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/*----------------------------------------------------------------------------*/
/* Modifications Copyright (c) FIRST 2017. All Rights Reserved. */
/* Open Source Software - may be modified and shared by FRC teams. The code */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project. */
/*----------------------------------------------------------------------------*/
/*
__ _____ _____ _____
__ | | __ | | | | 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 WPI_SUPPORT_JSON_H_
# define WPI_SUPPORT_JSON_H_
# include <cassert> // assert
# 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 <functional> // function, hash, less
# include <initializer_list> // initializer_list
# include <iterator> // advance, begin, back_inserter, bidirectional_iterator_tag, distance, end, inserter, iterator, iterator_traits, next, random_access_iterator_tag
# include <limits> // numeric_limits
# include <memory> // addressof, allocator, allocator_traits, unique_ptr
# 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 <vector> // vector
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# include "wpi/ArrayRef.h"
# include "wpi/raw_ostream.h"
# include "wpi/StringMap.h"
# include "wpi/StringRef.h"
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// 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__)
# if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) < 40800
# 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"
# pragma GCC diagnostic ignored "-Wtype-limits"
# endif
// disable documentation warnings on clang
# if defined(__clang__)
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wdocumentation"
# pragma GCC diagnostic ignored "-Wtautological-constant-out-of-range-compare"
# endif
// allow to disable exceptions
# if (defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)) && !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
namespace wpi
{
class raw_istream ;
/*!
@ brief unnamed namespace with internal helper functions
This namespace collects some functions that could not be defined inside the
@ ref json class .
@ since version 2.1 .0
*/
namespace detail
{
////////////////
// exceptions //
////////////////
/*!
@ brief general exception of the @ ref json class
Extension of std : : exception objects with a member @ a id for exception ids .
@ 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 .
@ since version 3.0 .0
*/
class exception : public std : : exception
{
public :
/// returns the explanatory string
virtual 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 ) ;
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 as well as when
using JSON Patch .
Member @ a byte holds 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 ) .
Exceptions have ids 1 xx .
name / id | example massage | 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 .111 | parse error : bad input stream | Parsing CBOR or MessagePack from an input stream where the [ ` badbit ` or ` failbit ` ] ( http : //en.cppreference.com/w/cpp/io/ios_base/iostate) is set.
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 .
@ 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 occured ( 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 , size_t byte_ , const std : : string & what_arg ) ;
/*!
@ 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 size_t byte ;
private :
parse_error ( int id_ , size_t byte_ , const char * what_arg )
: exception ( id_ , what_arg ) , byte ( byte_ )
{ }
} ;
/*!
@ brief exception indicating errors with iterators
Exceptions have ids 2 xx .
name / id | example massage | description
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - | - - - - - - - - - - - - - - - | - - - - - - - - - - - - - - - - - - - - - - - - -
json . exception . invalid_iterator .201 | iterators are not compatible | The iterators passed to constructor @ ref 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 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 compated , 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 ( ) .
@ since version 3.0 .0
*/
class invalid_iterator : public exception
{
public :
static invalid_iterator create ( int id , const std : : string & what_arg ) ;
private :
invalid_iterator ( int id_ , const char * what_arg )
: exception ( id_ , what_arg )
{ }
} ;
/*!
@ brief exception indicating executing a member function with a wrong type
Exceptions have ids 3 xx .
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 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 .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 .
@ since version 3.0 .0
*/
class type_error : public exception
{
public :
static type_error create ( int id , const std : : string & what_arg ) ;
private :
type_error ( int id_ , const char * what_arg )
: exception ( id_ , what_arg )
{ }
} ;
/*!
@ brief exception indicating access out of the defined range
Exceptions have ids 4 xx .
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 .
@ since version 3.0 .0
*/
class out_of_range : public exception
{
public :
static out_of_range create ( int id , const std : : string & what_arg ) ;
private :
out_of_range ( int id_ , const char * what_arg )
: exception ( id_ , what_arg )
{ }
} ;
/*!
@ brief exception indicating other errors
Exceptions have ids 5 xx .
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 )
@ since version 3.0 .0
*/
class other_error : public exception
{
public :
static other_error create ( int id , const std : : string & what_arg ) ;
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 json : : is_null ( ) ,
@ ref json : : is_object ( ) , @ ref json : : is_array ( ) ,
@ ref json : : is_string ( ) , @ ref json : : is_boolean ( ) ,
@ ref json : : is_number ( ) ( with @ ref json : : is_number_integer ( ) ,
@ ref json : : is_number_unsigned ( ) , and @ ref json : : is_number_float ( ) ) ,
@ ref json : : is_discarded ( ) , @ ref json : : is_primitive ( ) , and
@ ref 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 :
std : : uint64_t is used for unsigned integers ,
std : : int64_t is used for signed integers , and
double is used for floating - point numbers or to
approximate integers which do not fit in the limits of their respective type .
@ sa @ ref json : : 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 uint8_t order [ ] = {
0 , // null
3 , // object
4 , // array
5 , // string
1 , // boolean
2 , // integer
2 , // unsigned
2 , // float
} ;
// discarded values are not comparable
if ( lhs = = value_t : : discarded | | rhs = = value_t : : discarded )
{
return false ;
}
return order [ static_cast < std : : size_t > ( lhs ) ] <
order [ static_cast < std : : size_t > ( rhs ) ] ;
}
/////////////
// helpers //
/////////////
// 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 two C + + 17 constructs : conjunction , negation . This is needed
to avoid evaluating all the traits in a condition
For example : ! std : : is_same < void , T > : : value & & 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 , bool 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 >
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static void construct ( BasicJsonType & j , StringRef s )
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{
j . m_type = value_t : : string ;
j . m_value = s ;
j . assert_invariant ( ) ;
}
} ;
template < >
struct external_constructor < value_t : : number_float >
{
template < typename BasicJsonType >
static void construct ( BasicJsonType & j , double 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 , std : : uint64_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 , std : : int64_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 , typename T >
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static void construct ( BasicJsonType & j , ArrayRef < T > arr )
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{
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 , typename CompatibleArrayType ,
enable_if_t < ! 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 < >
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 , typename CompatibleObjectType ,
enable_if_t < ! std : : is_same < CompatibleObjectType ,
typename BasicJsonType : : object_t > : : value ,
int > = 0 >
static void construct ( BasicJsonType & j , const CompatibleObjectType & obj )
{
j . m_type = value_t : : object ;
j . m_value = value_t : : object ;
for ( const auto & x : obj )
{
j . m_value . object - > emplace_second ( x . first , x . second ) ;
}
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 WPI_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 ; \
}
WPI_JSON_HAS_HELPER ( mapped_type ) ;
WPI_JSON_HAS_HELPER ( key_type ) ;
WPI_JSON_HAS_HELPER ( value_type ) ;
WPI_JSON_HAS_HELPER ( iterator ) ;
# undef WPI_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 =
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std : : is_constructible < StringRef ,
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typename CompatibleObjectType : : key_type > : : value & &
std : : is_constructible < typename RealType : : mapped_type ,
typename CompatibleObjectType : : mapped_type > : : value ;
} ;
template < typename 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_json_nested_type
{
static auto constexpr value = std : : is_same < T , typename BasicJsonType : : iterator > : : value | |
std : : is_same < T , typename BasicJsonType : : const_iterator > : : value | |
std : : is_same < T , typename BasicJsonType : : json_pointer > : : value ;
} ;
template < typename 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 > > ,
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negation < std : : is_constructible < StringRef , CompatibleArrayType > > ,
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negation < is_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 & &
CompatibleLimits : : is_integer & &
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 & &
! std : : is_same < bool , CompatibleNumberIntegerType > : : value ,
RealIntegerType , CompatibleNumberIntegerType > : : value ;
} ;
/////////////
// to_json //
/////////////
template < typename BasicJsonType , typename T , enable_if_t <
std : : is_same < T , bool > : : value , int > = 0 >
inline
void to_json ( BasicJsonType & j , T b ) noexcept
{
detail : : external_constructor < value_t : : boolean > : : construct ( j , b ) ;
}
template < typename BasicJsonType , typename CompatibleString ,
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enable_if_t < std : : is_constructible < StringRef ,
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CompatibleString > : : value , int > = 0 >
inline
void to_json ( BasicJsonType & j , const CompatibleString & s )
{
external_constructor < value_t : : string > : : construct ( j , s ) ;
}
template < typename BasicJsonType , typename FloatType ,
enable_if_t < std : : is_floating_point < FloatType > : : value , int > = 0 >
inline
void to_json ( BasicJsonType & j , FloatType val ) noexcept
{
external_constructor < value_t : : number_float > : : construct ( j , static_cast < double > ( val ) ) ;
}
template <
typename BasicJsonType , typename CompatibleNumberUnsignedType ,
enable_if_t < is_compatible_integer_type < std : : uint64_t ,
CompatibleNumberUnsignedType > : : value , int > = 0 >
inline
void to_json ( BasicJsonType & j , CompatibleNumberUnsignedType val ) noexcept
{
external_constructor < value_t : : number_unsigned > : : construct ( j , static_cast < std : : uint64_t > ( val ) ) ;
}
template <
typename BasicJsonType , typename CompatibleNumberIntegerType ,
enable_if_t < is_compatible_integer_type < std : : int64_t ,
CompatibleNumberIntegerType > : : value , int > = 0 >
inline
void to_json ( BasicJsonType & j , CompatibleNumberIntegerType val ) noexcept
{
external_constructor < value_t : : number_integer > : : construct ( j , static_cast < std : : int64_t > ( val ) ) ;
}
template < typename BasicJsonType , typename EnumType ,
enable_if_t < std : : is_enum < EnumType > : : value , int > = 0 >
inline
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 ) ) ;
}
template < typename BasicJsonType >
inline
void to_json ( BasicJsonType & j , const std : : vector < bool > & e )
{
external_constructor < value_t : : array > : : construct ( j , e ) ;
}
template < typename BasicJsonType , typename T >
inline
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void to_json ( BasicJsonType & j , ArrayRef < T > arr )
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{
external_constructor < value_t : : array > : : construct ( j , arr ) ;
}
template <
typename BasicJsonType , typename CompatibleArrayType ,
enable_if_t <
is_compatible_array_type < BasicJsonType , CompatibleArrayType > : : value | |
std : : is_same < typename BasicJsonType : : array_t , CompatibleArrayType > : : value ,
int > = 0 >
inline
void to_json ( BasicJsonType & j , const CompatibleArrayType & arr )
{
external_constructor < value_t : : array > : : construct ( j , arr ) ;
}
template <
typename BasicJsonType , typename CompatibleObjectType ,
enable_if_t < is_compatible_object_type < BasicJsonType , CompatibleObjectType > : : value ,
int > = 0 >
inline
void to_json ( BasicJsonType & j , const CompatibleObjectType & arr )
{
external_constructor < value_t : : object > : : construct ( j , arr ) ;
}
template < typename BasicJsonType , typename T , std : : size_t N ,
enable_if_t < ! std : : is_constructible <
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StringRef , T ( & ) [ N ] > : : value ,
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int > = 0 >
inline
void to_json ( BasicJsonType & j , T ( & arr ) [ N ] )
{
external_constructor < value_t : : array > : : construct ( j , arr ) ;
}
template < typename BasicJsonType , typename CompatibleString , typename T ,
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enable_if_t < std : : is_constructible < StringRef ,
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CompatibleString > : : value , int > = 0 >
inline
void to_json ( BasicJsonType & j , std : : pair < CompatibleString , T > const & p )
{
j [ p . first ] = p . second ;
}
///////////////
// from_json //
///////////////
// overloads for json template parameters
template < typename BasicJsonType , typename ArithmeticType ,
enable_if_t < std : : is_arithmetic < ArithmeticType > : : value & &
! std : : is_same < ArithmeticType , bool > : : value ,
int > = 0 >
void get_arithmetic_value ( const BasicJsonType & j , ArithmeticType & val )
{
switch ( static_cast < value_t > ( j ) )
{
case value_t : : number_unsigned :
{
val = static_cast < ArithmeticType > (
* j . template get_ptr < const std : : uint64_t * > ( ) ) ;
break ;
}
case value_t : : number_integer :
{
val = static_cast < ArithmeticType > (
* j . template get_ptr < const std : : int64_t * > ( ) ) ;
break ;
}
case value_t : : number_float :
{
val = static_cast < ArithmeticType > (
* j . template get_ptr < const double * > ( ) ) ;
break ;
}
default :
{
JSON_THROW ( type_error : : create ( 302 , " type must be number, but is " + j . type_name ( ) ) ) ;
}
}
}
template < typename BasicJsonType >
inline
void from_json ( const BasicJsonType & j , bool & b )
{
if ( ! j . is_boolean ( ) )
{
JSON_THROW ( type_error : : create ( 302 , " type must be boolean, but is " + j . type_name ( ) ) ) ;
}
b = * j . template get_ptr < const bool * > ( ) ;
}
template < typename BasicJsonType >
inline
void from_json ( const BasicJsonType & j , std : : string & s )
{
if ( ! j . is_string ( ) )
{
JSON_THROW ( detail : : type_error : : create ( 302 , " type must be string, but is " + j . type_name ( ) ) ) ;
}
s = * j . template get_ptr < const std : : string * > ( ) ;
}
template < typename BasicJsonType >
inline
void from_json ( const BasicJsonType & j , double & val )
{
get_arithmetic_value ( j , val ) ;
}
template < typename BasicJsonType >
inline
void from_json ( const BasicJsonType & j , std : : uint64_t & val )
{
get_arithmetic_value ( j , val ) ;
}
template < typename BasicJsonType >
inline
void from_json ( const BasicJsonType & j , std : : int64_t & val )
{
get_arithmetic_value ( j , val ) ;
}
template < typename BasicJsonType , typename EnumType ,
enable_if_t < std : : is_enum < EnumType > : : value , int > = 0 >
inline
void from_json ( const BasicJsonType & j , EnumType & e )
{
typename std : : underlying_type < EnumType > : : type val ;
get_arithmetic_value ( j , val ) ;
e = static_cast < EnumType > ( val ) ;
}
template < typename BasicJsonType >
inline
void from_json ( const BasicJsonType & j , typename BasicJsonType : : array_t & arr )
{
if ( ! j . is_array ( ) )
{
JSON_THROW ( type_error : : create ( 302 , " type must be array, but is " + j . type_name ( ) ) ) ;
}
arr = * j . template get_ptr < const typename BasicJsonType : : array_t * > ( ) ;
}
template < typename BasicJsonType , typename CompatibleArrayType >
void from_json_array_impl ( const BasicJsonType & j , CompatibleArrayType & arr , detail : : priority_tag < 0 > )
{
using std : : begin ;
using std : : end ;
std : : transform ( j . begin ( ) , j . end ( ) ,
std : : inserter ( arr , end ( arr ) ) , [ ] ( const BasicJsonType & i )
{
// get<BasicJsonType>() returns *this, this won't call a from_json
// method when value_type is BasicJsonType
return i . template get < typename CompatibleArrayType : : value_type > ( ) ;
} ) ;
}
template < typename BasicJsonType , typename CompatibleArrayType >
auto from_json_array_impl ( const BasicJsonType & j , CompatibleArrayType & arr , detail : : priority_tag < 1 > )
- > decltype (
arr . reserve ( std : : declval < typename CompatibleArrayType : : size_type > ( ) ) ,
void ( ) )
{
using std : : begin ;
using std : : end ;
arr . reserve ( j . size ( ) ) ;
std : : transform ( j . begin ( ) , j . end ( ) ,
std : : inserter ( arr , end ( arr ) ) , [ ] ( const BasicJsonType & i )
{
// get<BasicJsonType>() returns *this, this won't call a from_json
// method when value_type is BasicJsonType
return i . template get < typename CompatibleArrayType : : value_type > ( ) ;
} ) ;
}
template < typename BasicJsonType , typename CompatibleArrayType ,
enable_if_t < is_compatible_array_type < BasicJsonType , CompatibleArrayType > : : value & &
std : : is_convertible < BasicJsonType , typename CompatibleArrayType : : value_type > : : value & &
! std : : is_same < typename BasicJsonType : : array_t , CompatibleArrayType > : : value , int > = 0 >
void from_json ( const BasicJsonType & j , CompatibleArrayType & arr )
{
if ( ! j . is_array ( ) )
{
JSON_THROW ( type_error : : create ( 302 , " type must be array, but is " + j . type_name ( ) ) ) ;
}
from_json_array_impl ( j , arr , priority_tag < 1 > { } ) ;
}
template < typename BasicJsonType >
inline
void from_json ( const BasicJsonType & j , typename BasicJsonType : : object_t & obj )
{
if ( ! j . is_object ( ) )
{
JSON_THROW ( type_error : : create ( 302 , " type must be object, but is " + j . type_name ( ) ) ) ;
}
auto inner_object = j . template get_ptr < const typename BasicJsonType : : object_t * > ( ) ;
for ( const auto & i : * inner_object ) {
obj . emplace_second ( i . first ( ) , i . second ) ;
}
}
template < typename BasicJsonType , typename CompatibleObjectType ,
enable_if_t < is_compatible_object_type < BasicJsonType , CompatibleObjectType > : : value & &
! std : : is_same < typename BasicJsonType : : object_t , CompatibleObjectType > : : value , int > = 0 >
void from_json ( const BasicJsonType & j , CompatibleObjectType & obj )
{
if ( ! j . is_object ( ) )
{
JSON_THROW ( type_error : : create ( 302 , " type must be object, but is " + j . type_name ( ) ) ) ;
}
auto inner_object = j . template get_ptr < const typename BasicJsonType : : object_t * > ( ) ;
using std : : begin ;
using std : : end ;
using value_type = typename CompatibleObjectType : : value_type ;
std : : vector < value_type > v ;
v . reserve ( j . size ( ) ) ;
for ( const auto & p : * inner_object )
{
v . emplace_back (
p . first ( ) ,
p . second
. template get < typename CompatibleObjectType : : mapped_type > ( ) ) ;
}
// we could avoid the assignment, but this might require a for loop, which
// might be less efficient than the container constructor for some
// containers (would it?)
