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From jianq...@apache.org
Subject [3/6] incubator-quickstep git commit: Initial commit
Date Mon, 21 Nov 2016 05:18:04 GMT
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/b060eb24/third_party/json/json.hpp
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diff --git a/third_party/json/json.hpp b/third_party/json/json.hpp
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+/*
+    __ _____ _____ _____
+ __|  |   __|     |   | |  JSON for Modern C++
+|  |  |__   |  |  | | | |  version 2.0.7
+|_____|_____|_____|_|___|  https://github.com/nlohmann/json
+
+Licensed under the MIT License <http://opensource.org/licenses/MIT>.
+Copyright (c) 2013-2016 Niels Lohmann <http://nlohmann.me>.
+
+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:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+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.
+*/
+
+#ifndef NLOHMANN_JSON_HPP
+#define NLOHMANN_JSON_HPP
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <cctype>
+#include <ciso646>
+#include <cmath>
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <functional>
+#include <initializer_list>
+#include <iomanip>
+#include <iostream>
+#include <iterator>
+#include <limits>
+#include <locale>
+#include <map>
+#include <memory>
+#include <numeric>
+#include <sstream>
+#include <stdexcept>
+#include <string>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+// exclude unsupported compilers
+#if defined(__clang__)
+    #define CLANG_VERSION (__clang_major__ * 10000 + __clang_minor__ * 100 + __clang_patchlevel__)
+    #if CLANG_VERSION < 30400
+        #error "unsupported Clang version - see https://github.com/nlohmann/json#supported-compilers"
+    #endif
+#elif defined(__GNUC__)
+    #define GCC_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
+    #if GCC_VERSION < 40900
+        #error "unsupported GCC version - see https://github.com/nlohmann/json#supported-compilers"
+    #endif
+#endif
+
+// disable float-equal warnings on GCC/clang
+#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
+    #pragma GCC diagnostic push
+    #pragma GCC diagnostic ignored "-Wfloat-equal"
+#endif
+
+// allow for portable deprecation warnings
+#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
+    #define JSON_DEPRECATED __attribute__((deprecated))
+#elif defined(_MSC_VER)
+    #define JSON_DEPRECATED __declspec(deprecated)
+#else
+    #define JSON_DEPRECATED
+#endif
+
+/*!
+@brief namespace for Niels Lohmann
+@see https://github.com/nlohmann
+@since version 1.0.0
+*/
+namespace nlohmann
+{
+
+
+/*!
+@brief unnamed namespace with internal helper functions
+@since version 1.0.0
+*/
+namespace
+{
+/*!
+@brief Helper to determine whether there's a key_type for T.
+
+Thus helper is used to tell associative containers apart from other containers
+such as sequence containers. For instance, `std::map` passes the test as it
+contains a `mapped_type`, whereas `std::vector` fails the test.
+
+@sa http://stackoverflow.com/a/7728728/266378
+@since version 1.0.0, overworked in version 2.0.6
+*/
+template<typename T>
+struct has_mapped_type
+{
+  private:
+    template <typename U, typename = typename U::mapped_type>
+    static int detect(U&&);
+
+    static void detect(...);
+  public:
+    static constexpr bool value =
+        std::is_integral<decltype(detect(std::declval<T>()))>::value;
+};
+
+/*!
+@brief helper class to create locales with decimal point
+
+This struct is used a default locale during the JSON serialization. JSON
+requires the decimal point to be `.`, so this function overloads the
+`do_decimal_point()` function to return `.`. This function is called by
+float-to-string conversions to retrieve the decimal separator between integer
+and fractional parts.
+
+@sa https://github.com/nlohmann/json/issues/51#issuecomment-86869315
+@since version 2.0.0
+*/
+struct DecimalSeparator : std::numpunct<char>
+{
+    char do_decimal_point() const
+    {
+        return '.';
+    }
+};
+
+}
+
+/*!
+@brief a class to store JSON values
+
+@tparam ObjectType type for JSON objects (`std::map` by default; will be used
+in @ref object_t)
+@tparam ArrayType type for JSON arrays (`std::vector` by default; will be used
+in @ref array_t)
+@tparam StringType type for JSON strings and object keys (`std::string` by
+default; will be used in @ref string_t)
+@tparam BooleanType type for JSON booleans (`bool` by default; will be used
+in @ref boolean_t)
+@tparam NumberIntegerType type for JSON integer numbers (`int64_t` by
+default; will be used in @ref number_integer_t)
+@tparam NumberUnsignedType type for JSON unsigned integer numbers (@c
+`uint64_t` by default; will be used in @ref number_unsigned_t)
+@tparam NumberFloatType type for JSON floating-point numbers (`double` by
+default; will be used in @ref number_float_t)
+@tparam AllocatorType type of the allocator to use (`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-constructed 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.
+
+@invariant The member variables @a m_value and @a m_type have the following
+relationship:
+- If `m_type == value_t::object`, then `m_value.object != nullptr`.
+- If `m_type == value_t::array`, then `m_value.array != nullptr`.
+- If `m_type == value_t::string`, then `m_value.string != nullptr`.
+The invariants are checked by member function assert_invariant().
