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json.hpp
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json.hpp
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/*
__ _____ _____ _____
__| | __| | | | JSON for Modern C++
| | |__ | | | | | | version 2.1.1
|_____|_____|_____|_|___| https://github.com/nlohmann/json
Licensed under the MIT License <http://opensource.org/licenses/MIT>.
Copyright (c) 2013-2017 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> // all_of, copy, fill, find, for_each, generate_n, none_of, remove, reverse, transform
#include <array> // array
#include <cassert> // assert
#include <ciso646> // and, not, or
#include <clocale> // lconv, localeconv
#include <cmath> // isfinite, labs, ldexp, signbit
#include <cstddef> // nullptr_t, ptrdiff_t, size_t
#include <cstdint> // int64_t, uint64_t
#include <cstdlib> // abort, strtod, strtof, strtold, strtoul, strtoll, strtoull
#include <cstring> // memcpy, strlen
#include <forward_list> // forward_list
#include <functional> // function, hash, less
#include <initializer_list> // initializer_list
#include <iomanip> // hex
#include <iosfwd> // istream, ostream
#include <iterator> // advance, begin, back_inserter, bidirectional_iterator_tag, distance, end, inserter, iterator, iterator_traits, next, random_access_iterator_tag, reverse_iterator
#include <limits> // numeric_limits
#include <locale> // locale
#include <map> // map
#include <memory> // addressof, allocator, allocator_traits, unique_ptr
#include <numeric> // accumulate
#include <sstream> // stringstream
#include <string> // getline, stoi, string, to_string
#include <type_traits> // add_pointer, conditional, decay, enable_if, false_type, integral_constant, is_arithmetic, is_base_of, is_const, is_constructible, is_convertible, is_default_constructible, is_enum, is_floating_point, is_integral, is_nothrow_move_assignable, is_nothrow_move_constructible, is_pointer, is_reference, is_same, is_scalar, is_signed, remove_const, remove_cv, remove_pointer, remove_reference, true_type, underlying_type
#include <utility> // declval, forward, make_pair, move, pair, swap
#include <valarray> // valarray
#include <vector> // vector
// exclude unsupported compilers
#if defined(__clang__)
#if (__clang_major__ * 10000 + __clang_minor__ * 100 + __clang_patchlevel__) < 30400
#error "unsupported Clang version - see https://github.com/nlohmann/json#supported-compilers"
#endif
#elif defined(__GNUC__) && !(defined(__ICC) || defined(__INTEL_COMPILER))
#if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) < 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
// disable documentation warnings on clang
#if defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdocumentation"
#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
// allow to disable exceptions
#if (defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)) && not defined(JSON_NOEXCEPTION)
#define JSON_THROW(exception) throw exception
#define JSON_TRY try
#define JSON_CATCH(exception) catch(exception)
#else
#define JSON_THROW(exception) std::abort()
#define JSON_TRY if(true)
#define JSON_CATCH(exception) if(false)
#endif
// manual branch prediction
#if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
#define JSON_LIKELY(x) __builtin_expect(!!(x), 1)
#define JSON_UNLIKELY(x) __builtin_expect(!!(x), 0)
#else
#define JSON_LIKELY(x) x
#define JSON_UNLIKELY(x) x
#endif
/*!
@brief namespace for Niels Lohmann
@see https://github.com/nlohmann
@since version 1.0.0
*/
namespace nlohmann
{
template<typename = void, typename = void>
struct adl_serializer;
// forward declaration of basic_json (required to split the class)
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,
template<typename T, typename SFINAE = void> class JSONSerializer =
adl_serializer>
class basic_json;
// Ugly macros to avoid uglier copy-paste when specializing basic_json
// This is only temporary and will be removed in 3.0
#define NLOHMANN_BASIC_JSON_TPL_DECLARATION \
template<template<typename, typename, typename...> class ObjectType, \
template<typename, typename...> class ArrayType, \
class StringType, class BooleanType, class NumberIntegerType, \
class NumberUnsignedType, class NumberFloatType, \
template<typename> class AllocatorType, \
template<typename, typename = void> class JSONSerializer>
#define NLOHMANN_BASIC_JSON_TPL \
basic_json<ObjectType, ArrayType, StringType, BooleanType, \
NumberIntegerType, NumberUnsignedType, NumberFloatType, \
AllocatorType, JSONSerializer>
/*!