obj = CompatibleObjectType ( std : : make_move_iterator ( begin ( v ) ) ,
std : : make_move_iterator ( end ( v ) ) ) ;
}
// overload for arithmetic types, not chosen for json template arguments;
template < typename BasicJsonType , typename ArithmeticType ,
enable_if_t <
std : : is_arithmetic < ArithmeticType > : : value & &
! std : : is_same < ArithmeticType , std : : uint64_t > : : value & &
! std : : is_same < ArithmeticType , std : : int64_t > : : value & &
! std : : is_same < ArithmeticType , double > : : value & &
! std : : is_same < ArithmeticType , bool > : : value ,
int > = 0 >
void from_json ( const BasicJsonType & j , ArithmeticType & val )
{
switch ( static_cast < value_t > ( j ) )
{
case value_t : : number_unsigned :
{
val = static_cast < ArithmeticType > ( * j . template get_ptr < const std : : uint64_t * > ( ) ) ;
break ;
}
case value_t : : number_integer :
{
val = static_cast < ArithmeticType > ( * j . template get_ptr < const std : : int64_t * > ( ) ) ;
break ;
}
case value_t : : number_float :
{
val = static_cast < ArithmeticType > ( * j . template get_ptr < const double * > ( ) ) ;
break ;
}
case value_t : : boolean :
{
val = static_cast < ArithmeticType > ( * j . template get_ptr < const bool * > ( ) ) ;
break ;
}
default :
{
JSON_THROW ( type_error : : create ( 302 , " type must be number, but is " + j . type_name ( ) ) ) ;
}
}
}
template < typename BasicJsonType , typename CompatibleString , typename T ,
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enable_if_t < std : : is_constructible < StringRef ,
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CompatibleString > : : value , int > = 0 >
void from_json ( const BasicJsonType & j , std : : pair < CompatibleString , T > & p )
{
if ( ! j . is_object ( ) )
{
JSON_THROW ( type_error : : create ( 302 , " type must be object, but is " + j . type_name ( ) ) ) ;
}
auto const inner_object = j . template get_ptr < const typename BasicJsonType : : object_t * > ( ) ;
auto const size = inner_object - > size ( ) ;
if ( size ! = 1 )
{
JSON_THROW ( other_error : : create ( 502 , " conversion to std::pair requires the object to have exactly one field, but it has " + std : : to_string ( size ) ) ) ;
}
auto const & obj = * inner_object - > begin ( ) ;
// cannot use *inner_object, need to convert both members
p = std : : make_pair ( CompatibleString ( obj . first ( ) ) , obj . second . template get < T > ( ) ) ;
}
struct to_json_fn
{
private :
template < typename BasicJsonType , typename T >
auto call ( BasicJsonType & j , T & & val , priority_tag < 1 > ) const noexcept ( noexcept ( to_json ( j , std : : forward < T > ( val ) ) ) )
- > decltype ( to_json ( j , std : : forward < T > ( val ) ) , void ( ) )
{
return to_json ( j , std : : forward < T > ( val ) ) ;
}
template < typename BasicJsonType , typename T >
void call ( BasicJsonType & , T & & , priority_tag < 0 > ) const noexcept
{
static_assert ( sizeof ( BasicJsonType ) = = 0 ,
" could not find to_json() method in T's namespace " ) ;
}
public :
template < typename BasicJsonType , typename T >
void operator ( ) ( BasicJsonType & j , T & & val ) const
noexcept ( noexcept ( std : : declval < to_json_fn > ( ) . call ( j , std : : forward < T > ( val ) , priority_tag < 1 > { } ) ) )
{
return call ( j , std : : forward < T > ( val ) , priority_tag < 1 > { } ) ;
}
} ;
struct from_json_fn
{
private :
template < typename BasicJsonType , typename T >
auto call ( const BasicJsonType & j , T & val , priority_tag < 1 > ) const
noexcept ( noexcept ( from_json ( j , val ) ) )
- > decltype ( from_json ( j , val ) , void ( ) )
{
return from_json ( j , val ) ;
}
template < typename BasicJsonType , typename T >
void call ( const BasicJsonType & , T & , priority_tag < 0 > ) const noexcept
{
static_assert ( sizeof ( BasicJsonType ) = = 0 ,
" could not find from_json() method in T's namespace " ) ;
}
public :
template < typename BasicJsonType , typename T >
void operator ( ) ( const BasicJsonType & j , T & val ) const
noexcept ( noexcept ( std : : declval < from_json_fn > ( ) . call ( j , val , priority_tag < 1 > { } ) ) )
{
return call ( j , val , priority_tag < 1 > { } ) ;
}
} ;
// taken from ranges-v3
template < typename T >
struct static_const
{
static constexpr T value { } ;
} ;
template < typename T >
constexpr T static_const < T > : : value ;
} // namespace detail
/// namespace to hold default `to_json` / `from_json` functions
namespace
{
constexpr const auto & to_json = detail : : static_const < detail : : to_json_fn > : : value ;
constexpr const auto & from_json = detail : : static_const < detail : : from_json_fn > : : value ;
}
/*!
@ brief a class to store JSON values
@ 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 ( ) .
@ see [ RFC 7159 : The JavaScript Object Notation ( JSON ) Data Interchange
Format ] ( http : //rfc7159.net/rfc7159)
@ since version 1.0 .0
@ nosubgrouping
*/
class json
{
private :
template < detail : : value_t > friend struct detail : : external_constructor ;
friend class JsonTest ;
public :
using value_t = detail : : value_t ;
// forward declarations
template < typename U > class iter_impl ;
class json_pointer ;
class parser ;
class serializer ;
class binary_writer ;
////////////////
// exceptions //
////////////////
/// @name exceptions
/// Classes to implement user-defined exceptions.
/// @{
/// @copydoc detail::exception
using exception = detail : : exception ;
/// @copydoc detail::parse_error
using parse_error = detail : : parse_error ;
/// @copydoc detail::invalid_iterator
using invalid_iterator = detail : : invalid_iterator ;
/// @copydoc detail::type_error
using type_error = detail : : type_error ;
/// @copydoc detail::out_of_range
using out_of_range = detail : : out_of_range ;
/// @copydoc detail::other_error
using other_error = detail : : other_error ;
/// @}
/////////////////////
// container types //
/////////////////////
/// @name container types
/// The canonic container types to use @ref json like any other STL
/// container.
/// @{
/// the type of elements in a json container
using value_type = 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 type of an element pointer
using pointer = json * ;
/// the type of an element const pointer
using const_pointer = const json * ;
/// an iterator for a json container
using iterator = iter_impl < json > ;
/// a const iterator for a json container
using const_iterator = iter_impl < const json > ;
/// @}
/*!
@ brief returns version information on the library
This function returns a JSON object with information about the library ,
including the version number and information on the platform and compiler .
@ return JSON object holding version information
key | description
- - - - - - - - - - - | - - - - - - - - - - - - - - -
` compiler ` | Information on the used compiler . It is an object with the following keys : ` c + + ` ( the used C + + standard ) , ` family ` ( the compiler family ; possible values are ` clang ` , ` icc ` , ` gcc ` , ` ilecpp ` , ` msvc ` , ` pgcpp ` , ` sunpro ` , and ` unknown ` ) , and ` version ` ( the compiler version ) .
` copyright ` | The copyright line for the library as string .
` name ` | The name of the library as string .
` platform ` | The used platform as string . Possible values are ` win32 ` , ` linux ` , ` apple ` , ` unix ` , and ` unknown ` .
` url ` | The URL of the project as string .
` version ` | The version of the library . It is an object with the following keys : ` major ` , ` minor ` , and ` patch ` as defined by [ Semantic Versioning ] ( http : //semver.org), and `string` (the version string).
@ liveexample { The following code shows an example output of the ` meta ( ) `
function . , meta }
@ complexity Constant .
@ since 2.1 .0
*/
static json meta ( ) ;
///////////////////////////
// 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 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 .
# ### 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 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 .
*/
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using object_t = StringMap < json > ;
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/*!
@ 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 .
# ### Default type
The default value for @ a array_t is :
@ code { . cpp }
std : : vector <
json // value_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 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 = std : : vector < 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 .
# ### Default type
The default value for @ a string_t is :
@ code { . cpp }
std : : string
@ endcode
# ### Encoding
Strings are stored in UTF - 8 encoding . Therefore , functions like
` std : : string : : size ( ) ` or ` std : : string : : length ( ) ` return the number of
bytes in the string rather than the number of characters or glyphs .
# ### 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 \u005C b " ` 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 = std : : string ;
/*!
@ 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 ` .
# ### Default type
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 = bool ;
/*!
@ 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 .
# ### Default type
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 = int64_t ;
/*!
@ 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 .
# ### Default type
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 = uint64_t ;
/*!
@ 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 .
# ### Default type
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 = double ;
/// @}
private :
/// helper for exception-safe object creation
template < typename T , typename . . . Args >
static T * create ( Args & & . . . args )
{
std : : allocator < 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 ! = nullptr ) ;
return object . release ( ) ;
}
////////////////////////
// JSON value storage //
////////////////////////
public :
/*!
@ brief a JSON value
The actual storage for a JSON value of the @ ref 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 std : : string
boolean | boolean | bool
number | number_integer | std : : int64_t
number | number_unsigned | std : : uint64_t
number | number_float | double
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)
std : : string * string ;
/// boolean
bool boolean ;
/// number (integer)
std : : int64_t number_integer ;
/// number (unsigned integer)
std : : uint64_t number_unsigned ;
/// number (floating-point)
double number_float ;
/// default constructor (for null values)
json_value ( ) = default ;
/// constructor for booleans
json_value ( bool v ) noexcept : boolean ( v ) { }
/// constructor for numbers (integer)
json_value ( std : : int64_t v ) noexcept : number_integer ( v ) { }
/// constructor for numbers (unsigned)
json_value ( std : : uint64_t v ) noexcept : number_unsigned ( v ) { }
/// constructor for numbers (floating-point)
json_value ( double v ) noexcept : number_float ( v ) { }
/// constructor for empty values of a given type
json_value ( value_t t ) ;
/// constructor for strings
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json_value ( StringRef value ) ;
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json_value ( const std : : string & value ) ;
/// constructor for objects
json_value ( const object_t & value ) ;
/// constructor for arrays
json_value ( const array_t & value ) ;
} ;
private :
/*!
@ 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 | | m_value . object ! = nullptr ) ;
assert ( m_type ! = value_t : : array | | m_value . array ! = nullptr ) ;
assert ( m_type ! = value_t : : string | | 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
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influenced . When passed to @ ref parse ( raw_istream & , const
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parser_callback_t ) or @ ref parse ( const CharT , 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 .
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@ sa @ ref parse ( raw_istream & , parser_callback_t ) or
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@ ref parse ( const CharT , const parser_callback_t ) for examples
@ since version 1.0 .0
*/
using parser_callback_t = std : : function < bool ( int depth ,
parse_event_t event ,
json & parsed ) > ;
//////////////////
// constructors //
//////////////////
/// @name constructors and destructors
/// Constructors of class @ref 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 .
@ liveexample { The following code shows the constructor for different @ ref
value_t values , json__value_t }
@ since version 1.0 .0
*/
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 . , json__nullptr_t }
@ since version 1.0 .0
*/
json ( std : : nullptr_t = nullptr ) noexcept
: json ( value_t : : null )
{
assert_invariant ( ) ;
}
/*!
@ brief create a JSON value
This is a " catch all " constructor for all compatible JSON types ; that is ,
types for which a ` to_json ( ) ` method exsits . The constructor forwards the
parameter @ a val to that method ( to ` json_serializer < U > : : to_json ` method
with ` U = uncvref_t < CompatibleType > ` , to be exact ) .
Template type @ a CompatibleType includes , but is not limited to , the
following types :
- * * arrays * * : @ ref array_t and all kinds of compatible containers such as
` 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 json
value can be constructed .
- * * objects * * : @ ref object_t and all kinds of compatible associative
containers such as ` std : : map ` , ` std : : unordered_map ` , ` std : : multimap ` ,
and ` std : : unordered_multimap ` with a ` key_type ` compatible to
std : : string and a ` value_type ` from which a @ ref json value can
be constructed .
- * * strings * * : std : : string , string literals , and all compatible string
containers can be used .
- * * numbers * * : std : : int64_t , std : : uint64_t ,
double , and all convertible number types such as ` int ` ,
` size_t ` , ` int64_t ` , ` float ` or ` double ` can be used .
- * * boolean * * : ` bool ` can be used .
See the examples below .
@ tparam CompatibleType a type such that :
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- @ a CompatibleType is not derived from ` raw_istream ` ,
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- @ a CompatibleType is not @ ref json ( to avoid hijacking copy / move
constructors ) ,
- @ a CompatibleType is not a @ ref json nested type ( e . g . ,
@ ref json_pointer , @ ref iterator , etc . . . )
- @ ref @ ref json_serializer < U > has a
` to_json ( json & , CompatibleType & & ) ` method
@ tparam U = ` uncvref_t < CompatibleType > `
@ param [ in ] val the value to be forwarded
@ complexity Usually linear in the size of the passed @ a val , also
depending on the implementation of the called ` to_json ( ) `
method .
@ throw what ` json_serializer < U > : : to_json ( ) ` throws
@ liveexample { The following code shows the constructor with several
compatible types . , json__CompatibleType }
@ since version 2.1 .0
*/
template < typename CompatibleType , typename U = detail : : uncvref_t < CompatibleType > ,
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detail : : enable_if_t < ! std : : is_base_of < raw_istream , U > : : value & &
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! std : : is_same < U , json > : : value & &
! detail : : is_json_nested_type < json , U > : : value ,
int > = 0 >
json ( CompatibleType & & val )
{
to_json ( * this , std : : forward < CompatibleType > ( 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 < json > )
with an empty initializer list in this case
- arrays whose elements satisfy rule 2 : use @ ref
array ( std : : initializer_list < json > ) with the same initializer list
in this case
@ note When used without parentheses around an empty initializer list , @ ref
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 < json > ) and
@ ref object ( std : : initializer_list < 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 type_error .301 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 . In this case , the constructor could not
create an object . If @ a type_deduction would have be ` true ` , an array
would have been created . See @ ref object ( std : : initializer_list < json > )
for an example .
@ complexity Linear in the size of the initializer list @ a init .
@ liveexample { The example below shows how JSON values are created from
initializer lists . , json__list_init_t }
@ sa @ ref array ( std : : initializer_list < json > ) - - create a JSON array
value from an initializer list
@ sa @ ref object ( std : : initializer_list < json > ) - - create a JSON object
value from an initializer list
@ since version 1.0 .0
*/
json ( std : : initializer_list < json > init ,
bool type_deduction = true ,
value_t manual_type = value_t : : array ) ;
/*!