+
+@internal
+@note ObjectType trick from http://stackoverflow.com/a/9860911
+@endinternal
+
+@see [RFC 7159: The JavaScript Object Notation (JSON) Data Interchange
+Format](http://rfc7159.net/rfc7159)
+
+@since version 1.0.0
+
+@nosubgrouping
+*/
+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 = std::int64_t,
+    class NumberUnsignedType = std::uint64_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, NumberUnsignedType, NumberFloatType,
+          AllocatorType>;
+
+  public:
+    // forward declarations
+    template<typename Base> class json_reverse_iterator;
+    class json_pointer;
+
+    /////////////////////
+    // container types //
+    /////////////////////
+
+    /// @name container types
+    /// The canonic container types to use @ref basic_json like any other STL
+    /// container.
+    /// @{
+
+    /// 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;
+
+    /// 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
+    /// The data types to store a JSON value. These types are derived from
+    /// the template arguments passed to class @ref basic_json.
+    /// @{
+
+    /*!
+    @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
+    described below.
+
+    @tparam ObjectType  the container to store objects (e.g., `std::map` or
+    `std::unordered_map`)
+    @tparam StringType the type of the keys or names (e.g., `std::string`).
+    The comparison function `std::less<StringType>` is used to order elements
+    inside the container.
+    @tparam AllocatorType the allocator to use for objects (e.g.,
+    `std::allocator`)
+
+    #### 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 @ref basic_json type. That is, for any
+    access to object values, a pointer of type `object_t*` must be
+    dereferenced.
+
+    @sa @ref array_t -- type for an array value
+
+    @since version 1.0.0
+
+    @note The order name/value pairs are added to the object is *not*
+    preserved by the library. Therefore, iterating an object may return
+    name/value pairs in a different order than they were originally stored. In
+    fact, keys will be traversed in alphabetical order as `std::map` with
+    `std::less` is used by default. Please note this behavior conforms to [RFC
+    7159](http://rfc7159.net/rfc7159), because any order implements the
+    specified "unordered" nature of JSON objects.
+    */
+    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
+    explained below.
+
+    @tparam ArrayType  container type to store arrays (e.g., `std::vector` or
+    `std::list`)
+    @tparam AllocatorType allocator to use for arrays (e.g., `std::allocator`)
+
+    #### 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 @ref basic_json type. That is, for any
+    access to array values, a pointer of type `array_t*` must be dereferenced.
+
+    @sa @ref object_t -- type for an object value
+
+    @since version 1.0.0
+    */
+    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 parameter
+    described below. Unicode values are split by the JSON class into
+    byte-sized characters during deserialization.
+
+    @tparam StringType  the container to store strings (e.g., `std::string`).
+    Note this container is used for keys/names in objects, see @ref object_t.
+
+    #### 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 @ref basic_json type. That is,
+    for any access to string values, a pointer of type `string_t*` must be
+    dereferenced.
+
+    @since version 1.0.0
+    */
+    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 @ref basic_json type.
+
+    @since version 1.0.0
+    */
+    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 a signed integer, an unsigned integer or a floating-point number.
+    Therefore, three different types, @ref number_integer_t, @ref
+    number_unsigned_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_unsigned_t or @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 @ref basic_json type.
+
+    @sa @ref number_float_t -- type for number values (floating-point)
+
+    @sa @ref number_unsigned_t -- type for number values (unsigned integer)
+
+    @since version 1.0.0
+    */
+    using number_integer_t = NumberIntegerType;
+
+    /*!
+    @brief a type for a number (unsigned)
+
+    [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 a signed integer, an unsigned integer or a floating-point number.
+    Therefore, three different types, @ref number_integer_t, @ref
+    number_unsigned_t and @ref number_float_t are used.
+
+    To store unsigned integer numbers in C++, a type is defined by the
+    template parameter @a NumberUnsignedType which chooses the type to use.
+
+    #### Default type
+
+    With the default values for @a NumberUnsignedType (`uint64_t`), the
+    default value for @a number_unsigned_t is:
+
+    @code {.cpp}
+    uint64_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 `18446744073709551615` (UINT64_MAX) and the minimal integer
+    number that can be stored is `0`. 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_integer_t or @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 (when considered in conjunction with the
+    number_integer_t type) of the exactly supported range [0, UINT64_MAX],
+    this class's integer type is interoperable.
+
+    #### Storage
+
+    Integer number values are stored directly inside a @ref basic_json type.
+
+    @sa @ref number_float_t -- type for number values (floating-point)
+    @sa @ref number_integer_t -- type for number values (integer)
+
+    @since version 2.0.0
+    */
+    using number_unsigned_t = NumberUnsignedType;
+
+    /*!
+    @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 a signed integer, an unsigned integer or a floating-point number.
+    Therefore, three different types, @ref number_integer_t, @ref
+    number_unsigned_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 greater 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 @ref basic_json
+    type.
