@endinternal
+
+@see RFC 7159 <http://rfc7159.net/rfc7159>
+*/
+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
+{
+  private:
+    /// workaround type for MSVC
+    using basic_json_t = basic_json<ObjectType,
+          ArrayType,
+          StringType,
+          BooleanType,
+          NumberIntegerType,
+          NumberFloatType,
+          AllocatorType>;
+
+  public:
+
+    /////////////////////
+    // container types //
+    /////////////////////
+
+    /// @name container types
+    /// @{
+
+    /// the type of elements in a basic_json container
+    using value_type = basic_json;
+
+    /// the type of an element reference
+    using reference = value_type&;
+
+    /// the type of an element const reference
+    using const_reference = const value_type&;
+
+    /// 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;
+
+    /// 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;
+
+    // forward declaration
+    template<typename Base> class json_reverse_iterator;
+
+    /// an iterator for a basic_json container
+    class iterator;
+    /// a const iterator for a basic_json container
+    class const_iterator;
+    /// a reverse iterator for a basic_json container
+    using reverse_iterator = json_reverse_iterator<typename basic_json::iterator>;
+    /// a const reverse iterator for a basic_json container
+    using const_reverse_iterator = json_reverse_iterator<typename basic_json::const_iterator>;
+
+    /// @}
+
+
+    /*!
+    @brief returns the allocator associated with the container
+    */
+    static allocator_type get_allocator()
+    {
+        return allocator_type();
+    }
+
+
+    ///////////////////////////
+    // JSON value data types //
+    ///////////////////////////
+
+    /// @name JSON value data types
+    /// @{
+
+    /*!
+    @brief a type for an object
+
+    [RFC 7159](http://rfc7159.net/rfc7159) describes JSON objects as follows:
+    > An object is an unordered collection of zero or more name/value pairs,
+    > where a name is a string and a value is a string, number, boolean, null,
+    > object, or array.
+
+    To store objects in C++, a type is defined by the template parameters @a
+    ObjectType which chooses the container (e.g., `std::map` or
+    `std::unordered_map`), @a StringType which chooses the type of the keys or
+    names, and @a AllocatorType which chooses the allocator to use.
+
+    #### Default type
+
+    With the default values for @a ObjectType (`std::map`), @a StringType
+    (`std::string`), and @a AllocatorType (`std::allocator`), the default value
+    for @a object_t is:
+
+    @code {.cpp}
+    std::map<
+      std::string, // key_type
+      basic_json, // value_type
+      std::less<std::string>, // key_compare
+      std::allocator<std::pair<const std::string, basic_json>> // allocator_type
+    >
+    @endcode
+
+    #### Behavior
+
+    The choice of @a object_t influences the behavior of the JSON class. With
+    the default type, objects have the following behavior:
+
+    - When all names are unique, objects will be interoperable in the sense
+      that all software implementations receiving that object will agree on the
+      name-value mappings.
+    - When the names within an object are not unique, later stored name/value
+      pairs overwrite previously stored name/value pairs, leaving the used
+      names unique. For instance, `{"key": 1}` and `{"key": 2, "key": 1}` will
+      be treated as equal and both stored as `{"key": 1}`.
+    - Internally, name/value pairs are stored in lexicographical order of the
+      names. Objects will also be serialized (see @ref dump) in this order. For
+      instance, `{"b": 1, "a": 2}` and `{"a": 2, "b": 1}` will be stored and
+      serialized as `{"a": 2, "b": 1}`.
+    - When comparing objects, the order of the name/value pairs is irrelevant.
+      This makes objects interoperable in the sense that they will not be
+      affected by these differences. For instance, `{"b": 1, "a": 2}` and
+      `{"a": 2, "b": 1}` will be treated as equal.
+
+    #### Limits
+
+    [RFC 7159](http://rfc7159.net/rfc7159) specifies:
+    > An implementation may set limits on the maximum depth of nesting.
+
+    In this class, the object's limit of nesting is not constraint explicitly.
+    However, a maximum depth of nesting may be introduced by the compiler or
+    runtime environment. A theoretical limit can be queried by calling the @ref
+    max_size function of a JSON object.
+
+    #### Storage
+
+    Objects are stored as pointers in a `basic_json` type. That is, for any
+    access to object values, a pointer of type `object_t*` must be dereferenced.
+
+    @sa array_t
+    */
+    using object_t = ObjectType<StringType,
+          basic_json,
+          std::less<StringType>,
+          AllocatorType<std::pair<const StringType,
+          basic_json>>>;
+
+    /*!
+    @brief a type for an array
+
+    [RFC 7159](http://rfc7159.net/rfc7159) describes JSON arrays as follows:
+    > An array is an ordered sequence of zero or more values.
+
+    To store objects in C++, a type is defined by the template parameters @a
+    ArrayType which chooses the container (e.g., `std::vector` or `std::list`)
+    and @a AllocatorType which chooses the allocator to use.
+
+    #### Default type
+
+    With the default values for @a ArrayType (`std::vector`) and @a
+    AllocatorType (`std::allocator`), the default value for @a array_t is:
+
+    @code {.cpp}
+    std::vector<
+      basic_json, // value_type
+      std::allocator<basic_json> // allocator_type
+    >
+    @endcode
+
+    #### Limits
+
+    [RFC 7159](http://rfc7159.net/rfc7159) specifies:
+    > An implementation may set limits on the maximum depth of nesting.
+
+    In this class, the array's limit of nesting is not constraint explicitly.
+    However, a maximum depth of nesting may be introduced by the compiler or
+    runtime environment. A theoretical limit can be queried by calling the @ref
+    max_size function of a JSON array.
+
+    #### Storage
+
+    Arrays are stored as pointers in a `basic_json` type. That is, for any
+    access to array values, a pointer of type `array_t*` must be dereferenced.
+    */
+    using array_t = ArrayType<basic_json, AllocatorType<basic_json>>;
+
+    /*!
+    @brief a type for a string
+
+    [RFC 7159](http://rfc7159.net/rfc7159) describes JSON strings as follows:
+    > A string is a sequence of zero or more Unicode characters.
+
+    To store objects in C++, a type is defined by the template parameters @a
+    StringType which chooses the container (e.g., `std::string`) to use.
+
+    Unicode values are split by the JSON class into byte-sized characters
+    during deserialization.
+
+    #### Default type
+
+    With the default values for @a StringType (`std::string`), the default
+    value for @a string_t is:
+
+    @code {.cpp}
+    std::string
+    @endcode
+
+    #### String comparison
+
+    [RFC 7159](http://rfc7159.net/rfc7159) states:
+    > Software implementations are typically required to test names of object
+    > members for equality. Implementations that transform the textual
+    > representation into sequences of Unicode code units and then perform the
+    > comparison numerically, code unit by code unit, are interoperable in the
+    > sense that implementations will agree in all cases on equality or
+    > inequality of two strings. For example, implementations that compare
+    > strings with escaped characters unconverted may incorrectly find that
+    > `"a\\b"` and `"a\u005Cb"` are not equal.
+
+    This implementation is interoperable as it does compare strings code unit
+    by code unit.
+
+    #### Storage
+
+    String values are stored as pointers in a `basic_json` type. That is, for
+    any access to string values, a pointer of type `string_t*` must be
+    dereferenced.
+    */
+    using string_t = StringType;
+
+    /*!
+    @brief a type for a boolean
+
+    [RFC 7159](http://rfc7159.net/rfc7159) implicitly describes a boolean as a
+    type which differentiates the two literals `true` and `false`.
+
+    To store objects in C++, a type is defined by the template parameter @a
+    BooleanType which chooses the type to use.
+
+    #### Default type
+
+    With the default values for @a BooleanType (`bool`), the default value for
+    @a boolean_t is:
+
+    @code {.cpp}
+    bool
+    @endcode
+
+    #### Storage
+
+    Boolean values are stored directly inside a `basic_json` type.
+    */
+    using boolean_t = BooleanType;
+
+    /*!
+    @brief a type for a number (integer)
+
+    [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows:
+    > The representation of numbers is similar to that used in most programming
+    > languages. A number is represented in base 10 using decimal digits. It
+    > contains an integer component that may be prefixed with an optional minus
+    > sign, which may be followed by a fraction part and/or an exponent part.
+    > Leading zeros are not allowed. (...) Numeric values that cannot be
+    > represented in the grammar below (such as Infinity and NaN) are not
+    > permitted.
+
+    This description includes both integer and floating-point numbers. However,
+    C++ allows more precise storage if it is known whether the number is an
+    integer or a floating-point number. Therefore, two different types, @ref
+    number_integer_t and @ref number_float_t are used.
+
+    To store integer numbers in C++, a type is defined by the template
+    parameter @a NumberIntegerType which chooses the type to use.
+
+    #### Default type
+
+    With the default values for @a NumberIntegerType (`int64_t`), the default
+    value for @a number_integer_t is:
+
+    @code {.cpp}
+    int64_t
+    @endcode
+
+    #### Default behavior
+
+    - The restrictions about leading zeros is not enforced in C++. Instead,
+      leading zeros in integer literals lead to an interpretation as octal
+      number. Internally, the value will be stored as decimal number. For
+      instance, the C++ integer literal `010` will be serialized to `8`. During
+      deserialization, leading zeros yield an error.
+    - Not-a-number (NaN) values will be serialized to `null`.
+
+    #### Limits
+
+    [RFC 7159](http://rfc7159.net/rfc7159) specifies:
+    > An implementation may set limits on the range and precision of numbers.
+
+    When the default type is used, the maximal integer number that can be
+    stored is `9223372036854775807` (INT64_MAX) and the minimal integer number
+    that can be stored is `-9223372036854775808` (INT64_MIN). Integer numbers
+    that are out of range will yield over/underflow when used in a constructor.
+    During deserialization, too large or small integer numbers will be
+    automatically be stored as @ref number_float_t.
+
+    [RFC 7159](http://rfc7159.net/rfc7159) further states:
+    > Note that when such software is used, numbers that are integers and are
+    > in the range \f$[-2^{53}+1, 2^{53}-1]\f$ are interoperable in the sense
+    > that implementations will agree exactly on their numeric values.
+
+    As this range is a subrange of the exactly supported range [INT64_MIN,
+    INT64_MAX], this class's integer type is interoperable.
+
+    #### Storage
+
+    Integer number values are stored directly inside a `basic_json` type.
+    */
+    using number_integer_t = NumberIntegerType;
+
+    /*!
+    @brief a type for a number (floating-point)
+
+    [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows:
+    > The representation of numbers is similar to that used in most programming
+    > languages. A number is represented in base 10 using decimal digits. It
+    > contains an integer component that may be prefixed with an optional minus
+    > sign, which may be followed by a fraction part and/or an exponent part.
+    > Leading zeros are not allowed. (...) Numeric values that cannot be
+    > represented in the grammar below (such as Infinity and NaN) are not
+    > permitted.
+
+    This description includes both integer and floating-point numbers. However,
+    C++ allows more precise storage if it is known whether the number is an
+    integer or a floating-point number. Therefore, two different types, @ref
+    number_integer_t and @ref number_float_t are used.
+
+    To store floating-point numbers in C++, a type is defined by the template
+    parameter @a NumberFloatType which chooses the type to use.
+
+    #### Default type
+
+    With the default values for @a NumberFloatType (`double`), the default
+    value for @a number_float_t is:
+
+    @code {.cpp}
+    double
+    @endcode
+
+    #### Default behavior
+
+    - The restrictions about leading zeros is not enforced in C++. Instead,
+      leading zeros in floating-point literals will be ignored. Internally, the
+      value will be stored as decimal number. For instance, the C++
+      floating-point literal `01.2` will be serialized to `1.2`. During
+      deserialization, leading zeros yield an error.
+    - Not-a-number (NaN) values will be serialized to `null`.
+
+    #### Limits
+
+    [RFC 7159](http://rfc7159.net/rfc7159) states:
+    > This specification allows implementations to set limits on the range and
+    > precision of numbers accepted. Since software that implements IEEE
+    > 754-2008 binary64 (double precision) numbers is generally available and
+    > widely used, good interoperability can be achieved by implementations that
+    > expect no more precision or range than these provide, in the sense that
+    > implementations will approximate JSON numbers within the expected
+    > precision.
+
+    This implementation does exactly follow this approach, as it uses double
+    precision floating-point numbers. Note values smaller than
+    `-1.79769313486232e+308` and values greather than `1.79769313486232e+308`
+    will be stored as NaN internally and be serialized to `null`.
+
+    #### Storage
+
+    Floating-point number values are stored directly inside a `basic_json` type.
+    */
+    using number_float_t = NumberFloatType;
+
+    /// @}
+
+
+    ///////////////////////////
+    // JSON type enumeration //
+    ///////////////////////////
+
+    /*!
+    @brief the JSON type enumeration
+
+    This enumeration collects the different JSON types. It is internally used
+    to distinguish the stored values, and the functions is_null, is_object,
+    is_array, is_string, is_boolean, is_number, and is_discarded rely on it.
+    */
+    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)
+        discarded       ///< discarded by the the parser callback function
+    };
+
+
+  private:
+    ////////////////////////
+    // 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;
+        /// boolean
+        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() noexcept = default;
+        /// constructor for booleans
+        json_value(boolean_t v) noexcept : boolean(v) {}
+        /// constructor for numbers (integer)
+        json_value(number_integer_t v) noexcept : number_integer(v) {}
+        /// constructor for numbers (floating-point)
+        json_value(number_float_t v) noexcept : number_float(v) {}
+        /// constructor for empty values of a given type
+        json_value(value_t t)
+        {
+            switch (t)
+            {
+                case (value_t::null):
+                case (value_t::discarded):
+                {
+                    break;
+                }
+
+                case (value_t::object):
+                {
+                    AllocatorType<object_t> alloc;
+                    object = alloc.allocate(1);
+                    alloc.construct(object);
+                    break;
+                }
+
+                case (value_t::array):
+                {
+                    AllocatorType<array_t> alloc;
+                    array = alloc.allocate(1);
+                    alloc.construct(array);
+                    break;
+                }
+
+                case (value_t::string):
+                {
+                    AllocatorType<string_t> alloc;
+                    string = alloc.allocate(1);
+                    alloc.construct(string, "");
+                    break;
+                }
+
+                case (value_t::boolean):
+                {
+                    boolean = boolean_t(false);
+                    break;
+                }
+
+                case (value_t::number_integer):
+                {
+                    number_integer = number_integer_t(0);
+                    break;
+                }
+
+                case (value_t::number_float):
+                {
+                    number_float = number_float_t(0.0);
+                    break;
+                }
+            }
+        }
+
+        /// constructor for strings
+        json_value(const string_t& value)
+        {
+            AllocatorType<string_t> alloc;
+            string = alloc.allocate(1);
+            alloc.construct(string, value);
+        }
+
+        /// constructor for objects
+        json_value(const object_t& value)
+        {
+            AllocatorType<object_t> alloc;
+            object = alloc.allocate(1);
+            alloc.construct(object, value);
+        }
+
+        /// constructor for arrays
+        json_value(const array_t& value)
+        {
+            AllocatorType<array_t> alloc;
+            array = alloc.allocate(1);
+            alloc.construct(array, value);
+        }
+    };
+
+
+  public:
+    //////////////////////////
+    // JSON parser callback //
+    //////////////////////////
+
+    /*!
+    @brief JSON callback events
+
+    This enumeration lists the parser events that can trigger calling a
+    callback function of type @ref parser_callback_t during parsing.
+    */
+    enum class parse_event_t : uint8_t
+    {
+        /// the parser read `{` and started to process a JSON object
+        object_start,
+        /// the parser read `}` and finished processing a JSON object
+        object_end,
+        /// the parser read `[` and started to process a JSON array
+        array_start,
+        /// the parser read `]` and finished processing a JSON array
+        array_end,
+        /// the parser read a key of a value in an object
+        key,
+        /// the parser finished reading a JSON value
+        value
+    };
+
+    /*!
+    @brief per-element parser callback type
+
+    With a parser callback function, the result of parsing a JSON text can be
+    influenced. When passed to @ref parse(std::istream&, parser_callback_t) or
+    @ref parse(const string_t&, parser_callback_t), it is called on certain
+    events (passed as @ref parse_event_t via parameter @a event) with a set
+    recursion depth @a depth and context JSON value @a parsed. The return value
+    of the callback function is a boolean indicating whether the element that
+    emitted the callback shall be kept or not.
+
+    We distinguish six scenarios (determined by the event type) in which the
+    callback function can be called. The following table describes the values
+    of the parameters @a depth, @a event, and @a parsed.
+
+    parameter @a event | description | parameter @a depth | parameter @a parsed
+    ------------------ | ----------- | ------------------ | -------------------
+    parse_event_t::object_start | the parser read `{` and started to process a JSON object | depth of the parent of the JSON object | a JSON value with type discarded
+    parse_event_t::key | the parser read a key of a value in an object | depth of the currently parsed JSON object | a JSON string containing the key
+    parse_event_t::object_end | the parser read `}` and finished processing a JSON object | depth of the parent of the JSON object | the parsed JSON object
+    parse_event_t::array_start | the parser read `[` and started to process a JSON array | depth of the parent of the JSON array | a JSON value with type discarded
+    parse_event_t::array_end | the parser read `]` and finished processing a JSON array | depth of the parent of the JSON array | the parsed JSON array
+    parse_event_t::value | the parser finished reading a JSON value | depth of the value | the parsed JSON value
+
+    Discarding a value (i.e., returning `false`) has different effects depending on the
+    context in which function was called:
+
+    - Discarded values in structured types are skipped. That is, the parser
+      will behave as if the discarded value was never read.
+    - In case a value outside a structured type is skipped, it is replaced with
+      `null`. This case happens if the top-level element is skipped.
+
+    @param[in] depth   the depth of the recursion during parsing
+
+    @param[in] event   an event of type parse_event_t indicating the context in
+    the callback function has been called
+
+    @param[in,out] parsed  the current intermediate parse result; note that
+    writing to this value has no effect for parse_event_t::key events
+
+    @return Whether the JSON value which called the function during parsing
+    should be kept (`true`) or not (`false`). In the latter case, it is either
+    skipped completely or replaced by an empty discarded object.
+
+    @sa @ref parse(std::istream&, parser_callback_t) or
+    @ref parse(const string_t&, parser_callback_t) for examples
+    */
+    using parser_callback_t = std::function<bool(
+                                  int depth, parse_event_t event, basic_json& parsed)>;
+
+
+    //////////////////
+    // constructors //
+    //////////////////
+
+    /*!
+    @brief create an empty value with a given type
+
+    Create an empty JSON value with a given type. The value will be default
+    initialized with an empty value which depends on the type:
+
+    Value type  | initial value
+    ----------- | -------------
+    null        | `null`
+    boolean     | `false`
+    string      | `""`
+    number      | `0`
+    object      | `{}`
+    array       | `[]`
+
+    @param[in] value  the type of the value to create
+
+    @complexity Constant.
+
+    @throw std::bad_alloc if allocation for object, array, or string value
+    fails
+
+    @liveexample{The following code shows the constructor for different @ref
+    value_t values,basic_json__value_t}
+    */
+    basic_json(const value_t value)
+        : m_type(value), m_value(value)
+    {}
+
+    /*!
+    @brief create a null object (implicitly)
+
+    Create a `null` JSON value. This is the implicit version of the `null`
+    value constructor as it takes no parameters.
+
+    @complexity Constant.
+
+    @requirement This function satisfies the Container requirements:
+    - The complexity is constant.
+    - As postcondition, it holds: `basic_json().empty() == true`.
+
+    @liveexample{The following code shows the constructor for a `null` JSON
+    value.,basic_json}
+
+    @sa basic_json(std::nullptr_t)
+    */
+    basic_json() noexcept = default;
+
+    /*!
+    @brief create a null object (explicitly)
+
+    Create a `null` JSON value. This is the explicitly version of the `null`
+    value constructor as it takes a null pointer as parameter. It allows to
+    create `null` values by explicitly assigning a @c nullptr to a JSON value.
+    The passed null pointer itself is not read - it is only used to choose the
+    right constructor.
+
+    @complexity Constant.
+
+    @liveexample{The following code shows the constructor with null pointer
+    parameter.,basic_json__nullptr_t}
+
+    @sa basic_json()
+    */
+    basic_json(std::nullptr_t) noexcept
+        : basic_json(value_t::null)
+    {}
+
+    /*!
+    @brief create an object (explicit)
+
+    Create an object JSON value with a given content.
+
+    @param[in] value  a value for the object
+
+    @complexity Linear in the size of the passed @a value.
+
+    @throw std::bad_alloc if allocation for object value fails
+
+    @liveexample{The following code shows the constructor with an @ref object_t
+    parameter.,basic_json__object_t}
+
+    @sa basic_json(const CompatibleObjectType&)
+    */
+    basic_json(const object_t& value)
+        : m_type(value_t::object), m_value(value)
+    {}
+
+    /*!
+    @brief create an object (implicit)
+
+    Create an object JSON value with a given content. This constructor allows
+    any type that can be used to construct values of type @ref object_t.
+    Examples include the types `std::map` and `std::unordered_map`.
+
+    @tparam CompatibleObjectType an object type whose `key_type` and
+    `value_type` is compatible to @ref object_t
+
+    @param[in] value  a value for the object
+
+    @complexity Linear in the size of the passed @a value.
+
+    @throw std::bad_alloc if allocation for object value fails
+
+    @liveexample{The following code shows the constructor with several
+    compatible object type parameters.,basic_json__CompatibleObjectType}
+
+    @sa basic_json(const object_t&)
+    */
+    template <class CompatibleObjectType, typename
+              std::enable_if<
+                  std::is_constructible<typename object_t::key_type, typename CompatibleObjectType::key_type>::value and
+                  std::is_constructible<basic_json, typename CompatibleObjectType::mapped_type>::value, int>::type
+              = 0>
+    basic_json(const CompatibleObjectType& 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));
+    }
+
+    /*!
+    @brief create an array (explicit)
+
+    Create an array JSON value with a given content.
+
+    @param[in] value  a value for the array
+
+    @complexity Linear in the size of the passed @a value.