@ 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
json ( std : : initializer_list < 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 json ( std : : initializer_list < json > , bool , value_t ) - -
create a JSON value from an initializer list
@ sa @ ref object ( std : : initializer_list < json > ) - - create a JSON object
value from an initializer list
@ since version 1.0 .0
*/
static json array ( std : : initializer_list < json > init =
std : : initializer_list < json > ( ) )
{
return 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 < 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 json ( std : : initializer_list < json > , bool , value_t ) .
@ param [ in ] init initializer list to create an object from ( optional )
@ return JSON object value
@ throw type_error .301 if @ a init is not a list of pairs whose first
elements are strings . In this case , no object can be created . When such a
value is passed to @ ref json ( std : : initializer_list < json > , bool , value_t ) ,
an array would have been created from the passed initializer list @ a init .
See example below .
@ complexity Linear in the size of @ a init .
@ liveexample { The following code shows an example for the ` object `
function . , object }
@ sa @ ref json ( std : : initializer_list < json > , bool , value_t ) - -
create a JSON value from an initializer list
@ sa @ ref array ( std : : initializer_list < json > ) - - create a JSON array
value from an initializer list
@ since version 1.0 .0
*/
static json object ( std : : initializer_list < json > init =
std : : initializer_list < json > ( ) )
{
return 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
json ( size_type \ , const json & )
constructor . , json__size_type_json }
@ since version 1.0 .0
*/
json ( size_type cnt , const json & val ) ;
/*!
@ 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 , invalid_iterator .204 is thrown .
- In case of structured types ( array , object ) , the constructor behaves as
similar versions for ` std : : vector ` .
- In case of a null type , invalid_iterator .206 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 . * *
@ pre Range ` [ first , last ) ` is valid . Usually , this precondition cannot be
checked efficiently . Only certain edge cases are detected ; see the
description of the exceptions below .
@ throw invalid_iterator .201 if iterators @ a first and @ a last are not
compatible ( i . e . , do not belong to the same JSON value ) . In this case ,
the range ` [ first , last ) ` is undefined .
@ throw invalid_iterator .204 if iterators @ a first and @ a last belong to a
primitive type ( number , boolean , or string ) , but @ a first does not point
to the first element any more . In this case , the range ` [ first , last ) ` is
undefined . See example code below .
@ throw invalid_iterator .206 if iterators @ a first and @ a last belong to a
null value . In this case , the range ` [ first , last ) ` is undefined .
@ 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 . , json__InputIt_InputIt }
@ since version 1.0 .0
*/
template < class InputIT , typename std : : enable_if <
std : : is_same < InputIT , json : : iterator > : : value | |
std : : is_same < InputIT , json : : const_iterator > : : value , int > : : type = 0 >
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 )
{
JSON_THROW ( invalid_iterator : : create ( 201 , " 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 ( ! first . m_it . primitive_iterator . is_begin ( ) | | ! last . m_it . primitive_iterator . is_end ( ) )
{
JSON_THROW ( invalid_iterator : : create ( 204 , " 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 : : array :
{
m_value . array = create < array_t > ( first . m_it . array_iterator ,
last . m_it . array_iterator ) ;
break ;
}
default :
{
JSON_THROW ( invalid_iterator : : create ( 206 , " cannot construct with iterators from " +
first . m_object - > type_name ( ) ) ) ;
}
}
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 ` json ` satisfying the
[ Container ] ( http : //en.cppreference.com/w/cpp/concept/Container)
requirements :
- The complexity is linear .
- As postcondition , it holds : ` other = = json ( other ) ` .
@ liveexample { The following code shows an example for the copy
constructor . , json__json }
@ since version 1.0 .0
*/
json ( const json & other ) ;
/*!
@ 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 . , json__moveconstructor }
@ since version 1.0 .0
*/
json ( 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 ` 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 . , json__copyassignment }
@ since version 1.0 .0
*/
reference & operator = ( json other ) noexcept (
std : : is_nothrow_move_constructible < value_t > : : value & &
std : : is_nothrow_move_assignable < value_t > : : value & &
std : : is_nothrow_move_constructible < json_value > : : value & &
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 ` 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
*/
~ json ( ) ;
/// @}
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 ; indentaction character added in version 3.0 .0
*/
std : : string dump ( const int indent = - 1 ) const ;
/*!
@ 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 , out ] os Output stream
@ 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 .
@ 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 ; indentaction character added in version 3.0 .0
*/
2018-04-29 23:33:19 -07:00
void dump ( raw_ostream & os , int indent = - 1 ) const ;
2017-06-15 13:22:55 -07:00
/*!
@ 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
*/
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
*/
bool is_primitive ( ) const noexcept
{
return is_null ( ) | | is_string ( ) | | is_boolean ( ) | | 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
*/
bool is_structured ( ) const noexcept
{
return is_array ( ) | | 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
*/
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
*/
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
*/
bool is_number ( ) const noexcept
{
return is_number_integer ( ) | | 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
*/
bool is_number_integer ( ) const noexcept
{
return m_type = = value_t : : number_integer | | 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
*/
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
*/
bool is_number_float ( ) const noexcept
{
return m_type = = value_t : : number_float ;
}
/*!
@ brief return whether value is an object
This function returns true iff the JSON value is an object .
@ return ` true ` if type is object , ` false ` otherwise .
@ complexity Constant .
@ exceptionsafety No - throw guarantee : this member function never throws
exceptions .
@ liveexample { The following code exemplifies ` is_object ( ) ` for all JSON
types . , is_object }
@ since version 1.0 .0
*/
bool is_object ( ) const noexcept
{
return m_type = = value_t : : object ;
}
/*!
@ brief return whether value is an array
This function returns true iff the JSON value is an array .
@ return ` true ` if type is array , ` false ` otherwise .
@ complexity Constant .
@ exceptionsafety No - throw guarantee : this member function never throws
exceptions .
@ liveexample { The following code exemplifies ` is_array ( ) ` for all JSON
types . , is_array }
@ since version 1.0 .0
*/
bool is_array ( ) const noexcept
{
return m_type = = value_t : : array ;
}
/*!
@ brief return whether value is a string
This function returns true iff the JSON value is a string .
@ return ` true ` if type is string , ` false ` otherwise .
@ complexity Constant .
@ exceptionsafety No - throw guarantee : this member function never throws
exceptions .
@ liveexample { The following code exemplifies ` is_string ( ) ` for all JSON
types . , is_string }
@ since version 1.0 .0
*/
bool is_string ( ) const noexcept
{
return m_type = = value_t : : string ;
}
/*!
@ brief return whether value is discarded
This function returns true iff the JSON value was discarded during parsing
with a callback function ( see @ ref parser_callback_t ) .
@ note This function will always be ` false ` for JSON values after parsing .
That is , discarded values can only occur during parsing , but will be
removed when inside a structured value or replaced by null in other cases .
@ return ` true ` if type is discarded , ` false ` otherwise .
@ complexity Constant .
@ exceptionsafety No - throw guarantee : this member function never throws
exceptions .
@ liveexample { The following code exemplifies ` is_discarded ( ) ` for all JSON
types . , is_discarded }
@ since version 1.0 .0
*/
bool is_discarded ( ) const noexcept
{
return m_type = = value_t : : discarded ;
}
/*!
@ brief return the type of the JSON value ( implicit )
Implicitly return the type of the JSON value as a value from the @ ref
value_t enumeration .
@ return the type of the JSON value
@ complexity Constant .
@ exceptionsafety No - throw guarantee : this member function never throws
exceptions .
@ liveexample { The following code exemplifies the @ ref value_t operator for
all JSON types . , operator__value_t }
@ since version 1.0 .0
*/
operator value_t ( ) const noexcept
{
return m_type ;
}
/// @}
private :
//////////////////
// value access //
//////////////////
/// get a boolean (explicit)
bool get_impl ( bool * /*unused*/ ) const
{
if ( is_boolean ( ) )
{
return m_value . boolean ;
}
JSON_THROW ( type_error : : create ( 302 , " type must be boolean, but is " + type_name ( ) ) ) ;
}
/// get a pointer to the value (object)
object_t * get_impl_ptr ( object_t * /*unused*/ ) noexcept
{
return is_object ( ) ? m_value . object : nullptr ;
}
/// get a pointer to the value (object)
const object_t * get_impl_ptr ( const object_t * /*unused*/ ) const noexcept
{
return is_object ( ) ? m_value . object : nullptr ;
}
/// get a pointer to the value (array)
array_t * get_impl_ptr ( array_t * /*unused*/ ) noexcept
{
return is_array ( ) ? m_value . array : nullptr ;
}
/// get a pointer to the value (array)
const array_t * get_impl_ptr ( const array_t * /*unused*/ ) const noexcept
{
return is_array ( ) ? m_value . array : nullptr ;
}
/// get a pointer to the value (string)
std : : string * get_impl_ptr ( std : : string * /*unused*/ ) noexcept
{
return is_string ( ) ? m_value . string : nullptr ;
}
/// get a pointer to the value (string)
const std : : string * get_impl_ptr ( const std : : string * /*unused*/ ) const noexcept
{
return is_string ( ) ? m_value . string : nullptr ;
}
/// get a pointer to the value (boolean)
bool * get_impl_ptr ( bool * /*unused*/ ) noexcept
{
return is_boolean ( ) ? & m_value . boolean : nullptr ;
}
/// get a pointer to the value (boolean)
const bool * get_impl_ptr ( const bool * /*unused*/ ) const noexcept
{
return is_boolean ( ) ? & m_value . boolean : nullptr ;
}
/// get a pointer to the value (integer number)
std : : int64_t * get_impl_ptr ( std : : int64_t * /*unused*/ ) noexcept
{
return is_number_integer ( ) ? & m_value . number_integer : nullptr ;
}
/// get a pointer to the value (integer number)
const std : : int64_t * get_impl_ptr ( const std : : int64_t * /*unused*/ ) const noexcept
{
return is_number_integer ( ) ? & m_value . number_integer : nullptr ;
}
/// get a pointer to the value (unsigned number)
std : : uint64_t * get_impl_ptr ( std : : uint64_t * /*unused*/ ) noexcept
{
return is_number_unsigned ( ) ? & m_value . number_unsigned : nullptr ;
}
/// get a pointer to the value (unsigned number)
const std : : uint64_t * get_impl_ptr ( const std : : uint64_t * /*unused*/ ) const noexcept
{
return is_number_unsigned ( ) ? & m_value . number_unsigned : nullptr ;
}
/// get a pointer to the value (floating-point number)
double * get_impl_ptr ( double * /*unused*/ ) noexcept
{
return is_number_float ( ) ? & m_value . number_float : nullptr ;
}
/// get a pointer to the value (floating-point number)
const double * get_impl_ptr ( const double * /*unused*/ ) const noexcept
{
return is_number_float ( ) ? & m_value . number_float : nullptr ;
}
/*!
@ brief helper function to implement get_ref ( )
This funcion helps to implement get_ref ( ) without code duplication for
const and non - const overloads
@ tparam ThisType will be deduced as ` json ` or ` const json `
@ throw type_error .303 if ReferenceType does not match underlying value
type of the current JSON
*/
template < typename ReferenceType , typename ThisType >
static ReferenceType get_ref_impl ( ThisType & obj )
{
// helper type
using PointerType = typename std : : add_pointer < ReferenceType > : : type ;
// delegate the call to get_ptr<>()
auto ptr = obj . template get_ptr < PointerType > ( ) ;
if ( ptr ! = nullptr )
{
return * ptr ;
}
JSON_THROW ( type_error : : create ( 303 , " incompatible ReferenceType for get_ref, actual type is " + obj . type_name ( ) ) ) ;
}
public :
/// @name value access
/// Direct access to the stored value of a JSON value.
/// @{
/*!
@ brief get special - case overload
This overloads avoids a lot of template boilerplate , it can be seen as the
identity method
@ tparam BasicJsonType = = @ ref json
@ return a copy of * this
@ complexity Constant .
@ since version 2.1 .0
*/
template <
typename BasicJsonType ,
detail : : enable_if_t < std : : is_same < typename std : : remove_const < BasicJsonType > : : type ,
json > : : value ,
int > = 0 >
json get ( ) const
{
return * this ;
}
/*!
@ brief get a value ( explicit )
Explicit type conversion between the JSON value and a compatible value
which is [ CopyConstructible ] ( http : //en.cppreference.com/w/cpp/concept/CopyConstructible)
and [ DefaultConstructible ] ( http : //en.cppreference.com/w/cpp/concept/DefaultConstructible).
The value is converted by calling the @ ref json_serializer < ValueType >
` from_json ( ) ` method .
The function is equivalent to executing
@ code { . cpp }
ValueType ret ;
adl_serializer < ValueType , void > : : from_json ( * this , ret ) ;
return ret ;
@ endcode
This overloads is chosen if :
- @ a ValueType is not @ ref json ,
- @ ref json_serializer < ValueType > has a ` from_json ( ) ` method of the form
` void from_json ( const json & , ValueType & ) ` , and
- @ ref json_serializer < ValueType > does not have a ` from_json ( ) ` method of
the form ` ValueType from_json ( const json & ) `
@ tparam ValueTypeCV the provided value type
@ tparam ValueType the returned value type
@ return copy of the JSON value , converted to @ a ValueType
@ throw what @ ref json_serializer < ValueType > ` from_json ( ) ` method throws
@ liveexample { The example below shows several conversions from JSON values
to other types . There a few things to note : ( 1 ) Floating - point numbers can
be converted to integers \ , ( 2 ) A JSON array can be converted to a standard
` std : : vector < short > ` \ , ( 3 ) A JSON object can be converted to C + +
associative containers such as ` std : : unordered_map < std : : string \ ,
json > ` . , get__ValueType_const }
@ since version 2.1 .0
*/
template <
typename ValueTypeCV ,
typename ValueType = detail : : uncvref_t < ValueTypeCV > ,
detail : : enable_if_t < ! std : : is_same < json , ValueType > : : value , int > = 0 >
ValueType get ( ) const
{
// we cannot static_assert on ValueTypeCV being non-const, because
// there is support for get<const json>(), which is why we
// still need the uncvref
static_assert ( ! std : : is_reference < ValueTypeCV > : : value ,
" get() cannot be used with reference types, you might want to use get_ref() " ) ;
static_assert ( std : : is_default_constructible < ValueType > : : value ,
" types must be DefaultConstructible when used with get() " ) ;
ValueType ret ;
from_json ( * this , ret ) ;
return ret ;
}
/*!
@ brief get a pointer value ( explicit )
Explicit pointer access to the internally stored JSON value . No copies are
made .
@ warning The pointer becomes invalid if the underlying JSON object
changes .
@ tparam PointerType pointer type ; must be a pointer to @ ref array_t , @ ref
object_t , std : : string , bool , std : : int64_t ,
std : : uint64_t , or double .
@ return pointer to the internally stored JSON value if the requested
pointer type @ a PointerType fits to the JSON value ; ` nullptr ` otherwise
@ complexity Constant .
@ liveexample { The example below shows how pointers to internal values of a
JSON value can be requested . Note that no type conversions are made and a
` nullptr ` is returned if the value and the requested pointer type does not
match . , get__PointerType }
@ sa @ ref get_ptr ( ) for explicit pointer - member access
@ since version 1.0 .0
*/
template < typename PointerType , typename std : : enable_if <
std : : is_pointer < PointerType > : : value , int > : : type = 0 >
PointerType get ( ) noexcept
{
// delegate the call to get_ptr
return get_ptr < PointerType > ( ) ;
}
/*!
@ brief get a pointer value ( explicit )
@ copydoc get ( )
*/
template < typename PointerType , typename std : : enable_if <
std : : is_pointer < PointerType > : : value , int > : : type = 0 >
const PointerType get ( ) const noexcept
{
// delegate the call to get_ptr
return get_ptr < PointerType > ( ) ;
}
/*!
@ brief get a pointer value ( implicit )
Implicit pointer access to the internally stored JSON value . No copies are
made .
@ warning Writing data to the pointee of the result yields an undefined
state .
@ tparam PointerType pointer type ; must be a pointer to @ ref array_t , @ ref
object_t , std : : string , bool , std : : int64_t ,
std : : uint64_t , or double . Enforced by a static
assertion .
@ return pointer to the internally stored JSON value if the requested
pointer type @ a PointerType fits to the JSON value ; ` nullptr ` otherwise
@ complexity Constant .