+
+    @sa @ref number_integer_t -- type for number values (integer)
+
+    @sa @ref number_unsigned_t -- type for number values (unsigned integer)
+
+    @since version 1.0.0
+    */
+    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 @ref is_null(), @ref
+    is_object(), @ref is_array(), @ref is_string(), @ref is_boolean(), @ref
+    is_number() (with @ref is_number_integer(), @ref is_number_unsigned(), and
+    @ref is_number_float()), @ref is_discarded(), @ref is_primitive(), and
+    @ref is_structured() rely on it.
+
+    @note There are three enumeration entries (number_integer,
+    number_unsigned, and number_float), because the library distinguishes
+    these three types for numbers: @ref number_unsigned_t is used for unsigned
+    integers, @ref number_integer_t is used for signed integers, and @ref
+    number_float_t is used for floating-point numbers or to approximate
+    integers which do not fit in the limits of their respective type.
+
+    @sa @ref basic_json(const value_t value_type) -- create a JSON value with
+    the default value for a given type
+
+    @since version 1.0.0
+    */
+    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 (signed integer)
+        number_unsigned, ///< number value (unsigned integer)
+        number_float,    ///< number value (floating-point)
+        discarded        ///< discarded by the the parser callback function
+    };
+
+
+  private:
+
+    /// helper for exception-safe object creation
+    template<typename T, typename... Args>
+    static T* create(Args&& ... args)
+    {
+        AllocatorType<T> alloc;
+        auto deleter = [&](T * object)
+        {
+            alloc.deallocate(object, 1);
+        };
+        std::unique_ptr<T, decltype(deleter)> object(alloc.allocate(1), deleter);
+        alloc.construct(object.get(), std::forward<Args>(args)...);
+        assert(object.get() != nullptr);
+        return object.release();
+    }
+
+    ////////////////////////
+    // JSON value storage //
+    ////////////////////////
+
+    /*!
+    @brief a JSON value
+
+    The actual storage for a JSON value of the @ref basic_json class. This
+    union combines the different storage types for the JSON value types
+    defined in @ref value_t.
+
+    JSON type | value_t type    | used type
+    --------- | --------------- | ------------------------
+    object    | object          | pointer to @ref object_t
+    array     | array           | pointer to @ref array_t
+    string    | string          | pointer to @ref string_t
+    boolean   | boolean         | @ref boolean_t
+    number    | number_integer  | @ref number_integer_t
+    number    | number_unsigned | @ref number_unsigned_t
+    number    | number_float    | @ref number_float_t
+    null      | null            | *no value is stored*
+
+    @note Variable-length types (objects, arrays, and strings) are stored as
+    pointers. The size of the union should not exceed 64 bits if the default
+    value types are used.
+
+    @since version 1.0.0
+    */
+    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 (unsigned integer)
+        number_unsigned_t number_unsigned;
+        /// number (floating-point)
+        number_float_t number_float;
+
+        /// default constructor (for null values)
+        json_value() = 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 (unsigned)
+        json_value(number_unsigned_t v) noexcept : number_unsigned(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::object:
+                {
+                    object = create<object_t>();
+                    break;
+                }
+
+                case value_t::array:
+                {
+                    array = create<array_t>();
+                    break;
+                }
+
+                case value_t::string:
+                {
+                    string = create<string_t>("");
+                    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_unsigned:
+                {
+                    number_unsigned = number_unsigned_t(0);
+                    break;
+                }
+
+                case value_t::number_float:
+                {
+                    number_float = number_float_t(0.0);
+                    break;
+                }
+
+                default:
+                {
+                    break;
+                }
+            }
+        }
+
+        /// constructor for strings
+        json_value(const string_t& value)
+        {
+            string = create<string_t>(value);
+        }
+
+        /// constructor for objects
+        json_value(const object_t& value)
+        {
+            object = create<object_t>(value);
+        }
+
+        /// constructor for arrays
+        json_value(const array_t& value)
+        {
+            array = create<array_t>(value);
+        }
+    };
+
+    /*!
+    @brief checks the class invariants
+
+    This function asserts the class invariants. It needs to be called at the
+    end of every constructor to make sure that created objects respect the
+    invariant. Furthermore, it has to be called each time the type of a JSON
+    value is changed, because the invariant expresses a relationship between
+    @a m_type and @a m_value.
+    */
+    void assert_invariant() const
+    {
+        assert(m_type != value_t::object or m_value.object != nullptr);
+        assert(m_type != value_t::array or m_value.array != nullptr);
+        assert(m_type != value_t::string or m_value.string != nullptr);
+    }
+
+  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.
+
+    @image html callback_events.png "Example when certain parse events are triggered"
+
+    @since version 1.0.0
+    */
+    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&, const
+    parser_callback_t) or @ref parse(const char*, const 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
+
+    @image html callback_events.png "Example when certain parse events are triggered"
+
+    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 char*, parser_callback_t) for examples
+
+    @since version 1.0.0
+    */
+    using parser_callback_t = std::function<bool(int depth,
+                              parse_event_t event,
+                              basic_json& parsed)>;
+
+
+    //////////////////
+    // constructors //
+    //////////////////
+
+    /// @name constructors and destructors
+    /// Constructors of class @ref basic_json, copy/move constructor, copy
+    /// assignment, static functions creating objects, and the destructor.