@brief unnamed namespace with internal helper functions
This namespace collects some functions that could not be defined inside the
@ref basic_json class.
@since version 2.1.0
*/
namespace detail
{
////////////////
// exceptions //
////////////////
/*!
@brief general exception of the @ref basic_json class
This class is an extension of `std::exception` objects with a member @a id for
exception ids. It is used as the base class for all exceptions thrown by the
@ref basic_json class. This class can hence be used as "wildcard" to catch
exceptions.
Subclasses:
- @ref parse_error for exceptions indicating a parse error
- @ref invalid_iterator for exceptions indicating errors with iterators
- @ref type_error for exceptions indicating executing a member function with
a wrong type
- @ref out_of_range for exceptions indicating access out of the defined range
- @ref other_error for exceptions indicating other library errors
@internal
@note To have nothrow-copy-constructible exceptions, we internally use
`std::runtime_error` which can cope with arbitrary-length error messages.
Intermediate strings are built with static functions and then passed to
the actual constructor.
@endinternal
@liveexample{The following code shows how arbitrary library exceptions can be
caught.,exception}
@since version 3.0.0
*/
class exception : public std::exception
{
public:
/// returns the explanatory string
const char* what() const noexcept override
{
return m.what();
}
/// the id of the exception
const int id;
protected:
exception(int id_, const char* what_arg) : id(id_), m(what_arg) {}
static std::string name(const std::string& ename, int id_)
{
return "[json.exception." + ename + "." + std::to_string(id_) + "] ";
}
private:
/// an exception object as storage for error messages
std::runtime_error m;
};
/*!
@brief exception indicating a parse error
This excpetion is thrown by the library when a parse error occurs. Parse errors
can occur during the deserialization of JSON text, CBOR, MessagePack, as well
as when using JSON Patch.
Member @a byte holds the byte index of the last read character in the input
file.
Exceptions have ids 1xx.
name / id | example message | description
------------------------------ | --------------- | -------------------------
json.exception.parse_error.101 | parse error at 2: unexpected end of input; expected string literal | This error indicates a syntax error while deserializing a JSON text. The error message describes that an unexpected token (character) was encountered, and the member @a byte indicates the error position.
json.exception.parse_error.102 | parse error at 14: missing or wrong low surrogate | JSON uses the `\uxxxx` format to describe Unicode characters. Code points above above 0xFFFF are split into two `\uxxxx` entries ("surrogate pairs"). This error indicates that the surrogate pair is incomplete or contains an invalid code point.
json.exception.parse_error.103 | parse error: code points above 0x10FFFF are invalid | Unicode supports code points up to 0x10FFFF. Code points above 0x10FFFF are invalid.
json.exception.parse_error.104 | parse error: JSON patch must be an array of objects | [RFC 6902](https://tools.ietf.org/html/rfc6902) requires a JSON Patch document to be a JSON document that represents an array of objects.
json.exception.parse_error.105 | parse error: operation must have string member 'op' | An operation of a JSON Patch document must contain exactly one "op" member, whose value indicates the operation to perform. Its value must be one of "add", "remove", "replace", "move", "copy", or "test"; other values are errors.
json.exception.parse_error.106 | parse error: array index '01' must not begin with '0' | An array index in a JSON Pointer ([RFC 6901](https://tools.ietf.org/html/rfc6901)) may be `0` or any number wihtout a leading `0`.
json.exception.parse_error.107 | parse error: JSON pointer must be empty or begin with '/' - was: 'foo' | A JSON Pointer must be a Unicode string containing a sequence of zero or more reference tokens, each prefixed by a `/` character.
json.exception.parse_error.108 | parse error: escape character '~' must be followed with '0' or '1' | In a JSON Pointer, only `~0` and `~1` are valid escape sequences.
json.exception.parse_error.109 | parse error: array index 'one' is not a number | A JSON Pointer array index must be a number.
json.exception.parse_error.110 | parse error at 1: cannot read 2 bytes from vector | When parsing CBOR or MessagePack, the byte vector ends before the complete value has been read.
json.exception.parse_error.112 | parse error at 1: error reading CBOR; last byte: 0xf8 | Not all types of CBOR or MessagePack are supported. This exception occurs if an unsupported byte was read.
json.exception.parse_error.113 | parse error at 2: expected a CBOR string; last byte: 0x98 | While parsing a map key, a value that is not a string has been read.