@ liveexample { The example below shows how pointers to internal values of a
JSON value can be requested . Note that no type conversions are made and a
` nullptr ` is returned if the value and the requested pointer type does not
match . , get_ptr }
@ since version 1.0 .0
*/
template < typename PointerType , typename std : : enable_if <
std : : is_pointer < PointerType > : : value , int > : : type = 0 >
PointerType get_ptr ( ) noexcept
{
// get the type of the PointerType (remove pointer and const)
using pointee_t = typename std : : remove_const < typename
std : : remove_pointer < typename
std : : remove_const < PointerType > : : type > : : type > : : type ;
// make sure the type matches the allowed types
static_assert (
std : : is_same < object_t , pointee_t > : : value
| | std : : is_same < array_t , pointee_t > : : value
| | std : : is_same < std : : string , pointee_t > : : value
| | std : : is_same < bool , pointee_t > : : value
| | std : : is_same < std : : int64_t , pointee_t > : : value
| | std : : is_same < std : : uint64_t , pointee_t > : : value
| | std : : is_same < double , pointee_t > : : value
, " incompatible pointer type " ) ;
// delegate the call to get_impl_ptr<>()
return get_impl_ptr ( static_cast < PointerType > ( nullptr ) ) ;
}
/*!
@ brief get a pointer value ( implicit )
@ copydoc get_ptr ( )
*/
template < typename PointerType , typename std : : enable_if <
std : : is_pointer < PointerType > : : value & &
std : : is_const < typename std : : remove_pointer < PointerType > : : type > : : value , int > : : type = 0 >
const PointerType get_ptr ( ) const noexcept
{
// get the type of the PointerType (remove pointer and const)
using pointee_t = typename std : : remove_const < typename
std : : remove_pointer < typename
std : : remove_const < PointerType > : : type > : : type > : : type ;
// make sure the type matches the allowed types
static_assert (
std : : is_same < object_t , pointee_t > : : value
| | std : : is_same < array_t , pointee_t > : : value
| | std : : is_same < std : : string , pointee_t > : : value
| | std : : is_same < bool , pointee_t > : : value
| | std : : is_same < std : : int64_t , pointee_t > : : value
| | std : : is_same < std : : uint64_t , pointee_t > : : value
| | std : : is_same < double , pointee_t > : : value
, " incompatible pointer type " ) ;
// delegate the call to get_impl_ptr<>() const
return get_impl_ptr ( static_cast < const PointerType > ( nullptr ) ) ;
}
/*!
@ brief get a reference value ( implicit )
Implicit reference access to the internally stored JSON value . No copies
are made .
@ warning Writing data to the referee of the result yields an undefined
state .
@ tparam ReferenceType reference type ; must be a reference to @ ref array_t ,
@ ref object_t , std : : string , bool , std : : int64_t , or
double . Enforced by static assertion .
@ return reference to the internally stored JSON value if the requested
reference type @ a ReferenceType fits to the JSON value ; throws
type_error .303 otherwise
@ throw type_error .303 in case passed type @ a ReferenceType is incompatible
with the stored JSON value ; see example below
@ complexity Constant .
@ liveexample { The example shows several calls to ` get_ref ( ) ` . , get_ref }
@ since version 1.1 .0
*/
template < typename ReferenceType , typename std : : enable_if <
std : : is_reference < ReferenceType > : : value , int > : : type = 0 >
ReferenceType get_ref ( )
{
// delegate call to get_ref_impl
return get_ref_impl < ReferenceType > ( * this ) ;
}
/*!
@ brief get a reference value ( implicit )
@ copydoc get_ref ( )
*/
template < typename ReferenceType , typename std : : enable_if <
std : : is_reference < ReferenceType > : : value & &
std : : is_const < typename std : : remove_reference < ReferenceType > : : type > : : value , int > : : type = 0 >
ReferenceType get_ref ( ) const
{
// delegate call to get_ref_impl
return get_ref_impl < ReferenceType > ( * this ) ;
}
/*!
@ brief get a value ( implicit )
Implicit type conversion between the JSON value and a compatible value .
The call is realized by calling @ ref get ( ) const .
@ tparam ValueType non - pointer type compatible to the JSON value , for
instance ` int ` for JSON integer numbers , ` bool ` for JSON booleans , or
` std : : vector ` types for JSON arrays . The character type of std : : string
as well as an initializer list of this type is excluded to avoid
ambiguities as these types implicitly convert to ` std : : string ` .
@ return copy of the JSON value , converted to type @ a ValueType
@ throw type_error .302 in case passed type @ a ValueType is incompatible
to the JSON value type ( e . g . , the JSON value is of type boolean , but a
string is requested ) ; see example below
@ complexity Linear in the size of the JSON value .
@ liveexample { The example below shows several conversions from JSON values
to other types . There a few things to note : ( 1 ) Floating - point numbers can
be converted to integers \ , ( 2 ) A JSON array can be converted to a standard
` std : : vector < short > ` \ , ( 3 ) A JSON object can be converted to C + +
associative containers such as ` std : : unordered_map < std : : string \ ,
json > ` . , operator__ValueType }
@ since version 1.0 .0
*/
template < typename ValueType , typename std : : enable_if <
! std : : is_pointer < ValueType > : : value & &
! std : : is_same < ValueType , std : : string : : value_type > : : value
# ifndef _MSC_VER // fix for issue #167 operator<< ambiguity under VS2015
& & ! std : : is_same < ValueType , std : : initializer_list < std : : string : : value_type > > : : value
# endif
# if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_MSC_VER) && _MSC_VER >1900 && defined(_HAS_CXX17) && _HAS_CXX17 == 1) // fix for issue #464
& & ! std : : is_same < ValueType , typename std : : string_view > : : value
# endif
, int > : : type = 0 >
operator ValueType ( ) const
{
// delegate the call to get<>() const
return get < ValueType > ( ) ;
}
/// @}
////////////////////
// element access //
////////////////////
/// @name element access
/// Access to the JSON value.
/// @{
/*!
@ brief access specified array element with bounds checking
Returns a reference to the element at specified location @ a idx , with
bounds checking .
@ param [ in ] idx index of the element to access
@ return reference to the element at index @ a idx
@ throw type_error .304 if the JSON value is not an array ; in this case ,
calling ` at ` with an index makes no sense . See example below .
@ throw out_of_range .401 if the index @ a idx is out of range of the array ;
that is , ` idx > = size ( ) ` . See example below .
@ exceptionsafety Strong guarantee : if an exception is thrown , there are no
changes in the JSON value .
@ complexity Constant .
@ since version 1.0 .0
@ liveexample { The example below shows how array elements can be read and
written using ` at ( ) ` . It also demonstrates the different exceptions that
can be thrown . , at__size_type }
*/
reference at ( size_type idx ) ;
/*!
@ brief access specified array element with bounds checking
Returns a const reference to the element at specified location @ a idx ,
with bounds checking .
@ param [ in ] idx index of the element to access
@ return const reference to the element at index @ a idx
@ throw type_error .304 if the JSON value is not an array ; in this case ,
calling ` at ` with an index makes no sense . See example below .
@ throw out_of_range .401 if the index @ a idx is out of range of the array ;
that is , ` idx > = size ( ) ` . See example below .
@ exceptionsafety Strong guarantee : if an exception is thrown , there are no
changes in the JSON value .
@ complexity Constant .
@ since version 1.0 .0
@ liveexample { The example below shows how array elements can be read using
` at ( ) ` . It also demonstrates the different exceptions that can be thrown . ,
at__size_type_const }
*/
const_reference at ( size_type idx ) const ;
/*!
@ brief access specified object element with bounds checking
Returns a reference to the element at with specified key @ a key , with
bounds checking .
@ param [ in ] key key of the element to access
@ return reference to the element at key @ a key
@ throw type_error .304 if the JSON value is not an object ; in this case ,
calling ` at ` with a key makes no sense . See example below .
@ throw out_of_range .403 if the key @ a key is is not stored in the object ;
that is , ` find ( key ) = = end ( ) ` . See example below .
@ exceptionsafety Strong guarantee : if an exception is thrown , there are no
changes in the JSON value .
@ complexity Logarithmic in the size of the container .
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@ sa @ ref operator [ ] ( StringRef ) for unchecked
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access by reference
@ sa @ ref value ( ) for access by value with a default value
@ since version 1.0 .0
@ liveexample { The example below shows how object elements can be read and
written using ` at ( ) ` . It also demonstrates the different exceptions that
can be thrown . , at__object_t_key_type }
*/
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reference at ( StringRef key ) ;
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/*!
@ brief access specified object element with bounds checking
Returns a const reference to the element at with specified key @ a key ,
with bounds checking .
@ param [ in ] key key of the element to access
@ return const reference to the element at key @ a key
@ throw type_error .304 if the JSON value is not an object ; in this case ,
calling ` at ` with a key makes no sense . See example below .
@ throw out_of_range .403 if the key @ a key is is not stored in the object ;
that is , ` find ( key ) = = end ( ) ` . See example below .
@ exceptionsafety Strong guarantee : if an exception is thrown , there are no
changes in the JSON value .
@ complexity Logarithmic in the size of the container .
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@ sa @ ref operator [ ] ( StringRef ) for unchecked
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access by reference
@ sa @ ref value ( ) for access by value with a default value
@ since version 1.0 .0
@ liveexample { The example below shows how object elements can be read using
` at ( ) ` . It also demonstrates the different exceptions that can be thrown . ,
at__object_t_key_type_const }
*/
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const_reference at ( StringRef key ) const ;
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/*!
@ brief access specified array element
Returns a reference to the element at specified location @ a idx .
@ note If @ a idx is beyond the range of the array ( i . e . , ` idx > = size ( ) ` ) ,
then the array is silently filled up with ` null ` values to make ` idx ` a
valid reference to the last stored element .
@ param [ in ] idx index of the element to access
@ return reference to the element at index @ a idx
@ throw type_error .305 if the JSON value is not an array or null ; in that
cases , using the [ ] operator with an index makes no sense .
@ complexity Constant if @ a idx is in the range of the array . Otherwise
linear in ` idx - size ( ) ` .
@ liveexample { The example below shows how array elements can be read and
written using ` [ ] ` operator . Note the addition of ` null `
values . , operatorarray__size_type }
@ since version 1.0 .0
*/
reference operator [ ] ( size_type idx ) ;
/*!
@ brief access specified array element
Returns a const reference to the element at specified location @ a idx .
@ param [ in ] idx index of the element to access
@ return const reference to the element at index @ a idx
@ throw type_error .305 if the JSON value is not an array ; in that cases ,
using the [ ] operator with an index makes no sense .
@ complexity Constant .
@ liveexample { The example below shows how array elements can be read using
the ` [ ] ` operator . , operatorarray__size_type_const }
@ since version 1.0 .0
*/
const_reference operator [ ] ( size_type idx ) const ;
/*!
@ brief access specified object element
Returns a reference to the element at with specified key @ a key .
@ note If @ a key is not found in the object , then it is silently added to
the object and filled with a ` null ` value to make ` key ` a valid reference .
In case the value was ` null ` before , it is converted to an object .
@ param [ in ] key key of the element to access
@ return reference to the element at key @ a key
@ throw type_error .305 if the JSON value is not an object or null ; in that
cases , using the [ ] operator with a key makes no sense .
@ complexity Logarithmic in the size of the container .
@ liveexample { The example below shows how object elements can be read and
written using the ` [ ] ` operator . , operatorarray__key_type }
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@ sa @ ref at ( StringRef ) for access by reference
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with range checking
@ sa @ ref value ( ) for access by value with a default value
@ since version 1.0 .0
*/
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reference operator [ ] ( StringRef key ) ;
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/*!
@ brief read - only access specified object element
Returns a const reference to the element at with specified key @ a key . No
bounds checking is performed .
@ warning If the element with key @ a key does not exist , the behavior is
undefined .
@ param [ in ] key key of the element to access
@ return const reference to the element at key @ a key
@ pre The element with key @ a key must exist . * * This precondition is
enforced with an assertion . * *
@ throw type_error .305 if the JSON value is not an object ; in that cases ,
using the [ ] operator with a key makes no sense .
@ complexity Logarithmic in the size of the container .
@ liveexample { The example below shows how object elements can be read using
the ` [ ] ` operator . , operatorarray__key_type_const }
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@ sa @ ref at ( StringRef ) for access by reference
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with range checking
@ sa @ ref value ( ) for access by value with a default value
@ since version 1.0 .0
*/
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const_reference operator [ ] ( StringRef key ) const ;
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/*!
@ brief access specified object element
Returns a reference to the element at with specified key @ a key .
@ note If @ a key is not found in the object , then it is silently added to
the object and filled with a ` null ` value to make ` key ` a valid reference .
In case the value was ` null ` before , it is converted to an object .
@ param [ in ] key key of the element to access
@ return reference to the element at key @ a key
@ throw type_error .305 if the JSON value is not an object or null ; in that
cases , using the [ ] operator with a key makes no sense .
@ complexity Logarithmic in the size of the container .
@ liveexample { The example below shows how object elements can be read and
written using the ` [ ] ` operator . , operatorarray__key_type }
@ sa @ ref at ( const typename object_t : : key_type & ) for access by reference
with range checking
@ sa @ ref value ( ) for access by value with a default value
@ since version 1.0 .0
*/
template < typename T , std : : size_t n >
reference operator [ ] ( T * ( & key ) [ n ] )
{
return operator [ ] ( static_cast < const T > ( key ) ) ;
}
/*!
@ brief read - only access specified object element
Returns a const reference to the element at with specified key @ a key . No
bounds checking is performed .
@ warning If the element with key @ a key does not exist , the behavior is
undefined .
@ note This function is required for compatibility reasons with Clang .
@ param [ in ] key key of the element to access
@ return const reference to the element at key @ a key
@ throw type_error .305 if the JSON value is not an object ; in that cases ,
using the [ ] operator with a key makes no sense .
@ complexity Logarithmic in the size of the container .
@ liveexample { The example below shows how object elements can be read using
the ` [ ] ` operator . , operatorarray__key_type_const }
@ sa @ ref at ( const typename object_t : : key_type & ) for access by reference
with range checking
@ sa @ ref value ( ) for access by value with a default value
@ since version 1.0 .0
*/
template < typename T , std : : size_t n >
const_reference operator [ ] ( T * ( & key ) [ n ] ) const
{
return operator [ ] ( static_cast < const T > ( key ) ) ;
}
/*!
@ brief access specified object element
Returns a reference to the element at with specified key @ a key .
@ note If @ a key is not found in the object , then it is silently added to
the object and filled with a ` null ` value to make ` key ` a valid reference .
In case the value was ` null ` before , it is converted to an object .
@ param [ in ] key key of the element to access
@ return reference to the element at key @ a key
@ throw type_error .305 if the JSON value is not an object or null ; in that
cases , using the [ ] operator with a key makes no sense .
@ complexity Logarithmic in the size of the container .
@ liveexample { The example below shows how object elements can be read and
written using the ` [ ] ` operator . , operatorarray__key_type }
@ sa @ ref at ( const typename object_t : : key_type & ) for access by reference
with range checking
@ sa @ ref value ( ) for access by value with a default value
@ since version 1.1 .0
*/
template < typename T >
reference operator [ ] ( T * key )
{
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return this - > operator [ ] ( StringRef ( key ) ) ;
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}
/*!
@ brief read - only access specified object element
Returns a const reference to the element at with specified key @ a key . No
bounds checking is performed .
@ warning If the element with key @ a key does not exist , the behavior is
undefined .
@ param [ in ] key key of the element to access
@ return const reference to the element at key @ a key
@ pre The element with key @ a key must exist . * * This precondition is
enforced with an assertion . * *
@ throw type_error .305 if the JSON value is not an object ; in that cases ,
using the [ ] operator with a key makes no sense .
@ complexity Logarithmic in the size of the container .
@ liveexample { The example below shows how object elements can be read using
the ` [ ] ` operator . , operatorarray__key_type_const }
@ sa @ ref at ( const typename object_t : : key_type & ) for access by reference
with range checking
@ sa @ ref value ( ) for access by value with a default value
@ since version 1.1 .0
*/
template < typename T >
const_reference operator [ ] ( T * key ) const
{
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return this - > operator [ ] ( StringRef ( key ) ) ;
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}
/*!
@ brief access specified object element with default value
Returns either a copy of an object ' s element at the specified key @ a key
or a given default value if no element with key @ a key exists .
The function is basically equivalent to executing
@ code { . cpp }
try {
return at ( key ) ;
} catch ( out_of_range ) {
return default_value ;
}
@ endcode
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@ note Unlike @ ref at ( StringRef ) , this function
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does not throw if the given key @ a key was not found .