+    /// @{
+
+    /*!
+    @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_type  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}
+
+    @sa @ref basic_json(std::nullptr_t) -- create a `null` value
+    @sa @ref basic_json(boolean_t value) -- create a boolean value
+    @sa @ref basic_json(const string_t&) -- create a string value
+    @sa @ref basic_json(const object_t&) -- create a object value
+    @sa @ref basic_json(const array_t&) -- create a array value
+    @sa @ref basic_json(const number_float_t) -- create a number
+    (floating-point) value
+    @sa @ref basic_json(const number_integer_t) -- create a number (integer)
+    value
+    @sa @ref basic_json(const number_unsigned_t) -- create a number (unsigned)
+    value
+
+    @since version 1.0.0
+    */
+    basic_json(const value_t value_type)
+        : m_type(value_type), m_value(value_type)
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create a null object
+
+    Create a `null` JSON value. It either takes a null pointer as parameter
+    (explicitly creating `null`) or no parameter (implicitly creating `null`).
+    The passed null pointer itself is not read -- it is only used to choose
+    the right constructor.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this constructor never throws
+    exceptions.
+
+    @liveexample{The following code shows the constructor with and without a
+    null pointer parameter.,basic_json__nullptr_t}
+
+    @since version 1.0.0
+    */
+    basic_json(std::nullptr_t = nullptr) noexcept
+        : basic_json(value_t::null)
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create an object (explicit)
+
+    Create an object JSON value with a given content.
+
+    @param[in] val  a value for the object
+
+    @complexity Linear in the size of the passed @a val.
+
+    @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 @ref basic_json(const CompatibleObjectType&) -- create an object value
+    from a compatible STL container
+
+    @since version 1.0.0
+    */
+    basic_json(const object_t& val)
+        : m_type(value_t::object), m_value(val)
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create an object (implicit)
+
+    Create an object JSON value with a given content. This constructor allows
+    any type @a CompatibleObjectType that can be used to construct values of
+    type @ref object_t.
+
+    @tparam CompatibleObjectType An object type whose `key_type` and
+    `value_type` is compatible to @ref object_t. Examples include `std::map`,
+    `std::unordered_map`, `std::multimap`, and `std::unordered_multimap` with
+    a `key_type` of `std::string`, and a `value_type` from which a @ref
+    basic_json value can be constructed.
+
+    @param[in] val  a value for the object
+
+    @complexity Linear in the size of the passed @a val.
+
+    @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 @ref basic_json(const object_t&) -- create an object value
+
+    @since version 1.0.0
+    */
+    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& val)
+        : m_type(value_t::object)
+    {
+        using std::begin;
+        using std::end;
+        m_value.object = create<object_t>(begin(val), end(val));
+        assert_invariant();
+    }
+
+    /*!
+    @brief create an array (explicit)
+
+    Create an array JSON value with a given content.
+
+    @param[in] val  a value for the array
+
+    @complexity Linear in the size of the passed @a val.
+
+    @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 @ref basic_json(const CompatibleArrayType&) -- create an array value
+    from a compatible STL containers
+
+    @since version 1.0.0
+    */
+    basic_json(const array_t& val)
+        : m_type(value_t::array), m_value(val)
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create an array (implicit)
+
+    Create an array JSON value with a given content. This constructor allows
+    any type @a CompatibleArrayType that can be used to construct values of
+    type @ref array_t.
+
+    @tparam CompatibleArrayType An object type whose `value_type` is
+    compatible to @ref array_t. Examples include `std::vector`, `std::deque`,
+    `std::list`, `std::forward_list`, `std::array`, `std::set`,
+    `std::unordered_set`, `std::multiset`, and `unordered_multiset` with a
+    `value_type` from which a @ref basic_json value can be constructed.
+
+    @param[in] val  a value for the array
+
+    @complexity Linear in the size of the passed @a val.
+
+    @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 @ref basic_json(const array_t&) -- create an array value
+
+    @since version 1.0.0
+    */
+    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& val)
+        : m_type(value_t::array)
+    {
+        using std::begin;
+        using std::end;
+        m_value.array = create<array_t>(begin(val), end(val));
+        assert_invariant();
+    }
+
+    /*!
+    @brief create a string (explicit)
+
+    Create an string JSON value with a given content.
+
+    @param[in] val  a value for the string
+
+    @complexity Linear in the size of the passed @a val.
+
+    @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 @ref basic_json(const typename string_t::value_type*) -- create a
+    string value from a character pointer
+    @sa @ref basic_json(const CompatibleStringType&) -- create a string value
+    from a compatible string container
+
+    @since version 1.0.0
+    */
+    basic_json(const string_t& val)
+        : m_type(value_t::string), m_value(val)
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create a string (explicit)
+
+    Create a string JSON value with a given content.
+
+    @param[in] val  a literal value for the string
+
+    @complexity Linear in the size of the passed @a val.
+
+    @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 @ref basic_json(const string_t&) -- create a string value
+    @sa @ref basic_json(const CompatibleStringType&) -- create a string value
+    from a compatible string container
+
+    @since version 1.0.0
+    */
+    basic_json(const typename string_t::value_type* val)
+        : basic_json(string_t(val))
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create a string (implicit)
+
+    Create a string JSON value with a given content.