@note For an input with n bytes, 1 is the index of the first character and n+1
is the index of the terminating null byte or the end of file. This also
holds true when reading a byte vector (CBOR or MessagePack).
@liveexample{The following code shows how a `parse_error` exception can be
caught.,parse_error}
@sa @ref exception for the base class of the library exceptions
@sa @ref invalid_iterator for exceptions indicating errors with iterators
@sa @ref type_error for exceptions indicating executing a member function with
a wrong type
@sa @ref out_of_range for exceptions indicating access out of the defined range
@sa @ref other_error for exceptions indicating other library errors
@since version 3.0.0
*/
class parse_error : public exception
{
public:
/*!
@brief create a parse error exception
@param[in] id_ the id of the exception
@param[in] byte_ the byte index where the error occurred (or 0 if the
position cannot be determined)
@param[in] what_arg the explanatory string
@return parse_error object
*/
static parse_error create(int id_, std::size_t byte_, const std::string& what_arg)
{
std::string w = exception::name("parse_error", id_) + "parse error" +
(byte_ != 0 ? (" at " + std::to_string(byte_)) : "") +
": " + what_arg;
return parse_error(id_, byte_, w.c_str());
}
/*!
@brief byte index of the parse error
The byte index of the last read character in the input file.
@note For an input with n bytes, 1 is the index of the first character and
n+1 is the index of the terminating null byte or the end of file.
This also holds true when reading a byte vector (CBOR or MessagePack).
*/
const std::size_t byte;
private:
parse_error(int id_, std::size_t byte_, const char* what_arg)
: exception(id_, what_arg), byte(byte_) {}
};
/*!
@brief exception indicating errors with iterators
This exception is thrown if iterators passed to a library function do not match
the expected semantics.
Exceptions have ids 2xx.
name / id | example message | description
----------------------------------- | --------------- | -------------------------
json.exception.invalid_iterator.201 | iterators are not compatible | The iterators passed to constructor @ref basic_json(InputIT first, InputIT last) are not compatible, meaning they do not belong to the same container. Therefore, the range (@a first, @a last) is invalid.
json.exception.invalid_iterator.202 | iterator does not fit current value | In an erase or insert function, the passed iterator @a pos does not belong to the JSON value for which the function was called. It hence does not define a valid position for the deletion/insertion.
json.exception.invalid_iterator.203 | iterators do not fit current value | Either iterator passed to function @ref erase(IteratorType first, IteratorType last) does not belong to the JSON value from which values shall be erased. It hence does not define a valid range to delete values from.
json.exception.invalid_iterator.204 | iterators out of range | When an iterator range for a primitive type (number, boolean, or string) is passed to a constructor or an erase function, this range has to be exactly (@ref begin(), @ref end()), because this is the only way the single stored value is expressed. All other ranges are invalid.
json.exception.invalid_iterator.205 | iterator out of range | When an iterator for a primitive type (number, boolean, or string) is passed to an erase function, the iterator has to be the @ref begin() iterator, because it is the only way to address the stored value. All other iterators are invalid.
json.exception.invalid_iterator.206 | cannot construct with iterators from null | The iterators passed to constructor @ref basic_json(InputIT first, InputIT last) belong to a JSON null value and hence to not define a valid range.
json.exception.invalid_iterator.207 | cannot use key() for non-object iterators | The key() member function can only be used on iterators belonging to a JSON object, because other types do not have a concept of a key.
json.exception.invalid_iterator.208 | cannot use operator[] for object iterators | The operator[] to specify a concrete offset cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
json.exception.invalid_iterator.209 | cannot use offsets with object iterators | The offset operators (+, -, +=, -=) cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
json.exception.invalid_iterator.210 | iterators do not fit | The iterator range passed to the insert function are not compatible, meaning they do not belong to the same container. Therefore, the range (@a first, @a last) is invalid.
json.exception.invalid_iterator.211 | passed iterators may not belong to container | The iterator range passed to the insert function must not be a subrange of the container to insert to.
json.exception.invalid_iterator.212 | cannot compare iterators of different containers | When two iterators are compared, they must belong to the same container.
json.exception.invalid_iterator.213 | cannot compare order of object iterators | The order of object iterators cannot be compared, because JSON objects are unordered.
json.exception.invalid_iterator.214 | cannot get value | Cannot get value for iterator: Either the iterator belongs to a null value or it is an iterator to a primitive type (number, boolean, or string), but the iterator is different to @ref begin().