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@ note Unlike @ ref operator [ ] ( StringRef key ) , this
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function does not implicitly add an element to the position defined by @ a
key . This function is furthermore also applicable to const objects .
@ param [ in ] key key of the element to access
@ param [ in ] default_value the value to return if @ a key is not found
@ tparam ValueType type compatible to JSON values , for instance ` int ` for
JSON integer numbers , ` bool ` for JSON booleans , or ` std : : vector ` types for
JSON arrays . Note the type of the expected value at @ a key and the default
value @ a default_value must be compatible .
@ return copy of the element at key @ a key or @ a default_value if @ a key
is not found
@ throw type_error .306 if the JSON value is not an objec ; in that cases ,
using ` value ( ) ` with a key makes no sense .
@ complexity Logarithmic in the size of the container .
@ liveexample { The example below shows how object elements can be queried
with a default value . , json__value }
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@ sa @ ref at ( StringRef ) for access by reference
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with range checking
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@ sa @ ref operator [ ] ( StringRef ) for unchecked
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access by reference
@ since version 1.0 .0
*/
template < class ValueType , typename std : : enable_if <
std : : is_convertible < json , ValueType > : : value , int > : : type = 0 >
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ValueType value ( StringRef key , ValueType default_value ) const
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{
// at only works for objects
if ( is_object ( ) )
{
// if key is found, return value and given default value otherwise
const auto it = find ( key ) ;
if ( it ! = end ( ) )
{
return * it ;
}
return default_value ;
}
else
{
JSON_THROW ( type_error : : create ( 306 , " cannot use value() with " + type_name ( ) ) ) ;
}
}
/*!
@ brief overload for a default value of type const char *
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@ copydoc json : : value ( StringRef , ValueType ) const
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*/
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std : : string value ( StringRef key , const char * default_value ) const
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{
return value ( key , std : : string ( default_value ) ) ;
}
/*!
@ brief access specified object element via JSON Pointer with default value
Returns either a copy of an object ' s element at the specified key @ a key
or a given default value if no element with key @ a key exists .
The function is basically equivalent to executing
@ code { . cpp }
try {
return at ( ptr ) ;
} catch ( out_of_range ) {
return default_value ;
}
@ endcode
@ note Unlike @ ref at ( const json_pointer & ) , this function does not throw
if the given key @ a key was not found .
@ param [ in ] ptr a JSON pointer to the element to access
@ param [ in ] default_value the value to return if @ a ptr found no value
@ tparam ValueType type compatible to JSON values , for instance ` int ` for
JSON integer numbers , ` bool ` for JSON booleans , or ` std : : vector ` types for
JSON arrays . Note the type of the expected value at @ a key and the default
value @ a default_value must be compatible .
@ return copy of the element at key @ a key or @ a default_value if @ a key
is not found
@ throw type_error .306 if the JSON value is not an objec ; in that cases ,
using ` value ( ) ` with a key makes no sense .
@ complexity Logarithmic in the size of the container .
@ liveexample { The example below shows how object elements can be queried
with a default value . , json__value_ptr }
@ sa @ ref operator [ ] ( const json_pointer & ) for unchecked access by reference
@ since version 2.0 .2
*/
template < class ValueType , typename std : : enable_if <
std : : is_convertible < json , ValueType > : : value , int > : : type = 0 >
ValueType value ( const json_pointer & ptr , ValueType default_value ) const
{
// at only works for objects
if ( is_object ( ) )
{
// if pointer resolves a value, return it or use default value
JSON_TRY
{
return ptr . get_checked ( this ) ;
}
JSON_CATCH ( out_of_range & )
{
return default_value ;
}
}
JSON_THROW ( type_error : : create ( 306 , " cannot use value() with " + type_name ( ) ) ) ;
}
/*!
@ brief overload for a default value of type const char *
@ copydoc json : : value ( const json_pointer & , ValueType ) const
*/
std : : string value ( const json_pointer & ptr , const char * default_value ) const
{
return value ( ptr , std : : string ( default_value ) ) ;
}
/*!
@ brief access the first element
Returns a reference to the first element in the container . For a JSON
container ` c ` , the expression ` c . front ( ) ` is equivalent to ` * c . begin ( ) ` .
@ return In case of a structured type ( array or object ) , a reference to the
first element is returned . In case of number , string , or boolean values , a
reference to the value is returned .
@ complexity Constant .
@ pre The JSON value must not be ` null ` ( would throw ` std : : out_of_range ` )
or an empty array or object ( undefined behavior , * * guarded by
assertions * * ) .
@ post The JSON value remains unchanged .
@ throw invalid_iterator .214 when called on ` null ` value
@ liveexample { The following code shows an example for ` front ( ) ` . , front }
@ sa @ ref back ( ) - - access the last element
@ since version 1.0 .0
*/
reference front ( )
{
return * begin ( ) ;
}
/*!
@ copydoc json : : front ( )
*/
const_reference front ( ) const
{
return * cbegin ( ) ;
}
/*!
@ brief access the last element
Returns a reference to the last element in the container . For a JSON
container ` c ` , the expression ` c . back ( ) ` is equivalent to
@ code { . cpp }
auto tmp = c . end ( ) ;
- - tmp ;
return * tmp ;
@ endcode
@ return In case of a structured type ( array or object ) , a reference to the
last element is returned . In case of number , string , or boolean values , a
reference to the value is returned .
@ complexity Constant .
@ pre The JSON value must not be ` null ` ( would throw ` std : : out_of_range ` )
or an empty array or object ( undefined behavior , * * guarded by
assertions * * ) .
@ post The JSON value remains unchanged .
@ throw invalid_iterator .214 when called on a ` null ` value . See example
below .
@ liveexample { The following code shows an example for ` back ( ) ` . , back }
@ sa @ ref front ( ) - - access the first element
@ since version 1.0 .0
*/
reference back ( ) ;
/*!
@ copydoc json : : back ( )
*/
const_reference back ( ) const ;
/*!
@ brief remove element given an iterator
Removes the element specified by iterator @ a pos . The iterator @ a pos must
be valid and dereferenceable . Thus the ` end ( ) ` iterator ( which is valid ,
but is not dereferenceable ) cannot be used as a value for @ a pos .
If called on a primitive type other than ` null ` , the resulting JSON value
will be ` null ` .
@ param [ in ] pos iterator to the element to remove
@ tparam IteratorType an @ ref iterator or @ ref const_iterator
@ post Invalidates iterators and references at or after the point of the
erase , including the ` end ( ) ` iterator .
@ throw type_error .307 if called on a ` null ` value ; example : ` " cannot use
erase ( ) with null " `
@ throw invalid_iterator .202 if called on an iterator which does not belong
to the current JSON value ; example : ` " iterator does not fit current
value " `
@ throw invalid_iterator .205 if called on a primitive type with invalid
iterator ( i . e . , any iterator which is not ` begin ( ) ` ) ; example : ` " iterator
out of range " `
@ complexity The complexity depends on the type :
- objects : amortized constant
- arrays : linear in distance between @ a pos and the end of the container
- strings : linear in the length of the string
- other types : constant
@ liveexample { The example shows the result of ` erase ( ) ` for different JSON
types . , erase__IteratorType }
@ sa @ ref erase ( IteratorType , IteratorType ) - - removes the elements in
the given range
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@ sa @ ref erase ( StringRef ) - - removes the element
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from an object at the given key
@ sa @ ref erase ( const size_type ) - - removes the element from an array at
the given index
@ since version 1.0 .0
*/
template < class IteratorType , typename std : : enable_if <
std : : is_same < IteratorType , json : : iterator > : : value | |
std : : is_same < IteratorType , json : : const_iterator > : : value , int > : : type
= 0 >
void erase ( IteratorType pos )
{
// make sure iterator fits the current value
if ( this ! = pos . m_object )
{
JSON_THROW ( invalid_iterator : : create ( 202 , " iterator does not fit current value " ) ) ;
}
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 ( ! pos . m_it . primitive_iterator . is_begin ( ) )
{
JSON_THROW ( invalid_iterator : : create ( 205 , " iterator out of range " ) ) ;
}
if ( is_string ( ) )
{
std : : allocator < std : : string > alloc ;
alloc . destroy ( m_value . string ) ;
alloc . deallocate ( m_value . string , 1 ) ;
m_value . string = nullptr ;
}
m_type = value_t : : null ;
assert_invariant ( ) ;
break ;
}
case value_t : : object :
{
m_value . object - > erase ( pos . m_it . object_iterator ) ;
break ;
}
case value_t : : array :
{
m_value . array - > erase ( pos . m_it . array_iterator ) ;
break ;
}
default :
{
JSON_THROW ( type_error : : create ( 307 , " cannot use erase() with " + type_name ( ) ) ) ;
}
}
}
/*!
@ brief remove elements given an iterator range
Removes the element specified by the range ` [ first ; last ) ` . The iterator
@ a first does not need to be dereferenceable if ` first = = last ` : erasing
an empty range is a no - op .
If called on a primitive type other than ` null ` , the resulting JSON value
will be ` null ` .
@ param [ in ] first iterator to the beginning of the range to remove
@ param [ in ] last iterator past the end of the range to remove
@ return Iterator following the last removed element . If the iterator @ a
second refers to the last element , the ` end ( ) ` iterator is returned .
@ tparam IteratorType an @ ref iterator or @ ref const_iterator
@ post Invalidates iterators and references at or after the point of the
erase , including the ` end ( ) ` iterator .
@ throw type_error .307 if called on a ` null ` value ; example : ` " cannot use
erase ( ) with null " `
@ throw invalid_iterator .203 if called on iterators which does not belong
to the current JSON value ; example : ` " iterators do not fit current value " `
@ throw invalid_iterator .204 if called on a primitive type with invalid
iterators ( i . e . , if ` first ! = begin ( ) ` and ` last ! = end ( ) ` ) ; example :
` " iterators out of range " `
@ complexity The complexity depends on the type :
- objects : ` log ( size ( ) ) + std : : distance ( first , last ) `
- arrays : linear in the distance between @ a first and @ a last , plus linear
in the distance between @ a last and end of the container
- strings : linear in the length of the string
- other types : constant
@ liveexample { The example shows the result of ` erase ( ) ` for different JSON
types . , erase__IteratorType_IteratorType }
@ sa @ ref erase ( IteratorType ) - - removes the element at a given position
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@ sa @ ref erase ( StringRef ) - - removes the element
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from an object at the given key
@ sa @ ref erase ( const size_type ) - - removes the element from an array at
the given index
@ since version 1.0 .0
*/
template < class IteratorType , typename std : : enable_if <
std : : is_same < IteratorType , json : : iterator > : : value | |
std : : is_same < IteratorType , json : : const_iterator > : : value , int > : : type
= 0 >
void erase ( IteratorType first , IteratorType last )
{
// make sure iterator fits the current value
if ( this ! = first . m_object | | this ! = last . m_object )
{
JSON_THROW ( invalid_iterator : : create ( 203 , " iterators do not fit current value " ) ) ;
}
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 ( ! first . m_it . primitive_iterator . is_begin ( ) | | ! last . m_it . primitive_iterator . is_end ( ) )
{
JSON_THROW ( invalid_iterator : : create ( 204 , " iterators out of range " ) ) ;
}
if ( is_string ( ) )
{
std : : allocator < std : : string > alloc ;
alloc . destroy ( m_value . string ) ;
alloc . deallocate ( m_value . string , 1 ) ;
m_value . string = nullptr ;
}
m_type = value_t : : null ;
assert_invariant ( ) ;
break ;
}
case value_t : : array :
{
m_value . array - > erase ( first . m_it . array_iterator ,
last . m_it . array_iterator ) ;
break ;
}
default :
{
JSON_THROW ( type_error : : create ( 307 , " cannot use erase() with " + type_name ( ) ) ) ;
}
}
}
/*!
@ brief remove element from a JSON object given a key
Removes elements from a JSON object with the key value @ a key .
@ param [ in ] key value of the elements to remove
@ return Number of elements removed .
The return value will always be ` 0 ` ( @ a key was not
found ) or ` 1 ` ( @ a key was found ) .
@ post References and iterators to the erased elements are invalidated .
Other references and iterators are not affected .
@ throw type_error .307 when called on a type other than JSON object ;
example : ` " cannot use erase() with null " `
@ complexity ` log ( size ( ) ) + count ( key ) `
@ liveexample { The example shows the effect of ` erase ( ) ` . , erase__key_type }
@ sa @ ref erase ( IteratorType ) - - removes the element at a given position
@ sa @ ref erase ( IteratorType , IteratorType ) - - removes the elements in
the given range
@ sa @ ref erase ( const size_type ) - - removes the element from an array at
the given index
@ since version 1.0 .0
*/
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size_type erase ( StringRef key ) ;
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/*!
@ brief remove element from a JSON array given an index
Removes element from a JSON array at the index @ a idx .
@ param [ in ] idx index of the element to remove
@ throw type_error .307 when called on a type other than JSON object ;
example : ` " cannot use erase() with null " `
@ throw out_of_range .401 when ` idx > = size ( ) ` ; example : ` " array index 17
is out of range " `
@ complexity Linear in distance between @ a idx and the end of the container .
@ liveexample { The example shows the effect of ` erase ( ) ` . , erase__size_type }
@ sa @ ref erase ( IteratorType ) - - removes the element at a given position
@ sa @ ref erase ( IteratorType , IteratorType ) - - removes the elements in
the given range
2018-04-29 23:33:19 -07:00
@ sa @ ref erase ( StringRef ) - - removes the element
2017-06-15 13:22:55 -07:00
from an object at the given key
@ since version 1.0 .0
*/
void erase ( const size_type idx ) ;
/// @}
////////////
// lookup //
////////////
/// @name lookup
/// @{
/*!
@ brief find an element in a JSON object
Finds an element in a JSON object with key equivalent to @ a key . If the
element is not found or the JSON value is not an object , end ( ) is
returned .
@ note This method always returns @ ref end ( ) when executed on a JSON type
that is not an object .
@ param [ in ] key key value of the element to search for
@ return Iterator to an element with key equivalent to @ a key . If no such
element is found or the JSON value is not an object , past - the - end ( see
@ ref end ( ) ) iterator is returned .
@ complexity Logarithmic in the size of the JSON object .
@ liveexample { The example shows how ` find ( ) ` is used . , find__key_type }
@ since version 1.0 .0
*/
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iterator find ( StringRef key ) ;
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/*!
@ brief find an element in a JSON object
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@ copydoc find ( StringRef )
2017-06-15 13:22:55 -07:00
*/
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const_iterator find ( StringRef key ) const ;
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/*!
@ brief returns the number of occurrences of a key in a JSON object
Returns the number of elements with key @ a key .
The return value will always be ` 0 ` ( @ a key was
not found ) or ` 1 ` ( @ a key was found ) .
@ note This method always returns ` 0 ` when executed on a JSON type that is
not an object .
@ param [ in ] key key value of the element to count
@ return Number of elements with key @ a key . If the JSON value is not an
object , the return value will be ` 0 ` .
@ complexity Logarithmic in the size of the JSON object .
@ liveexample { The example shows how ` count ( ) ` is used . , count }
@ since version 1.0 .0
*/
2018-04-29 23:33:19 -07:00
size_type count ( StringRef key ) const
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{
// return 0 for all nonobject types
return is_object ( ) ? m_value . object - > count ( key ) : 0 ;
}
/// @}
///////////////
// iterators //
///////////////
/// @name iterators
/// @{
/*!
@ brief returns an iterator to the first element
Returns an iterator to the first element .
@ image html range - begin - end . svg " Illustration from cppreference.com "
@ return iterator to the first element
@ complexity Constant .
@ requirement This function helps ` json ` satisfying the
[ Container ] ( http : //en.cppreference.com/w/cpp/concept/Container)
requirements :
- The complexity is constant .
@ liveexample { The following code shows an example for ` begin ( ) ` . , begin }
@ sa @ ref cbegin ( ) - - returns a const iterator to the beginning
@ sa @ ref end ( ) - - returns an iterator to the end
@ sa @ ref cend ( ) - - returns a const iterator to the end
@ since version 1.0 .0
*/
iterator begin ( ) noexcept
{
iterator result ( this ) ;
result . set_begin ( ) ;
return result ;
}
/*!
@ copydoc json : : cbegin ( )
*/
const_iterator begin ( ) const noexcept
{
return cbegin ( ) ;
}
/*!