+
+    @param[in] val  a value for the string
+
+    @tparam CompatibleStringType an string type which is compatible to @ref
+    string_t, for instance `std::string`.
+
+    @complexity Linear in the size of the passed @a val.
+
+    @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 @ref basic_json(const string_t&) -- create a string value
+    @sa @ref basic_json(const typename string_t::value_type*) -- create a
+    string value from a character pointer
+
+    @since version 1.0.0
+    */
+    template<class CompatibleStringType, typename std::enable_if<
+                 std::is_constructible<string_t, CompatibleStringType>::value, int>::type = 0>
+    basic_json(const CompatibleStringType& val)
+        : basic_json(string_t(val))
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create a boolean (explicit)
+
+    Creates a JSON boolean type from a given value.
+
+    @param[in] val  a boolean value to store
+
+    @complexity Constant.
+
+    @liveexample{The example below demonstrates boolean
+    values.,basic_json__boolean_t}
+
+    @since version 1.0.0
+    */
+    basic_json(boolean_t val) noexcept
+        : m_type(value_t::boolean), m_value(val)
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create an integer number (explicit)
+
+    Create an integer number JSON value with a given content.
+
+    @tparam T A helper type to remove this function via SFINAE in case @ref
+    number_integer_t is the same as `int`. In this case, this constructor
+    would have the same signature as @ref basic_json(const int value). Note
+    the helper type @a T is not visible in this constructor's interface.
+
+    @param[in] val  an integer to create a JSON number from
+
+    @complexity Constant.
+
+    @liveexample{The example below shows the construction of an integer
+    number value.,basic_json__number_integer_t}
+
+    @sa @ref basic_json(const int) -- create a number value (integer)
+    @sa @ref basic_json(const CompatibleNumberIntegerType) -- create a number
+    value (integer) from a compatible number type
+
+    @since version 1.0.0
+    */
+    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 val) noexcept
+        : m_type(value_t::number_integer), m_value(val)
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create an integer number from an enum type (explicit)
+
+    Create an integer number JSON value with a given content.
+
+    @param[in] val  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 an integer
+    number value from an anonymous enum.,basic_json__const_int}
+
+    @sa @ref basic_json(const number_integer_t) -- create a number value
+    (integer)
+    @sa @ref basic_json(const CompatibleNumberIntegerType) -- create a number
+    value (integer) from a compatible number type
+
+    @since version 1.0.0
+    */
+    basic_json(const int val) noexcept
+        : m_type(value_t::number_integer),
+          m_value(static_cast<number_integer_t>(val))
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create an integer number (implicit)
+
+    Create an integer number JSON value with a given content. This constructor
+    allows any type @a CompatibleNumberIntegerType that can be used to
+    construct values of type @ref number_integer_t.
+
+    @tparam CompatibleNumberIntegerType An integer type which is compatible to
+    @ref number_integer_t. Examples include the types `int`, `int32_t`,
+    `long`, and `short`.
+
+    @param[in] val  an integer to create a JSON number from
+
+    @complexity Constant.
+
+    @liveexample{The example below shows the construction of several integer
+    number values from compatible
+    types.,basic_json__CompatibleIntegerNumberType}
+
+    @sa @ref basic_json(const number_integer_t) -- create a number value
+    (integer)
+    @sa @ref basic_json(const int) -- create a number value (integer)
+
+    @since version 1.0.0
+    */
+    template<typename CompatibleNumberIntegerType, typename std::enable_if<
+                 std::is_constructible<number_integer_t, CompatibleNumberIntegerType>::value and
+                 std::numeric_limits<CompatibleNumberIntegerType>::is_integer and
+                 std::numeric_limits<CompatibleNumberIntegerType>::is_signed,
+                 CompatibleNumberIntegerType>::type = 0>
+    basic_json(const CompatibleNumberIntegerType val) noexcept
+        : m_type(value_t::number_integer),
+          m_value(static_cast<number_integer_t>(val))
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create an unsigned integer number (explicit)
+
+    Create an unsigned integer number JSON value with a given content.
+
+    @tparam T  helper type to compare number_unsigned_t and unsigned int (not
+    visible in) the interface.
+
+    @param[in] val  an integer to create a JSON number from
+
+    @complexity Constant.
+
+    @sa @ref basic_json(const CompatibleNumberUnsignedType) -- create a number
+    value (unsigned integer) from a compatible number type
+
+    @since version 2.0.0
+    */
+    template<typename T, typename std::enable_if<
+                 not (std::is_same<T, int>::value) and
+                 std::is_same<T, number_unsigned_t>::value, int>::type = 0>
+    basic_json(const number_unsigned_t val) noexcept
+        : m_type(value_t::number_unsigned), m_value(val)
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create an unsigned number (implicit)
+
+    Create an unsigned number JSON value with a given content. This
+    constructor allows any type @a CompatibleNumberUnsignedType that can be
+    used to construct values of type @ref number_unsigned_t.