@liveexample{The following code shows how an `invalid_iterator` exception can be
caught.,invalid_iterator}
@sa @ref exception for the base class of the library exceptions
@sa @ref parse_error for exceptions indicating a parse error
@sa @ref type_error for exceptions indicating executing a member function with
a wrong type
@sa @ref out_of_range for exceptions indicating access out of the defined range
@sa @ref other_error for exceptions indicating other library errors
@since version 3.0.0
*/
class invalid_iterator : public exception
{
public:
static invalid_iterator create(int id_, const std::string& what_arg)
{
std::string w = exception::name("invalid_iterator", id_) + what_arg;
return invalid_iterator(id_, w.c_str());
}
private:
invalid_iterator(int id_, const char* what_arg)
: exception(id_, what_arg) {}
};
/*!
@brief exception indicating executing a member function with a wrong type
This exception is thrown in case of a type error; that is, a library function is
executed on a JSON value whose type does not match the expected semantics.
Exceptions have ids 3xx.
name / id | example message | description
----------------------------- | --------------- | -------------------------
json.exception.type_error.301 | cannot create object from initializer list | To create an object from an initializer list, the initializer list must consist only of a list of pairs whose first element is a string. When this constraint is violated, an array is created instead.
json.exception.type_error.302 | type must be object, but is array | During implicit or explicit value conversion, the JSON type must be compatible to the target type. For instance, a JSON string can only be converted into string types, but not into numbers or boolean types.
json.exception.type_error.303 | incompatible ReferenceType for get_ref, actual type is object | To retrieve a reference to a value stored in a @ref basic_json object with @ref get_ref, the type of the reference must match the value type. For instance, for a JSON array, the @a ReferenceType must be @ref array_t&.
json.exception.type_error.304 | cannot use at() with string | The @ref at() member functions can only be executed for certain JSON types.
json.exception.type_error.305 | cannot use operator[] with string | The @ref operator[] member functions can only be executed for certain JSON types.
json.exception.type_error.306 | cannot use value() with string | The @ref value() member functions can only be executed for certain JSON types.
json.exception.type_error.307 | cannot use erase() with string | The @ref erase() member functions can only be executed for certain JSON types.
json.exception.type_error.308 | cannot use push_back() with string | The @ref push_back() and @ref operator+= member functions can only be executed for certain JSON types.
json.exception.type_error.309 | cannot use insert() with | The @ref insert() member functions can only be executed for certain JSON types.
json.exception.type_error.310 | cannot use swap() with number | The @ref swap() member functions can only be executed for certain JSON types.
json.exception.type_error.311 | cannot use emplace_back() with string | The @ref emplace_back() member function can only be executed for certain JSON types.
json.exception.type_error.312 | cannot use update() with string | The @ref update() member functions can only be executed for certain JSON types.
json.exception.type_error.313 | invalid value to unflatten | The @ref unflatten function converts an object whose keys are JSON Pointers back into an arbitrary nested JSON value. The JSON Pointers must not overlap, because then the resulting value would not be well defined.
json.exception.type_error.314 | only objects can be unflattened | The @ref unflatten function only works for an object whose keys are JSON Pointers.
json.exception.type_error.315 | values in object must be primitive | The @ref unflatten function only works for an object whose keys are JSON Pointers and whose values are primitive.
@liveexample{The following code shows how a `type_error` exception can be
caught.,type_error}
@sa @ref exception for the base class of the library exceptions
@sa @ref parse_error for exceptions indicating a parse error
@sa @ref invalid_iterator for exceptions indicating errors with iterators
@sa @ref out_of_range for exceptions indicating access out of the defined range
@sa @ref other_error for exceptions indicating other library errors
@since version 3.0.0
*/
class type_error : public exception
{
public:
static type_error create(int id_, const std::string& what_arg)
{
std::string w = exception::name("type_error", id_) + what_arg;
return type_error(id_, w.c_str());
}
private:
type_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
};
/*!
@brief exception indicating access out of the defined range
This exception is thrown in case a library function is called on an input
parameter that exceeds the expected range, for instance in case of array
indices or nonexisting object keys.