@ brief returns a const iterator to the first element
Returns a const iterator to the first element .
@ image html range - begin - end . svg " Illustration from cppreference.com "
@ return const iterator to the first element
@ complexity Constant .
@ requirement This function helps ` json ` satisfying the
[ Container ] ( http : //en.cppreference.com/w/cpp/concept/Container)
requirements :
- The complexity is constant .
- Has the semantics of ` const_cast < const json & > ( * this ) . begin ( ) ` .
@ liveexample { The following code shows an example for ` cbegin ( ) ` . , cbegin }
@ sa @ ref begin ( ) - - returns an iterator to the beginning
@ sa @ ref end ( ) - - returns an iterator to the end
@ sa @ ref cend ( ) - - returns a const iterator to the end
@ since version 1.0 .0
*/
const_iterator cbegin ( ) const noexcept
{
const_iterator result ( this ) ;
result . set_begin ( ) ;
return result ;
}
/*!
@ brief returns an iterator to one past the last element
Returns an iterator to one past the last element .
@ image html range - begin - end . svg " Illustration from cppreference.com "
@ return iterator one past the last element
@ complexity Constant .
@ requirement This function helps ` json ` satisfying the
[ Container ] ( http : //en.cppreference.com/w/cpp/concept/Container)
requirements :
- The complexity is constant .
@ liveexample { The following code shows an example for ` end ( ) ` . , end }
@ sa @ ref cend ( ) - - returns a const iterator to the end
@ sa @ ref begin ( ) - - returns an iterator to the beginning
@ sa @ ref cbegin ( ) - - returns a const iterator to the beginning
@ since version 1.0 .0
*/
iterator end ( ) noexcept
{
iterator result ( this ) ;
result . set_end ( ) ;
return result ;
}
/*!
@ copydoc json : : cend ( )
*/
const_iterator end ( ) const noexcept
{
return cend ( ) ;
}
/*!
@ brief returns a const iterator to one past the last element
Returns a const iterator to one past the last element .
@ image html range - begin - end . svg " Illustration from cppreference.com "
@ return const iterator one past the last element
@ complexity Constant .
@ requirement This function helps ` json ` satisfying the
[ Container ] ( http : //en.cppreference.com/w/cpp/concept/Container)
requirements :
- The complexity is constant .
- Has the semantics of ` const_cast < const json & > ( * this ) . end ( ) ` .
@ liveexample { The following code shows an example for ` cend ( ) ` . , cend }
@ sa @ ref end ( ) - - returns an iterator to the end
@ sa @ ref begin ( ) - - returns an iterator to the beginning
@ sa @ ref cbegin ( ) - - returns a const iterator to the beginning
@ since version 1.0 .0
*/
const_iterator cend ( ) const noexcept
{
const_iterator result ( this ) ;
result . set_end ( ) ;
return result ;
}
private :
// forward declaration
template < typename IteratorType > class iteration_proxy ;
public :
/*!
@ brief wrapper to access iterator member functions in range - based for
This function allows to access @ ref iterator : : key ( ) and @ ref
iterator : : value ( ) during range - based for loops . In these loops , a
reference to the JSON values is returned , so there is no access to the
underlying iterator .
@ liveexample { The following code shows how the wrapper is used , iterator_wrapper }
@ note The name of this function is not yet final and may change in the
future .
*/
static iteration_proxy < iterator > iterator_wrapper ( reference cont )
{
return iteration_proxy < iterator > ( cont ) ;
}
/*!
@ copydoc iterator_wrapper ( reference )
*/
static iteration_proxy < const_iterator > iterator_wrapper ( const_reference cont )
{
return iteration_proxy < const_iterator > ( cont ) ;
}
/// @}
//////////////
// capacity //
//////////////
/// @name capacity
/// @{
/*!
@ brief checks whether the container is empty
Checks if a JSON value has no elements .
@ return The return value depends on the different types and is
defined as follows :
Value type | return value
- - - - - - - - - - - | - - - - - - - - - - - - -
null | ` true `
boolean | ` false `
string | ` false `
number | ` false `
object | result of function ` object_t : : empty ( ) `
array | result of function ` array_t : : empty ( ) `
@ note This function does not return whether a string stored as JSON value
is empty - it returns whether the JSON container itself is empty which is
false in the case of a string .
@ complexity Constant , as long as @ ref array_t and @ ref object_t satisfy
the Container concept ; that is , their ` empty ( ) ` functions have constant
complexity .
@ requirement This function helps ` json ` satisfying the
[ Container ] ( http : //en.cppreference.com/w/cpp/concept/Container)
requirements :
- The complexity is constant .
- Has the semantics of ` begin ( ) = = end ( ) ` .
@ liveexample { The following code uses ` empty ( ) ` to check if a JSON
object contains any elements . , empty }
@ sa @ ref size ( ) - - returns the number of elements
@ since version 1.0 .0
*/
bool empty ( ) const noexcept ;
/*!
@ brief returns the number of elements
Returns the number of elements in a JSON value .
@ return The return value depends on the different types and is
defined as follows :
Value type | return value
- - - - - - - - - - - | - - - - - - - - - - - - -
null | ` 0 `
boolean | ` 1 `
string | ` 1 `
number | ` 1 `
object | result of function object_t : : size ( )
array | result of function array_t : : size ( )
@ note This function does not return the length of a string stored as JSON
value - it returns the number of elements in the JSON value which is 1 in
the case of a string .
@ complexity Constant , as long as @ ref array_t and @ ref object_t satisfy
the Container concept ; that is , their size ( ) functions have constant
complexity .
@ requirement This function helps ` json ` satisfying the
[ Container ] ( http : //en.cppreference.com/w/cpp/concept/Container)
requirements :
- The complexity is constant .
- Has the semantics of ` std : : distance ( begin ( ) , end ( ) ) ` .
@ liveexample { The following code calls ` size ( ) ` on the different value
types . , size }
@ sa @ ref empty ( ) - - checks whether the container is empty
@ sa @ ref max_size ( ) - - returns the maximal number of elements
@ since version 1.0 .0
*/
size_type size ( ) const noexcept ;
/*!
@ brief returns the maximum possible number of elements
Returns the maximum number of elements a JSON value is able to hold due to
system or library implementation limitations , i . e . ` std : : distance ( begin ( ) ,
end ( ) ) ` for the JSON value .
@ return The return value depends on the different types and is
defined as follows :
Value type | return value
- - - - - - - - - - - | - - - - - - - - - - - - -
null | ` 0 ` ( same as ` size ( ) ` )
boolean | ` 1 ` ( same as ` size ( ) ` )
string | ` 1 ` ( same as ` size ( ) ` )
number | ` 1 ` ( same as ` size ( ) ` )
object | result of function ` object_t : : max_size ( ) `
array | result of function ` array_t : : max_size ( ) `
@ complexity Constant , as long as @ ref array_t and @ ref object_t satisfy
the Container concept ; that is , their ` max_size ( ) ` functions have constant
complexity .
@ requirement This function helps ` json ` satisfying the
[ Container ] ( http : //en.cppreference.com/w/cpp/concept/Container)
requirements :
- The complexity is constant .
- Has the semantics of returning ` b . size ( ) ` where ` b ` is the largest
possible JSON value .
@ liveexample { The following code calls ` max_size ( ) ` on the different value
types . Note the output is implementation specific . , max_size }
@ sa @ ref size ( ) - - returns the number of elements
@ since version 1.0 .0
*/
size_type max_size ( ) const noexcept ;
/// @}
///////////////
// modifiers //
///////////////
/// @name modifiers
/// @{
/*!
@ brief clears the contents
Clears the content of a JSON value and resets it to the default value as
if @ ref json ( value_t ) would have been called :
Value type | initial value
- - - - - - - - - - - | - - - - - - - - - - - - -
null | ` null `
boolean | ` false `
string | ` " " `
number | ` 0 `
object | ` { } `
array | ` [ ] `
@ complexity Linear in the size of the JSON value .
@ liveexample { The example below shows the effect of ` clear ( ) ` to different
JSON types . , clear }
@ since version 1.0 .0
*/
void clear ( ) noexcept ;
/*!
@ brief add an object to an array
Appends the given element @ a val to the end of the JSON value . If the
function is called on a JSON null value , an empty array is created before
appending @ a val .
@ param [ in ] val the value to add to the JSON array
@ throw type_error .308 when called on a type other than JSON array or
null ; example : ` " cannot use push_back() with number " `
@ complexity Amortized constant .
@ liveexample { The example shows how ` push_back ( ) ` and ` + = ` can be used to
add elements to a JSON array . Note how the ` null ` value was silently
converted to a JSON array . , push_back }
@ since version 1.0 .0
*/
void push_back ( json & & val ) ;
/*!
@ brief add an object to an array
@ copydoc push_back ( json & & )
*/
reference operator + = ( json & & val )
{
push_back ( std : : move ( val ) ) ;
return * this ;
}
/*!
@ brief add an object to an array
@ copydoc push_back ( json & & )
*/
void push_back ( const json & val ) ;
/*!
@ brief add an object to an array
@ copydoc push_back ( json & & )
*/
reference operator + = ( const json & val )
{
push_back ( val ) ;
return * this ;
}
/*!
@ brief add an object to an object
Inserts the given element @ a val to the JSON object . If the function is
called on a JSON null value , an empty object is created before inserting
@ a val .
@ param [ in ] val the value to add to the JSON object
@ throw type_error .308 when called on a type other than JSON object or
null ; example : ` " cannot use push_back() with number " `
@ complexity Logarithmic in the size of the container , O ( log ( ` size ( ) ` ) ) .
@ liveexample { The example shows how ` push_back ( ) ` and ` + = ` can be used to
add elements to a JSON object . Note how the ` null ` value was silently
converted to a JSON object . , push_back__object_t__value }
@ since version 1.0 .0
*/
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void push_back ( const std : : pair < StringRef , json > & val ) ;
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/*!
@ brief add an object to an object
@ copydoc push_back ( const typename object_t : : value_type & )
*/
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reference operator + = ( const std : : pair < StringRef , json > & val )
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{
push_back ( val ) ;
return * this ;
}
/*!
@ brief add an object to an object
This function allows to use ` push_back ` with an initializer list . In case
1. the current value is an object ,
2. the initializer list @ a init contains only two elements , and
3. the first element of @ a init is a string ,
@ a init is converted into an object element and added using
@ ref push_back ( const typename object_t : : value_type & ) . Otherwise , @ a init
is converted to a JSON value and added using @ ref push_back ( json & & ) .
@ param [ in ] init an initializer list
@ complexity Linear in the size of the initializer list @ a init .
@ note This function is required to resolve an ambiguous overload error ,
because pairs like ` { " key " , " value " } ` can be both interpreted as
` object_t : : value_type ` or ` std : : initializer_list < json > ` , see
https : //github.com/nlohmann/json/issues/235 for more information.
@ liveexample { The example shows how initializer lists are treated as
objects when possible . , push_back__initializer_list }
*/
void push_back ( std : : initializer_list < json > init ) ;
/*!
@ brief add an object to an object
@ copydoc push_back ( std : : initializer_list < json > )
*/
reference operator + = ( std : : initializer_list < json > init )
{
push_back ( init ) ;
return * this ;
}
/*!
@ brief add an object to an array
Creates a JSON value from the passed parameters @ a args to the end of the
JSON value . If the function is called on a JSON null value , an empty array
is created before appending the value created from @ a args .
@ param [ in ] args arguments to forward to a constructor of @ ref json
@ tparam Args compatible types to create a @ ref json object
@ throw type_error .311 when called on a type other than JSON array or
null ; example : ` " cannot use emplace_back() with number " `
@ complexity Amortized constant .
@ liveexample { The example shows how ` push_back ( ) ` can be used to add
elements to a JSON array . Note how the ` null ` value was silently converted
to a JSON array . , emplace_back }
@ since version 2.0 .8
*/
template < class . . . Args >
void emplace_back ( Args & & . . . args )
{
// emplace_back only works for null objects or arrays
if ( ! ( is_null ( ) | | is_array ( ) ) )
{
JSON_THROW ( type_error : : create ( 311 , " cannot use emplace_back() with " + type_name ( ) ) ) ;
}
// transform null object into an array
if ( is_null ( ) )
{
m_type = value_t : : array ;
m_value = value_t : : array ;
assert_invariant ( ) ;
}
// add element to array (perfect forwarding)
m_value . array - > emplace_back ( std : : forward < Args > ( args ) . . . ) ;
}
/*!
@ brief add an object to an object if key does not exist
Inserts a new element into a JSON object constructed in - place with the
given @ a args if there is no element with the key in the container . If the
function is called on a JSON null value , an empty object is created before
appending the value created from @ a args .
@ param [ in ] args arguments to forward to a constructor of @ ref json
@ tparam Args compatible types to create a @ ref json object
@ return a pair consisting of an iterator to the inserted element , or the
already - existing element if no insertion happened , and a bool
denoting whether the insertion took place .
@ throw type_error .311 when called on a type other than JSON object or
null ; example : ` " cannot use emplace() with number " `
@ complexity Logarithmic in the size of the container , O ( log ( ` size ( ) ` ) ) .
@ liveexample { The example shows how ` emplace ( ) ` can be used to add elements
to a JSON object . Note how the ` null ` value was silently converted to a
JSON object . Further note how no value is added if there was already one
value stored with the same key . , emplace }
@ since version 2.0 .8
*/
template < class . . . Args >
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std : : pair < iterator , bool > emplace ( StringRef key , Args & & . . . args )
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{
// emplace only works for null objects or arrays
if ( ! ( is_null ( ) | | is_object ( ) ) )
{
JSON_THROW ( type_error : : create ( 311 , " cannot use emplace() with " + type_name ( ) ) ) ;
}
// transform null object into an object
if ( is_null ( ) )
{
m_type = value_t : : object ;
m_value = value_t : : object ;
assert_invariant ( ) ;
}
// add element to array (perfect forwarding)
auto res = m_value . object - > emplace_second ( key , std : : forward < Args > ( args ) . . . ) ;
// create result iterator and set iterator to the result of emplace
auto it = begin ( ) ;
it . m_it . object_iterator = res . first ;
// return pair of iterator and boolean
return { it , res . second } ;
}
/*!
@ brief inserts element
Inserts element @ a val before iterator @ a pos .
@ param [ in ] pos iterator before which the content will be inserted ; may be
the end ( ) iterator
@ param [ in ] val element to insert
@ return iterator pointing to the inserted @ a val .
@ throw type_error .309 if called on JSON values other than arrays ;
example : ` " cannot use insert() with string " `
@ throw invalid_iterator .202 if @ a pos is not an iterator of * this ;
example : ` " iterator does not fit current value " `
@ complexity Constant plus linear in the distance between @ a pos and end of
the container .
@ liveexample { The example shows how ` insert ( ) ` is used . , insert }
@ since version 1.0 .0
*/
iterator insert ( const_iterator pos , const json & val ) ;
/*!
@ brief inserts element
@ copydoc insert ( const_iterator , const json & )
*/
iterator insert ( const_iterator pos , json & & val )
{
return insert ( pos , val ) ;
}
/*!
@ brief inserts elements
Inserts @ a cnt copies of @ a val before iterator @ a pos .
@ param [ in ] pos iterator before which the content will be inserted ; may be
the end ( ) iterator
@ param [ in ] cnt number of copies of @ a val to insert
@ param [ in ] val element to insert
@ return iterator pointing to the first element inserted , or @ a pos if
` cnt = = 0 `
@ throw type_error .309 if called on JSON values other than arrays ; example :
` " cannot use insert() with string " `
@ throw invalid_iterator .202 if @ a pos is not an iterator of * this ;
example : ` " iterator does not fit current value " `
@ complexity Linear in @ a cnt plus linear in the distance between @ a pos
and end of the container .
@ liveexample { The example shows how ` insert ( ) ` is used . , insert__count }
@ since version 1.0 .0
*/
iterator insert ( const_iterator pos , size_type cnt , const json & val ) ;
/*!
@ brief inserts elements
Inserts elements from range ` [ first , last ) ` before iterator @ a pos .