+
+    @tparam CompatibleNumberUnsignedType An integer type which is compatible
+    to @ref number_unsigned_t. Examples may include the types `unsigned int`,
+    `uint32_t`, or `unsigned short`.
+
+    @param[in] val  an unsigned integer to create a JSON number from
+
+    @complexity Constant.
+
+    @sa @ref basic_json(const number_unsigned_t) -- create a number value
+    (unsigned)
+
+    @since version 2.0.0
+    */
+    template<typename CompatibleNumberUnsignedType, typename std::enable_if <
+                 std::is_constructible<number_unsigned_t, CompatibleNumberUnsignedType>::value and
+                 std::numeric_limits<CompatibleNumberUnsignedType>::is_integer and
+                 not std::numeric_limits<CompatibleNumberUnsignedType>::is_signed,
+                 CompatibleNumberUnsignedType>::type = 0>
+    basic_json(const CompatibleNumberUnsignedType val) noexcept
+        : m_type(value_t::number_unsigned),
+          m_value(static_cast<number_unsigned_t>(val))
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @brief create a floating-point number (explicit)
+
+    Create a floating-point number JSON value with a given content.
+
+    @param[in] val  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 val 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}
+
+    @sa @ref basic_json(const CompatibleNumberFloatType) -- create a number
+    value (floating-point) from a compatible number type
+
+    @since version 1.0.0
+    */
+    basic_json(const number_float_t val) noexcept
+        : m_type(value_t::number_float), m_value(val)
+    {
+        // replace infinity and NAN by null
+        if (not std::isfinite(val))
+        {
+            m_type = value_t::null;
+            m_value = json_value();
+        }
+
+        assert_invariant();
+    }
+
+    /*!
+    @brief create an floating-point number (implicit)
+
+    Create an floating-point number JSON value with a given content. This
+    constructor allows any type @a CompatibleNumberFloatType that can be used
+    to construct values of type @ref number_float_t.
+
+    @tparam CompatibleNumberFloatType A floating-point type which is
+    compatible to @ref number_float_t. Examples may include the types `float`
+    or `double`.
+
+    @param[in] val  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 val is not a number, a JSON null value is
+    created instead.
+
+    @complexity Constant.
+
+    @liveexample{The example below shows the construction of several
+    floating-point number values from compatible
+    types.,basic_json__CompatibleNumberFloatType}
+
+    @sa @ref basic_json(const number_float_t) -- create a number value
+    (floating-point)
+
+    @since version 1.0.0
+    */
+    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 val) noexcept
+        : basic_json(number_float_t(val))
+    {
+        assert_invariant();
+    }
+
+    /*!
+    @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 rationale 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; example: `"cannot create object from
+    initializer list"`
+
+    @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 @ref array(std::initializer_list<basic_json>) -- create a JSON array
+    value from an initializer list
+    @sa @ref object(std::initializer_list<basic_json>) -- create a JSON object
+    value from an initializer list
+
+    @since version 1.0.0
+    */
+    basic_json(std::initializer_list<basic_json> init,
+               bool type_deduction = true,
+               value_t manual_type = value_t::array)
+    {
+        // check if each element is an array with two elements whose first
+        // element is a string
+        bool is_an_object = std::all_of(init.begin(), init.end(),
+                                        [](const basic_json & element)
+        {
+            return element.is_array() and element.size() == 2 and element[0].is_string();
+        });
+
+        // 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_an_object = false;
+            }
+
+            // if object is wanted but impossible, throw an exception
+            if (manual_type == value_t::object and not is_an_object)
+            {
+                throw std::domain_error("cannot create object from initializer list");
+            }
+        }
+
+        if (is_an_object)
+        {
+            // the initializer list is a list of pairs -> create object
+            m_type = value_t::object;
+            m_value = value_t::object;
+
+            std::for_each(init.begin(), init.end(), [this](const basic_json & element)
+            {
+                m_value.object->emplace(*(element[0].m_value.string), element[1]);
+            });
+        }
+        else
+        {
+            // the initializer list describes an array -> create array
+            m_type = value_t::array;
+            m_value.array = create<array_t>(init);
+        }
+
+        assert_invariant();
+    }
+
+    /*!
+    @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 `array`
+    function.,array}
+
+    @sa @ref basic_json(std::initializer_list<basic_json>, bool, value_t) --
+    create a JSON value from an initializer list
+    @sa @ref object(std::initializer_list<basic_json>) -- create a JSON object
+    value from an initializer list
+
+    @since version 1.0.0
+    */
+    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 elements 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 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 `object`
+    function.,object}
+
+    @sa @ref basic_json(std::initializer_list<basic_json>, bool, value_t) --
+    create a JSON value from an initializer list
+    @sa @ref array(std::initializer_list<basic_json>) -- create a JSON array
+    value from an initializer list
+
+    @since version 1.0.0
+    */
+    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 cnt copies of a passed value.
+    In case @a cnt is `0`, an empty array is created. As postcondition,
+    `std::distance(begin(),end()) == cnt` holds.
+
+    @param[in] cnt  the number of JSON copies of @a val to create
+    @param[in] val  the JSON value to copy
+
+    @complexity Linear in @a cnt.