Exceptions have ids 4xx.
name / id | example message | description
------------------------------- | --------------- | -------------------------
json.exception.out_of_range.401 | array index 3 is out of range | The provided array index @a i is larger than @a size-1.
json.exception.out_of_range.402 | array index '-' (3) is out of range | The special array index `-` in a JSON Pointer never describes a valid element of the array, but the index past the end. That is, it can only be used to add elements at this position, but not to read it.
json.exception.out_of_range.403 | key 'foo' not found | The provided key was not found in the JSON object.
json.exception.out_of_range.404 | unresolved reference token 'foo' | A reference token in a JSON Pointer could not be resolved.
json.exception.out_of_range.405 | JSON pointer has no parent | The JSON Patch operations 'remove' and 'add' can not be applied to the root element of the JSON value.
json.exception.out_of_range.406 | number overflow parsing '10E1000' | A parsed number could not be stored as without changing it to NaN or INF.
@liveexample{The following code shows how an `out_of_range` exception can be
caught.,out_of_range}
@sa @ref exception for the base class of the library exceptions
@sa @ref parse_error for exceptions indicating a parse error
@sa @ref invalid_iterator for exceptions indicating errors with iterators
@sa @ref type_error for exceptions indicating executing a member function with
a wrong type
@sa @ref other_error for exceptions indicating other library errors
@since version 3.0.0
*/
class out_of_range : public exception
{
public:
static out_of_range create(int id_, const std::string& what_arg)
{
std::string w = exception::name("out_of_range", id_) + what_arg;
return out_of_range(id_, w.c_str());
}
private:
out_of_range(int id_, const char* what_arg) : exception(id_, what_arg) {}
};
/*!
@brief exception indicating other library errors
This exception is thrown in case of errors that cannot be classified with the
other exception types.
Exceptions have ids 5xx.
name / id | example message | description
------------------------------ | --------------- | -------------------------
json.exception.other_error.501 | unsuccessful: {"op":"test","path":"/baz", "value":"bar"} | A JSON Patch operation 'test' failed. The unsuccessful operation is also printed.
json.exception.other_error.502 | invalid object size for conversion | Some conversions to user-defined types impose constraints on the object size (e.g. std::pair)
@sa @ref exception for the base class of the library exceptions
@sa @ref parse_error for exceptions indicating a parse error
@sa @ref invalid_iterator for exceptions indicating errors with iterators
@sa @ref type_error for exceptions indicating executing a member function with
a wrong type
@sa @ref out_of_range for exceptions indicating access out of the defined range
@liveexample{The following code shows how an `other_error` exception can be
caught.,other_error}
@since version 3.0.0
*/
class other_error : public exception
{
public:
static other_error create(int id_, const std::string& what_arg)
{
std::string w = exception::name("other_error", id_) + what_arg;
return other_error(id_, w.c_str());
}
private:
other_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
};
///////////////////////////
// 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 basic_json::is_null(),
@ref basic_json::is_object(), @ref basic_json::is_array(),
@ref basic_json::is_string(), @ref basic_json::is_boolean(),
@ref basic_json::is_number() (with @ref basic_json::is_number_integer(),
@ref basic_json::is_number_unsigned(), and @ref basic_json::is_number_float()),
@ref basic_json::is_discarded(), @ref basic_json::is_primitive(), and
@ref basic_json::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 basic_json::number_unsigned_t is used for unsigned integers,
@ref basic_json::number_integer_t is used for signed integers, and
@ref basic_json::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::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
};
/*!