+
+    @throw std::bad_alloc if allocation for array value fails
+
+    @liveexample{The following code shows the constructor with an @ref array_t
+    parameter.,basic_json__array_t}
+
+    @sa basic_json(const CompatibleArrayType&)
+    */
+    basic_json(const array_t& value)
+        : m_type(value_t::array), m_value(value)
+    {}
+
+    /*!
+    @brief create an array (implicit)
+
+    Create an array JSON value with a given content. This constructor allows
+    any type that can be used to construct values of type @ref array_t.
+    Examples include the types `std::vector`, `std::list`, and `std::set`.
+
+    @tparam CompatibleArrayType an object type whose `value_type` is compatible
+    to @ref array_t
+
+    @param[in] value  a value for the array
+
+    @complexity Linear in the size of the passed @a value.
+
+    @throw std::bad_alloc if allocation for array value fails
+
+    @liveexample{The following code shows the constructor with several
+    compatible array type parameters.,basic_json__CompatibleArrayType}
+
+    @sa basic_json(const array_t&)
+    */
+    template <class CompatibleArrayType, typename
+              std::enable_if<
+                  not std::is_same<CompatibleArrayType, typename basic_json_t::iterator>::value and
+                  not std::is_same<CompatibleArrayType, typename basic_json_t::const_iterator>::value and
+                  not std::is_same<CompatibleArrayType, typename basic_json_t::reverse_iterator>::value and
+                  not std::is_same<CompatibleArrayType, typename basic_json_t::const_reverse_iterator>::value and
+                  not std::is_same<CompatibleArrayType, typename array_t::iterator>::value and
+                  not std::is_same<CompatibleArrayType, typename array_t::const_iterator>::value and
+                  std::is_constructible<basic_json, typename CompatibleArrayType::value_type>::value, int>::type
+              = 0>
+    basic_json(const CompatibleArrayType& 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));
+    }
+
+    /*!
+    @brief create a string (explicit)
+
+    Create an string JSON value with a given content.
+
+    @param[in] value  a value for the string
+
+    @complexity Linear in the size of the passed @a value.
+
+    @throw std::bad_alloc if allocation for string value fails
+
+    @liveexample{The following code shows the constructor with an @ref string_t
+    parameter.,basic_json__string_t}
+
+    @sa basic_json(const typename string_t::value_type*)
+    @sa basic_json(const CompatibleStringType&)
+    */
+    basic_json(const string_t& value)
+        : m_type(value_t::string), m_value(value)
+    {}
+
+    /*!
+    @brief create a string (explicit)
+
+    Create a string JSON value with a given content.
+
+    @param[in] value  a literal value for the string
+
+    @complexity Linear in the size of the passed @a value.
+
+    @throw std::bad_alloc if allocation for string value fails
+
+    @liveexample{The following code shows the constructor with string literal
+    parameter.,basic_json__string_t_value_type}
+
+    @sa basic_json(const string_t&)
+    @sa basic_json(const CompatibleStringType&)
+    */
+    basic_json(const typename string_t::value_type* value)
+        : basic_json(string_t(value))
+    {}
+
+    /*!
+    @brief create a string (implicit)
+
+    Create a string JSON value with a given content.
+
+    @param[in] value  a value for the string
+
+    @tparam CompatibleStringType an string type which is compatible to @ref
+    string_t
+
+    @complexity Linear in the size of the passed @a value.
+
+    @throw std::bad_alloc if allocation for string value fails
+
+    @liveexample{The following code shows the construction of a string value
+    from a compatible type.,basic_json__CompatibleStringType}
+
+    @sa basic_json(const string_t&)
+    */
+    template <class CompatibleStringType, typename
+              std::enable_if<
+                  std::is_constructible<string_t, CompatibleStringType>::value, int>::type
+              = 0>
+    basic_json(const CompatibleStringType& value)
+        : basic_json(string_t(value))
+    {}
+
+    /*!
+    @brief create a boolean (explicit)
+
+    Creates a JSON boolean type from a given value.
+
+    @param[in] value  a boolean value to store
+
+    @complexity Constant.
+
+    @liveexample{The example below demonstrates boolean
+    values.,basic_json__boolean_t}
+    */
+    basic_json(boolean_t value)
+        : m_type(value_t::boolean), m_value(value)
+    {}
+
+    /*!
+    @brief create an integer number (explicit)
+
+    Create an interger number JSON value with a given content.
+
+    @tparam T  helper type to compare number_integer_t and int (not visible in)
+    the interface.
+
+    @param[in] value  an integer to create a JSON number from
+
+    @note This constructor would have the same signature as @ref
+    basic_json(const int value), so we need to switch this one off in case
+    number_integer_t is the same as int. This is done via the helper type @a T.
+
+    @complexity Constant.
+
+    @liveexample{The example below shows the construction of a JSON integer
+    number value.,basic_json__number_integer_t}
+
+    @sa basic_json(const int)
+    */
+    template<typename T,
+             typename std::enable_if<
+                 not (std::is_same<T, int>::value)
+                 and std::is_same<T, number_integer_t>::value
+                 , int>::type = 0>
+    basic_json(const number_integer_t value)
+        : m_type(value_t::number_integer), m_value(value)
+    {}
+
+    /*!
+    @brief create an integer number from an enum type (explicit)
+
+    Create an integer number JSON value with a given content.
+
+    @param[in] value  an integer to create a JSON number from
+
+    @note This constructor allows to pass enums directly to a constructor. As
+    C++ has no way of specifying the type of an anonymous enum explicitly, we
+    can only rely on the fact that such values implicitly convert to int. As
+    int may already be the same type of number_integer_t, we may need to switch
+    off the constructor @ref basic_json(const number_integer_t).
+
+    @complexity Constant.
+
+    @liveexample{The example below shows the construction of a JSON integer
+    number value from an anonymous enum.,basic_json__const_int}
+
+    @sa basic_json(const number_integer_t)
+    */
+    basic_json(const int value)
+        : m_type(value_t::number_integer),
+          m_value(static_cast<number_integer_t>(value))
+    {}
+
+    /*!
+    @brief create an integer number (implicit)
+
+    Create an integer number JSON value with a given content. This constructor
+    allows any type that can be used to construct values of type @ref
+    number_integer_t. Examples may include the types `int`, `int32_t`, or
+    `short`.
+
+    @tparam CompatibleNumberIntegerType an integer type which is compatible to
+    @ref number_integer_t.
+
+    @param[in] value  an integer to create a JSON number from
+
+    @complexity Constant.
+
+    @liveexample{The example below shows the construction of several JSON
+    integer number values from compatible
+    types.,basic_json__CompatibleIntegerNumberType}
+
+    @sa basic_json(const number_integer_t)
+    */
+    template<typename CompatibleNumberIntegerType, typename
+             std::enable_if<
+                 std::is_constructible<number_integer_t, CompatibleNumberIntegerType>::value and
+                 std::numeric_limits<CompatibleNumberIntegerType>::is_integer, CompatibleNumberIntegerType>::type
+             = 0>
+    basic_json(const CompatibleNumberIntegerType value) noexcept
+        : m_type(value_t::number_integer),
+          m_value(static_cast<number_integer_t>(value))
+    {}
+
+    /*!
+    @brief create a floating-point number (explicit)
+
+    Create a floating-point number JSON value with a given content.
+
+    @param[in] value  a floating-point value to create a JSON number from
+
+    @note RFC 7159 <http://www.rfc-editor.org/rfc/rfc7159.txt>, section 6
+    disallows NaN values:
+    > Numeric values that cannot be represented in the grammar below (such
+    > as Infinity and NaN) are not permitted.
+    In case the parameter @a value is not a number, a JSON null value is
+    created instead.
+
+    @complexity Constant.
+
+    @liveexample{The following example creates several floating-point
+    values.,basic_json__number_float_t}
+    */
+    basic_json(const number_float_t value)
+        : m_type(value_t::number_float), m_value(value)
+    {
+        // replace infinity and NAN by null
+        if (not std::isfinite(value))
+        {
+            m_type = value_t::null;
+            m_value = json_value();
+        }
+    }
+
+    /*!
+    @brief create an floating-point number (implicit)
+
+    Create an floating-point number JSON value with a given content. This
+    constructor allows any type that can be used to construct values of type
+    @ref number_float_t. Examples may include the types `float`.
+
+    @tparam CompatibleNumberFloatType a floating-point type which is compatible
+    to @ref number_float_t.
+
+    @param[in] value  a floating-point to create a JSON number from
+
+    @note RFC 7159 <http://www.rfc-editor.org/rfc/rfc7159.txt>, section 6
+    disallows NaN values:
+    > Numeric values that cannot be represented in the grammar below (such
+    > as Infinity and NaN) are not permitted.
+    In case the parameter @a value is not a number, a JSON null value is
+    created instead.
+
+    @complexity Constant.
+
+    @liveexample{The example below shows the construction of several JSON
+    floating-point number values from compatible
+    types.,basic_json__CompatibleNumberFloatType}
+
+    @sa basic_json(const number_float_t)
+    */
+    template<typename CompatibleNumberFloatType, typename = typename
+             std::enable_if<
+                 std::is_constructible<number_float_t, CompatibleNumberFloatType>::value and
+                 std::is_floating_point<CompatibleNumberFloatType>::value>::type
+             >
+    basic_json(const CompatibleNumberFloatType value) noexcept
+        : basic_json(number_float_t(value))
+    {}
+
+    /*!
+    @brief create a container (array or object) from an initializer list
+
+    Creates a JSON value of type array or object from the passed initializer
+    list @a init. In case @a type_deduction is `true` (default), the type of
+    the JSON value to be created is deducted from the initializer list @a init
+    according to the following rules:
+
+    1. If the list is empty, an empty JSON object value `{}` is created.
+    2. If the list consists of pairs whose first element is a string, a JSON
+    object value is created where the first elements of the pairs are treated
+    as keys and the second elements are as values.
+    3. In all other cases, an array is created.
+
+    The rules aim to create the best fit between a C++ initializer list and
+    JSON values. The ratioinale is as follows:
+
+    1. The empty initializer list is written as `{}` which is exactly an empty
+    JSON object.
+    2. C++ has now way of describing mapped types other than to list a list of
+    pairs. As JSON requires that keys must be of type string, rule 2 is the
+    weakest constraint one can pose on initializer lists to interpret them as
+    an object.
+    3. In all other cases, the initializer list could not be interpreted as
+    JSON object type, so interpreting it as JSON array type is safe.
+
+    With the rules described above, the following JSON values cannot be
+    expressed by an initializer list:
+
+    - the empty array (`[]`): use @ref array(std::initializer_list<basic_json>)
+      with an empty initializer list in this case
+    - arrays whose elements satisfy rule 2: use @ref
+      array(std::initializer_list<basic_json>) with the same initializer list
+      in this case
+
+    @note When used without parentheses around an empty initializer list, @ref
+    basic_json() is called instead of this function, yielding the JSON null
+    value.
+
+    @param[in] init  initializer list with JSON values
+
+    @param[in] type_deduction internal parameter; when set to `true`, the type
+    of the JSON value is deducted from the initializer list @a init; when set
+    to `false`, the type provided via @a manual_type is forced. This mode is
+    used by the functions @ref array(std::initializer_list<basic_json>) and
+    @ref object(std::initializer_list<basic_json>).
+
+    @param[in] manual_type internal parameter; when @a type_deduction is set to
+    `false`, the created JSON value will use the provided type (only @ref
+    value_t::array and @ref value_t::object are valid); when @a type_deduction
+    is set to `true`, this parameter has no effect
+
+    @throw std::domain_error if @a type_deduction is `false`, @a manual_type is
+    `value_t::object`, but @a init contains an element which is not a pair
+    whose first element is a string
+
+    @complexity Linear in the size of the initializer list @a init.
+
+    @liveexample{The example below shows how JSON values are created from
+    initializer lists,basic_json__list_init_t}
+
+    @sa basic_json array(std::initializer_list<basic_json>) - create a JSON
+    array value from an initializer list
+    @sa basic_json object(std::initializer_list<basic_json>) - create a JSON
+    object value from an initializer list
+    */
+    basic_json(std::initializer_list<basic_json> init,
+               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 : init)
+        {
+            if (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)
+        {
+            // 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::domain_error("cannot create object from initializer list");
+            }
+        }
+
+        if (is_object)
+        {
+            // the initializer list is a list of pairs -> create object
+            m_type = value_t::object;
+            m_value = value_t::object;
+
+            for (auto& element : init)
+            {
+                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(init));
+        }
+    }
+
+    /*!
+    @brief explicitly create an array from an initializer list
+
+    Creates a JSON array value from a given initializer list. That is, given a
+    list of values `a, b, c`, creates the JSON value `[a, b, c]`. If the
+    initializer list is empty, the empty array `[]` is created.
+
+    @note This function is only needed to express two edge cases that cannot be
+    realized with the initializer list constructor (@ref
+    basic_json(std::initializer_list<basic_json>, bool, value_t)). These cases
+    are:
+    1. creating an array whose elements are all pairs whose first element is a
+    string - in this case, the initializer list constructor would create an
+    object, taking the first elements as keys
+    2. creating an empty array - passing the empty initializer list to the
+    initializer list constructor yields an empty object
+
+    @param[in] init  initializer list with JSON values to create an array from
+    (optional)
+
+    @return JSON array value
+
+    @complexity Linear in the size of @a init.
+
+    @liveexample{The following code shows an example for the @ref array
+    function.,array}
+
+    @sa basic_json(std::initializer_list<basic_json>, bool, value_t) - create a
+    JSON value from an initializer list
+    @sa basic_json object(std::initializer_list<basic_json>) - create a JSON
+    object value from an initializer list
+    */
+    static basic_json array(std::initializer_list<basic_json> init =
+                                std::initializer_list<basic_json>())
+    {
+        return basic_json(init, false, value_t::array);
+    }
+
+    /*!
+    @brief explicitly create an object from an initializer list
+
+    Creates a JSON object value from a given initializer list. The initializer
+    lists elements must be pairs, and their first elments must be strings. If
+    the initializer list is empty, the empty object `{}` is created.
+
+    @note This function is only added for symmetry reasons. In contrast to the
+    related function @ref basic_json array(std::initializer_list<basic_json>),
+    there are no cases which can only be expressed by this function. That is,
+    any initializer list @a init can also be passed to the initializer list
+    constructor @ref basic_json(std::initializer_list<basic_json>, bool,
+    value_t).
+
+    @param[in] init  initializer list to create an object from (optional)
+
+    @return JSON object value
+
+    @throw std::domain_error if @a init is not a pair whose first elements are
+    strings; thrown by @ref basic_json(std::initializer_list<basic_json>, bool,
+    value_t)
+
+    @complexity Linear in the size of @a init.
+
+    @liveexample{The following code shows an example for the @ref object
+    function.,object}
+
+    @sa basic_json(std::initializer_list<basic_json>, bool, value_t) - create a
+    JSON value from an initializer list
+    @sa basic_json array(std::initializer_list<basic_json>) - create a JSON
+    array value from an initializer list
+    */
+    static basic_json object(std::initializer_list<basic_json> init =
+                                 std::initializer_list<basic_json>())
+    {
+        return basic_json(init, false, value_t::object);
+    }
+
+    /*!
+    @brief construct an array with count copies of given value
+
+    Constructs a JSON array value by creating @a count copies of a passed
+    value. In case @a count is `0`, an empty array is created. As postcondition,
+    `std::distance(begin(),end()) == count` holds.
+
+    @param[in] count  the number of JSON copies of @a value to create
+    @param[in] value  the JSON value to copy
+
+    @complexity Linear in @a count.
+
+    @liveexample{The following code shows examples for the @ref
+    basic_json(size_type\, const basic_json&)
+    constructor.,basic_json__size_type_basic_json}
+    */
+    basic_json(size_type count, const basic_json& value)
+        : m_type(value_t::array)
+    {
+        AllocatorType<array_t> alloc;
+        m_value.array = alloc.allocate(1);
+        alloc.construct(m_value.array, count, value);
+    }
+
+    /*!
+    @brief construct a JSON container given an iterator range
+
+    Constructs the JSON value with the contents of the range `[first, last)`.
+    The semantics depends on the different types a JSON value can have:
+    - In case of primitive types (number, boolean, or string), @a first must
+      be `begin()` and @a last must be `end()`. In this case, the value is
+      copied. Otherwise, std::out_of_range is thrown.
+    - In case of structured types (array, object), the constructor behaves
+      as similar versions for `std::vector`.
+    - In case of a null type, std::domain_error is thrown.
+
+    @tparam InputIT an input iterator type (@ref iterator or @ref
+    const_iterator)
+
+    @param[in] first begin of the range to copy from (included)
+    @param[in] last end of the range to copy from (excluded)
+
+    @throw std::domain_error if iterators are not compatible; that is, do not
+    belong to the same JSON value
+    @throw std::out_of_range if iterators are for a primitive type (number,
+    boolean, or string) where an out of range error can be detected easily
+    @throw std::bad_alloc if allocation for object, array, or string fails
+    @throw std::domain_error if called with a null value
+
+    @complexity Linear in distance between @a first and @a last.
+
+    @liveexample{The example below shows several ways to create JSON values by
+    specifying a subrange with iterators.,basic_json__InputIt_InputIt}
+    */
+    template <class InputIT, typename
+              std::enable_if<
+                  std::is_same<InputIT, typename basic_json_t::iterator>::value or
+                  std::is_same<InputIT, typename basic_json_t::const_iterator>::value
+                  , int>::type
+              = 0>
+    basic_json(InputIT first, InputIT last) : m_type(first.m_object->m_type)
+    {
+        // make sure iterator fits the current value
+        if (first.m_object != last.m_object)
+        {
+            throw std::domain_error("iterators are not compatible");
+        }
+
+        // check if iterator range is complete for primitive values
+        switch (m_type)
+        {
+            case value_t::number_integer:
+            case value_t::number_float:
+            case value_t::boolean:
+            case value_t::string:
+            {
+                if (not first.m_it.primitive_iterator.is_begin() or not last.m_it.primitive_iterator.is_end())
+                {
+                    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:
+            {
+                m_value = *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::domain_error("cannot use construct with iterators from " + first.m_object->type_name());
+            }
+        }
+    }
+
+    ///////////////////////////////////////
+    // other constructors and destructor //
+    ///////////////////////////////////////
+
+    /*!
+    @brief copy constructor
+
+    Creates a copy of a given JSON value.
+
+    @param[in] other  the JSON value to copy
+
+    @complexity Linear in the size of @a other.
+
+    @requirement This function satisfies the Container requirements:
+    - The complexity is linear.
+    - As postcondition, it holds: `other == basic_json(other)`.
+
+    @throw std::bad_alloc if allocation for object, array, or string fails.
+
+    @liveexample{The following code shows an example for the copy
+    constructor.,basic_json__basic_json}
+    */
+    basic_json(const basic_json& other)
+        : m_type(other.m_type)
+    {
+        switch (m_type)
+        {
+            case (value_t::null):
+            case (value_t::discarded):
+            {
+                break;
+            }
+
+            case (value_t::object):
+            {
+                m_value = *other.m_value.object;
+                break;
+            }
+
+            case (value_t::array):
+            {
+                m_value = *other.m_value.array;
+                break;
+            }
+
+            case (value_t::string):
+            {
+                m_value = *other.m_value.string;
+                break;
+            }
+
+            case (value_t::boolean):
+            {
+                m_value = other.m_value.boolean;
+                break;
+            }
+
+            case (value_t::number_integer):
+            {
+                m_value = other.m_value.number_integer;
+                break;
+            }
+
+            case (value_t::number_float):
+            {
+                m_value = other.m_value.number_float;
+                break;
+            }
+        }
+    }
+
+    /*!
+    @brief move constructor
+
+    Move constructor. Constructs a JSON value with the contents of the given
+    value @a other using move semantics. It "steals" the resources from @a
+    other and leaves it as JSON null value.
+
+    @param[in,out] other  value to move to this object
+
+    @post @a other is a JSON null value
+
+    @complexity Constant.
+
+    @liveexample{The code below shows the move constructor explicitly called
+    via std::move.,basic_json__moveconstructor}
+    */
+    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
+
+    Copy assignment operator. Copies a JSON value via the "copy and swap"
+    strategy: It is expressed in terms of the copy constructor, destructor, and
+    the swap() member function.
+
+    @param[in] other  value to copy from
+
+    @complexity Linear.
+
+    @requirement This function satisfies the Container requirements:
+    - The complexity is linear.
+
+    @liveexample{The code below shows and example for the copy assignment. It
+    creates a copy of value `a` which is then swapped with `b`. Finally\, the
+    copy of `a` (which is the null value after the swap) is
+    destroyed.,basic_json__copyassignment}
+    */
+    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
+    )
+    {
+        using std::swap;
+        std::swap(m_type, other.m_type);
+        std::swap(m_value, other.m_value);
+        return *this;
+    }
+
+    /*!
+    @brief destructor
+
+    Destroys the JSON value and frees all allocated memory.
+
+    @complexity Linear.
+
+    @requirement This function satisfies the Container requirements:
+    - The complexity is linear.
+    - All stored elements are destroyed and all memory is freed.
+    */
+    ~basic_json()
+    {
+        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 //
+    ///////////////////////
+
+    /// @name object inspection
+    /// @{
+
+    /*!
+    @brief serialization
+
+    Serialization function for JSON values. The function tries to mimick
+    Python's @p json.dumps() function, and currently supports its @p indent
+    parameter.
+
+    @param[in] 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
+
+    @return string containing the serialization of the JSON value
+
+    @complexity Linear.
+
+    @liveexample{The following example shows the effect of different @a indent
+    parameters to the result of the serializaion.,dump}
+
+    @see https://docs.python.org/2/library/json.html#json.dump
+    */
+    string_t dump(const int indent = -1) const
+    {
+        std::stringstream ss;
+
+        if (indent >= 0)
+        {
+            dump(ss, true, static_cast<unsigned int>(indent));
+        }
+        else
+        {
+            dump(ss, false, 0);
+        }
+
+        return ss.str();
+    }
+
+    /*!