+
+    @liveexample{The following code shows examples for the @ref
+    basic_json(size_type\, const basic_json&)
+    constructor.,basic_json__size_type_basic_json}
+
+    @since version 1.0.0
+    */
+    basic_json(size_type cnt, const basic_json& val)
+        : m_type(value_t::array)
+    {
+        m_value.array = create<array_t>(cnt, val);
+        assert_invariant();
+    }
+
+    /*!
+    @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)
+
+    @pre Iterators @a first and @a last must be initialized. **This
+         precondition is enforced with an assertion.**
+
+    @throw std::domain_error if iterators are not compatible; that is, do not
+    belong to the same JSON value; example: `"iterators are not compatible"`
+    @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;
+    example: `"iterators out of range"`
+    @throw std::bad_alloc if allocation for object, array, or string fails
+    @throw std::domain_error if called with a null value; example: `"cannot
+    use construct with iterators from null"`
+
+    @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}
+
+    @since version 1.0.0
+    */
+    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)
+    {
+        assert(first.m_object != nullptr);
+        assert(last.m_object != nullptr);
+
+        // make sure iterator fits the current value
+        if (first.m_object != last.m_object)
+        {
+            throw std::domain_error("iterators are not compatible");
+        }
+
+        // copy type from first iterator
+        m_type = first.m_object->m_type;
+
+        // check if iterator range is complete for primitive values
+        switch (m_type)
+        {
+            case value_t::boolean:
+            case value_t::number_float:
+            case value_t::number_integer:
+            case value_t::number_unsigned:
+            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_unsigned:
+            {
+                m_value.number_unsigned = first.m_object->m_value.number_unsigned;
+                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:
+            {
+                m_value.object = create<object_t>(first.m_it.object_iterator, last.m_it.object_iterator);
+                break;
+            }
+
+            case value_t::array:
+            {
+                m_value.array = create<array_t>(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());
+            }
+        }
+
+        assert_invariant();
+    }
+
+    /*!
+    @brief construct a JSON value given an input 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)
+
+    @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.
+
+    @note A UTF-8 byte order mark is silently ignored.
+
+    @deprecated This constructor is deprecated and will be removed in version
+      3.0.0 to unify the interface of the library. Deserialization will be
+      done by stream operators or by calling one of the `parse` functions,
+      e.g. @ref parse(std::istream&, const parser_callback_t). That is, calls
+      like `json j(i);` for an input stream @a i need to be replaced by
+      `json j = json::parse(i);`. See the example below.
+
+    @liveexample{The example below demonstrates constructing a JSON value from
+    a `std::stringstream` with and without callback
+    function.,basic_json__istream}
+
+    @since version 2.0.0, deprecated in version 2.0.3, to be removed in
+           version 3.0.0
+    */
+    JSON_DEPRECATED
+    explicit basic_json(std::istream& i, const parser_callback_t cb = nullptr)
+    {
+        *this = parser(i, cb).parse();
+        assert_invariant();
+    }
+
+    ///////////////////////////////////////
+    // 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 helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/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}
+
+    @since version 1.0.0
+    */
+    basic_json(const basic_json& other)
+        : m_type(other.m_type)
+    {
+        // check of passed value is valid
+        other.assert_invariant();
+
+        switch (m_type)
+        {
+            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_unsigned:
+            {
+                m_value = other.m_value.number_unsigned;
+                break;
+            }
+
+            case value_t::number_float:
+            {
+                m_value = other.m_value.number_float;
+                break;
+            }
+
+            default:
+            {
+                break;
+            }
+        }
+
+        assert_invariant();
+    }
+
+    /*!
+    @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}
+
+    @since version 1.0.0
+    */
+    basic_json(basic_json&& other) noexcept
+        : m_type(std::move(other.m_type)),
+          m_value(std::move(other.m_value))
+    {
+        // check that passed value is valid
+        other.assert_invariant();
+
+        // invalidate payload
+        other.m_type = value_t::null;
+        other.m_value = {};
+
+        assert_invariant();
+    }
+
+    /*!
+    @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 helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/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}
+
+    @since version 1.0.0
+    */
+    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
+    )
+    {
+        // check that passed value is valid
+        other.assert_invariant();
+
+        using std::swap;
+        swap(m_type, other.m_type);
+        swap(m_value, other.m_value);
+
+        assert_invariant();
+        return *this;
+    }
+
+    /*!
+    @brief destructor
+
+    Destroys the JSON value and frees all allocated memory.
+
+    @complexity Linear.
+
+    @requirement This function helps `basic_json` satisfying the
+    [Container](http://en.cppreference.com/w/cpp/concept/Container)
+    requirements:
+    - The complexity is linear.
+    - All stored elements are destroyed and all memory is freed.