@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
@since version 1.0.0
*/
inline bool operator<(const value_t lhs, const value_t rhs) noexcept
{
static constexpr std::array<uint8_t, 8> order = {{
0, // null
3, // object
4, // array
5, // string
1, // boolean
2, // integer
2, // unsigned
2, // float
}
};
// discarded values are not comparable
return lhs != value_t::discarded and rhs != value_t::discarded and
order[static_cast<std::size_t>(lhs)] < order[static_cast<std::size_t>(rhs)];
}
/////////////
// helpers //
/////////////
template<typename> struct is_basic_json : std::false_type {};
NLOHMANN_BASIC_JSON_TPL_DECLARATION
struct is_basic_json<NLOHMANN_BASIC_JSON_TPL> : std::true_type {};
// alias templates to reduce boilerplate
template<bool B, typename T = void>
using enable_if_t = typename std::enable_if<B, T>::type;
template<typename T>
using uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
// implementation of C++14 index_sequence and affiliates
// source: https://stackoverflow.com/a/32223343
template<std::size_t... Ints>
struct index_sequence
{
using type = index_sequence;
using value_type = std::size_t;
static constexpr std::size_t size() noexcept
{
return sizeof...(Ints);
}
};
template<class Sequence1, class Sequence2>
struct merge_and_renumber;
template<std::size_t... I1, std::size_t... I2>
struct merge_and_renumber<index_sequence<I1...>, index_sequence<I2...>>
: index_sequence < I1..., (sizeof...(I1) + I2)... >
{};
template<std::size_t N>
struct make_index_sequence
: merge_and_renumber < typename make_index_sequence < N / 2 >::type,
typename make_index_sequence < N - N / 2 >::type >
{};
template<> struct make_index_sequence<0> : index_sequence<> { };
template<> struct make_index_sequence<1> : index_sequence<0> { };
template<typename... Ts>
using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
/*
Implementation of two C++17 constructs: conjunction, negation. This is needed
to avoid evaluating all the traits in a condition
For example: not std::is_same<void, T>::value and has_value_type<T>::value
will not compile when T = void (on MSVC at least). Whereas
conjunction<negation<std::is_same<void, T>>, has_value_type<T>>::value will
stop evaluating if negation<...>::value == false
Please note that those constructs must be used with caution, since symbols can
become very long quickly (which can slow down compilation and cause MSVC
internal compiler errors). Only use it when you have to (see example ahead).
*/
template<class...> struct conjunction : std::true_type {};
template<class B1> struct conjunction<B1> : B1 {};
template<class B1, class... Bn>
struct conjunction<B1, Bn...> : std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
template<class B> struct negation : std::integral_constant < bool, !B::value > {};
// dispatch utility (taken from ranges-v3)
template<unsigned N> struct priority_tag : priority_tag < N - 1 > {};
template<> struct priority_tag<0> {};
//////////////////
// constructors //
//////////////////
template<value_t> struct external_constructor;
template<>
struct external_constructor<value_t::boolean>
{
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::boolean_t b) noexcept
{
j.m_type = value_t::boolean;
j.m_value = b;
j.assert_invariant();
}
};
template<>
struct external_constructor<value_t::string>
{
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const typename BasicJsonType::string_t& s)
{
j.m_type = value_t::string;
j.m_value = s;
j.assert_invariant();
}
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::string_t&& s)
{
j.m_type = value_t::string;
j.m_value = std::move(s);
j.assert_invariant();
}
};
template<>
struct external_constructor<value_t::number_float>
{
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::number_float_t val) noexcept
{
j.m_type = value_t::number_float;
j.m_value = val;
j.assert_invariant();
}
};
template<>
struct external_constructor<value_t::number_unsigned>
{
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::number_unsigned_t val) noexcept
{
j.m_type = value_t::number_unsigned;
j.m_value = val;
j.assert_invariant();
}
};
template<>
struct external_constructor<value_t::number_integer>
{
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::number_integer_t val) noexcept
{
j.m_type = value_t::number_integer;
j.m_value = val;
j.assert_invariant();
}
};
template<>
struct external_constructor<value_t::array>
{
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const typename BasicJsonType::array_t& arr)
{
j.m_type = value_t::array;
j.m_value = arr;
j.assert_invariant();
}
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::array_t&& arr)
{
j.m_type = value_t::array;
j.m_value = std::move(arr);
j.assert_invariant();
}
template<typename BasicJsonType, typename CompatibleArrayType,
enable_if_t<not std::is_same<CompatibleArrayType,
typename BasicJsonType::array_t>::value,
int> = 0>
static void construct(BasicJsonType& j, const CompatibleArrayType& arr)
{
using std::begin;
using std::end;
j.m_type = value_t::array;
j.m_value.array = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
j.assert_invariant();
}
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const std::vector<bool>& arr)
{
j.m_type = value_t::array;
j.m_value = value_t::array;
j.m_value.array->reserve(arr.size());
for (bool x : arr)
{
j.m_value.array->push_back(x);
}
j.assert_invariant();
}
template<typename BasicJsonType, typename T,
enable_if_t<std::is_convertible<T, BasicJsonType>::value, int> = 0>
static void construct(BasicJsonType& j, const std::valarray<T>& arr)
{
j.m_type = value_t::array;
j.m_value = value_t::array;
j.m_value.array->resize(arr.size());
std::copy(std::begin(arr), std::end(arr), j.m_value.array->begin());
j.assert_invariant();
}
};
template<>
struct external_constructor<value_t::object>
{
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const typename BasicJsonType::object_t& obj)
{
j.m_type = value_t::object;
j.m_value = obj;
j.assert_invariant();
}
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
{
j.m_type = value_t::object;
j.m_value = std::move(obj);
j.assert_invariant();
}
template<typename BasicJsonType, typename CompatibleObjectType,
enable_if_t<not std::is_same<CompatibleObjectType,
typename BasicJsonType::object_t>::value, int> = 0>
static void construct(BasicJsonType& j, const CompatibleObjectType& obj)
{
using std::begin;
using std::end;
j.m_type = value_t::object;
j.m_value.object = j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj));
j.assert_invariant();
}
};
////////////////////////
// has_/is_ functions //
////////////////////////
/*!