+    @brief return the type of the JSON value (explicit)
+
+    Return the type of the JSON value as a value from the @ref value_t
+    enumeration.
+
+    @return the type of the JSON value
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref type() for all JSON
+    types.,type}
+    */
+    value_t type() const noexcept
+    {
+        return m_type;
+    }
+
+    /*!
+    @brief return whether type is primitive
+
+    This function returns true iff the JSON type is primitive (string, number,
+    boolean, or null).
+
+    @return `true` if type is primitive (string, number, boolean, or null),
+    `false` otherwise.
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref is_primitive for all JSON
+    types.,is_primitive}
+    */
+    bool is_primitive() const noexcept
+    {
+        return is_null() or is_string() or is_boolean() or is_number();
+    }
+
+    /*!
+    @brief return whether type is structured
+
+    This function returns true iff the JSON type is structured (array or
+    object).
+
+    @return `true` if type is structured (array or object), `false` otherwise.
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref is_structured for all JSON
+    types.,is_structured}
+    */
+    bool is_structured() const noexcept
+    {
+        return is_array() or is_object();
+    }
+
+    /*!
+    @brief return whether value is null
+
+    This function returns true iff the JSON value is null.
+
+    @return `true` if type is null, `false` otherwise.
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref is_null for all JSON
+    types.,is_null}
+    */
+    bool is_null() const noexcept
+    {
+        return m_type == value_t::null;
+    }
+
+    /*!
+    @brief return whether value is a boolean
+
+    This function returns true iff the JSON value is a boolean.
+
+    @return `true` if type is boolean, `false` otherwise.
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref is_boolean for all JSON
+    types.,is_boolean}
+    */
+    bool is_boolean() const noexcept
+    {
+        return m_type == value_t::boolean;
+    }
+
+    /*!
+    @brief return whether value is a number
+
+    This function returns true iff the JSON value is a number. This includes
+    both integer and floating-point values.
+
+    @return `true` if type is number, `false` otherwise.
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref is_number for all JSON
+    types.,is_number}
+    */
+    bool is_number() const noexcept
+    {
+        return is_number_integer() or is_number_float();
+    }
+
+    /*!
+    @brief return whether value is an integer number
+
+    This function returns true iff the JSON value is an integer number. This
+    excludes floating-point values.
+
+    @return `true` if type is an integer number, `false` otherwise.
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref is_number_integer for all
+    JSON types.,is_number_integer}
+    */
+    bool is_number_integer() const noexcept
+    {
+        return m_type == value_t::number_integer;
+    }
+
+    /*!
+    @brief return whether value is a floating-point number
+
+    This function returns true iff the JSON value is a floating-point number.
+    This excludes integer values.
+
+    @return `true` if type is a floating-point number, `false` otherwise.
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref is_number_float for all
+    JSON types.,is_number_float}
+    */
+    bool is_number_float() const noexcept
+    {
+        return m_type == value_t::number_float;
+    }
+
+    /*!
+    @brief return whether value is an object
+
+    This function returns true iff the JSON value is an object.
+
+    @return `true` if type is object, `false` otherwise.
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref is_object for all JSON
+    types.,is_object}
+    */
+    bool is_object() const noexcept
+    {
+        return m_type == value_t::object;
+    }
+
+    /*!
+    @brief return whether value is an array
+
+    This function returns true iff the JSON value is an array.
+
+    @return `true` if type is array, `false` otherwise.
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref is_array for all JSON
+    types.,is_array}
+    */
+    bool is_array() const noexcept
+    {
+        return m_type == value_t::array;
+    }
+
+    /*!
+    @brief return whether value is a string
+
+    This function returns true iff the JSON value is a string.
+
+    @return `true` if type is string, `false` otherwise.
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref is_string for all JSON
+    types.,is_string}
+    */
+    bool is_string() const noexcept
+    {
+        return m_type == value_t::string;
+    }
+
+    /*!
+    @brief return whether value is discarded
+
+    This function returns true iff the JSON value was discarded during parsing
+    with a callback function (see @ref parser_callback_t).
+
+    @note This function will always be `false` for JSON values after parsing.
+    That is, discarded values can only occur during parsing, but will be
+    removed when inside a structured value or replaced by null in other cases.
+
+    @return `true` if type is discarded, `false` otherwise.
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies @ref is_discarded for all JSON
+    types.,is_discarded}
+    */
+    bool is_discarded() const noexcept
+    {
+        return m_type == value_t::discarded;
+    }
+
+    /*!
+    @brief return the type of the JSON value (implicit)
+
+    Implicitly return the type of the JSON value as a value from the @ref
+    value_t enumeration.
+
+    @return the type of the JSON value
+
+    @complexity Constant.
+
+    @liveexample{The following code exemplifies the value_t operator for all
+    JSON types.,operator__value_t}
+    */
+    operator value_t() const noexcept
+    {
+        return m_type;
+    }
+
+    /// @}
+
+  private:
+    //////////////////
+    // value access //
+    //////////////////
+
+    /// 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_t, typename T::mapped_type>::value
+                  , int>::type = 0>
+    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::domain_error("type must be object, but is " + type_name());
+            }
+        }
+    }
+
+    /// get an object (explicit)
+    object_t get_impl(object_t*) const
+    {
+        switch (m_type)
+        {
+            case (value_t::object):
+            {
+                return *(m_value.object);
+            }
+            default:
+            {
+                throw std::domain_error("type must be object, but is " + type_name());
+            }
+        }
+    }
+
+    /// get an array (explicit)
+    template <class T, typename
+              std::enable_if<
+                  std::is_convertible<basic_json_t, typename T::value_type>::value and
+                  not std::is_same<basic_json_t, 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>
+    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::domain_error("type must be array, but is " + type_name());
+            }
+        }
+    }
+
+    /// get an array (explicit)
+    template <class T, typename
+              std::enable_if<
+                  std::is_convertible<basic_json_t, T>::value and
+                  not std::is_same<basic_json_t, T>::value
+                  , int>::type = 0>
+    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::domain_error("type must be array, but is " + type_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>
+    T get_impl(T*) const
+    {
+        switch (m_type)
+        {
+            case (value_t::array):
+            {
+                return T(m_value.array->begin(), m_value.array->end());
+            }
+            default:
+            {
+                throw std::domain_error("type must be array, but is " + type_name());
+            }
+        }
+    }
+
+    /// get an array (explicit)
+    array_t get_impl(array_t*) const
+    {
+        switch (m_type)
+        {
+            case (value_t::array):
+            {
+                return *(m_value.array);
+            }
+            default:
+            {
+                throw std::domain_error("type must be array, but is " + type_name());
+            }
+        }
+    }
+
+    /// get a string (explicit)
+    template <typename T, typename
+              std::enable_if<
+                  std::is_convertible<string_t, T>::value
+                  , int>::type = 0>
+    T get_impl(T*) const
+    {
+        switch (m_type)
+        {
+            case (value_t::string):
+            {
+                return *m_value.string;
+            }
+            default:
+            {
+                throw std::domain_error("type must be string, but is " + type_name());
+            }
+        }
+    }
+
+    /// get a number (explicit)
+    template<typename T, typename
+             std::enable_if<
+                 std::is_arithmetic<T>::value
+                 , int>::type = 0>
+    T get_impl(T*) 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::domain_error("type must be number, but is " + type_name());
+            }
+        }
+    }
+
+    /// get a boolean (explicit)
+    boolean_t get_impl(boolean_t*) const
+    {
+        switch (m_type)
+        {
+            case (value_t::boolean):
+            {
+                return m_value.boolean;
+            }
+            default:
+            {
+                throw std::domain_error("type must be boolean, but is " + type_name());
+            }
+        }
+    }
+
+    /// get a pointer to the value (object)
+    object_t* get_impl_ptr(object_t*) noexcept
+    {
+        return is_object() ? m_value.object : nullptr;
+    }
+
+    /// get a pointer to the value (object)
+    const object_t* get_impl_ptr(const object_t*) const noexcept
+    {
+        return is_object() ? m_value.object : nullptr;
+    }
+
+    /// get a pointer to the value (array)
+    array_t* get_impl_ptr(array_t*) noexcept
+    {
+        return is_array() ? m_value.array : nullptr;
+    }
+
+    /// get a pointer to the value (array)
+    const array_t* get_impl_ptr(const array_t*) const noexcept
+    {
+        return is_array() ? m_value.array : nullptr;
+    }
+
+    /// get a pointer to the value (string)
+    string_t* get_impl_ptr(string_t*) noexcept
+    {
+        return is_string() ? m_value.string : nullptr;
+    }
+
+    /// get a pointer to the value (string)
+    const string_t* get_impl_ptr(const string_t*) const noexcept
+    {
+        return is_string() ? m_value.string : nullptr;
+    }
+
+    /// get a pointer to the value (boolean)
+    boolean_t* get_impl_ptr(boolean_t*) noexcept
+    {
+        return is_boolean() ? &m_value.boolean : nullptr;
+    }
+
+    /// get a pointer to the value (boolean)
+    const boolean_t* get_impl_ptr(const boolean_t*) const noexcept
+    {
+        return is_boolean() ? &m_value.boolean : nullptr;
+    }
+
+    /// get a pointer to the value (integer number)
+    number_integer_t* get_impl_ptr(number_integer_t*) noexcept
+    {
+        return is_number_integer() ? &m_value.number_integer : nullptr;
+    }
+
+    /// get a pointer to the value (integer number)
+    const number_integer_t* get_impl_ptr(const number_integer_t*) const noexcept
+    {
+        return is_number_integer() ? &m_value.number_integer : nullptr;
+    }
+
+    /// get a pointer to the value (floating-point number)
+    number_float_t* get_impl_ptr(number_float_t*) noexcept
+    {
+        return is_number_float() ? &m_value.number_float : nullptr;
+    }
+
+    /// get a pointer to the value (floating-point number)
+    const number_float_t* get_impl_ptr(const number_float_t*) const noexcept
+    {
+        return is_number_float() ? &m_value.number_float : nullptr;
+    }
+
+  public:
+
+    /// @name value access
+    /// @{
+
+    /*!
+    @brief get a value (explicit)
+
+    Explicit type conversion between the JSON value and a compatible value.
+
+    @tparam ValueType non-pointer type compatible to the JSON value, for
+    instance `int` for JSON integer numbers, `bool` for JSON booleans, or
+    `std::vector` types for JSON arrays
+
+    @return copy of the JSON value, converted to type @a ValueType
+
+    @throw std::domain_error in case passed type @a ValueType is incompatible
+    to JSON
+
+    @complexity Linear in the size of the JSON value.
+
+    @liveexample{The example below shows serveral conversions from JSON values
+    to other types. There a few things to note: (1) Floating-point numbers can
+    be converted to integers\, (2) A JSON array can be converted to a standard
+    `std::vector<short>`\, (3) A JSON object can be converted to C++
+    assiciative containers such as `std::unordered_map<std::string\,
+    json>`.,get__ValueType_const}
+
+    @internal
+    The idea of using a casted null pointer to choose the correct
+    implementation is from <http://stackoverflow.com/a/8315197/266378>.
+    @endinternal
+
+    @sa @ref operator ValueType() const for implicit conversion
+    @sa @ref get() for pointer-member access
+    */
+    template<typename ValueType, typename
+             std::enable_if<
+                 not std::is_pointer<ValueType>::value
+                 , int>::type = 0>
+    ValueType get() const
+    {
+        return get_impl(static_cast<ValueType*>(nullptr));
+    }
+
+    /*!
+    @brief get a pointer value (explicit)
+
+    Explicit pointer access to the internally stored JSON value. No copies are
+    made.
+
+    @warning Writing data to the pointee of the result yields an undefined
+    state.
+
+    @tparam PointerType pointer type; must be a pointer to @ref array_t, @ref
+    object_t, @ref string_t, @ref boolean_t, @ref number_integer_t, or @ref
+    number_float_t.
+
+    @return pointer to the internally stored JSON value if the requested pointer
+    type @a PointerType fits to the JSON value; `nullptr` otherwise
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how pointers to internal values of a
+    JSON value can be requested. Note that no type conversions are made and a
+    `nullptr` is returned if the value and the requested pointer type does not
+    match.,get__PointerType}
+
+    @sa @ref get_ptr() for explicit pointer-member access
+    */
+    template<typename PointerType, typename
+             std::enable_if<
+                 std::is_pointer<PointerType>::value
+                 , int>::type = 0>
+    PointerType get() noexcept
+    {
+        // delegate the call to get_ptr
+        return get_ptr<PointerType>();
+    }
+
+    /*!
+    @brief get a pointer value (explicit)
+    @copydoc get()
+    */
+    template<typename PointerType, typename
+             std::enable_if<
+                 std::is_pointer<PointerType>::value
+                 , int>::type = 0>
+    const PointerType get() const noexcept
+    {
+        // delegate the call to get_ptr
+        return get_ptr<PointerType>();
+    }
+
+    /*!
+    @brief get a pointer value (implicit)
+
+    Implict pointer access to the internally stored JSON value. No copies are
+    made.
+
+    @warning Writing data to the pointee of the result yields an undefined
+    state.
+
+    @tparam PointerType pointer type; must be a pointer to @ref array_t, @ref
+    object_t, @ref string_t, @ref boolean_t, @ref number_integer_t, or @ref
+    number_float_t.
+
+    @return pointer to the internally stored JSON value if the requested pointer
+    type @a PointerType fits to the JSON value; `nullptr` otherwise
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how pointers to internal values of a
+    JSON value can be requested. Note that no type conversions are made and a
+    `nullptr` is returned if the value and the requested pointer type does not
+    match.,get_ptr}
+    */
+    template<typename PointerType, typename
+             std::enable_if<
+                 std::is_pointer<PointerType>::value
+                 , int>::type = 0>
+    PointerType get_ptr() noexcept
+    {
+        // delegate the call to get_impl_ptr<>()
+        return get_impl_ptr(static_cast<PointerType>(nullptr));
+    }
+
+    /*!
+    @brief get a pointer value (implicit)
+    @copydoc get_ptr()
+    */
+    template<typename PointerType, typename
+             std::enable_if<
+                 std::is_pointer<PointerType>::value
+                 and std::is_const<PointerType>::value
+                 , int>::type = 0>
+    const PointerType get_ptr() const noexcept
+    {
+        // delegate the call to get_impl_ptr<>() const
+        return get_impl_ptr(static_cast<const PointerType>(nullptr));
+    }
+
+    /*!
+    @brief get a value (implicit)
+
+    Implict type conversion between the JSON value and a compatible value. The
+    call is realized by calling @ref get() const.
+
+    @tparam ValueType non-pointer type compatible to the JSON value, for
+    instance `int` for JSON integer numbers, `bool` for JSON booleans, or
+    `std::vector` types for JSON arrays
+
+    @return copy of the JSON value, converted to type @a ValueType
+
+    @throw std::domain_error in case passed type @a ValueType is incompatible
+    to JSON, thrown by @ref get() const
+
+    @complexity Linear in the size of the JSON value.
+
+    @liveexample{The example below shows serveral conversions from JSON values
+    to other types. There a few things to note: (1) Floating-point numbers can
+    be converted to integers\, (2) A JSON array can be converted to a standard
+    `std::vector<short>`\, (3) A JSON object can be converted to C++
+    assiciative containers such as `std::unordered_map<std::string\,
+    json>`.,operator__ValueType}
+    */
+    template<typename ValueType, typename
+             std::enable_if<
+                 not std::is_pointer<ValueType>::value
+                 , int>::type = 0>
+    operator ValueType() const
+    {
+        // delegate the call to get<>() const
+        return get<ValueType>();
+    }
+
+    /// @}
+
+
+    ////////////////////
+    // element access //
+    ////////////////////
+
+    /// @name element access
+    /// @{
+
+    /*!
+    @brief access specified array element with bounds checking
+
+    Returns a reference to the element at specified location @a idx, with
+    bounds checking.
+
+    @param[in] idx  index of the element to access
+
+    @return reference to the element at index @a idx
+
+    @throw std::domain_error if JSON is not an array
+    @throw std::out_of_range if the index @a idx is out of range of the array;
+    that is, `idx >= size()`
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how array elements can be read and
+    written using at.,at__size_type}
+    */
+    reference at(size_type idx)
+    {
+        // at only works for arrays
+        if (m_type != value_t::array)
+        {
+            throw std::domain_error("cannot use at() with " + type_name());
+        }
+
+        return m_value.array->at(idx);
+    }
+
+    /*!
+    @brief access specified array element with bounds checking
+
+    Returns a const reference to the element at specified location @a idx, with
+    bounds checking.
+
+    @param[in] idx  index of the element to access
+
+    @return const reference to the element at index @a idx
+
+    @throw std::domain_error if JSON is not an array
+    @throw std::out_of_range if the index @a idx is out of range of the array;
+    that is, `idx >= size()`
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how array elements can be read using
+    at.,at__size_type_const}
+    */
+    const_reference at(size_type idx) const
+    {
+        // at only works for arrays
+        if (m_type != value_t::array)
+        {
+            throw std::domain_error("cannot use at() with " + type_name());
+        }
+
+        return m_value.array->at(idx);
+    }
+
+    /*!
+    @brief access specified object element with bounds checking
+
+    Returns a reference to the element at with specified key @a key, with
+    bounds checking.
+
+    @param[in] key  key of the element to access
+
+    @return reference to the element at key @a key
+
+    @throw std::domain_error if JSON is not an object
+    @throw std::out_of_range if the key @a key is is not stored in the object;
+    that is, `find(key) == end()`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read and
+    written using at.,at__object_t_key_type}
+    */
+    reference at(const typename object_t::key_type& key)
+    {
+        // at only works for objects
+        if (m_type != value_t::object)
+        {
+            throw std::domain_error("cannot use at() with " + type_name());
+        }
+
+        return m_value.object->at(key);
+    }
+
+    /*!
+    @brief access specified object element with bounds checking
+
+    Returns a const reference to the element at with specified key @a key, with
+    bounds checking.
+
+    @param[in] key  key of the element to access
+
+    @return const reference to the element at key @a key
+
+    @throw std::domain_error if JSON is not an object
+    @throw std::out_of_range if the key @a key is is not stored in the object;
+    that is, `find(key) == end()`
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read using
+    at.,at__object_t_key_type_const}
+    */
+    const_reference at(const typename object_t::key_type& key) const
+    {
+        // at only works for objects
+        if (m_type != value_t::object)
+        {
+            throw std::domain_error("cannot use at() with " + type_name());
+        }
+
+        return m_value.object->at(key);
+    }
+
+    /*!
+    @brief access specified array element
+
+    Returns a reference to the element at specified location @a idx.
+
+    @note If @a idx is beyond the range of the array (i.e., `idx >= size()`),
+    then the array is silently filled up with `null` values to make `idx` a
+    valid reference to the last stored element.
+
+    @param[in] idx  index of the element to access
+
+    @return reference to the element at index @a idx
+
+    @throw std::domain_error if JSON is not an array or null
+
+    @complexity Constant if @a idx is in the range of the array. Otherwise
+    linear in `idx - size()`.
+
+    @liveexample{The example below shows how array elements can be read and
+    written using [] operator. Note the addition of `null`
+    values.,operatorarray__size_type}
+    */
+    reference operator[](size_type idx)
+    {
+        // implicitly convert null to object
+        if (m_type == value_t::null)
+        {
+            m_type = value_t::array;
+            AllocatorType<array_t> alloc;
+            m_value.array = alloc.allocate(1);
+            alloc.construct(m_value.array);
+        }
+
+        // [] only works for arrays
+        if (m_type != value_t::array)
+        {
+            throw std::domain_error("cannot use operator[] with " + type_name());
+        }
+
+        for (size_t i = m_value.array->size(); i <= idx; ++i)
+        {
+            m_value.array->push_back(basic_json());
+        }
+
+        return m_value.array->operator[](idx);
+    }
+
+    /*!
+    @brief access specified array element
+
+    Returns a const reference to the element at specified location @a idx.
+
+    @param[in] idx  index of the element to access
+
+    @return const reference to the element at index @a idx
+
+    @throw std::domain_error if JSON is not an array
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how array elements can be read using
+    the [] operator.,operatorarray__size_type_const}
+    */
+    const_reference operator[](size_type idx) const
+    {
+        // at only works for arrays
+        if (m_type != value_t::array)
+        {
+            throw std::domain_error("cannot use operator[] with " + type_name());
+        }
+
+        return m_value.array->operator[](idx);
+    }
+
+    /*!
+    @brief access specified object element
+
+    Returns a reference to the element at with specified key @a key.
+
+    @note If @a key is not found in the object, then it is silently added to
+    the object and filled with a `null` value to make `key` a valid reference.
+    In case the value was `null` before, it is converted to an object.
+
+    @param[in] key  key of the element to access
+
+    @return reference to the element at key @a key
+
+    @throw std::domain_error if JSON is not an object or null
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read and
+    written using the [] operator.,operatorarray__key_type}
+    */
+    reference operator[](const typename object_t::key_type& key)
+    {
+        // implicitly convert null to object
+        if (m_type == value_t::null)
+        {
+            m_type = value_t::object;
+            AllocatorType<object_t> alloc;
+            m_value.object = alloc.allocate(1);
+            alloc.construct(m_value.object);
+        }
+
+        // [] only works for objects
+        if (m_type != value_t::object)
+        {
+            throw std::domain_error("cannot use operator[] with " + type_name());
+        }
+
+        return m_value.object->operator[](key);
+    }
+
+    /*!
+    @brief access specified object element
+
+    Returns a reference to the element at with specified key @a key.
+
+    @param[in] key  key of the element to access
+
+    @return reference to the element at key @a key
+
+    @throw std::domain_error if JSON is not an object or null
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read using
+    the [] operator.,operatorarray__key_type_const}
+    */
+    const_reference operator[](const typename object_t::key_type& key) const
+    {
+        // at only works for objects
+        if (m_type != value_t::object)
+        {
+            throw std::domain_error("cannot use operator[] with " + type_name());
+        }
+
+        return m_value.object->operator[](key);
+    }
+
+    /*!