@ param [ in ] pos iterator before which the content will be inserted ; may be
the end ( ) iterator
@ param [ in ] first begin of the range of elements to insert
@ param [ in ] last end of the range of elements to insert
@ throw type_error .309 if called on JSON values other than arrays ; example :
` " cannot use insert() with string " `
@ throw invalid_iterator .202 if @ a pos is not an iterator of * this ;
example : ` " iterator does not fit current value " `
@ throw invalid_iterator .210 if @ a first and @ a last do not belong to the
same JSON value ; example : ` " iterators do not fit " `
@ throw invalid_iterator .211 if @ a first or @ a last are iterators into
container for which insert is called ; example : ` " passed iterators may not
belong to container " `
@ return iterator pointing to the first element inserted , or @ a pos if
` first = = last `
@ complexity Linear in ` std : : distance ( first , last ) ` plus linear in the
distance between @ a pos and end of the container .
@ liveexample { The example shows how ` insert ( ) ` is used . , insert__range }
@ since version 1.0 .0
*/
iterator insert ( const_iterator pos , const_iterator first , const_iterator last ) ;
/*!
@ brief inserts elements
Inserts elements from initializer list @ a ilist before iterator @ a pos .
@ param [ in ] pos iterator before which the content will be inserted ; may be
the end ( ) iterator
@ param [ in ] ilist initializer list to insert the values from
@ throw type_error .309 if called on JSON values other than arrays ; example :
` " cannot use insert() with string " `
@ throw invalid_iterator .202 if @ a pos is not an iterator of * this ;
example : ` " iterator does not fit current value " `
@ return iterator pointing to the first element inserted , or @ a pos if
` ilist ` is empty
@ complexity Linear in ` ilist . size ( ) ` plus linear in the distance between
@ a pos and end of the container .
@ liveexample { The example shows how ` insert ( ) ` is used . , insert__ilist }
@ since version 1.0 .0
*/
iterator insert ( const_iterator pos , std : : initializer_list < json > ilist ) ;
/*!
@ brief inserts elements
Inserts elements from range ` [ first , last ) ` .
@ param [ in ] first begin of the range of elements to insert
@ param [ in ] last end of the range of elements to insert
@ throw type_error .309 if called on JSON values other than objects ; example :
` " cannot use insert() with string " `
@ throw invalid_iterator .202 if iterator @ a first or @ a last does does not
point to an object ; example : ` " iterators first and last must point to
objects " `
@ throw invalid_iterator .210 if @ a first and @ a last do not belong to the
same JSON value ; example : ` " iterators do not fit " `
@ complexity Logarithmic : ` O ( N * log ( size ( ) + N ) ) ` , where ` N ` is the number
of elements to insert .
@ liveexample { The example shows how ` insert ( ) ` is used . , insert__range_object }
@ since version 3.0 .0
*/
void insert ( const_iterator first , const_iterator last ) ;
/*!
@ brief exchanges the values
Exchanges the contents of the JSON value with those of @ a other . Does not
invoke any move , copy , or swap operations on individual elements . All
iterators and references remain valid . The past - the - end iterator is
invalidated .
@ param [ in , out ] other JSON value to exchange the contents with
@ complexity Constant .
@ liveexample { The example below shows how JSON values can be swapped with
` swap ( ) ` . , swap__reference }
@ since version 1.0 .0
*/
void swap ( reference other ) noexcept (
std : : is_nothrow_move_constructible < value_t > : : value & &
std : : is_nothrow_move_assignable < value_t > : : value & &
std : : is_nothrow_move_constructible < json_value > : : value & &
std : : is_nothrow_move_assignable < json_value > : : value
)
{
std : : swap ( m_type , other . m_type ) ;
std : : swap ( m_value , other . m_value ) ;
assert_invariant ( ) ;
}
/*!
@ brief exchanges the values
Exchanges the contents of a JSON array with those of @ a other . Does not
invoke any move , copy , or swap operations on individual elements . All
iterators and references remain valid . The past - the - end iterator is
invalidated .
@ param [ in , out ] other array to exchange the contents with
@ throw type_error .310 when JSON value is not an array ; example : ` " cannot
use swap ( ) with string " `
@ complexity Constant .
@ liveexample { The example below shows how arrays can be swapped with
` swap ( ) ` . , swap__array_t }
@ since version 1.0 .0
*/
void swap ( array_t & other )
{
// swap only works for arrays
if ( is_array ( ) )
{
std : : swap ( * ( m_value . array ) , other ) ;
}
else
{
JSON_THROW ( type_error : : create ( 310 , " cannot use swap() with " + type_name ( ) ) ) ;
}
}
/*!
@ brief exchanges the values
Exchanges the contents of a JSON object with those of @ a other . Does not
invoke any move , copy , or swap operations on individual elements . All
iterators and references remain valid . The past - the - end iterator is
invalidated .
@ param [ in , out ] other object to exchange the contents with
@ throw type_error .310 when JSON value is not an object ; example :
` " cannot use swap() with string " `
@ complexity Constant .
@ liveexample { The example below shows how objects can be swapped with
` swap ( ) ` . , swap__object_t }
@ since version 1.0 .0
*/
void swap ( object_t & other )
{
// swap only works for objects
if ( is_object ( ) )
{
std : : swap ( * ( m_value . object ) , other ) ;
}
else
{
JSON_THROW ( type_error : : create ( 310 , " cannot use swap() with " + type_name ( ) ) ) ;
}
}
/*!
@ brief exchanges the values
Exchanges the contents of a JSON string with those of @ a other . Does not
invoke any move , copy , or swap operations on individual elements . All
iterators and references remain valid . The past - the - end iterator is
invalidated .
@ param [ in , out ] other string to exchange the contents with
@ throw type_error .310 when JSON value is not a string ; example : ` " cannot
use swap ( ) with boolean " `
@ complexity Constant .
@ liveexample { The example below shows how strings can be swapped with
` swap ( ) ` . , swap__std : : string }
@ since version 1.0 .0
*/
void swap ( std : : string & other )
{
// swap only works for strings
if ( is_string ( ) )
{
std : : swap ( * ( m_value . string ) , other ) ;
}
else
{
JSON_THROW ( type_error : : create ( 310 , " cannot use swap() with " + type_name ( ) ) ) ;
}
}
/// @}
public :
//////////////////////////////////////////
// lexicographical comparison operators //
//////////////////////////////////////////
/// @name lexicographical comparison operators
/// @{
/*!
@ brief comparison : equal
Compares two JSON values for equality according to the following rules :
- Two JSON values are equal if ( 1 ) they are from the same type and ( 2 )
their stored values are the same according to their respective
` operator = = ` .
- Integer and floating - point numbers are automatically converted before
comparison . Floating - point numbers are compared indirectly : two
floating - point numbers ` f1 ` and ` f2 ` are considered equal if neither
` f1 > f2 ` nor ` f2 > f1 ` holds . Note than two NaN values are always
treated as unequal .
- Two JSON null values are equal .
@ note NaN values never compare equal to themselves or to other NaN values .
@ param [ in ] lhs first JSON value to consider
@ param [ in ] rhs second JSON value to consider
@ return whether the values @ a lhs and @ a rhs are equal
@ complexity Linear .
@ liveexample { The example demonstrates comparing several JSON
types . , operator__equal }
@ since version 1.0 .0
*/
friend bool operator = = ( const_reference lhs , const_reference rhs ) noexcept ;
/*!
@ brief comparison : equal
@ copydoc operator = = ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator = = ( const_reference lhs , const ScalarType rhs ) noexcept
{
return ( lhs = = json ( rhs ) ) ;
}
/*!
@ brief comparison : equal
@ copydoc operator = = ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator = = ( const ScalarType lhs , const_reference rhs ) noexcept
{
return ( json ( lhs ) = = rhs ) ;
}
/*!
@ brief comparison : not equal
Compares two JSON values for inequality by calculating ` not ( lhs = = rhs ) ` .
@ param [ in ] lhs first JSON value to consider
@ param [ in ] rhs second JSON value to consider
@ return whether the values @ a lhs and @ a rhs are not equal
@ complexity Linear .
@ liveexample { The example demonstrates comparing several JSON
types . , operator__notequal }
@ since version 1.0 .0
*/
friend bool operator ! = ( const_reference lhs , const_reference rhs ) noexcept
{
return ! ( lhs = = rhs ) ;
}
/*!
@ brief comparison : not equal
@ copydoc operator ! = ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator ! = ( const_reference lhs , const ScalarType rhs ) noexcept
{
return ( lhs ! = json ( rhs ) ) ;
}
/*!
@ brief comparison : not equal
@ copydoc operator ! = ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator ! = ( const ScalarType lhs , const_reference rhs ) noexcept
{
return ( json ( lhs ) ! = rhs ) ;
}
/*!
@ brief comparison : less than
Compares whether one JSON value @ a lhs is less than another JSON value @ a
rhs according to the following rules :
- If @ a lhs and @ a rhs have the same type , the values are compared using
the default ` < ` operator .
- Integer and floating - point numbers are automatically converted before
comparison
- In case @ a lhs and @ a rhs have different types , the values are ignored
and the order of the types is considered , see
@ ref operator < ( const value_t , const value_t ) .
@ param [ in ] lhs first JSON value to consider
@ param [ in ] rhs second JSON value to consider
@ return whether @ a lhs is less than @ a rhs
@ complexity Linear .
@ liveexample { The example demonstrates comparing several JSON
types . , operator__less }
@ since version 1.0 .0
*/
friend bool operator < ( const_reference lhs , const_reference rhs ) noexcept ;
/*!
@ brief comparison : less than
@ copydoc operator < ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator < ( const_reference lhs , const ScalarType rhs ) noexcept
{
return ( lhs < json ( rhs ) ) ;
}
/*!
@ brief comparison : less than
@ copydoc operator < ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator < ( const ScalarType lhs , const_reference rhs ) noexcept
{
return ( json ( lhs ) < rhs ) ;
}
/*!
@ brief comparison : less than or equal
Compares whether one JSON value @ a lhs is less than or equal to another
JSON value by calculating ` not ( rhs < lhs ) ` .
@ param [ in ] lhs first JSON value to consider
@ param [ in ] rhs second JSON value to consider
@ return whether @ a lhs is less than or equal to @ a rhs
@ complexity Linear .
@ liveexample { The example demonstrates comparing several JSON
types . , operator__greater }
@ since version 1.0 .0
*/
friend bool operator < = ( const_reference lhs , const_reference rhs ) noexcept
{
return ! ( rhs < lhs ) ;
}
/*!
@ brief comparison : less than or equal
@ copydoc operator < = ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator < = ( const_reference lhs , const ScalarType rhs ) noexcept
{
return ( lhs < = json ( rhs ) ) ;
}
/*!
@ brief comparison : less than or equal
@ copydoc operator < = ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator < = ( const ScalarType lhs , const_reference rhs ) noexcept
{
return ( json ( lhs ) < = rhs ) ;
}
/*!
@ brief comparison : greater than
Compares whether one JSON value @ a lhs is greater than another
JSON value by calculating ` not ( lhs < = rhs ) ` .
@ param [ in ] lhs first JSON value to consider
@ param [ in ] rhs second JSON value to consider
@ return whether @ a lhs is greater than to @ a rhs
@ complexity Linear .
@ liveexample { The example demonstrates comparing several JSON
types . , operator__lessequal }
@ since version 1.0 .0
*/
friend bool operator > ( const_reference lhs , const_reference rhs ) noexcept
{
return ! ( lhs < = rhs ) ;
}
/*!
@ brief comparison : greater than
@ copydoc operator > ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator > ( const_reference lhs , const ScalarType rhs ) noexcept
{
return ( lhs > json ( rhs ) ) ;
}
/*!
@ brief comparison : greater than
@ copydoc operator > ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator > ( const ScalarType lhs , const_reference rhs ) noexcept
{
return ( json ( lhs ) > rhs ) ;
}
/*!
@ brief comparison : greater than or equal
Compares whether one JSON value @ a lhs is greater than or equal to another
JSON value by calculating ` not ( lhs < rhs ) ` .
@ param [ in ] lhs first JSON value to consider
@ param [ in ] rhs second JSON value to consider
@ return whether @ a lhs is greater than or equal to @ a rhs
@ complexity Linear .
@ liveexample { The example demonstrates comparing several JSON
types . , operator__greaterequal }
@ since version 1.0 .0
*/
friend bool operator > = ( const_reference lhs , const_reference rhs ) noexcept
{
return ! ( lhs < rhs ) ;
}
/*!
@ brief comparison : greater than or equal
@ copydoc operator > = ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator > = ( const_reference lhs , const ScalarType rhs ) noexcept
{
return ( lhs > = json ( rhs ) ) ;
}
/*!
@ brief comparison : greater than or equal
@ copydoc operator > = ( const_reference , const_reference )
*/
template < typename ScalarType , typename std : : enable_if <
std : : is_scalar < ScalarType > : : value , int > : : type = 0 >
friend bool operator > = ( const ScalarType lhs , const_reference rhs ) noexcept
{
return ( json ( lhs ) > = rhs ) ;
}
/// @}
///////////////////
// serialization //
///////////////////
/// @name serialization
/// @{
public :
/*!
@ brief serialize to stream
Serialize the given JSON value @ a j to the output stream @ a o . The JSON
value will be serialized using the @ ref dump member function .
- The indentation of the output can be controlled with the member variable
` width ` of the output stream @ a o . For instance , using the manipulator
` std : : setw ( 4 ) ` on @ a o sets the indentation level to ` 4 ` and the
serialization result is the same as calling ` dump ( 4 ) ` .
- The indentation characrer can be controlled with the member variable
` fill ` of the output stream @ a o . For instance , the manipulator
` std : : setfill ( ' \ \ t ' ) ` sets indentation to use a tab character rather than
the default space character .
@ param [ in , out ] o stream to serialize to
@ param [ in ] j JSON value to serialize
@ return the stream @ a o
@ complexity Linear .
@ liveexample { The example below shows the serialization with different
parameters to ` width ` to adjust the indentation level . , operator_serialize }
@ since version 1.0 .0 ; indentaction character added in version 3.0 .0
*/
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friend raw_ostream & operator < < ( raw_ostream & o , const json & j ) ;
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/// @}
/////////////////////
// deserialization //
/////////////////////
/// @name deserialization
/// @{
/*!
@ brief deserialize from string literal
@ tparam CharT character / literal type with size of 1 byte
@ param [ in ] s string literal to read a serialized JSON value from
@ param [ in ] cb a parser callback function of type @ ref parser_callback_t
which is used to control the deserialization by filtering unwanted values
( optional )
@ return result of the deserialization
@ throw parse_error .101 in case of an unexpected token
@ throw parse_error .102 if to_unicode fails or surrogate error
@ throw parse_error .103 if to_unicode fails
@ 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 .
@ note String containers like ` std : : string ` can be parsed
with @ ref parse ( const ContiguousContainer & , const parser_callback_t )
@ liveexample { The example below demonstrates the ` parse ( ) ` function with
and without callback function . , parse__string__parser_callback_t }
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@ sa @ ref parse ( raw_istream & , const parser_callback_t ) for a version
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that reads from an input stream
@ since version 1.0 .0 ( originally for std : : string )
*/
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static json parse ( StringRef s ,
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const parser_callback_t cb = nullptr ) ;
/*!
@ brief deserialize from stream
@ param [ in , out ] i stream to read a serialized JSON value from
@ param [ in ] cb a parser callback function of type @ ref parser_callback_t
which is used to control the deserialization by filtering unwanted values
( optional )
@ return result of the deserialization
@ throw parse_error .101 in case of an unexpected token
@ throw parse_error .102 if to_unicode fails or surrogate error
@ throw parse_error .103 if to_unicode fails
@ throw parse_error .111 if input stream is in a bad state
@ 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 .
@ liveexample { The example below demonstrates the ` parse ( ) ` function with
and without callback function . , parse__raw_istream__parser_callback_t }
@ sa @ ref parse ( const CharT , const parser_callback_t ) for a version
that reads from a string
@ since version 1.0 .0
*/
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static json parse ( raw_istream & i ,
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const parser_callback_t cb = nullptr ) ;
/*!
@ brief deserialize from stream
Deserializes an input stream to a JSON value .
@ param [ in , out ] i input stream to read a serialized JSON value from
@ param [ in , out ] j JSON value to write the deserialized input to
@ throw parse_error .101 in case of an unexpected token
@ throw parse_error .102 if to_unicode fails or surrogate error
@ throw parse_error .103 if to_unicode fails
@ throw parse_error .111 if input stream is in a bad state
@ complexity Linear in the length of the input . The parser is a predictive
LL ( 1 ) parser .
@ note A UTF - 8 byte order mark is silently ignored .