@brief Helper to determine whether there's a key_type for T.
This 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
*/
#define NLOHMANN_JSON_HAS_HELPER(type) \
template<typename T> struct has_##type { \
private: \
template<typename U, typename = typename U::type> \
static int detect(U &&); \
static void detect(...); \
public: \
static constexpr bool value = \
std::is_integral<decltype(detect(std::declval<T>()))>::value; \
}
NLOHMANN_JSON_HAS_HELPER(mapped_type);
NLOHMANN_JSON_HAS_HELPER(key_type);
NLOHMANN_JSON_HAS_HELPER(value_type);
NLOHMANN_JSON_HAS_HELPER(iterator);
#undef NLOHMANN_JSON_HAS_HELPER
template<bool B, class RealType, class CompatibleObjectType>
struct is_compatible_object_type_impl : std::false_type {};
template<class RealType, class CompatibleObjectType>
struct is_compatible_object_type_impl<true, RealType, CompatibleObjectType>
{
static constexpr auto value =
std::is_constructible<typename RealType::key_type, typename CompatibleObjectType::key_type>::value and
std::is_constructible<typename RealType::mapped_type, typename CompatibleObjectType::mapped_type>::value;
};
template<class BasicJsonType, class CompatibleObjectType>
struct is_compatible_object_type
{
static auto constexpr value = is_compatible_object_type_impl <
conjunction<negation<std::is_same<void, CompatibleObjectType>>,
has_mapped_type<CompatibleObjectType>,
has_key_type<CompatibleObjectType>>::value,
typename BasicJsonType::object_t, CompatibleObjectType >::value;
};
template<typename BasicJsonType, typename T>
struct is_basic_json_nested_type
{
static auto constexpr value = std::is_same<T, typename BasicJsonType::iterator>::value or
std::is_same<T, typename BasicJsonType::const_iterator>::value or
std::is_same<T, typename BasicJsonType::reverse_iterator>::value or
std::is_same<T, typename BasicJsonType::const_reverse_iterator>::value;
};
template<class BasicJsonType, class CompatibleArrayType>
struct is_compatible_array_type
{
static auto constexpr value =
conjunction<negation<std::is_same<void, CompatibleArrayType>>,
negation<is_compatible_object_type<
BasicJsonType, CompatibleArrayType>>,
negation<std::is_constructible<typename BasicJsonType::string_t,
CompatibleArrayType>>,
negation<is_basic_json_nested_type<BasicJsonType, CompatibleArrayType>>,
has_value_type<CompatibleArrayType>,
has_iterator<CompatibleArrayType>>::value;
};
template<bool, typename, typename>
struct is_compatible_integer_type_impl : std::false_type {};
template<typename RealIntegerType, typename CompatibleNumberIntegerType>
struct is_compatible_integer_type_impl<true, RealIntegerType, CompatibleNumberIntegerType>
{
// is there an assert somewhere on overflows?