+    @brief access specified object element
+
+    Returns a reference to the element at with specified key @a key.
+
+    @note If @a key is not found in the object, then it is silently added to
+    the object and filled with a `null` value to make `key` a valid reference.
+    In case the value was `null` before, it is converted to an object.
+
+    @note This function is required for compatibility reasons with Clang.
+
+    @param[in] key  key of the element to access
+
+    @return reference to the element at key @a key
+
+    @throw std::domain_error if JSON is not an object or null
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read and
+    written using the [] operator.,operatorarray__key_type}
+    */
+    template<typename T, std::size_t n>
+    reference operator[](const T (&key)[n])
+    {
+        // implicitly convert null to object
+        if (m_type == value_t::null)
+        {
+            m_type = value_t::object;
+            m_value = value_t::object;
+        }
+
+        // at only works for objects
+        if (m_type != value_t::object)
+        {
+            throw std::domain_error("cannot use operator[] with " + type_name());
+        }
+
+        return m_value.object->operator[](key);
+    }
+
+    /*!
+    @brief access specified object element
+
+    Returns a reference to the element at with specified key @a key.
+
+    @note This function is required for compatibility reasons with Clang.
+
+    @param[in] key  key of the element to access
+
+    @return reference to the element at key @a key
+
+    @throw std::domain_error if JSON is not an object or null
+
+    @complexity Logarithmic in the size of the container.
+
+    @liveexample{The example below shows how object elements can be read using
+    the [] operator.,operatorarray__key_type_const}
+    */
+    template<typename T, std::size_t n>
+    const_reference operator[](const T (&key)[n]) const
+    {
+        // at only works for objects
+        if (m_type != value_t::object)
+        {
+            throw std::domain_error("cannot use operator[] with " + type_name());
+        }
+
+        return m_value.object->operator[](key);
+    }
+
+    /*!
+    @brief access the first element
+
+    Returns a reference to the first element in the container. For a JSON
+    container `c`, the expression `c.front()` is equivalent to `*c.begin()`.
+
+    @return In case of a structured type (array or object), a reference to the
+    first element is returned. In cast of number, string, or boolean values, a
+    reference to the value is returned.
+
+    @complexity Constant.
+
+    @note Calling `front` on an empty container is undefined.
+
+    @throw std::out_of_range when called on null value
+
+    @liveexample{The following code shows an example for @ref front.,front}
+    */
+    reference front()
+    {
+        return *begin();
+    }
+
+    /*!
+    @copydoc basic_json::front()
+    */
+    const_reference front() const
+    {
+        return *cbegin();
+    }
+
+    /*!
+    @brief access the last element
+
+    Returns a reference to the last element in the container. For a JSON
+    container `c`, the expression `c.back()` is equivalent to `{ auto tmp =
+    c.end(); --tmp; return *tmp; }`.
+
+    @return In case of a structured type (array or object), a reference to the
+    last element is returned. In cast of number, string, or boolean values, a
+    reference to the value is returned.
+
+    @complexity Constant.
+
+    @note Calling `back` on an empty container is undefined.
+
+    @throw std::out_of_range when called on null value.
+
+    @liveexample{The following code shows an example for @ref back.,back}
+    */
+    reference back()
+    {
+        auto tmp = end();
+        --tmp;
+        return *tmp;
+    }
+
+    /*!
+    @copydoc basic_json::back()
+    */
+    const_reference back() const
+    {
+        auto tmp = cend();
+        --tmp;
+        return *tmp;
+    }
+
+    /*!
+    @brief remove element given an iterator
+
+    Removes the element specified by iterator @a pos. Invalidates iterators and
+    references at or after the point of the erase, including the end()
+    iterator. The iterator @a pos must be valid and dereferenceable. Thus the
+    end() iterator (which is valid, but is not dereferencable) cannot be used
+    as a value for @a pos.
+
+    If called on a primitive type other than null, the resulting JSON value
+    will be `null`.
+
+    @param[in] pos iterator to the element to remove
+    @return Iterator following the last removed element. If the iterator @a pos
+    refers to the last element, the end() iterator is returned.
+
+    @tparam InteratorType an @ref iterator or @ref const_iterator
+
+    @throw std::domain_error if called on a `null` value
+    @throw std::domain_error if called on an iterator which does not belong to
+    the current JSON value
+    @throw std::out_of_range if called on a primitive type with invalid iterator
+    (i.e., any iterator which is not end())
+
+    @complexity The complexity depends on the type:
+    - objects: amortized constant
+    - arrays: linear in distance between pos and the end of the container
+    - strings: linear in the length of the string
+    - other types: constant
+
+    @liveexample{The example shows the result of erase for different JSON
+    types.,erase__IteratorType}
+    */
+    template <class InteratorType, typename
+              std::enable_if<
+                  std::is_same<InteratorType, typename basic_json_t::iterator>::value or
+                  std::is_same<InteratorType, typename basic_json_t::const_iterator>::value
+                  , int>::type
+              = 0>
+    InteratorType erase(InteratorType pos)
+    {
+        // make sure iterator fits the current value
+        if (this != pos.m_object)
+        {
+            throw std::domain_error("iterator does not fit current value");
+        }
+
+        InteratorType result = end();
+
+        switch (m_type)
+        {
+            case value_t::number_integer:
+            case value_t::number_float:
+            case value_t::boolean:
+            case value_t::string:
+            {
+                if (not pos.m_it.primitive_iterator.is_begin())
+                {
+                    throw std::out_of_range("iterator out of range");
+                }
+
+                if (m_type == value_t::string)
+                {
+                    delete m_value.string;
+                    m_value.string = nullptr;
+                }
+
+                m_type = value_t::null;
+                break;
+            }
+
+            case value_t::object:
+            {
+                result.m_it.object_iterator = m_value.object->erase(pos.m_it.object_iterator);
+                break;
+            }
+
+            case value_t::array:
+            {
+                result.m_it.array_iterator = m_value.array->erase(pos.m_it.array_iterator);
+                break;
+            }
+
+            default:
+            {
+                throw std::domain_error("cannot use erase() with " + type_name());
+            }
+        }
+
+        return result;
+    }
+
+    /*!
+    @brief remove elements given an iterator range
+
+    Removes the element specified by the range `[first; last)`. Invalidates
+    iterators and references at or after the point of the erase, including the
+    end() iterator. The iterator @a first does not need to be dereferenceable
+    if `first == last`: erasing an empty range is a no-op.
+
+    If called on a primitive type other than null, the resulting JSON value
+    will be `null`.
+
+    @param[in] first iterator to the beginning of the range to remove
+    @param[in] last iterator past the end of the range to remove
+    @return Iterator following the last removed element. If the iterator @a
+    second refers to the last element, the end() iterator is returned.
+
+    @tparam InteratorType an @ref iterator or @ref const_iterator
+
+    @throw std::domain_error if called on a `null` value
+    @throw std::domain_error if called on iterators which does not belong to
+    the current JSON value
+    @throw std::out_of_range if called on a primitive type with invalid iterators
+    (i.e., if `first != begin()` and `last != end()`)
+
+    @complexity The complexity depends on the type:
+    - objects: `log(size()) + std::distance(first, last)`
+    - arrays: linear in the distance between @a first and @a last, plus linear
+      in the distance between @a last and end of the container
+    - strings: linear in the length of the string
+    - other types: constant
+
+    @liveexample{The example shows the result of erase for different JSON
+    types.,erase__IteratorType_IteratorType}
+    */
+    template <class InteratorType, typename
+              std::enable_if<
+                  std::is_same<InteratorType, typename basic_json_t::iterator>::value or
+                  std::is_same<InteratorType, typename basic_json_t::const_iterator>::value
+                  , int>::type
+              = 0>
+    InteratorType erase(InteratorType first, InteratorType last)
+    {
+        // make sure iterator fits the current value
+        if (this != first.m_object or this != last.m_object)
+        {
+            throw std::domain_error("iterators do not fit current value");
+        }
+
+        InteratorType result = end();
+
+        switch (m_type)
+        {
+            case value_t::number_integer:
+            case value_t::number_float:
+            case value_t::boolean:
+            case value_t::string:
+            {
+                if (not first.m_it.primitive_iterator.is_begin() or not last.m_it.primitive_iterator.is_end())
+                {
+                    throw std::out_of_range("iterators out of range");
+                }
+
+                if (m_type == value_t::string)
+                {
+                    delete m_value.string;
+                    m_value.string = nullptr;
+                }
+
+                m_type = value_t::null;
+                break;
+            }
+
+            case value_t::object:
+            {
+                result.m_it.object_iterator = m_value.object->erase(first.m_it.object_iterator,
+                                              last.m_it.object_iterator);
+                break;
+            }
+
+            case value_t::array:
+            {
+                result.m_it.array_iterator = m_value.array->erase(first.m_it.array_iterator,
+                                             last.m_it.array_iterator);
+                break;
+            }
+
+            default:
+            {
+                throw std::domain_error("cannot use erase with " + type_name());
+            }
+        }
+
+        return result;
+    }
+
+    /*!
+    @brief remove element from a JSON object given a key
+
+    Removes elements from a JSON object with the key value @a key.
+
+    @param[in] key value of the elements to remove
+
+    @return Number of elements removed. If ObjectType is the default `std::map`
+    type, the return value will always be `0` (@a key was not found) or `1` (@a
+    key was found).
+
+    @throw std::domain_error when called on a type other than JSON object
+
+    @complexity `log(size()) + count(key)`
+
+    @liveexample{The example shows the effect of erase.,erase__key_type}
+    */
+    size_type erase(const typename object_t::key_type& key)
+    {
+        // this erase only works for objects
+        if (m_type != value_t::object)
+        {
+            throw std::domain_error("cannot use erase() with " + type_name());
+        }
+
+        return m_value.object->erase(key);
+    }
+
+    /*!
+    @brief remove element from a JSON array given an index
+
+    Removes element from a JSON array at the index @a idx.
+
+    @param[in] idx index of the element to remove
+
+    @throw std::domain_error when called on a type other than JSON array
+    @throw std::out_of_range when `idx >= size()`
+
+    @complexity Linear in distance between @a idx and the end of the container.
+
+    @liveexample{The example shows the effect of erase.,erase__size_type}
+    */
+    void erase(const size_type idx)
+    {
+        // this erase only works for arrays
+        if (m_type != value_t::array)
+        {
+            throw std::domain_error("cannot use erase() with " + type_name());
+        }
+
+        if (idx >= size())
+        {
+            throw std::out_of_range("index out of range");
+        }
+
+        m_value.array->erase(m_value.array->begin() + static_cast<difference_type>(idx));
+    }
+
+    /*!
+    @brief find an element in a JSON object
+
+    Finds an element in a JSON object with key equivalent to @a key. If the
+    element is not found or the JSON value is not an object, end() is returned.
+
+    @param[in] key key value of the element to search for
+
+    @return Iterator to an element with key equivalent to @a key. If no such
+    element is found, past-the-end (see end()) iterator is returned.
+
+    @complexity Logarithmic in the size of the JSON object.
+
+    @liveexample{The example shows how find is used.,find__key_type}
+    */
+    iterator find(typename object_t::key_type key)
+    {
+        auto result = end();
+
+        if (m_type == value_t::object)
+        {
+            result.m_it.object_iterator = m_value.object->find(key);
+        }
+
+        return result;
+    }
+
+    /*!
+    @brief find an element in a JSON object
+    @copydoc find(typename object_t::key_type)
+    */
+    const_iterator find(typename object_t::key_type key) const
+    {
+        auto result = cend();
+
+        if (m_type == value_t::object)
+        {
+            result.m_it.object_iterator = m_value.object->find(key);
+        }
+
+        return result;
+    }
+
+    /*!
+    @brief returns the number of occurrences of a key in a JSON object
+
+    Returns the number of elements with key @a key. If ObjectType is the
+    default `std::map` type, the return value will always be `0` (@a key was
+    not found) or `1` (@a key was found).
+
+    @param[in] key key value of the element to count
+
+    @return Number of elements with key @a key. If the JSON value is not an
+    object, the return value will be `0`.
+
+    @complexity Logarithmic in the size of the JSON object.
+
+    @liveexample{The example shows how count is used.,count}
+    */
+    size_type count(typename object_t::key_type key) const
+    {
+        // return 0 for all nonobject types
+        return (m_type == value_t::object) ? m_value.object->count(key) : 0;
+    }
+
+    /// @}
+
+
+    ///////////////
+    // iterators //
+    ///////////////
+
+    /// @name iterators
+    /// @{
+
+    /*!
+    @brief returns an iterator to the first element
+
+    Returns an iterator to the first element.
+
+    @image html range-begin-end.svg "Illustration from cppreference.com"
+
+    @return iterator to the first element
+
+    @complexity Constant.
+
+    @requirement This function satisfies the Container requirements:
+    - The complexity is constant.
+
+    @liveexample{The following code shows an example for @ref begin.,begin}
+    */
+    iterator begin()
+    {
+        iterator result(this);
+        result.set_begin();
+        return result;
+    }
+
+    /*!
+    @copydoc basic_json::cbegin()
+    */
+    const_iterator begin() const
+    {
+        return cbegin();
+    }
+
+    /*!
+    @brief returns a const iterator to the first element
+
+    Returns a const iterator to the first element.
+
+    @image html range-begin-end.svg "Illustration from cppreference.com"
+
+    @return const iterator to the first element
+
+    @complexity Constant.
+
+    @requirement This function satisfies the Container requirements:
+    - The complexity is constant.
+    - Has the semantics of `const_cast<const basic_json&>(*this).begin()`.
+
+    @liveexample{The following code shows an example for @ref cbegin.,cbegin}
+    */
+    const_iterator cbegin() const
+    {
+        const_iterator result(this);
+        result.set_begin();
+        return result;
+    }
+
+    /*!
+    @brief returns an iterator to one past the last element
+
+    Returns an iterator to one past the last element.
+
+    @image html range-begin-end.svg "Illustration from cppreference.com"
+
+    @return iterator one past the last element
+
+    @complexity Constant.
+
+    @requirement This function satisfies the Container requirements:
+    - The complexity is constant.
+
+    @liveexample{The following code shows an example for @ref end.,end}
+    */
+    iterator end()
+    {
+        iterator result(this);
+        result.set_end();
+        return result;
+    }
+
+    /*!
+    @copydoc basic_json::cend()
+    */
+    const_iterator end() const
+    {
+        return cend();
+    }
+
+    /*!
+    @brief returns a const iterator to one past the last element
+
+    Returns a const iterator to one past the last element.
+
+    @image html range-begin-end.svg "Illustration from cppreference.com"
+
+    @return const iterator one past the last element
+
+    @complexity Constant.
+
+    @requirement This function satisfies the Container requirements:
+    - The complexity is constant.
+    - Has the semantics of `const_cast<const basic_json&>(*this).end()`.
+
+    @liveexample{The following code shows an example for @ref cend.,cend}
+    */
+    const_iterator cend() const
+    {
+        const_iterator result(this);
+        result.set_end();
+        return result;
+    }
+
+    /*!
+    @brief returns an iterator to the reverse-beginning
+
+    Returns an iterator to the reverse-beginning; that is, the last element.
+
+    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
+
+    @complexity Constant.
+
+    @requirement This function satisfies the ReversibleContainer requirements:
+    - The complexity is constant.
+    - Has the semantics of `reverse_iterator(end())`.
+
+    @liveexample{The following code shows an example for @ref rbegin.,rbegin}
+    */
+    reverse_iterator rbegin()
+    {
+        return reverse_iterator(end());
+    }
+
+    /*!
+    @copydoc basic_json::crbegin()
+    */
+    const_reverse_iterator rbegin() const
+    {
+        return crbegin();
+    }
+
+    /*!
+    @brief returns an iterator to the reverse-end
+
+    Returns an iterator to the reverse-end; that is, one before the first
+    element.
+
+    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
+
+    @complexity Constant.
+
+    @requirement This function satisfies the ReversibleContainer requirements:
+    - The complexity is constant.
+    - Has the semantics of `reverse_iterator(begin())`.
+
+    @liveexample{The following code shows an example for @ref rend.,rend}
+    */
+    reverse_iterator rend()
+    {
+        return reverse_iterator(begin());
+    }
+
+    /*!
+    @copydoc basic_json::crend()
+    */
+    const_reverse_iterator rend() const
+    {
+        return crend();
+    }
+
+    /*!
+    @brief returns a const reverse iterator to the last element
+
+    Returns a const iterator to the reverse-beginning; that is, the last
+    element.
+
+    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
+
+    @complexity Constant.
+
+    @requirement This function satisfies the ReversibleContainer requirements:
+    - The complexity is constant.
+    - Has the semantics of `const_cast<const basic_json&>(*this).rbegin()`.
+
+    @liveexample{The following code shows an example for @ref crbegin.,crbegin}
+    */
+    const_reverse_iterator crbegin() const
+    {
+        return const_reverse_iterator(cend());
+    }
+
+    /*!
+    @brief returns a const reverse iterator to one before the first
+
+    Returns a const reverse iterator to the reverse-end; that is, one before
+    the first element.
+
+    @image html range-rbegin-rend.svg "Illustration from cppreference.com"
+
+    @complexity Constant.
+
+    @requirement This function satisfies the ReversibleContainer requirements:
+    - The complexity is constant.
+    - Has the semantics of `const_cast<const basic_json&>(*this).rend()`.
+
+    @liveexample{The following code shows an example for @ref crend.,crend}
+    */
+    const_reverse_iterator crend() const
+    {
+        return const_reverse_iterator(cbegin());
+    }
+
+    /// @}
+
+
+    //////////////
+    // capacity //
+    //////////////
+
+    /// @name capacity
+    /// @{
+
+    /*!
+    @brief checks whether the container is empty
+
+    Checks if a JSON value has no elements.
+
+    @return The return value depends on the different types and is
+            defined as follows:
+            Value type  | return value
+            ----------- | -------------
+            null        | @c true
+            boolean     | @c false
+            string      | @c false
+            number      | @c false
+            object      | result of function object_t::empty()
+            array       | result of function array_t::empty()
+
+    @complexity Constant, as long as @ref array_t and @ref object_t satisfy the
+                Container concept; that is, their empty() functions have
+                constant complexity.
+
+    @requirement This function satisfies the Container requirements:
+    - The complexity is constant.
+    - Has the semantics of `begin() == end()`.
+
+    @liveexample{The following code uses @ref empty to check if a @ref json
+    object contains any elements.,empty}
+    */
+    bool empty() const noexcept
+    {
+        switch (m_type)
+        {
+            case (value_t::null):
+            {
+                return true;
+            }
+
+            case (value_t::array):
+            {
+                return m_value.array->empty();
+            }
+
+            case (value_t::object):
+            {
+                return m_value.object->empty();
+            }
+
+            default:
+            {
+                // all other types are nonempty
+                return false;
+            }
+        }
+    }
+
+    /*!
+    @brief returns the number of elements
+
+    Returns the number of elements in a JSON value.
+
+    @return The return value depends on the different types and is
+            defined as follows:
+            Value type  | return value
+            ----------- | -------------
+            null        | @c 0
+            boolean     | @c 1
+            string      | @c 1
+            number      | @c 1
+            object      | result of function object_t::size()
+            array       | result of function array_t::size()
+
+    @complexity Constant, as long as @ref array_t and @ref object_t satisfy the
+                Container concept; that is, their size() functions have
+                constant complexity.
+
+    @requirement This function satisfies the Container requirements:
+    - The complexity is constant.
+    - Has the semantics of `std::distance(begin(), end())`.
+
+    @liveexample{The following code calls @ref size on the different value
+    types.,size}
+    */
+    size_type size() const noexcept
+    {
+        switch (m_type)
+        {
+            case (value_t::null):
+            {
+                return 0;
+            }
+
+            case (value_t::array):
+            {
+                return m_value.array->size();
+            }
+
+            case (value_t::object):
+            {
+                return m_value.object->size();
+            }
+
+            default:
+            {
+                // all other types have size 1
+                return 1;
+            }
+        }
+    }
+
+    /*!
+    @brief returns the maximum possible number of elements
+
+    Returns the maximum number of elements a JSON value is able to hold due to
+    system or library implementation limitations, i.e. `std::distance(begin(),
+    end())` for the JSON value.
+
+    @return The return value depends on the different types and is
+            defined as follows:
+            Value type  | return value
+            ----------- | -------------
+            null        | @c 0 (same as size())
+            boolean     | @c 1 (same as size())
+            string      | @c 1 (same as size())
+            number      | @c 1 (same as size())
+            object      | result of function object_t::max_size()
+            array       | result of function array_t::max_size()
+
+    @complexity Constant, as long as @ref array_t and @ref object_t satisfy the
+                Container concept; that is, their max_size() functions have
+                constant complexity.
+
+    @requirement This function satisfies the Container requirements:
+    - The complexity is constant.
+    - Has the semantics of returning `b.size()` where `b` is the largest
+      possible JSON value.
+
+    @liveexample{The following code calls @ref max_size on the different value
+    types. Note the output is implementation specific.,max_size}
+    */
+    size_type max_size() const noexcept
+    {
+        switch (m_type)
+        {
+            case (value_t::array):
+            {
+                return m_value.array->max_size();
+            }
+
+            case (value_t::object):
+            {
+                return m_value.object->max_size();
+            }
+
+            default:
+            {
+                // all other types have max_size() == size()
+                return size();
+            }
+        }
+    }
+
+    /// @}
+
+
+    ///////////////
+    // modifiers //
+    ///////////////
+
+    /// @name modifiers
+    /// @{
+
+    /*!
+    @brief clears the contents
+
+    Clears the content of a JSON value and resets it to the default value as
+    if @ref basic_json(value_t) would have been called:
+
+    Value type  | initial value
+    ----------- | -------------
+    null        | `null`
+    boolean     | `false`
+    string      | `""`
+    number      | `0`
+    object      | `{}`
+    array       | `[]`
+
+    @note Floating-point numbers are set to `0.0` which will be serialized to
+    `0`. The vale type remains @ref number_float_t.
+
+    @complexity Linear in the size of the JSON value.