+
+    @since version 1.0.0
+    */
+    ~basic_json()
+    {
+        assert_invariant();
+
+        switch (m_type)
+        {
+            case value_t::object:
+            {
+                AllocatorType<object_t> alloc;
+                alloc.destroy(m_value.object);
+                alloc.deallocate(m_value.object, 1);
+                break;
+            }
+
+            case value_t::array:
+            {
+                AllocatorType<array_t> alloc;
+                alloc.destroy(m_value.array);
+                alloc.deallocate(m_value.array, 1);
+                break;
+            }
+
+            case value_t::string:
+            {
+                AllocatorType<string_t> alloc;
+                alloc.destroy(m_value.string);
+                alloc.deallocate(m_value.string, 1);
+                break;
+            }
+
+            default:
+            {
+                // all other types need no specific destructor
+                break;
+            }
+        }
+    }
+
+    /// @}
+
+  public:
+    ///////////////////////
+    // object inspection //
+    ///////////////////////
+
+    /// @name object inspection
+    /// Functions to inspect the type of a JSON value.
+    /// @{
+
+    /*!
+    @brief serialization
+
+    Serialization function for JSON values. The function tries to mimic
+    Python's `json.dumps()` function, and currently supports its @a 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 serialization.,dump}
+
+    @see https://docs.python.org/2/library/json.html#json.dump
+
+    @since version 1.0.0
+    */
+    string_t dump(const int indent = -1) const
+    {
+        std::stringstream ss;
+        // fix locale problems
+        const static std::locale loc(std::locale(), new DecimalSeparator);
+        ss.imbue(loc);
+
+        // 6, 15 or 16 digits of precision allows round-trip IEEE 754
+        // string->float->string, string->double->string or string->long
+        // double->string; to be safe, we read this value from
+        // std::numeric_limits<number_float_t>::digits10
+        ss.precision(std::numeric_limits<double>::digits10);
+
+        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.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `type()` for all JSON
+    types.,type}
+
+    @since version 1.0.0
+    */
+    constexpr 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.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_primitive()` for all JSON
+    types.,is_primitive}
+
+    @sa @ref is_structured() -- returns whether JSON value is structured
+    @sa @ref is_null() -- returns whether JSON value is `null`
+    @sa @ref is_string() -- returns whether JSON value is a string
+    @sa @ref is_boolean() -- returns whether JSON value is a boolean
+    @sa @ref is_number() -- returns whether JSON value is a number
+
+    @since version 1.0.0
+    */
+    constexpr 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.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_structured()` for all JSON
+    types.,is_structured}
+
+    @sa @ref is_primitive() -- returns whether value is primitive
+    @sa @ref is_array() -- returns whether value is an array
+    @sa @ref is_object() -- returns whether value is an object
+
+    @since version 1.0.0
+    */
+    constexpr 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.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_null()` for all JSON
+    types.,is_null}
+
+    @since version 1.0.0
+    */
+    constexpr 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.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_boolean()` for all JSON
+    types.,is_boolean}
+
+    @since version 1.0.0
+    */
+    constexpr 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 (regardless whether integer, unsigned
+    integer or floating-type), `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_number()` for all JSON
+    types.,is_number}
+
+    @sa @ref is_number_integer() -- check if value is an integer or unsigned
+    integer number
+    @sa @ref is_number_unsigned() -- check if value is an unsigned integer
+    number
+    @sa @ref is_number_float() -- check if value is a floating-point number
+
+    @since version 1.0.0
+    */
+    constexpr 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 or unsigned
+    integer number. This excludes floating-point values.
+
+    @return `true` if type is an integer or unsigned integer number, `false`
+    otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_number_integer()` for all
+    JSON types.,is_number_integer}
+
+    @sa @ref is_number() -- check if value is a number
+    @sa @ref is_number_unsigned() -- check if value is an unsigned integer
+    number
+    @sa @ref is_number_float() -- check if value is a floating-point number
+
+    @since version 1.0.0
+    */
+    constexpr bool is_number_integer() const noexcept
+    {
+        return m_type == value_t::number_integer or m_type == value_t::number_unsigned;
+    }
+
+    /*!
+    @brief return whether value is an unsigned integer number
+
+    This function returns true iff the JSON value is an unsigned integer
+    number. This excludes floating-point and (signed) integer values.
+
+    @return `true` if type is an unsigned integer number, `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_number_unsigned()` for all
+    JSON types.,is_number_unsigned}
+
+    @sa @ref is_number() -- check if value is a number
+    @sa @ref is_number_integer() -- check if value is an integer or unsigned
+    integer number
+    @sa @ref is_number_float() -- check if value is a floating-point number
+
+    @since version 2.0.0
+    */
+    constexpr bool is_number_unsigned() const noexcept
+    {
+        return m_type == value_t::number_unsigned;
+    }
+
+    /*!
+    @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 and unsigned integer values.
+
+    @return `true` if type is a floating-point number, `false` otherwise.
+
+    @complexity Constant.
+
+    @exceptionsafety No-throw guarantee: this member function never throws
+    exceptions.
+
+    @liveexample{The following code exemplifies `is_number_float()` for all
+    JSON types.,is_number_float}
+
+    @sa @ref is_number() -- check if value is number
+    @sa @ref is_number_integer() -- check if value is an integer number
+    @sa @ref is_number_unsigned() -- check if value is an unsigned integer
+    number
+
+    @since version 1.0.0
+    */
+    constexpr bool is_number_float() const noexcept
+    {
+        return 

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