using RealLimits = std::numeric_limits<RealIntegerType>;
using CompatibleLimits = std::numeric_limits<CompatibleNumberIntegerType>;
static constexpr auto value =
std::is_constructible<RealIntegerType, CompatibleNumberIntegerType>::value and
CompatibleLimits::is_integer and
RealLimits::is_signed == CompatibleLimits::is_signed;
};
template<typename RealIntegerType, typename CompatibleNumberIntegerType>
struct is_compatible_integer_type
{
static constexpr auto value =
is_compatible_integer_type_impl <
std::is_integral<CompatibleNumberIntegerType>::value and
not std::is_same<bool, CompatibleNumberIntegerType>::value,
RealIntegerType, CompatibleNumberIntegerType > ::value;
};
// trait checking if JSONSerializer<T>::from_json(json const&, udt&) exists
template<typename BasicJsonType, typename T>
struct has_from_json
{
private:
// also check the return type of from_json
template<typename U, typename = enable_if_t<std::is_same<void, decltype(uncvref_t<U>::from_json(
std::declval<BasicJsonType>(), std::declval<T&>()))>::value>>
static int detect(U&&);
static void detect(...);
public:
static constexpr bool value = std::is_integral<decltype(
detect(std::declval<typename BasicJsonType::template json_serializer<T, void>>()))>::value;
};
// This trait checks if JSONSerializer<T>::from_json(json const&) exists
// this overload is used for non-default-constructible user-defined-types
template<typename BasicJsonType, typename T>
struct has_non_default_from_json
{
private:
template <
typename U,
typename = enable_if_t<std::is_same<
T, decltype(uncvref_t<U>::from_json(std::declval<BasicJsonType>()))>::value >>
static int detect(U&&);
static void detect(...);
public:
static constexpr bool value = std::is_integral<decltype(detect(
std::declval<typename BasicJsonType::template json_serializer<T, void>>()))>::value;
};
// This trait checks if BasicJsonType::json_serializer<T>::to_json exists
template<typename BasicJsonType, typename T>
struct has_to_json
{
private:
template<typename U, typename = decltype(uncvref_t<U>::to_json(
std::declval<BasicJsonType&>(), std::declval<T>()))>
static int detect(U&&);
static void detect(...);
public:
static constexpr bool value = std::is_integral<decltype(detect(
std::declval<typename BasicJsonType::template json_serializer<T, void>>()))>::value;
};
/////////////
// to_json //
/////////////
template<typename BasicJsonType, typename T, enable_if_t<
std::is_same<T, typename BasicJsonType::boolean_t>::value, int> = 0>
void to_json(BasicJsonType& j, T b) noexcept
{
external_constructor<value_t::boolean>::construct(j, b);
}
template<typename BasicJsonType, typename CompatibleString,
enable_if_t<std::is_constructible<typename BasicJsonType::string_t,
CompatibleString>::value, int> = 0>
void to_json(BasicJsonType& j, const CompatibleString& s)
{
external_constructor<value_t::string>::construct(j, s);
}
template <typename BasicJsonType>
void to_json(BasicJsonType& j, typename BasicJsonType::string_t&& s)
{
external_constructor<value_t::string>::construct(j, std::move(s));
}
template<typename BasicJsonType, typename FloatType,
enable_if_t<std::is_floating_point<FloatType>::value, int> = 0>
void to_json(BasicJsonType& j, FloatType val) noexcept
{
external_constructor<value_t::number_float>::construct(j, static_cast<typename BasicJsonType::number_float_t>(val));
}
template <
typename BasicJsonType, typename CompatibleNumberUnsignedType,
enable_if_t<is_compatible_integer_type<typename BasicJsonType::number_unsigned_t,
CompatibleNumberUnsignedType>::value, int> = 0 >
void to_json(BasicJsonType& j, CompatibleNumberUnsignedType val) noexcept
{
external_constructor<value_t::number_unsigned>::construct(j, static_cast<typename BasicJsonType::number_unsigned_t>(val));
}
template <
typename BasicJsonType, typename CompatibleNumberIntegerType,
enable_if_t<is_compatible_integer_type<typename BasicJsonType::number_integer_t,
CompatibleNumberIntegerType>::value, int> = 0 >
void to_json(BasicJsonType& j, CompatibleNumberIntegerType val) noexcept
{
external_constructor<value_t::number_integer>::construct(j, static_cast<typename BasicJsonType::number_integer_t>(val));
}
template<typename BasicJsonType, typename EnumType,
enable_if_t<std::is_enum<EnumType>::value, int> = 0>
void to_json(BasicJsonType& j, EnumType e) noexcept
{
using underlying_type = typename std::underlying_type<EnumType>::type;
external_constructor<value_t::number_integer>::construct(j, static_cast<underlying_type>(e));
}