+
+    @liveexample{The example below shows the effect of @ref clear to different
+    JSON types.,clear}
+    */
+    void clear() noexcept
+    {
+        switch (m_type)
+        {
+            case (value_t::null):
+            case (value_t::discarded):
+            {
+                break;
+            }
+
+            case (value_t::number_integer):
+            {
+                m_value.number_integer = 0;
+                break;
+            }
+
+            case (value_t::number_float):
+            {
+                m_value.number_float = 0.0;
+                break;
+            }
+
+            case (value_t::boolean):
+            {
+                m_value.boolean = false;
+                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;
+            }
+        }
+    }
+
+    /*!
+    @brief add an object to an array
+
+    Appends the given element @a value to the end of the JSON value. If the
+    function is called on a JSON null value, an empty array is created before
+    appending @a value.
+
+    @param value the value to add to the JSON array
+
+    @throw std::domain_error when called on a type other than JSON array or null
+
+    @complexity Amortized constant.
+
+    @liveexample{The example shows how `push_back` and `+=` can be used to add
+    elements to a JSON array. Note how the `null` value was silently converted
+    to a JSON array.,push_back}
+    */
+    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::domain_error("cannot use push_back() with " + type_name());
+        }
+
+        // transform null object into an array
+        if (m_type == value_t::null)
+        {
+            m_type = value_t::array;
+            m_value = value_t::array;
+        }
+
+        // add element to array (move semantics)
+        m_value.array->push_back(std::move(value));
+        // invalidate object
+        value.m_type = value_t::null;
+    }
+
+    /*!
+    @brief add an object to an array
+    @copydoc push_back(basic_json&&)
+    */
+    reference operator+=(basic_json&& value)
+    {
+        push_back(std::move(value));
+        return *this;
+    }
+
+    /*!
+    @brief add an object to an array
+    @copydoc push_back(basic_json&&)
+    */
+    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::domain_error("cannot use push_back() with " + type_name());
+        }
+
+        // transform null object into an array
+        if (m_type == value_t::null)
+        {
+            m_type = value_t::array;
+            m_value = value_t::array;
+        }
+
+        // add element to array
+        m_value.array->push_back(value);
+    }
+
+    /*!
+    @brief add an object to an array
+    @copydoc push_back(basic_json&&)
+    */
+    reference operator+=(const basic_json& value)
+    {
+        push_back(value);
+        return *this;
+    }
+
+    /*!
+    @brief add an object to an object
+
+    Inserts the given element @a value to the JSON object. If the function is
+    called on a JSON null value, an empty object is created before inserting @a
+    value.
+
+    @param[in] value the value to add to the JSON object
+
+    @throw std::domain_error when called on a type other than JSON object or
+    null
+
+    @complexity Logarithmic in the size of the container, O(log(`size()`)).
+
+    @liveexample{The example shows how `push_back` and `+=` can be used to add
+    elements to a JSON object. Note how the `null` value was silently converted
+    to a JSON object.,push_back__object_t__value}
+    */
+    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::domain_error("cannot use push_back() with " + type_name());
+        }
+
+        // transform null object into an object
+        if (m_type == value_t::null)
+        {
+            m_type = value_t::object;
+            m_value = value_t::object;
+        }
+
+        // add element to array
+        m_value.object->insert(value);
+    }
+
+    /*!
+    @brief add an object to an object
+    @copydoc push_back(const typename object_t::value_type&)
+    */
+    reference operator+=(const typename object_t::value_type& value)
+    {
+        push_back(value);
+        return operator[](value.first);
+    }
+
+    /*!
+    @brief inserts element
+
+    Inserts element @a value before iterator @a pos.
+
+    @param[in] pos iterator before which the content will be inserted; may be
+    the end() iterator
+    @param[in] value element to insert
+    @return iterator pointing to the inserted @a value.
+
+    @throw std::domain_error if called on JSON values other than arrays
+    @throw std::domain_error if @a pos is not an iterator of *this
+
+    @complexity Constant plus linear in the distance between pos and end of the
+    container.
+
+    @liveexample{The example shows how insert is used.,insert}
+    */
+    iterator insert(const_iterator pos, const basic_json& value)
+    {
+        // insert only works for arrays
+        if (m_type != value_t::array)
+        {
+            throw std::domain_error("cannot use insert() with " + type_name());
+        }
+
+        // check if iterator pos fits to this JSON value
+        if (pos.m_object != this)
+        {
+            throw std::domain_error("iterator does not fit current value");
+        }
+
+        // insert to array and return iterator
+        iterator result(this);
+        result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator, value);
+        return result;
+    }
+
+    /*!
+    @brief inserts element
+    @copydoc insert(const_iterator, const basic_json&)
+    */
+    iterator insert(const_iterator pos, basic_json&& value)
+    {
+        return insert(pos, value);
+    }
+
+    /*!
+    @brief inserts elements
+
+    Inserts @a count copies of @a value before iterator @a pos.
+
+    @param[in] pos iterator before which the content will be inserted; may be
+    the end() iterator
+    @param[in] count number of copies of @a value to insert
+    @param[in] value element to insert
+    @return iterator pointing to the first element inserted, or @a pos if
+    `count==0`
+
+    @throw std::domain_error if called on JSON values other than arrays
+    @throw std::domain_error if @a pos is not an iterator of *this
+
+    @complexity Linear in @a count plus linear in the distance between @a pos
+    and end of the container.
+
+    @liveexample{The example shows how insert is used.,insert__count}
+    */
+    iterator insert(const_iterator pos, size_type count, const basic_json& value)
+    {
+        // insert only works for arrays
+        if (m_type != value_t::array)
+        {
+            throw std::domain_error("cannot use insert() with " + type_name());
+        }
+
+        // check if iterator pos fits to this JSON value
+        if (pos.m_object != this)
+        {
+            throw std::domain_error("iterator does not fit current value");
+        }
+
+        // insert to array and return iterator
+        iterator result(this);
+        result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator, count, value);
+        return result;
+    }
+
+    /*!
+    @brief inserts elements
+
+    Inserts elements from range `[first, last)` before iterator @a pos.
+
+    @param[in] pos iterator before which the content will be inserted; may be
+    the end() iterator
+    @param[in] first begin of the range of elements to insert
+    @param[in] last end of the range of elements to insert
+
+    @throw std::domain_error if called on JSON values other than arrays
+    @throw std::domain_error if @a pos is not an iterator of *this
+    @throw std::domain_error if @a first and @a last do not belong to the same
+    JSON value
+    @throw std::domain_error if @a first or @a last are iterators into
+    container for which insert is called
+    @return iterator pointing to the first element inserted, or @a pos if
+    `first==last`
+
+    @complexity Linear in `std::distance(first, last)` plus linear in the
+    distance between @a pos and end of the container.
+
+    @liveexample{The example shows how insert is used.,insert__range}
+    */
+    iterator insert(const_iterator pos, const_iterator first, const_iterator last)
+    {
+        // insert only works for arrays
+        if (m_type != value_t::array)
+        {
+            throw std::domain_error("cannot use insert() with " + type_name());
+        }
+
+        // check if iterator pos fits to this JSON value
+        if (pos.m_object != this)
+        {
+            throw std::domain_error("iterator does not fit current value");
+        }
+
+        if (first.m_object != last.m_object)
+        {
+            throw std::domain_error("iterators does not fit");
+        }
+
+        if (first.m_object == this or last.m_object == this)
+        {
+            throw std::domain_error("passed iterators may not belong to container");
+        }
+
+        // insert to array and return iterator
+        iterator result(this);
+        result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator,
+                                     first.m_it.array_iterator, last.m_it.array_iterator);
+        return result;
+    }
+
+    /*!
+    @brief inserts elements
+
+    Inserts elements from initializer list @a ilist before iterator @a pos.
+
+    @param[in] pos iterator before which the content will be inserted; may be
+    the end() iterator
+    @param[in] ilist initializer list to insert the values from
+
+    @throw std::domain_error if called on JSON values other than arrays
+    @throw std::domain_error if @a pos is not an iterator of *this
+    @return iterator pointing to the first element inserted, or @a pos if
+    `ilist` is empty
+
+    @complexity Linear in `ilist.size()` plus linear in the distance between @a
+    pos and end of the container.
+
+    @liveexample{The example shows how insert is used.,insert__ilist}
+    */
+    iterator insert(const_iterator pos, std::initializer_list<basic_json> ilist)
+    {
+        // insert only works for arrays
+        if (m_type != value_t::array)
+        {
+            throw std::domain_error("cannot use insert() with " + type_name());
+        }
+
+        // check if iterator pos fits to this JSON value
+        if (pos.m_object != this)
+        {
+            throw std::domain_error("iterator does not fit current value");
+        }
+
+        // insert to array and return iterator
+        iterator result(this);
+        result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator, ilist);
+        return result;
+    }
+
+    /*!
+    @brief exchanges the values
+
+    Exchanges the contents of the JSON value with those of @a other. Does not
+    invoke any move, copy, or swap operations on individual elements. All
+    iterators and references remain valid. The past-the-end iterator is
+    invalidated.
+
+    @param[in,out] other JSON value to exchange the contents with
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how JSON arrays can be
+    swapped.,swap__reference}
+    */
+    void swap(reference 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);
+    }
+
+    /*!
+    @brief exchanges the values
+
+    Exchanges the contents of a JSON array with those of @a other. Does not
+    invoke any move, copy, or swap operations on individual elements. All
+    iterators and references remain valid. The past-the-end iterator is
+    invalidated.
+
+    @param[in,out] other array to exchange the contents with
+
+    @throw std::domain_error when JSON value is not an array
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how JSON values can be
+    swapped.,swap__array_t}
+    */
+    void swap(array_t& other)
+    {
+        // swap only works for arrays
+        if (m_type != value_t::array)
+        {
+            throw std::domain_error("cannot use swap() with " + type_name());
+        }
+
+        // swap arrays
+        std::swap(*(m_value.array), other);
+    }
+
+    /*!
+    @brief exchanges the values
+
+    Exchanges the contents of a JSON object with those of @a other. Does not
+    invoke any move, copy, or swap operations on individual elements. All
+    iterators and references remain valid. The past-the-end iterator is
+    invalidated.
+
+    @param[in,out] other object to exchange the contents with
+
+    @throw std::domain_error when JSON value is not an object
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how JSON values can be
+    swapped.,swap__object_t}
+    */
+    void swap(object_t& other)
+    {
+        // swap only works for objects
+        if (m_type != value_t::object)
+        {
+            throw std::domain_error("cannot use swap() with " + type_name());
+        }
+
+        // swap objects
+        std::swap(*(m_value.object), other);
+    }
+
+    /*!
+    @brief exchanges the values
+
+    Exchanges the contents of a JSON string with those of @a other. Does not
+    invoke any move, copy, or swap operations on individual elements. All
+    iterators and references remain valid. The past-the-end iterator is
+    invalidated.
+
+    @param[in,out] other string to exchange the contents with
+
+    @throw std::domain_error when JSON value is not a string
+
+    @complexity Constant.
+
+    @liveexample{The example below shows how JSON values can be
+    swapped.,swap__string_t}
+    */
+    void swap(string_t& other)
+    {
+        // swap only works for strings
+        if (m_type != value_t::string)
+        {
+            throw std::domain_error("cannot use swap() with " + type_name());
+        }
+
+        // swap strings
+        std::swap(*(m_value.string), other);
+    }
+
+    /// @}
+
+
+    //////////////////////////////////////////
+    // lexicographical comparison operators //
+    //////////////////////////////////////////
+
+    /// @name lexicographical comparison operators
+    /// @{
+
+  private:
+    /*!
+    @brief comparison operator for JSON 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)
+    {
+        static constexpr std::array<uint8_t, 7> order = {{
+                0, // null
+                3, // object
+                4, // array
+                5, // string
+                1, // boolean
+                2, // integer
+                2  // float
+            }
+        };
+
+        // discarded values are not comparable
+        if (lhs == value_t::discarded or rhs == value_t::discarded)
+        {
+            return false;
+        }
+
+        return order[static_cast<std::size_t>(lhs)] < order[static_cast<std::size_t>(rhs)];
+    }
+
+  public:
+    /*!
+    @brief comparison: equal
+
+    Compares two JSON values for equality according to the following rules:
+    - Two JSON values are equal if (1) they are from the same type and (2)
+      their stored values are the same.
+    - Integer and floating-point numbers are automatically converted before
+      comparison. Floating-point numbers are compared indirectly: two
+      floating-point numbers `f1` and `f2` are considered equal if neither
+      `f1 > f2` nor `f2 > f1` holds.
+    - Two JSON null values are equal.
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether the values @a lhs and @a rhs are equal
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__equal}
+    */
+    friend bool operator==(const_reference lhs, const_reference rhs) noexcept
+    {
+        const auto lhs_type = lhs.type();
+        const auto rhs_type = rhs.type();
+
+        if (lhs_type == rhs_type)
+        {
+            switch (lhs_type)
+            {
+                case (value_t::array):
+                    return *lhs.m_value.array == *rhs.m_value.array;
+                case (value_t::object):
+                    return *lhs.m_value.object == *rhs.m_value.object;
+                case (value_t::null):
+                    return true;
+                case (value_t::string):
+                    return *lhs.m_value.string == *rhs.m_value.string;
+                case (value_t::boolean):
+                    return lhs.m_value.boolean == rhs.m_value.boolean;
+                case (value_t::number_integer):
+                    return lhs.m_value.number_integer == rhs.m_value.number_integer;
+                case (value_t::number_float):
+                    return approx(lhs.m_value.number_float, rhs.m_value.number_float);
+                case (value_t::discarded):
+                    return false;
+            }
+        }
+        else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_float)
+        {
+            return approx(static_cast<number_float_t>(lhs.m_value.number_integer),
+                          rhs.m_value.number_float);
+        }
+        else if (lhs_type == value_t::number_float and rhs_type == value_t::number_integer)
+        {
+            return approx(lhs.m_value.number_float,
+                          static_cast<number_float_t>(rhs.m_value.number_integer));
+        }
+        return false;
+    }
+
+    /*!
+    @brief comparison: equal
+
+    The functions compares the given JSON value against a null pointer. As the
+    null pointer can be used to initialize a JSON value to null, a comparison
+    of JSON value @a v with a null pointer should be equivalent to call
+    `v.is_null()`.
+
+    @param[in] v  JSON value to consider
+    @return whether @a v is null
+
+    @complexity Constant.
+
+    @liveexample{The example compares several JSON types to the null pointer.
+    ,operator__equal__nullptr_t}
+    */
+    friend bool operator==(const_reference v, std::nullptr_t) noexcept
+    {
+        return v.is_null();
+    }
+
+    /*!
+    @brief comparison: equal
+    @copydoc operator==(const_reference, std::nullptr_t)
+    */
+    friend bool operator==(std::nullptr_t, const_reference v) noexcept
+    {
+        return v.is_null();
+    }
+
+    /*!
+    @brief comparison: not equal
+
+    Compares two JSON values for inequality by calculating `not (lhs == rhs)`.
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether the values @a lhs and @a rhs are not equal
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__notequal}
+    */
+    friend bool operator!=(const_reference lhs, const_reference rhs) noexcept
+    {
+        return not (lhs == rhs);
+    }
+
+    /*!
+    @brief comparison: not equal
+
+    The functions compares the given JSON value against a null pointer. As the
+    null pointer can be used to initialize a JSON value to null, a comparison
+    of JSON value @a v with a null pointer should be equivalent to call
+    `not v.is_null()`.
+
+    @param[in] v  JSON value to consider
+    @return whether @a v is not null
+
+    @complexity Constant.
+
+    @liveexample{The example compares several JSON types to the null pointer.
+    ,operator__notequal__nullptr_t}
+    */
+    friend bool operator!=(const_reference v, std::nullptr_t) noexcept
+    {
+        return not v.is_null();
+    }
+
+    /*!
+    @brief comparison: not equal
+    @copydoc operator!=(const_reference, std::nullptr_t)
+    */
+    friend bool operator!=(std::nullptr_t, const_reference v) noexcept
+    {
+        return not v.is_null();
+    }
+
+    /*!
+    @brief comparison: less than
+
+    Compares whether one JSON value @a lhs is less than another JSON value @a
+    rhs according to the following rules:
+    - If @a lhs and @a rhs have the same type, the values are compared using
+      the default `<` operator.
+    - Integer and floating-point numbers are automatically converted before
+      comparison
+    - In case @a lhs and @a rhs have different types, the values are ignored
+      and the order of the types is considered, see
+      @ref operator<(const value_t, const value_t).
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether @a lhs is less than @a rhs
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__less}
+    */
+    friend bool operator<(const_reference lhs, const_reference rhs) noexcept
+    {
+        const auto lhs_type = lhs.type();
+        const auto rhs_type = rhs.type();
+
+        if (lhs_type == rhs_type)
+        {
+            switch (lhs_type)
+            {
+                case (value_t::array):
+                    return *lhs.m_value.array < *rhs.m_value.array;
+                case (value_t::object):
+                    return *lhs.m_value.object < *rhs.m_value.object;
+                case (value_t::null):
+                    return false;
+                case (value_t::string):
+                    return *lhs.m_value.string < *rhs.m_value.string;
+                case (value_t::boolean):
+                    return lhs.m_value.boolean < rhs.m_value.boolean;
+                case (value_t::number_integer):
+                    return lhs.m_value.number_integer < rhs.m_value.number_integer;
+                case (value_t::number_float):
+                    return lhs.m_value.number_float < rhs.m_value.number_float;
+                case (value_t::discarded):
+                    return false;
+            }
+        }
+        else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_float)
+        {
+            return static_cast<number_float_t>(lhs.m_value.number_integer) <
+                   rhs.m_value.number_float;
+        }
+        else if (lhs_type == value_t::number_float and rhs_type == value_t::number_integer)
+        {
+            return lhs.m_value.number_float <
+                   static_cast<number_float_t>(rhs.m_value.number_integer);
+        }
+
+        // We only reach this line if we cannot compare values. In that case,
+        // we compare types. Note we have to call the operator explicitly,
+        // because MSVC has problems otherwise.
+        return operator<(lhs_type, rhs_type);
+    }
+
+    /*!
+    @brief comparison: less than or equal
+
+    Compares whether one JSON value @a lhs is less than or equal to another
+    JSON value by calculating `not (rhs < lhs)`.
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether @a lhs is less than or equal to @a rhs
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__greater}
+    */
+    friend bool operator<=(const_reference lhs, const_reference rhs) noexcept
+    {
+        return not (rhs < lhs);
+    }
+
+    /*!
+    @brief comparison: greater than
+
+    Compares whether one JSON value @a lhs is greater than another
+    JSON value by calculating `not (lhs <= rhs)`.
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether @a lhs is greater than to @a rhs
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__lessequal}
+    */
+    friend bool operator>(const_reference lhs, const_reference rhs) noexcept
+    {
+        return not (lhs <= rhs);
+    }
+
+    /*!
+    @brief comparison: greater than or equal
+
+    Compares whether one JSON value @a lhs is greater than or equal to another
+    JSON value by calculating `not (lhs < rhs)`.
+
+    @param[in] lhs  first JSON value to consider
+    @param[in] rhs  second JSON value to consider
+    @return whether @a lhs is greater than or equal to @a rhs
+
+    @complexity Linear.
+
+    @liveexample{The example demonstrates comparing several JSON
+    types.,operator__greaterequal}
+    */
+    friend bool operator>=(const_reference lhs, const_reference rhs) noexcept
+    {
+        return not (lhs < rhs);
+    }
+
+    /// @}
+
+
+    ///////////////////
+    // serialization //
+    ///////////////////
+
+    /// @name serialization
+    /// @{
+
+    /*!
+    @brief serialize to stream
+
+    Serialize the given JSON value @a j to the output stream @a o. The JSON
+    value will be serialized using the @ref dump member function. The
+    indentation of the output can be controlled with the member variable
+    `width` of the output stream @a o. For instance, using the manipulator
+    `std::setw(4)` on @a o sets the indentation level to `4` and the
+    serialization result is the same as calling `dump(4)`.
+
+    @param[in,out] o  stream to serialize to
+    @param[in] j  JSON value to serialize
+
+    @return the stream @a o
+
+    @complexity Linear.
+
+    @liveexample{The example below shows the serialization with different
+    parameters to `width` to adjust the indentation level.,operator_serialize}
+    */
+    friend std::ostream& operator<<(std::ostream& o, const basic_json& j)
+    {
+        // read width member and use it as indentation parameter if nonzero
+        const bool pretty_print = (o.width() > 0);
+        const auto indentation = (pretty_print ? o.width() : 0);
+
+        // reset width to 0 for subsequent calls to this stream
+        o.width(0);
+
+        // do the actual serialization
+        j.dump(o, pretty_print, static_cast<unsigned int>(indentation));
+        return o;
+    }
+
+    /*!
+    @brief serialize to stream
+    @copydoc operator<<(std::ostream&, const basic_json&)
+    */
+    friend std::ostream& operator>>(const basic_json& j, std::ostream& o)
+    {
+        return o << j;
+    }
+
+    /// @}
+
+
+    /////////////////////
+    // deserialization //
+    /////////////////////
+
+    /// @name deserialization
+    /// @{
+
+    /*!
+    @brief deserialize from string
+
+    @param[in] s  string to read a serialized JSON value from
+    @param[in] cb a parser callback function of type @ref parser_callback_t
+    which is used to control the deserialization by filtering unwanted values
+    (optional)
+
+    @return result of the deserialization
+
+    @complexity Linear in the length of the input. The parser is a predictive
+    LL(1) parser. The complexity can be higher if the parser callback function
+    @a cb has a super-linear complexity.
+
+    @liveexample{The example below demonstrates the parse function with and
+    without callback function.,parse__string__parser_callback_t}
+
+    @sa parse(std::istream&, parser_callback_t) for a version that reads from
+    an input stream
+    */
+    static basic_json parse(const string_t& s, parser_callback_t cb = nullptr)
+    {
+        return parser(s, cb).parse();
+    }
+
+    /*!
+    @brief deserialize from stream
+
+    @param[in,out] i  stream to read a serialized JSON value from
+    @param[in] cb a parser callback function of type @ref parser_callback_t
+    which is used to control the deserialization by filtering unwanted values
+    (optional)
+
+    @return result of the deserialization
+
+    @complexity Linear in the length of the input. The parser is a predictive
+    LL(1) parser. The complexity can be higher if the parser callback function
+    @a cb has a super-linear complexity.
+
+    @liveexample{The example below demonstrates the parse function with and
+    without callback function.,parse__istream__parser_callback_t}
+
+    @sa parse(const string_t&, parser_callback_t) for a version that reads
+    from a string
+    */
+    static basic_json parse(std::istream& i, parser_callback_t cb = nullptr)
+    {
+        return parser(i, cb).parse();
+    }
+
+    /*!
+    @brief deserialize from stream
+
+    Deserializes an input stream to a JSON value.
+
+    @param[in,out] i  input stream to read a serialized JSON value from
+    @param[in,out] j  JSON value to write the deserialized input to
+
+    @throw std::invalid_argument in case of parse errors
+
+    @complexity Linear in the length of the input. The parser is a predictive
+    LL(1) parser.
+
+    @liveexample{The example below shows how a JSON value is constructed by
+    reading a serialization from a stream.,operator_deserialize}
+
+    @sa parse(std::istream&, parser_callback_t) for a variant with a parser
+    callback function to filter values while parsing
+    */
+    friend std::istream& operator<<(basic_json& j, std::istream& i)
+    {
+        j = parser(i).parse();
+        return i;
+    }
+
+    /*!
+    @brief deserialize from stream
+    @copydoc operator<<(basic_json&, std::istream&)
+    */
+    friend std::istream& operator>>(std::istream& i, basic_json& j)
+    {
+        j = parser(i).parse();
+        return i;
+    }
+
+    /// @}
+
+
+  private:
+    ///////////////////////////
+    // convenience functions //
+    ///////////////////////////
+
+    /// return the type as string
+    string_t type_name() const
+    {
+        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::discarded):
+            {
+                return "discarded";
+            }
+
+            default:
+            {
+                return "number";
+            }
+        }
+    }
+
+    /*!
+    @brief calculates the extra space to escape a JSON string
+
+    @param[in] s  the string to escape
+    @return the number of characters required to escape string @a s
+
+    @complexity Linear in the length of string @a s.
+    */
+    static std::size_t extra_space(const string_t& s) noexcept
+    {
+        std::size_t result = 0;
+
+        for (const auto& c : s)
+        {
+            switch (c)
+            {
+                case '"':
+                case '\\':
+                case '\b':
+                case '\f':
+                case '\n':
+                case '\r':
+                case '\t':
+                {
+                    // from c (1 byte) to \x (2 bytes)
+                    result += 1;
+                    break;
+                }
+
+                default:
+                {
+                    if (c >= 0x00 and c <= 0x1f)
+                    {
+                        // from c (1 byte) to \uxxxx (6 bytes)
+                        result += 5;
+                    }
+                    break;
+                }
+            }
+        }
+
+        return result;
+    }
+
+    /*!
+    @brief escape a string
+
+    Escape a string by replacing certain special characters by a sequence of an
+    escape character (backslash) and another character and other control
+    characters by a sequence of "\u" followed by a four-digit hex
+    representation.
+
+    @param[in] s  the string to escape
+    @return  the escaped string
+
+    @complexity Linear in the length of string @a s.
+    */
+    static string_t escape_string(const string_t& s) noexcept
+    {
+        const auto space = extra_space(s);
+        if (space == 0)
+        {
+            return s;
+        }
+
+        // create a result string of necessary size
+        string_t result(s.size() + space, '\\');
+        std::size_t pos = 0;
+
+        for (const auto& c : s)
+        {
+            switch (c)
+            {
+                // quotation mark (0x22)
+                case '"':
+                {
+                    result[pos + 1] = '"';
+                    pos += 2;
+                    break;
+                }
+
+                // reverse solidus (0x5c)
+                case '\\':
+                {
+                    // nothing to change
+                    pos += 2;
+                    break;
+                }
+
+                // backspace (0x08)
+                case '\b':
+                {
+                    result[pos + 1] = 'b';
+                    pos += 2;
+                    break;
+                }
+
+                // formfeed (0x0c)
+                case '\f':
+                {
+                    result[pos + 1] = 'f';
+                    pos += 2;
+                    break;
+                }
+
+                // newline (0x0a)
+                case '\n':
+                {
+                    result[pos + 1] = 'n';
+                    pos += 2;
+                    break;
+                }
+
+                // carriage return (0x0d)
+                case '\r':
+                {
+                    result[pos + 1] = 'r';
+                    pos += 2;
+                    break;
+                }
+
+                // horizontal tab (0x09)
+                case '\t':
+                {
+                    result[pos + 1] = 't';
+                    pos += 2;
+                    break;
+                }
+
+                default:
+                {
+                    if (c >= 0x00 and c <= 0x1f)
+                    {
+                        // print character c as \uxxxx
+                        sprintf(&result[pos + 1], "u%04x", int(c));
+                        pos += 6;
+                        // overwrite trailing null character
+                        result[pos] = '\\';
+                    }
+                    else
+                    {
+                        // all other characters are added as-is
+                        result[pos++] = c;
+                    }
+                    break;
+                }
+            }
+        }
+
+        return result;
+    }
+
+    /*!
+    @brief internal implementation of the serialization function
+
+    This function is called by the public member function dump and organizes
+    the serializaion internally. The indentation level is propagated as
+    additional parameter. In case of arrays and objects, the function is called
+    recursively. Note that
+
+    - strings and object keys are escaped using escape_string()
+    - integer numbers are converted implictly via operator<<
+    - floating-point numbers are converted to a string using "%g" format
+
+    @param[out] o              stream to write to
+    @param[in] pretty_print    whether the output shall be pretty-printed
+    @param[in] indent_step     the indent level
+    @param[in] current_indent  the current indent level (only used internally)
+    */
+    void dump(std::ostream& o, const bool pretty_print, const unsigned int indent_step,
+              const unsigned int current_indent = 0) const
+    {
+        // variable to hold indentation for recursive calls
+        unsigned int new_indent = current_indent;
+
+        switch (m_type)
+        {
+            case (value_t::object):
+            {
+                if (m_value.object->empty())
+                {
+                    o << "{}";
+                    return;
+                }
+
+                o << "{";
+
+                // increase indentation
+                if (pretty_print)
+                {
+                    new_indent += indent_step;
+                    o << "\n";
+                }
+
+                for (auto i = m_value.object->cbegin(); i != m_value.object->cend(); ++i)
+                {
+                    if (i != m_value.object->cbegin())
+                    {
+                        o << (pretty_print ? ",\n" : ",");
+                    }
+                    o << string_t(new_indent, ' ') << "\""
+                      << escape_string(i->first) << "\":"
+                      << (pretty_print ? " " : "");
+                    i->second.dump(o, pretty_print, indent_step, new_indent);
+                }
+
+                // decrease indentation
+                if (pretty_print)
+                {
+                    new_indent -= indent_step;
+                    o << "\n";
+                }
+
+                o << string_t(new_indent, ' ') + "}";
+                return;
+            }
+
+            case (value_t::array):
+            {
+                if (m_value.array->empty())
+                {
+                    o << "[]";
+                    return;
+                }
+
+                o << "[";
+
+                // increase indentation
+                if (pretty_print)
+                {
+                    new_indent += indent_step;
+                    o << "\n";
+                }
+
+                for (auto i = m_value.array->cbegin(); i != m_value.array->cend(); ++i)
+                {
+                    if (i != m_value.array->cbegin())
+                    {
+                        o << (pretty_print ? ",\n" : ",");
+                    }
+                    o << string_t(new_indent, ' ');
+                    i->dump(o, pretty_print, indent_step, new_indent);
+                }
+
+                // decrease indentation
+                if (pretty_print)
+                {
+                    new_indent -= indent_step;
+                    o << "\n";
+                }
+
+                o << string_t(new_indent, ' ') << "]";
+                return;
+            }
+
+            case (value_t::string):
+            {
+                o << string_t("\"") << escape_string(*m_value.string) << "\"";
+                return;
+            }
+
+            case (value_t::boolean):
+            {
+                o << (m_value.boolean ? "true" : "false");
+                return;
+            }
+
+            case (value_t::number_integer):
+            {
+                o << m_value.number_integer;
+                return;
+            }
+
+            case (value_t::number_float):
+            {
+                // 15 digits of precision allows round-trip IEEE 754
+                // string->double->string; to be safe, we read this value from
+                // std::numeric_limits<number_float_t>::digits10
+                o << std::setprecision(std::numeric_limits<number_float_t>::digits10) << m_value.number_float;
+                return;
+            }
+
+            case (value_t::discarded):
+            {
+                o << "<discarded>";
+                return;
+            }
+
+            default:
+            {
+                o << "null";
+                return;
+            }
+        }
+    }
+
+  private:
+    //////////////////////
+    // member variables //
+    //////////////////////
+
+    /// the type of the current element
+    value_t m_type = value_t::null;
+
+    /// the value of the current element
+    json_value m_value = {};
+
+
+  private:
+    ///////////////
+    // iterators //
+    ///////////////
+
+    /*!
+    @brief an iterator for primitive JSON types
+
+    This class models an iterator for primitive JSON types (boolean, number,
+    string). It's only purpose is to allow the iterator/const_iterator classes
+    to "iterate" over primitive values. Internally, the iterator is modeled by
+    a `difference_type` variable. Value begin_value (`0`) models the begin,
+    end_value (`1`) models past the end.
+    */
+    class primitive_iterator_t
+    {
+      public:
+        /// set iterator to a defined beginning
+        void set_begin()
+        {
+            m_it = begin_value;
+        }
+
+        /// set iterator to a defined past the end
+        void set_end()
+        {
+            m_it = end_value;
+        }
+
+        /// return whether the iterator can be dereferenced
+        bool is_begin() const
+        {
+            return (m_it == begin_value);
+        }
+
+        /// return whether the iterator is at end
+        bool is_end() const
+        {
+            return (m_it == end_value);
+        }
+
+        /// return reference to the value to change and compare
+        operator difference_type& ()
+        {
+            return m_it;
+        }
+
+        /// return value to compare
+        operator difference_type () const
+        {
+            return m_it;
+        }
+
+      private:
+        static constexpr difference_type begin_value = 0;
+        static constexpr difference_type end_value = begin_value + 1;
+
+        /// iterator as signed integer type
+        difference_type m_it = std::numeric_limits<std::ptrdiff_t>::min();
+    };
+
+    /*!
+    @brief an iterator value
+
+    @note This structure could easily be a union, but MSVC currently does not
+    allow unions members with complex constructors, see
+    https://github.com/nlohmann/json/pull/105.
+    */
+    struct internal_iterator
+    {
+        /// iterator for JSON objects
+        typename object_t::iterator object_iterator;
+        /// iterator for JSON arrays
+        typename array_t::iterator array_iterator;
+        /// generic iterator for all other types
+        primitive_iterator_t primitive_iterator;
+
+        /// create an uninitialized internal_iterator
+        internal_iterator()
+            : object_iterator(), array_iterator(), primitive_iterator()
+        {}
+    };
+
+  public:
+    /*!
+    @brief a const random access iterator for the @ref basic_json class
+
+    This class implements a const iterator for the @ref basic_json class. From
+    this class, the @ref iterator class is derived.
+
+    @requirement The class satisfies the following concept requirements:
+    - [RandomAccessIterator](http://en.cppreference.com/w/cpp/concept/RandomAccessIterator):
+      The iterator that can be moved to point (forward and backward) to any
+      element in constant time.
+    */
+    class const_iterator : public std::iterator<std::random_access_iterator_tag, const basic_json>
+    {
+        /// allow basic_json to access private members
+        friend class basic_json;
+
+      public:
+        /// the type of the values when the iterator is dereferenced
+        using value_type = typename basic_json::value_type;
+        /// a type to represent differences between iterators
+        using difference_type = typename basic_json::difference_type;
+        /// defines a pointer to the type iterated over (value_type)
+        using pointer = typename basic_json::const_pointer;
+        /// defines a reference to the type iterated over (value_type)
+        using reference = typename basic_json::const_reference;
+        /// the category of the iterator
+        using iterator_category = std::bidirectional_iterator_tag;
+
+        /// default constructor
+        const_iterator() = default;
+
+        /// constructor for a given JSON instance
+        const_iterator(pointer object) : m_object(object)
+        {
+            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.primitive_iterator = primitive_iterator_t();
+                    break;
+                }
+            }
+        }
+
+        /// copy constructor given a nonconst iterator
+        const_iterator(const iterator& other) : m_object(other.m_object)
+        {
+            switch (m_object->m_type)
+            {
+                case (basic_json::value_t::object):
+                {
+                    m_it.object_iterator = other.m_it.object_iterator;
+                    break;
+                }
+
+                case (basic_json::value_t::array):
+                {
+                    m_it.array_iterator = other.m_it.array_iterator;
+                    break;
+                }
+
+                default:
+                {
+                    m_it.primitive_iterator = other.m_it.primitive_iterator;
+                    break;
+                }
+            }
+        }
+
+        /// copy constructor
+        const_iterator(const const_iterator& other) noexcept
+            : m_object(other.m_object), m_it(other.m_it)
+        {}
+
+        /// copy assignment
+        const_iterator& operator=(const_iterator other) noexcept(
+            std::is_nothrow_move_constructible<pointer>::value and
+            std::is_nothrow_move_assignable<pointer>::value and
+            std::is_nothrow_move_constructible<internal_iterator>::value and
+            std::is_nothrow_move_assignable<internal_iterator>::value
+        )
+        {
+            std::swap(m_object, other.m_object);
+            std::swap(m_it, other.m_it);
+            return *this;
+        }
+
+      private:
+        /// set the iterator to the first value
+        void set_begin()
+        {
+            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):
+                {
+                    // set to end so begin()==end() is true: null is empty
+                    m_it.primitive_iterator.set_end();
+                    break;
+                }
+
+                default:
+                {
+                    m_it.primitive_iterator.set_begin();
+                    break;
+                }
+            }
+        }
+
+        /// set the iterator past the last value
+        void set_end()
+        {
+            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.primitive_iterator.set_end();
+                    break;
+                }
+            }
+        }
+
+      public:
+        /// return a reference to the value pointed to by the iterator
+        reference operator*() const
+        {
+            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.primitive_iterator.is_begin())
+                    {
+                        return *m_object;
+                    }
+                    else
+                    {
+                        throw std::out_of_range("cannot get value");
+                    }
+                }
+            }
+        }
+
+        /// dereference the iterator
+        pointer operator->() const
+        {
+            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.primitive_iterator.is_begin())
+                    {
+                        return m_object;
+                    }
+                    else
+                    {
+                        throw std::out_of_range("cannot get value");
+                    }
+                }
+            }
+        }
+
+        /// post-increment (it++)
+        const_iterator operator++(int)
+        {
+            auto result = *this;
+            ++(*this);
+
+            return result;
+        }
+
+        /// pre-increment (++it)
+        const_iterator& operator++()
+        {
+            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.primitive_iterator;
+                    break;
+                }
+            }
+
+            return *this;
+        }
+
+        /// post-decrement (it--)
+        const_iterator operator--(int)
+        {
+            auto result = *this;
+            --(*this);
+
+            return result;
+        }
+
+        /// pre-decrement (--it)
+        const_iterator& operator--()
+        {
+            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.primitive_iterator;
+                    break;
+                }
+            }
+
+            return *this;
+        }
+
+        /// comparison: equal
+        bool operator==(const const_iterator& other) const
+        {
+            // if objects are not the same, the comparison is undefined
+            if (m_object != other.m_object)
+            {
+                throw std::domain_error("cannot compare iterators of different containers");
+            }
+
+            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.primitive_iterator == other.m_it.primitive_iterator);
+                }
+            }
+        }
+
+        /// comparison: not equal
+        bool operator!=(const const_iterator& other) const
+        {
+            return not operator==(other);
+        }
+
+        /// comparison: smaller
+        bool operator<(const const_iterator& other) const
+        {
+            // if objects are not the same, the comparison is undefined
+            if (m_object != other.m_object)
+            {
+                throw std::domain_error("cannot compare iterators of different containers");
+            }
+
+            switch (m_object->m_type)
+            {
+                case (basic_json::value_t::object):
+                {
+                    throw std::domain_error("cannot use operator< for object iterators");
+                }
+
+                case (basic_json::value_t::array):
+                {
+                    return (m_it.array_iterator < other.m_it.array_iterator);
+                }
+
+                default:
+                {
+                    return (m_it.primitive_iterator < other.m_it.primitive_iterator);
+                }
+            }
+        }
+
+        /// comparison: less than or equal
+        bool operator<=(const const_iterator& other) const
+        {
+            return not other.operator < (*this);
+        }
+
+        /// comparison: greater than
+        bool operator>(const const_iterator& other) const
+        {
+            return not operator<=(other);
+        }
+
+        /// comparison: greater than or equal
+        bool operator>=(const const_iterator& other) const
+        {
+            return not operator<(other);
+        }
+
+        /// add to iterator
+        const_iterator& operator+=(difference_type i)
+        {
+            switch (m_object->m_type)
+            {
+                case (basic_json::value_t::object):
+                {
+                    throw std::domain_error("cannot use operator+= for object iterators");
+                }
+
+                case (basic_json::value_t::array):
+                {
+                    m_it.array_iterator += i;
+                    break;
+                }
+
+                default:
+                {
+                    m_it.primitive_iterator += i;
+                    break;
+                }
+            }
+
+            return *this;
+        }
+
+        /// subtract from iterator
+        const_iterator& operator-=(difference_type i)
+        {
+            return operator+=(-i);
+        }
+
+        /// add to iterator
+        const_iterator operator+(difference_type i)
+        {
+            auto result = *this;
+            result += i;
+            return result;
+        }
+
+        /// subtract from iterator
+        const_iterator operator-(difference_type i)
+        {
+            auto result = *this;
+            result -= i;
+            return result;
+        }
+
+        /// return difference
+        difference_type operator-(const const_iterator& other) const
+        {
+            switch (m_object->m_type)
+            {
+                case (basic_json::value_t::object):
+                {
+                    throw std::domain_error("cannot use operator- for object iterators");
+                }
+
+                case (basic_json::value_t::array):
+                {
+                    return m_it.array_iterator - other.m_it.array_iterator;
+                }
+
+                default:
+                {
+                    return m_it.primitive_iterator - other.m_it.primitive_iterator;
+                }
+            }
+        }
+
+        /// access to successor
+        reference operator[](difference_type n) const
+        {
+            switch (m_object->m_type)
+            {
+                case (basic_json::value_t::object):
+                {
+                    throw std::domain_error("cannot use operator[] for object iterators");
+                }
+
+                case (basic_json::value_t::array):
+                {
+                    return *(m_it.array_iterator + n);
+                }
+
+                case (basic_json::value_t::null):
+                {
+                    throw std::out_of_range("cannot get value");
+                }
+
+                default:
+                {
+                    if (m_it.primitive_iterator == -n)
+                    {
+                        return *m_object;
+                    }
+                    else
+                    {
+                        throw std::out_of_range("cannot get value");
+                    }
+                }
+            }
+        }
+
+        /// return the key of an object iterator
+        typename object_t::key_type key() const
+        {
+            switch (m_object->m_type)
+            {
+                case (basic_json::value_t::object):
+                {
+                    return m_it.object_iterator->first;
+                }
+
+                default:
+                {
+                    throw std::domain_error("cannot use key() for non-object iterators");
+                }
+            }
+        }
+
+        /// return the value of an iterator
+        reference value() const
+        {
+            return operator*();
+        }
+
+      private:
+        /// associated JSON instance
+        pointer m_object = nullptr;
+        /// the actual iterator of the associated instance
+        internal_iterator m_it = internal_iterator();
+    };
+
+    /*!
+    @brief a mutable random access iterator for the @ref basic_json class
+
+    @requirement The class satisfies the following concept requirements:
+    - [RandomAccessIterator](http://en.cppreference.com/w/cpp/concept/RandomAccessIterator):
+      The iterator that can be moved to point (forward and backward) to any
+      element in constant time.
+    - [OutputIterator](http://en.cppreference.com/w/cpp/concept/OutputIterator):
+      It is possible to write to the pointed-to element.
+    */
+    class iterator : public const_iterator
+    {
+      public:
+        using base_iterator = const_iterator;
+        using pointer = typename basic_json::pointer;
+        using reference = typename basic_json::reference;
+
+        /// default constructor
+        iterator() = default;
+
+        /// constructor for a given JSON instance
+        iterator(pointer object) noexcept : base_iterator(object)
+        {}
+
+        /// copy constructor
+        iterator(const iterator& other) noexcept
+            : base_iterator(other)
+        {}
+
+        /// copy assignment
+        iterator& operator=(iterator other) noexcept(
+            std::is_nothrow_move_constructible<pointer>::value and
+            std::is_nothrow_move_assignable<pointer>::value and
+            std::is_nothrow_move_constructible<internal_iterator>::value and
+            std::is_nothrow_move_assignable<internal_iterator>::value
+        )
+        {
+            base_iterator::operator=(other);
+            return *this;
+        }
+
+        /// return a reference to the value pointed to by the iterator
+        reference operator*()
+        {
+            return const_cast<reference>(base_iterator::operator*());
+        }
+
+        /// dereference the iterator
+        pointer operator->()
+        {
+            return const_cast<pointer>(base_iterator::operator->());
+        }
+
+        /// post-increment (it++)
+        iterator operator++(int)
+        {
+            iterator result = *this;
+            base_iterator::operator++();
+            return result;
+        }
+
+        /// pre-increment (++it)
+        iterator& operator++()
+        {
+            base_iterator::operator++();
+            return *this;
+        }
+
+        /// post-decrement (it--)
+        iterator operator--(int)
+        {
+            iterator result = *this;
+            base_iterator::operator--();
+            return result;
+        }
+
+        /// pre-decrement (--it)
+        iterator& operator--()
+        {
+            base_iterator::operator--();
+            return *this;
+        }
+
+        /// add to iterator
+        iterator& operator+=(difference_type i)
+        {
+            base_iterator::operator+=(i);
+            return *this;
+        }
+
+        /// subtract from iterator
+        iterator& operator-=(difference_type i)
+        {
+            base_iterator::operator-=(i);
+            return *this;
+        }
+
+        /// add to iterator
+        iterator operator+(difference_type i)
+        {
+            auto result = *this;
+            result += i;
+            return result;
+        }
+
+        /// subtract from iterator
+        iterator operator-(difference_type i)
+        {
+            auto result = *this;
+            result -= i;
+            return result;
+        }
+
+        difference_type operator-(const iterator& other) const
+        {
+            return base_iterator::operator-(other);
+        }
+
+        /// access to successor
+        reference operator[](difference_type n) const
+        {
+            return const_cast<reference>(base_iterator::operator[](n));
+        }
+
+        /// return the value of an iterator
+        reference value() const
+        {
+            return const_cast<reference>(base_iterator::value());
+        }
+    };
+
+    /*!
+    @brief a template for a reverse iterator class
+
+    @tparam Base the base iterator type to reverse. Valid types are @ref
+    iterator (to create @ref reverse_iterator) and @ref const_iterator (to
+    create @ref const_reverse_iterator).
+
+    @requirement The class satisfies the following concept requirements:
+    - [RandomAccessIterator](http://en.cppreference.com/w/cpp/concept/RandomAccessIterator):
+      The iterator that can be moved to point (forward and backward) to any
+      element in constant time.
+    - [OutputIterator](http://en.cppreference.com/w/cpp/concept/OutputIterator):
+      It is possible to write to the pointed-to element (only if @a Base is
+      @ref iterator).
+    */
+    template<typename Base>
+    class json_reverse_iterator : public std::reverse_iterator<Base>
+    {
+      public:
+        /// shortcut to the reverse iterator adaptor
+        using base_iterator = std::reverse_iterator<Base>;
+        /// the reference type for the pointed-to element
+        using reference = typename Base::reference;
+
+        /// create reverse iterator from iterator
+        json_reverse_iterator(const typename base_iterator::iterator_type& it)
+            : base_iterator(it) {}
+
+        /// create reverse iterator from base class
+        json_reverse_iterator(const base_iterator& it) : base_iterator(it) {}
+
+        /// post-increment (it++)
+        json_reverse_iterator operator++(int)
+        {
+            return base_iterator::operator++(1);
+        }
+
+        /// pre-increment (++it)
+        json_reverse_iterator& operator++()
+        {
+            base_iterator::operator++();
+            return *this;
+        }
+
+        /// post-decrement (it--)
+        json_reverse_iterator operator--(int)
+        {
+            return base_iterator::operator--(1);
+        }
+
+        /// pre-decrement (--it)
+        json_reverse_iterator& operator--()
+        {
+            base_iterator::operator--();
+            return *this;
+        }
+
+        /// add to iterator
+        json_reverse_iterator& operator+=(difference_type i)
+        {
+            base_iterator::operator+=(i);
+            return *this;
+        }
+
+        /// add to iterator
+        json_reverse_iterator operator+(difference_type i) const
+        {
+            auto result = *this;
+            result += i;
+            return result;
+        }
+
+        /// subtract from iterator
+        json_reverse_iterator operator-(difference_type i) const
+        {
+            auto result = *this;
+            result -= i;
+            return result;
+        }
+
+        /// return difference
+        difference_type operator-(const json_reverse_iterator& other) const
+        {
+            return this->base() - other.base();
+        }
+
+        /// access to successor
+        reference operator[](difference_type n) const
+        {
+            return *(this->operator+(n));
+        }
+
+        /// return the key of an object iterator
+        typename object_t::key_type key() const
+        {
+            auto it = --this->base();
+            return it.key();
+        }
+
+        /// return the value of an iterator
+        reference value() const
+        {
+            auto it = --this->base();
+            return it.operator * ();
+        }
+    };
+
+    /*!
+    @brief wrapper to access iterator member functions in range-based for
+
+    This class allows to access @ref key() and @ref value() during range-based
+    for loops. In these loops, a reference to the JSON values is returned, so
+    there is no access to the underlying iterator.
+    */
+    class iterator_wrapper
+    {
+      private:
+        /// the container to iterate
+        basic_json& container;
+        /// the type of the iterator to use while iteration
+        using json_iterator = decltype(std::begin(container));
+
+        /// internal iterator wrapper
+        class iterator_wrapper_internal
+        {
+          private:
+            /// the iterator
+            json_iterator anchor;
+            /// an index for arrays
+            size_t array_index = 0;
+
+          public:
+            /// construct wrapper given an iterator
+            iterator_wrapper_internal(json_iterator i) : anchor(i)
+            {}
+
+            /// dereference operator (needed for range-based for)
+            iterator_wrapper_internal& operator*()
+            {
+                return *this;
+            }
+
+            /// increment operator (needed for range-based for)
+            iterator_wrapper_internal& operator++()
+            {
+                ++anchor;
+                ++array_index;
+
+                return *this;
+            }
+
+            /// inequality operator (needed for range-based for)
+            bool operator!= (const iterator_wrapper_internal& o)
+            {
+                return anchor != o.anchor;
+            }
+
+            /// stream operator
+            friend std::ostream& operator<<(std::ostream& o, const iterator_wrapper_internal& w)
+            {
+                return o << w.value();
+            }
+
+            /// return key of the iterator
+            typename basic_json::string_t key() const
+            {
+                switch (anchor.m_object->type())
+                {
+                    /// use integer array index as key
+                    case (value_t::array):
+                    {
+                        return std::to_string(array_index);
+                    }
+
+                    /// use key from the object
+                    case (value_t::object):
+                    {
+                        return anchor.key();
+                    }
+
+                    /// use an empty key for all primitive types
+                    default:
+                    {
+                        return "";
+                    }
+                }
+            }
+
+            /// return value of the iterator
+            typename json_iterator::reference value() const
+            {
+                return anchor.value();
+            }
+        };
+
+      public:
+        /// construct iterator wrapper from a container
+        iterator_wrapper(basic_json& cont)
+            : container(cont)
+        {}
+
+        /// return iterator begin (needed for range-based for)
+        iterator_wrapper_internal begin()
+        {
+            return iterator_wrapper_internal(container.begin());
+        }
+
+        /// return iterator end (needed for range-based for)
+        iterator_wrapper_internal end()
+        {
+            return iterator_wrapper_internal(container.end());
+        }
+    };
+
+  private:
+    //////////////////////
+    // lexer and parser //
+    //////////////////////
+
+    /*!
+    @brief lexical analysis
+
+    This class organizes the lexical analysis during JSON deserialization. The
+    core of it is a scanner generated by re2c <http://re2c.org> that processes
+    a buffer and recognizes tokens according to RFC 7159.
+    */
+    class lexer
+    {
+      public:
+        /// token types for the parser
+        enum class token_type
+        {
+            uninitialized,    ///< indicating the scanner is uninitialized
+            literal_true,     ///< the "true" literal
+            literal_false,    ///< the "false" literal
+            literal_null,     ///< the "null" literal
+            value_string,     ///< a string - use get_string() for actual value
+            value_number,     ///< a number - use get_number() for actual value
+            begin_array,      ///< the character for array begin "["
+            begin_object,     ///< the character for object begin "{"
+            end_array,        ///< the character for array end "]"
+            end_object,       ///< the character for object end "}"
+            name_separator,   ///< the name separator ":"
+            value_separator,  ///< the value separator ","
+            parse_error,      ///< indicating a parse error
+            end_of_input      ///< indicating the end of the input buffer
+        };
+
+        /// the char type to use in the lexer
+        using lexer_char_t = unsigned char;
+
+        /// constructor with a given buffer
+        explicit lexer(const string_t& s) noexcept
+            : m_stream(nullptr), m_buffer(s)
+        {
+            m_content = reinterpret_cast<const lexer_char_t*>(s.c_str());
+            m_start = m_cursor = m_content;
+            m_limit = m_content + s.size();
+        }
+        explicit lexer(std::istream* s) noexcept
+            : m_stream(s), m_buffer()
+        {
+            getline(*m_stream, m_buffer);
+            m_content = reinterpret_cast<const lexer_char_t*>(m_buffer.c_str());
+            m_start = m_cursor = m_content;
+            m_limit = m_content + m_buffer.size();
+        }
+
+        /// default constructor
+        lexer() = default;
+
+        // switch of unwanted functions
+        lexer(const lexer&) = delete;
+        lexer operator=(const lexer&) = delete;
+
+        /*!
+        @brief create a string from a Unicode code point
+
+        @param[in] codepoint1  the code point (can be high surrogate)
+        @param[in] codepoint2  the code point (can be low surrogate or 0)
+        @return string representation of the code point
+        @throw std::out_of_range if code point is >0x10ffff
+        @throw std::invalid_argument if the low surrogate is invalid
+
+        @see <http://en.wikipedia.org/wiki/UTF-8#Sample_code>
+        */
+        static string_t to_unicode(const std::size_t codepoint1,
+                                   const std::size_t codepoint2 = 0)
+        {
+            string_t result;
+
+            // calculate the codepoint from the given code points
+            std::size_t codepoint = codepoint1;
+
+            // check if codepoint1 is a high surrogate
+            if (codepoint1 >= 0xD800 and codepoint1 <= 0xDBFF)
+            {
+                // check if codepoint2 is a low surrogate
+                if (codepoint2 >= 0xDC00 and codepoint2 <= 0xDFFF)
+                {
+                    codepoint =
+                        // high surrogate occupies the most significant 22 bits
+                        (codepoint1 << 10)
+                        // low surrogate occupies the least significant 15 bits
+                        + codepoint2
+                        // there is still the 0xD800, 0xDC00 and 0x10000 noise
+                        // in the result so we have to substract with:
+                        // (0xD800 << 10) + DC00 - 0x10000 = 0x35FDC00
+                        - 0x35FDC00;
+                }
+                else
+                {
+                    throw std::invalid_argument("missing or wrong low surrogate");
+                }
+            }
+
+            if (codepoint < 0x80)
+            {
+                // 1-byte characters: 0xxxxxxx (ASCII)
+                result.append(1, static_cast<typename string_t::value_type>(codepoint));
+            }
+            else if (codepoint <= 0x7ff)
+            {
+                // 2-byte characters: 110xxxxx 10xxxxxx
+                result.append(1, static_cast<typename string_t::value_type>(0xC0 | ((codepoint >> 6) & 0x1F)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | (codepoint & 0x3F)));
+            }
+            else if (codepoint <= 0xffff)
+            {
+                // 3-byte characters: 1110xxxx 10xxxxxx 10xxxxxx
+                result.append(1, static_cast<typename string_t::value_type>(0xE0 | ((codepoint >> 12) & 0x0F)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | ((codepoint >> 6) & 0x3F)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | (codepoint & 0x3F)));
+            }
+            else if (codepoint <= 0x10ffff)
+            {
+                // 4-byte characters: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+                result.append(1, static_cast<typename string_t::value_type>(0xF0 | ((codepoint >> 18) & 0x07)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | ((codepoint >> 12) & 0x3F)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | ((codepoint >> 6) & 0x3F)));
+                result.append(1, static_cast<typename string_t::value_type>(0x80 | (codepoint & 0x3F)));
+            }
+            else
+            {
+                throw std::out_of_range("code points above 0x10FFFF are invalid");
+            }
+
+            return result;
+        }
+
+        /// return name of values of type token_type
+        static std::string token_type_name(token_type t)
+        {
+            switch (t)
+            {
+                case (token_type::uninitialized):
+                    return "<uninitialized>";
+                case (token_type::literal_true):
+                    return "true literal";
+                case (token_type::literal_false):
+                    return "false literal";
+                case (token_type::literal_null):
+                    return "null literal";
+                case (token_type::value_string):
+                    return "string literal";
+                case (token_type::value_number):
+                    return "number literal";
+                case (token_type::begin_array):
+                    return "[";
+                case (token_type::begin_object):
+                    return "{";
+                case (token_type::end_array):
+                    return "]";
+                case (token_type::end_object):
+                    return "}";
+                case (token_type::name_separator):
+                    return ":";
+                case (token_type::value_separator):
+                    return ",";
+                case (token_type::end_of_input):
+                    return "<end of input>";
+                default:
+                    return "<parse error>";
+            }
+        }
+
+        /*!
+        This function implements a scanner for JSON. It is specified using
+        regular expressions that try to follow RFC 7159 as close as possible.
+        These regular expressions are then translated into a deterministic
+        finite automaton (DFA) by the tool re2c <http://re2c.org>. As a result,
+        the translated code for this function consists of a large block of code
+        with goto jumps.
+
+        @return the class of the next token read from the buffer
+        */
+        token_type scan() noexcept
+        {
+            // pointer for backtracking information
+            m_marker = nullptr;
+
+            // remember the begin of the token
+            m_start = m_cursor;
+
+
+            {
+                lexer_char_t yych;
+                unsigned int yyaccept = 0;
+                static const unsigned char yybm[] =
+                {
+                    0,   0,   0,   0,   0,   0,   0,   0,
+                    0,  32,  32,   0,   0,  32,   0,   0,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    96,  64,   0,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    192, 192, 192, 192, 192, 192, 192, 192,
+                    192, 192,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,   0,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                    64,  64,  64,  64,  64,  64,  64,  64,
+                };
+
+                if ((m_limit - m_cursor) < 5)
+                {
+                    yyfill();    // LCOV_EXCL_LINE;
+                }
+                yych = *m_cursor;
+                if (yych <= '9')
+                {
+                    if (yych <= ' ')
+                    {
+                        if (yych <= '\n')
+                        {
+                            if (yych <= 0x00)
+                            {
+                                goto basic_json_parser_27;
+                            }
+                            if (yych <= 0x08)
+                            {
+                                goto basic_json_parser_29;
+                            }
+                            if (yych >= '\n')
+                            {
+                                goto basic_json_parser_4;
+                            }
+                        }
+                        else
+                        {
+                            if (yych == '\r')
+                            {
+                                goto basic_json_parser_2;
+                            }
+                            if (yych <= 0x1F)
+                            {
+                                goto basic_json_parser_29;
+                            }
+                        }
+                    }
+                    else
+                    {
+                        if (yych <= ',')
+                        {
+                            if (yych == '"')
+                            {
+                                goto basic_json_parser_26;
+                            }
+                            if (yych <= '+')
+                            {
+                                goto basic_json_parser_29;
+                            }
+                            goto basic_json_parser_14;
+                        }
+                        else
+                        {
+                            if (yych <= '-')
+                            {
+                                goto basic_json_parser_22;
+                            }
+                            if (yych <= '/')
+                            {
+                                goto basic_json_parser_29;
+                            }
+                            if (yych <= '0')
+                            {
+                                goto basic_json_parser_23;
+                            }
+                            goto basic_json_parser_25;
+                        }
+                    }
+                }
+                else
+                {
+                    if (yych <= 'm')
+                    {
+                        if (yych <= '\\')
+                        {
+                            if (yych <= ':')
+                            {
+                                goto basic_json_parser_16;
+                            }
+                            if (yych == '[')
+                            {
+                                goto basic_json_parser_6;
+                            }
+                            goto basic_json_parser_29;
+                        }
+                        else
+                        {
+                            if (yych <= ']')
+                            {
+                                goto basic_json_parser_8;
+                            }
+                            if (yych == 'f')
+                            {
+                                goto basic_json_parser_21;
+                            }
+                            goto basic_json_parser_29;
+                        }
+                    }
+                    else
+                    {
+                        if (yych <= 'z')
+                        {
+                            if (yych <= 'n')
+                            {
+                                goto basic_json_parser_18;
+                            }
+                            if (yych == 't')
+                            {
+                                goto basic_json_parser_20;
+                            }
+                            goto basic_json_parser_29;
+                        }
+                        else
+                        {
+                            if (yych <= '{')
+                            {
+                                goto basic_json_parser_10;
+                            }
+                            if (yych == '}')
+                            {
+                                goto basic_json_parser_12;
+                            }
+                            goto basic_json_parser_29;
+                        }
+                    }
+                }
+basic_json_parser_2:
+                ++m_cursor;
+                yych = *m_cursor;
+                goto basic_json_parser_5;
+basic_json_parser_3:
+                {
+                    return scan();
+                }
+basic_json_parser_4:
+                ++m_cursor;
+                if (m_limit <= m_cursor)
+                {
+                    yyfill();    // LCOV_EXCL_LINE;
+                }
+                yych = *m_cursor;
+basic_json_parser_5:
+                if (yybm[0 + yych] & 32)
+                {
+                    goto basic_json_parser_4;
+                }
+                goto basic_json_parser_3;
+basic_json_parser_6:
+                ++m_cursor;
+                {
+                    return token_type::begin_array;
+                }
+basic_json_parser_8:
+                ++m_cursor;
+                {
+                    return token_type::end_array;
+                }
+basic_json_parser_10:
+                ++m_cursor;
+                {
+                    return token_type::begin_object;
+                }
+basic_json_parser_12:
+                ++m_cursor;
+                {
+                    return token_type::end_object;
+                }
+basic_json_parser_14:
+                ++m_cursor;
+                {
+                    return token_type::value_separator;
+                }
+basic_json_parser_16:
+                ++m_cursor;
+                {
+                    return token_type::name_separator;
+                }
+basic_json_parser_18:
+                yyaccept = 0;
+                yych = *(m_marker = ++m_cursor);
+                if (yych == 'u')
+                {
+                    goto basic_json_parser_59;
+                }
+basic_json_parser_19:
+                {
+                    return token_type::parse_error;
+                }
+basic_json_parser_20:
+                yyaccept = 0;
+                yych = *(m_marker = ++m_cursor);
+                if (yych == 'r')
+                {
+                    goto basic_json_parser_55;
+                }
+                goto basic_json_parser_19;
+basic_json_parser_21:
+                yyaccept = 0;
+                yych = *(m_marker = ++m_cursor);
+                if (yych == 'a')
+                {
+                    goto basic_json_parser_50;
+                }
+                goto basic_json_parser_19;
+basic_json_parser_22:
+                yych = *++m_cursor;
+                if (yych <= '/')
+                {
+                    goto basic_json_parser_19;
+                }
+                if (yych <= '0')
+                {
+                    goto basic_json_parser_49;
+                }
+                if (yych <= '9')
+                {
+                    goto basic_json_parser_40;
+                }
+                goto basic_json_parser_19;
+basic_json_parser_23:
+                yyaccept = 1;
+                yych = *(m_marker = ++m_cursor);
+                if (yych <= 'D')
+                {
+                    if (yych == '.')
+                    {
+                        goto basic_json_parser_42;
+                    }
+                }
+                else
+                {
+                    if (yych <= 'E')
+                    {
+                        goto basic_json_parser_43;
+                    }
+                    if (yych == 'e')
+                    {
+                        goto basic_json_parser_43;
+                    }
+                }
+basic_json_parser_24:
+                {
+                    return token_type::value_number;
+                }
+basic_json_parser_25:
+                yyaccept = 1;
+                yych = *(m_marker = ++m_cursor);
+                goto basic_json_parser_41;
+basic_json_parser_26:
+                yyaccept = 0;
+                yych = *(m_marker = ++m_cursor);
+                if (yych <= 0x0F)
+                {
+                    goto basic_json_parser_19;
+                }
+                goto basic_json_parser_31;
+basic_json_parser_27:
+                ++m_cursor;
+                {
+                    return token_type::end_of_input;
+                }
+basic_json_parser_29:
+                yych = *++m_cursor;
+                goto basic_json_parser_19;
+basic_json_parser_30:
+                ++m_cursor;
+                if (m_limit <= m_cursor)
+                {
+                    yyfill();    // LCOV_EXCL_LINE;
+                }
+                yych = *m_cursor;
+basic_json_parser_31:
+                if (yybm[0 + yych] & 64)
+                {
+                    goto basic_json_parser_30;
+                }
+                if (yych <= 0x0F)
+                {
+                    goto basic_json_parser_32;
+                }
+                if (yych <= '"')
+                {
+                    goto basic_json_parser_34;
+                }
+                goto basic_json_parser_33;
+basic_json_parser_32:
+                m_cursor = m_marker;
+                if (yyaccept == 0)
+                {
+                    goto basic_json_parser_19;
+                }
+                else
+                {
+                    goto basic_json_parser_24;
+                }
+basic_json_parser_33:
+                ++m_cursor;
+                if (m_limit <= m_cursor)
+                {
+                    yyfill();    // LCOV_EXCL_LINE;
+                }
+                yych = *m_cursor;
+                if (yych <= 'e')
+                {
+                    if (yych <= '/')
+                    {
+                        if (yych == '"')
+                        {
+                            goto basic_json_parser_30;
+                        }
+                        if (yych <= '.')
+                        {
+                            goto basic_json_parser_32;
+                        }
+                        goto basic_json_parser_30;
+                    }
+                    else
+                    {
+                        if (yych <= '\\')
+                        {
+                            if (yych <= '[')
+                            {
+                                goto basic_json_parser_32;
+                            }
+                            goto basic_json_parser_30;
+                        }
+                        else
+                        {
+                            if (yych == 'b')
+                            {
+                                goto basic_json_parser_30;
+                            }
+                            goto basic_json_parser_32;
+                        }
+                    }
+                }
+                else
+                {
+                    if (yych <= 'q')
+                    {
+                        if (yych <= 'f')
+                        {
+                            goto basic_json_parser_30;
+                        }
+                        if (yych == 'n')
+                        {
+                            goto basic_json_parser_30;
+                        }
+                        goto basic_json_parser_32;
+                    }
+                    else
+                    {
+                        if (yych <= 's')
+                        {
+                            if (yych <= 'r')
+                            {
+                                goto basic_json_parser_30;
+                            }
+                            goto basic_json_parser_32;
+                        }
+                        else
+                        {
+                            if (yych <= 't')
+                            {
+                                goto basic_json_parser_30;
+                            }
+                            if (yych <= 'u')
+                            {
+                                goto basic_json_parser_36;
+                            }
+                            goto basic_json_parser_32;
+                        }
+                    }
+                }
+basic_json_parser_34:
+                ++m_cursor;
+                {
+                    return token_type::value_string;
+                }
+basic_json_parser_36:
+                ++m_cursor;
+                if (m_limit <= m_cursor)
+                {
+                    yyfill();    // LCOV_EXCL_LINE;
+                }
+                yych = *m_cursor;
+                if (yych <= '@')
+                {
+                    if (yych <= '/')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych >= ':')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                }
+                else
+                {
+                    if (yych <= 'F')
+                    {
+                        goto basic_json_parser_37;
+                    }
+                    if (yych <= '`')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych >= 'g')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                }
+basic_json_parser_37:
+                ++m_cursor;
+                if (m_limit <= m_cursor)
+                {
+                    yyfill();    // LCOV_EXCL_LINE;
+                }
+                yych = *m_cursor;
+                if (yych <= '@')
+                {
+                    if (yych <= '/')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych >= ':')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                }
+                else
+                {
+                    if (yych <= 'F')
+                    {
+                        goto basic_json_parser_38;
+                    }
+                    if (yych <= '`')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych >= 'g')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                }
+basic_json_parser_38:
+                ++m_cursor;
+                if (m_limit <= m_cursor)
+                {
+                    yyfill();    // LCOV_EXCL_LINE;
+                }
+                yych = *m_cursor;
+                if (yych <= '@')
+                {
+                    if (yych <= '/')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych >= ':')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                }
+                else
+                {
+                    if (yych <= 'F')
+                    {
+                        goto basic_json_parser_39;
+                    }
+                    if (yych <= '`')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych >= 'g')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                }
+basic_json_parser_39:
+                ++m_cursor;
+                if (m_limit <= m_cursor)
+                {
+                    yyfill();    // LCOV_EXCL_LINE;
+                }
+                yych = *m_cursor;
+                if (yych <= '@')
+                {
+                    if (yych <= '/')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych <= '9')
+                    {
+                        goto basic_json_parser_30;
+                    }
+                    goto basic_json_parser_32;
+                }
+                else
+                {
+                    if (yych <= 'F')
+                    {
+                        goto basic_json_parser_30;
+                    }
+                    if (yych <= '`')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych <= 'f')
+                    {
+                        goto basic_json_parser_30;
+                    }
+                    goto basic_json_parser_32;
+                }
+basic_json_parser_40:
+                yyaccept = 1;
+                m_marker = ++m_cursor;
+                if ((m_limit - m_cursor) < 3)
+                {
+                    yyfill();    // LCOV_EXCL_LINE;
+                }
+                yych = *m_cursor;
+basic_json_parser_41:
+                if (yybm[0 + yych] & 128)
+                {
+                    goto basic_json_parser_40;
+                }
+                if (yych <= 'D')
+                {
+                    if (yych != '.')
+                    {
+                        goto basic_json_parser_24;
+                    }
+                }
+                else
+                {
+                    if (yych <= 'E')
+                    {
+                        goto basic_json_parser_43;
+                    }
+                    if (yych == 'e')
+                    {
+                        goto basic_json_parser_43;
+                    }
+                    goto basic_json_parser_24;
+                }
+basic_json_parser_42:
+                yych = *++m_cursor;
+                if (yych <= '/')
+                {
+                    goto basic_json_parser_32;
+                }
+                if (yych <= '9')
+                {
+                    goto basic_json_parser_47;
+                }
+                goto basic_json_parser_32;
+basic_json_parser_43:
+                yych = *++m_cursor;
+                if (yych <= ',')
+                {
+                    if (yych != '+')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                }
+                else
+                {
+                    if (yych <= '-')
+                    {
+                        goto basic_json_parser_44;
+                    }
+                    if (yych <= '/')
+                    {
+                        goto basic_json_parser_32;
+                    }
+                    if (yych <= '9')
+                    {
+                        goto basic_json_parser_45;
+                    }
+                    goto basic_json_parser_32;
+                }
+basic_json_parser_44:
+                yych = *++m_cursor;
+                if (yych <= '/')
+                {
+                    goto basic_json_parser_32;
+                }
+                if (yych >= ':')
+                {
+                    goto basic_json_parser_32;
+                }
+basic_json_parser_45:
+                ++m_cursor;
+                if (m_limit <= m_cursor)
+                {
+                    yyfill();    // LCOV_EXCL_LINE;
+                }
+                yych = *m_cursor;
+                if (yych <= '/')
+                {
+                    goto basic_json_parser_24;
+                }
+                if (yych <= '9')
+                {
+                    goto basic_json_parser_45;
+                }
+                goto basic_json_parser_24;
+basic_json_parser_47:
+                yyaccept = 1;
+                m_marker = ++m_cursor;
+                if ((m_limit - m_cursor) < 3)
+                {
+                    yyfill();    // LCOV_EXCL_LINE;
+                }
+                yych = *m_cursor;
+                if (yych <= 'D')
+                {
+                    if (yych <= '/')
+                    {
+                        goto basic_json_parser_24;
+                    }
+                    if (yych <= '9')
+                    {
+                        goto basic_json_parser_47;
+                    }
+                    goto basic_json_parser_24;
+                }
+                else
+                {
+                    if (yych <= 'E')
+                    {
+                        goto basic_json_parser_43;
+                    }
+                    if (yych == 'e')
+                    {
+                        goto basic_json_parser_43;
+                    }
+                    goto basic_json_parser_24;
+                }
+basic_json_parser_49:
+                yyaccept = 1;
+                yych = *(m_marker = ++m_cursor);
+                if (yych <= 'D')
+                {
+                    if (yych == '.')
+                    {
+                        goto basic_json_parser_42;
+                    }
+                    goto basic_json_parser_24;
+                }
+                else
+                {
+                    if (yych <= 'E')
+                    {
+                        goto basic_json_parser_43;
+                    }
+                    if (yych == 'e')
+                    {
+                        goto basic_json_parser_43;
+                    }
+                    goto basic_json_parser_24;
+                }
+basic_json_parser_50:
+                yych = *++m_cursor;
+                if (yych != 'l')
+                {
+                    goto basic_json_parser_32;
+                }
+                yych = *++m_cursor;
+                if (yych != 's')
+                {
+                    goto basic_json_parser_32;
+                }
+                yych = *++m_cursor;
+                if (yych != 'e')
+                {
+                    goto basic_json_parser_32;
+                }
+                ++m_cursor;
+                {
+                    return token_type::literal_false;
+                }
+basic_json_parser_55:
+                yych = *++m_cursor;
+                if (yych != 'u')
+                {
+                    goto basic_json_parser_32;
+                }
+                yych = *++m_cursor;
+                if (yych != 'e')
+                {
+                    goto basic_json_parser_32;
+                }
+                ++m_cursor;
+                {
+                    return token_type::literal_true;
+                }
+basic_json_parser_59:
+                yych = *++m_cursor;
+                if (yych != 'l')
+                {
+                    goto basic_json_parser_32;
+                }
+                yych = *++m_cursor;
+                if (yych != 'l')
+                {
+                    goto basic_json_parser_32;
+                }
+                ++m_cursor;
+                {
+                    return token_type::literal_null;
+                }
+            }
+
+
+        }
+
+        /// append data from the stream to the internal buffer
+        void yyfill() noexcept
+        {
+            if (not m_stream or not * m_stream)
+            {
+                return;
+            }
+
+            const ssize_t offset_start = m_start - m_content;
+            const ssize_t offset_marker = m_marker - m_start;
+            const ssize_t offset_cursor = m_cursor - m_start;
+
+            m_buffer.erase(0, static_cast<size_t>(offset_start));
+            std::string line;
+            std::getline(*m_stream, line);
+            m_buffer += "\n" + line; // add line with newline symbol
+
+            m_content = reinterpret_cast<const lexer_char_t*>(m_buffer.c_str());
+            m_start  = m_content;
+            m_marker = m_start + offset_marker;
+            m_cursor = m_start + offset_cursor;
+            m_limit  = m_start + m_buffer.size() - 1;
+        }
+
+        /// return string representation of last read token
+        string_t get_token() const noexcept
+        {
+            return string_t(reinterpret_cast<typename string_t::const_pointer>(m_start),
+                            static_cast<size_t>(m_cursor - m_start));
+        }
+
+        /*!
+        @brief return string value for string tokens
+
+        The function iterates the characters between the opening and closing
+        quotes of the string value. The complete string is the range
+        [m_start,m_cursor). Consequently, we iterate from m_start+1 to
+        m_cursor-1.
+
+        We differentiate two cases:
+
+        1. Escaped characters. In this case, a new character is constructed
+           according to the nature of the escape. Some escapes create new
+           characters (e.g., @c "\\n" is replaced by @c "\n"), some are copied
+           as is (e.g., @c "\\\\"). Furthermore, Unicode escapes of the shape
+           @c "\\uxxxx" need special care. In this case, to_unicode takes care
+           of the construction of the values.
+        2. Unescaped characters are copied as is.
+
+        @return string value of current token without opening and closing quotes
+        @throw std::out_of_range if to_unicode fails
+        */
+        string_t get_string() const
+        {
+            string_t result;
+            result.reserve(static_cast<size_t>(m_cursor - m_start - 2));
+
+            // iterate the result between the quotes
+            for (const lexer_char_t* i = m_start + 1; i < m_cursor - 1; ++i)
+            {
+                // process escaped characters
+                if (*i == '\\')
+                {
+                    // read next character
+                    ++i;
+
+                    switch (*i)
+                    {
+                        // the default escapes
+                        case 't':
+                        {
+                            result += "\t";
+                            break;
+                        }
+                        case 'b':
+                        {
+                            result += "\b";
+                            break;
+                        }
+                        case 'f':
+                        {
+                            result += "\f";
+                            break;
+                        }
+                        case 'n':
+                        {
+                            result += "\n";
+                            break;
+                        }
+                        case 'r':
+                        {
+                            result += "\r";
+                            break;
+                        }
+                        case '\\':
+                        {
+                            result += "\\";
+                            break;
+                        }
+                        case '/':
+                        {
+                            result += "/";
+                            break;
+                        }
+                        case '"':
+                        {
+                            result += "\"";
+                            break;
+                        }
+
+                        // unicode
+                        case 'u':
+                        {
+                            // get code xxxx from uxxxx
+                            auto codepoint = std::strtoul(std::string(reinterpret_cast<typename string_t::const_pointer>(i + 1),
+                                                          4).c_str(), nullptr, 16);
+
+                            // check if codepoint is a high surrogate
+                            if (codepoint >= 0xD800 and codepoint <= 0xDBFF)
+                            {
+                                // make sure there is a subsequent unicode
+                                if ((i + 6 >= m_limit) or * (i + 5) != '\\' or * (i + 6) != 'u')
+                                {
+                                    throw std::invalid_argument("missing low surrogate");
+                                }
+
+                                // get code yyyy from uxxxx\uyyyy
+                                auto codepoint2 = std::strtoul(std::string(reinterpret_cast<typename string_t::const_pointer>
+                                                               (i + 7), 4).c_str(), nullptr, 16);
+                                result += to_unicode(codepoint, codepoint2);
+                                // skip the next 11 characters (xxxx\uyyyy)
+                                i += 11;
+                            }
+                            else
+                            {
+                                // add unicode character(s)
+                                result += to_unicode(codepoint);
+                                // skip the next four characters (xxxx)
+                                i += 4;
+                            }
+                            break;
+                        }
+                    }
+                }
+                else
+                {
+                    // all other characters are just copied to the end of the
+                    // string
+                    result.append(1, static_cast<typename string_t::value_type>(*i));
+                }
+            }
+
+            return result;
+        }
+
+        /*!
+        @brief return number value for number tokens
+
+        This function translates the last token into a floating point number.
+        The pointer m_begin points to the beginning of the parsed number. We
+        pass this pointer to std::strtod which sets endptr to the first
+        character past the converted number. If this pointer is not the same as
+        m_cursor, then either more or less characters have been used during the
+        comparison. This can happen for inputs like "01" which will be treated
+        like number 0 followed by number 1.
+
+        @return the result of the number conversion or NAN if the conversion
+        read past the current token. The latter case needs to be treated by the
+        caller function.
+
+        @throw std::range_error if passed value is out of range
+        */
+        long double get_number() const
+        {
+            // conversion
+            typename string_t::value_type* endptr;
+            const auto float_val = std::strtold(reinterpret_cast<typename string_t::const_pointer>(m_start),
+                                                &endptr);
+
+            // return float_val if the whole number was translated and NAN
+            // otherwise
+            return (reinterpret_cast<lexer_char_t*>(endptr) == m_cursor) ? float_val : NAN;
+        }
+
+      private:
+        /// optional input stream
+        std::istream* m_stream;
+        /// the buffer
+        string_t m_buffer;
+        /// the buffer pointer
+        const lexer_char_t* m_content = nullptr;
+        /// pointer to the beginning of the current symbol
+        const lexer_char_t* m_start = nullptr;
+        /// pointer for backtracking information
+        const lexer_char_t* m_marker = nullptr;
+        /// pointer to the current symbol
+        const lexer_char_t* m_cursor = nullptr;
+        /// pointer to the end of the buffer
+        const lexer_char_t* m_limit = nullptr;
+    };
+
+    /*!
+    @brief syntax analysis
+    */
+    class parser
+    {
+      public:
+        /// constructor for strings
+        parser(const string_t& s, parser_callback_t cb = nullptr)
+            : callback(cb), m_lexer(s)
+        {
+            // read first token
+            get_token();
+        }
+
+        /// a parser reading from an input stream
+        parser(std::istream& _is, parser_callback_t cb = nullptr)
+            : callback(cb), m_lexer(&_is)
+        {
+            // read first token
+            get_token();
+        }
+
+        /// public parser interface
+        basic_json parse()
+        {
+            basic_json result = parse_internal(true);
+
+            expect(lexer::token_type::end_of_input);
+
+            // return parser result and replace it with null in case the
+            // top-level value was discarded by the callback function
+            return result.is_discarded() ? basic_json() : result;
+        }
+
+      private:
+        /// the actual parser
+        basic_json parse_internal(bool keep)
+        {
+            auto result = basic_json(value_t::discarded);
+
+            switch (last_token)
+            {
+                case (lexer::token_type::begin_object):
+                {
+                    if (keep and (not callback or (keep = callback(depth++, parse_event_t::object_start, result))))
+                    {
+                        // explicitly set result to object to cope with {}
+                        result.m_type = value_t::object;
+                        result.m_value = json_value(value_t::object);
+                    }
+
+                    // read next token
+                    get_token();
+
+                    // closing } -> we are done
+                    if (last_token == lexer::token_type::end_object)
+                    {
+                        get_token();
+                        if (keep and callback and not callback(--depth, parse_event_t::object_end, result))
+                        {
+                            result = basic_json(value_t::discarded);
+                        }
+                        return result;
+                    }
+
+                    // no comma is expected here
+                    unexpect(lexer::token_type::value_separator);
+
+                    // otherwise: parse key-value pairs
+                    do
+                    {
+                        // ugly, but could be fixed with loop reorganization
+                        if (last_token == lexer::token_type::value_separator)
+                        {
+                            get_token();
+                        }
+
+                        // store key
+                        expect(lexer::token_type::value_string);
+                        const auto key = m_lexer.get_string();
+
+                        bool keep_tag = false;
+                        if (keep)
+                        {
+                            if (callback)
+                            {
+                                basic_json k(key);
+                                keep_tag = callback(depth, parse_event_t::key, k);
+                            }
+                            else
+                            {
+                                keep_tag = true;
+                            }
+                        }
+
+                        // parse separator (:)
+                        get_token();
+                        expect(lexer::token_type::name_separator);
+
+                        // parse and add value
+                        get_token();
+                        auto value = parse_internal(keep);
+                        if (keep and keep_tag and not value.is_discarded())
+                        {
+                            result[key] = std::move(value);
+                        }
+                    }
+                    while (last_token == lexer::token_type::value_separator);
+
+                    // closing }
+                    expect(lexer::token_type::end_object);
+                    get_token();
+                    if (keep and callback and not callback(--depth, parse_event_t::object_end, result))
+                    {
+                        result = basic_json(value_t::discarded);
+                    }
+
+                    return result;
+                }
+
+                case (lexer::token_type::begin_array):
+                {
+                    if (keep and (not callback or (keep = callback(depth++, parse_event_t::array_start, result))))
+                    {
+                        // explicitly set result to object to cope with []
+                        result.m_type = value_t::array;
+                        result.m_value = json_value(value_t::array);
+                    }
+
+                    // read next token
+                    get_token();
+
+                    // closing ] -> we are done
+                    if (last_token == lexer::token_type::end_array)
+                    {
+                        get_token();
+                        if (callback and not callback(--depth, parse_event_t::array_end, result))
+                        {
+                            result = basic_json(value_t::discarded);
+                        }
+                        return result;
+                    }
+
+                    // no comma is expected here
+                    unexpect(lexer::token_type::value_separator);
+
+                    // otherwise: parse values
+                    do
+                    {
+                        // ugly, but could be fixed with loop reorganization
+                        if (last_token == lexer::token_type::value_separator)
+                        {
+                            get_token();
+                        }
+
+                        // parse value
+                        auto value = parse_internal(keep);
+                        if (keep and not value.is_discarded())
+                        {
+                            result.push_back(std::move(value));
+                        }
+                    }
+                    while (last_token == lexer::token_type::value_separator);
+
+                    // closing ]
+                    expect(lexer::token_type::end_array);
+                    get_token();
+                    if (keep and callback and not callback(--depth, parse_event_t::array_end, result))
+                    {
+                        result = basic_json(value_t::discarded);
+                    }
+
+                    return result;
+                }
+
+                case (lexer::token_type::literal_null):
+                {
+                    get_token();
+                    result.m_type = value_t::null;
+                    break;
+                }
+
+                case (lexer::token_type::value_string):
+                {
+                    const auto s = m_lexer.get_string();
+                    get_token();
+                    result = basic_json(s);
+                    break;
+                }
+
+                case (lexer::token_type::literal_true):
+                {
+                    get_token();
+                    result.m_type = value_t::boolean;
+                    result.m_value = true;
+                    break;
+                }
+
+                case (lexer::token_type::literal_false):
+                {
+                    get_token();
+                    result.m_type = value_t::boolean;
+                    result.m_value = false;
+                    break;
+                }
+
+                case (lexer::token_type::value_number):
+                {
+                    auto float_val = m_lexer.get_number();
+
+                    // NAN is returned if token could not be translated
+                    // completely
+                    if (std::isnan(float_val))
+                    {
+                        throw std::invalid_argument(std::string("parse error - ") +
+                                                    m_lexer.get_token() + " is not a number");
+                    }
+
+                    get_token();
+
+                    // check if conversion loses precision
+                    const auto int_val = static_cast<number_integer_t>(float_val);
+                    if (approx(float_val, static_cast<long double>(int_val)))
+                    {
+                        // we basic_json not lose precision -> return int
+                        result.m_type = value_t::number_integer;
+                        result.m_value = int_val;
+                    }
+                    else
+                    {
+                        // we would lose precision -> returnfloat
+                        result.m_type = value_t::number_float;
+                        result.m_value = static_cast<number_float_t>(float_val);
+                    }
+                    break;
+                }
+
+                default:
+                {
+                    // the last token was unexpected
+                    unexpect(last_token);
+                }
+            }
+
+            if (keep and callback and not callback(depth, parse_event_t::value, result))
+            {
+                result = basic_json(value_t::discarded);
+            }
+            return result;
+        }
+
+        /// get next token from lexer
+        typename lexer::token_type get_token()
+        {
+            last_token = m_lexer.scan();
+            return last_token;
+        }
+
+        void expect(typename lexer::token_type t) const
+        {
+            if (t != last_token)
+            {
+                std::string error_msg = "parse error - unexpected \'";
+                error_msg += m_lexer.get_token();
+                error_msg += "\' (" + lexer::token_type_name(last_token);
+                error_msg += "); expected " + lexer::token_type_name(t);
+                throw std::invalid_argument(error_msg);
+            }
+        }
+
+        void unexpect(typename lexer::token_type t) const
+        {
+            if (t == last_token)
+            {
+                std::string error_msg = "parse error - unexpected \'";
+                error_msg += m_lexer.get_token();
+                error_msg += "\' (";
+                error_msg += lexer::token_type_name(last_token) + ")";
+                throw std::invalid_argument(error_msg);
+            }
+        }
+
+      private:
+        /// current level of recursion
+        int depth = 0;
+        /// callback function
+        parser_callback_t callback;
+        /// the type of the last read token
+        typename lexer::token_type last_token = lexer::token_type::uninitialized;
+        /// the lexer
+        lexer m_lexer;
+    };
+};
+
+
+/////////////
+// presets //
+/////////////
+
+/*!
+@brief default JSON class
+
+This type is the default specialization of the @ref basic_json class which uses
+the standard template types.
+*/
+using json = basic_json<>;
+}
+
+
+/////////////////////////
+// nonmember functions //
+/////////////////////////
+
+// specialization of std::swap, and std::hash
+namespace std
+{
+/*!
+@brief exchanges 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>
+{
+    /// return a hash value for a JSON object
+    std::size_t operator()(const nlohmann::json& j) const
+    {
+        // a naive hashing via the string representation
+        const auto& h = hash<nlohmann::json::string_t>();
+        return h(j.dump());
+    }
+};
+}
+
+/*!
+@brief user-defined string literal for JSON values
+
+This operator implements a user-defined string literal for JSON objects. It can
+be used by adding \p "_json" to a string literal and returns a JSON object if
+no parse error occurred.
+
+@param[in] s  a string representation of a JSON object
+@return a JSON object
+*/
+inline nlohmann::json operator "" _json(const char* s, std::size_t)
+{
+    return nlohmann::json::parse(reinterpret_cast<nlohmann::json::string_t::value_type*>
+                                 (const_cast<char*>(s)));
+}
+
+#endif