@ liveexample { The example below shows how a JSON value is constructed by
reading a serialization from a stream . , operator_deserialize }
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@ sa parse ( raw_istream & , const parser_callback_t ) for a variant with a
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parser callback function to filter values while parsing
@ since version 1.0 .0
*/
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friend raw_istream & operator > > ( raw_istream & i , json & j ) ;
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/// @}
///////////////////////////
// convenience functions //
///////////////////////////
/*!
@ brief return the type as string
Returns the type name as string to be used in error messages - usually to
indicate that a function was called on a wrong JSON type .
@ return basically a string representation of a the @ a m_type member
@ complexity Constant .
@ liveexample { The following code exemplifies ` type_name ( ) ` for all JSON
types . , type_name }
@ since version 1.0 .0 , public since 2.1 .0
*/
std : : string type_name ( ) const ;
private :
//////////////////////
// member variables //
//////////////////////
/// the type of the current element
value_t m_type = value_t : : null ;
/// the value of the current element
json_value m_value = { } ;
private :
///////////////
// iterators //
///////////////
/*!
@ brief an iterator for primitive JSON types
This class models an iterator for primitive JSON types ( boolean , number ,
string ) . It ' s only purpose is to allow the iterator / const_iterator classes
to " iterate " over primitive values . Internally , the iterator is modeled by
a ` difference_type ` variable . Value begin_value ( ` 0 ` ) models the begin ,
end_value ( ` 1 ` ) models past the end .
*/
class primitive_iterator_t
{
public :
difference_type get_value ( ) const noexcept
{
return m_it ;
}
/// set iterator to a defined beginning
void set_begin ( ) noexcept
{
m_it = begin_value ;
}
/// set iterator to a defined past the end
void set_end ( ) noexcept
{
m_it = end_value ;
}
/// return whether the iterator can be dereferenced
constexpr bool is_begin ( ) const noexcept
{
return ( m_it = = begin_value ) ;
}
/// return whether the iterator is at end
constexpr bool is_end ( ) const noexcept
{
return ( m_it = = end_value ) ;
}
friend constexpr bool operator = = ( primitive_iterator_t lhs , primitive_iterator_t rhs ) noexcept
{
return lhs . m_it = = rhs . m_it ;
}
friend constexpr bool operator ! = ( primitive_iterator_t lhs , primitive_iterator_t rhs ) noexcept
{
return ! ( lhs = = rhs ) ;
}
friend constexpr bool operator < ( primitive_iterator_t lhs , primitive_iterator_t rhs ) noexcept
{
return lhs . m_it < rhs . m_it ;
}
friend constexpr bool operator < = ( primitive_iterator_t lhs , primitive_iterator_t rhs ) noexcept
{
return lhs . m_it < = rhs . m_it ;
}
friend constexpr bool operator > ( primitive_iterator_t lhs , primitive_iterator_t rhs ) noexcept
{
return lhs . m_it > rhs . m_it ;
}
friend constexpr bool operator > = ( primitive_iterator_t lhs , primitive_iterator_t rhs ) noexcept
{
return lhs . m_it > = rhs . m_it ;
}
primitive_iterator_t operator + ( difference_type i )
{
auto result = * this ;
result + = i ;
return result ;
}
friend constexpr difference_type operator - ( primitive_iterator_t lhs , primitive_iterator_t rhs ) noexcept
{
return lhs . m_it - rhs . m_it ;
}
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friend raw_ostream & operator < < ( raw_ostream & os , primitive_iterator_t it )
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{
return os < < it . m_it ;
}
primitive_iterator_t & operator + + ( )
{
+ + m_it ;
return * this ;
}
primitive_iterator_t operator + + ( int )
{
auto result = * this ;
m_it + + ;
return result ;
}
primitive_iterator_t & operator - - ( )
{
- - m_it ;
return * this ;
}
primitive_iterator_t operator - - ( int )
{
auto result = * this ;
m_it - - ;
return result ;
}
primitive_iterator_t & operator + = ( difference_type n )
{
m_it + = n ;
return * this ;
}
primitive_iterator_t & operator - = ( difference_type n )
{
m_it - = n ;
return * this ;
}
private :
static constexpr difference_type begin_value = 0 ;
static constexpr difference_type end_value = begin_value + 1 ;
/// iterator as signed integer type
difference_type m_it = std : : numeric_limits < std : : ptrdiff_t > : : denorm_min ( ) ;
} ;
/*!
@ brief an iterator value
@ note This structure could easily be a union , but MSVC currently does not
allow unions members with complex constructors , see
https : //github.com/nlohmann/json/pull/105.
*/
struct internal_iterator
{
/// iterator for JSON objects
typename object_t : : iterator object_iterator ;
/// iterator for JSON arrays
typename array_t : : iterator array_iterator ;
/// generic iterator for all other types
primitive_iterator_t primitive_iterator ;
/// create an uninitialized internal_iterator
internal_iterator ( ) noexcept
: object_iterator ( ) , array_iterator ( ) , primitive_iterator ( )
{ }
} ;
/// proxy class for the iterator_wrapper functions
template < typename IteratorType >
class iteration_proxy
{
private :
/// helper class for iteration
class iteration_proxy_internal
{
private :
/// the iterator
IteratorType anchor ;
/// an index for arrays (used to create key names)
size_t array_index = 0 ;
public :
explicit iteration_proxy_internal ( IteratorType it ) noexcept
: anchor ( it )
{ }
/// dereference operator (needed for range-based for)
iteration_proxy_internal & operator * ( )
{
return * this ;
}
/// increment operator (needed for range-based for)
iteration_proxy_internal & operator + + ( )
{
+ + anchor ;
+ + array_index ;
return * this ;
}
/// inequality operator (needed for range-based for)
bool operator ! = ( const iteration_proxy_internal & o ) const
{
return anchor ! = o . anchor ;
}
/// return key of the iterator
std : : string key ( ) const
{
assert ( anchor . m_object ! = nullptr ) ;
switch ( anchor . m_object - > type ( ) )
{
// use integer array index as key
case value_t : : array :
{
return std : : to_string ( array_index ) ;
}
// use key from the object
case value_t : : object :
{
return anchor . key ( ) ;
}
// use an empty key for all primitive types
default :
{
return " " ;
}
}
}
/// return value of the iterator
typename IteratorType : : reference value ( ) const
{
return anchor . value ( ) ;
}
} ;
/// the container to iterate
typename IteratorType : : reference container ;
public :
/// construct iteration proxy from a container
explicit iteration_proxy ( typename IteratorType : : reference cont )
: container ( cont )
{ }
/// return iterator begin (needed for range-based for)
iteration_proxy_internal begin ( ) noexcept
{
return iteration_proxy_internal ( container . begin ( ) ) ;
}
/// return iterator end (needed for range-based for)
iteration_proxy_internal end ( ) noexcept
{
return iteration_proxy_internal ( container . end ( ) ) ;
}
} ;
public :
/*!
@ brief a template for a random access iterator for the @ ref json class
This class implements a both iterators ( iterator and const_iterator ) for the
@ ref json class .
@ note An iterator is called * initialized * when a pointer to a JSON value
has been set ( e . g . , by a constructor or a copy assignment ) . If the
iterator is default - constructed , it is * uninitialized * and most
methods are undefined . * * The library uses assertions to detect calls
on uninitialized iterators . * *
@ requirement The class satisfies the following concept requirements :
- [ RandomAccessIterator ] ( http : //en.cppreference.com/w/cpp/concept/RandomAccessIterator):
The iterator that can be moved to point ( forward and backward ) to any
element in constant time .
@ since version 1.0 .0 , simplified in version 2.0 .9
*/
template < typename U >
class iter_impl : public std : : iterator < std : : random_access_iterator_tag , U >
{
/// allow json to access private members
friend class json ;
friend class JsonTest ;
// make sure U is json or const json
static_assert ( std : : is_same < U , json > : : value
| | std : : is_same < U , const json > : : value ,
" iter_impl only accepts (const) json " ) ;
public :
/// the type of the values when the iterator is dereferenced
using value_type = typename json : : value_type ;
/// a type to represent differences between iterators
using difference_type = typename json : : difference_type ;
/// defines a pointer to the type iterated over (value_type)
using pointer = typename std : : conditional < std : : is_const < U > : : value ,
typename json : : const_pointer ,
typename json : : pointer > : : type ;
/// defines a reference to the type iterated over (value_type)
using reference = typename std : : conditional < std : : is_const < U > : : value ,
typename json : : const_reference ,
typename json : : reference > : : type ;
/// the category of the iterator
using iterator_category = std : : bidirectional_iterator_tag ;
/// default constructor
iter_impl ( ) noexcept : m_object ( nullptr ) { }
/*!
@ brief constructor for a given JSON instance
@ param [ in ] object pointer to a JSON object for this iterator
@ pre object ! = nullptr
@ post The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
explicit iter_impl ( pointer object ) noexcept
: m_object ( object )
{
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
m_it . object_iterator = typename object_t : : iterator ( ) ;
break ;
}
case json : : value_t : : array :
{
m_it . array_iterator = typename array_t : : iterator ( ) ;
break ;
}
default :
{
m_it . primitive_iterator = primitive_iterator_t ( ) ;
break ;
}
}
}
/*!
@ note The conventional copy constructor and copy assignment are
implicitly defined .
Combined with the following converting constructor and assigment ,
they support : copy from iterator to iterator ,
copy from const iterator to const iterator ,
and conversion from iterator to const iterator .
However conversion from const iterator to iterator is not defined .
*/
/*!
@ brief converting constructor
@ param [ in ] other non - const iterator to copy from
@ note It is not checked whether @ a other is initialized .
*/
iter_impl ( const iter_impl < json > & other ) noexcept
: m_object ( other . m_object ) , m_it ( other . m_it )
{ }
/*!
@ brief converting assignment
@ param [ in , out ] other non - const iterator to copy from
@ return const / non - const iterator
@ note It is not checked whether @ a other is initialized .
*/
iter_impl & operator = ( const iter_impl < json > & other ) noexcept
{
m_object = other . m_object ;
m_it = other . m_it ;
return * this ;
}
private :
/*!
@ brief set the iterator to the first value
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
void set_begin ( ) noexcept
{
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
m_it . object_iterator = m_object - > m_value . object - > begin ( ) ;
break ;
}
case json : : value_t : : array :
{
m_it . array_iterator = m_object - > m_value . array - > begin ( ) ;
break ;
}
case json : : value_t : : null :
{
// set to end so begin()==end() is true: null is empty
m_it . primitive_iterator . set_end ( ) ;
break ;
}
default :
{
m_it . primitive_iterator . set_begin ( ) ;
break ;
}
}
}
/*!
@ brief set the iterator past the last value
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
void set_end ( ) noexcept
{
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
m_it . object_iterator = m_object - > m_value . object - > end ( ) ;
break ;
}
case json : : value_t : : array :
{
m_it . array_iterator = m_object - > m_value . array - > end ( ) ;
break ;
}
default :
{
m_it . primitive_iterator . set_end ( ) ;
break ;
}
}
}
public :
/*!
@ brief return a reference to the value pointed to by the iterator
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
reference operator * ( ) const
{
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
assert ( m_it . object_iterator ! = m_object - > m_value . object - > end ( ) ) ;
return m_it . object_iterator - > second ;
}
case json : : value_t : : array :
{
assert ( m_it . array_iterator ! = m_object - > m_value . array - > end ( ) ) ;
return * m_it . array_iterator ;
}
case json : : value_t : : null :
{
JSON_THROW ( invalid_iterator : : create ( 214 , " cannot get value " ) ) ;
}
default :
{
if ( m_it . primitive_iterator . is_begin ( ) )
{
return * m_object ;
}
JSON_THROW ( invalid_iterator : : create ( 214 , " cannot get value " ) ) ;
}
}
}
/*!
@ brief dereference the iterator
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
pointer operator - > ( ) const
{
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
assert ( m_it . object_iterator ! = m_object - > m_value . object - > end ( ) ) ;
return & ( m_it . object_iterator - > second ) ;
}
case json : : value_t : : array :
{
assert ( m_it . array_iterator ! = m_object - > m_value . array - > end ( ) ) ;
return & * m_it . array_iterator ;
}
default :
{
if ( m_it . primitive_iterator . is_begin ( ) )
{
return m_object ;
}
JSON_THROW ( invalid_iterator : : create ( 214 , " cannot get value " ) ) ;
}
}
}
/*!
@ brief post - increment ( it + + )
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
iter_impl operator + + ( int )
{
auto result = * this ;
+ + ( * this ) ;
return result ;
}
/*!
@ brief pre - increment ( + + it )
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
iter_impl & operator + + ( )
{
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
+ + m_it . object_iterator ;
break ;
}
case json : : value_t : : array :
{
+ + m_it . array_iterator ;
break ;
}
default :
{
+ + m_it . primitive_iterator ;
break ;
}
}
return * this ;
}
/*!
@ brief post - decrement ( it - - )
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
iter_impl operator - - ( int )
{
auto result = * this ;
- - ( * this ) ;
return result ;
}
/*!
@ brief pre - decrement ( - - it )
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
iter_impl & operator - - ( )
{
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
JSON_THROW ( invalid_iterator : : create ( 209 , " cannot decrement object iterators " ) ) ;
break ;
}
case json : : value_t : : array :
{
std : : advance ( m_it . array_iterator , - 1 ) ;
break ;
}
default :
{
- - m_it . primitive_iterator ;
break ;
}
}
return * this ;
}
/*!
@ brief comparison : equal
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
bool operator = = ( const iter_impl & other ) const
{
// if objects are not the same, the comparison is undefined
if ( m_object ! = other . m_object )
{
JSON_THROW ( invalid_iterator : : create ( 212 , " cannot compare iterators of different containers " ) ) ;
}
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
return ( m_it . object_iterator = = other . m_it . object_iterator ) ;
}
case json : : value_t : : array :
{
return ( m_it . array_iterator = = other . m_it . array_iterator ) ;
}
default :
{
return ( m_it . primitive_iterator = = other . m_it . primitive_iterator ) ;
}
}
}
/*!
@ brief comparison : not equal
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
bool operator ! = ( const iter_impl & other ) const
{
return ! operator = = ( other ) ;
}
/*!
@ brief comparison : smaller
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
bool operator < ( const iter_impl & other ) const
{
// if objects are not the same, the comparison is undefined
if ( m_object ! = other . m_object )
{
JSON_THROW ( invalid_iterator : : create ( 212 , " cannot compare iterators of different containers " ) ) ;
}
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
JSON_THROW ( invalid_iterator : : create ( 213 , " cannot compare order of object iterators " ) ) ;
}
case json : : value_t : : array :
{
return ( m_it . array_iterator < other . m_it . array_iterator ) ;
}
default :
{
return ( m_it . primitive_iterator < other . m_it . primitive_iterator ) ;
}
}
}
/*!
@ brief comparison : less than or equal
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
bool operator < = ( const iter_impl & other ) const
{
return ! ( other . operator < ( * this ) ) ;
}
/*!
@ brief comparison : greater than
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
bool operator > ( const iter_impl & other ) const
{
return ! operator < = ( other ) ;
}
/*!
@ brief comparison : greater than or equal
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
bool operator > = ( const iter_impl & other ) const
{
return ! operator < ( other ) ;
}
/*!
@ brief add to iterator
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
iter_impl & operator + = ( difference_type i )
{
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
JSON_THROW ( invalid_iterator : : create ( 209 , " cannot use offsets with object iterators " ) ) ;
}
case json : : value_t : : array :
{
std : : advance ( m_it . array_iterator , i ) ;
break ;
}
default :
{
m_it . primitive_iterator + = i ;
break ;
}
}
return * this ;
}
/*!
@ brief subtract from iterator
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
iter_impl & operator - = ( difference_type i )
{
return operator + = ( - i ) ;
}
/*!
@ brief add to iterator
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
iter_impl operator + ( difference_type i ) const
{
auto result = * this ;
result + = i ;
return result ;
}
/*!
@ brief addition of distance and iterator
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
friend iter_impl operator + ( difference_type i , const iter_impl & it )
{
auto result = it ;
result + = i ;
return result ;
}
/*!
@ brief subtract from iterator
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
iter_impl operator - ( difference_type i ) const
{
auto result = * this ;
result - = i ;
return result ;
}
/*!
@ brief return difference
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
difference_type operator - ( const iter_impl & other ) const
{
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
JSON_THROW ( invalid_iterator : : create ( 209 , " cannot use offsets with object iterators " ) ) ;
}
case json : : value_t : : array :
{
return m_it . array_iterator - other . m_it . array_iterator ;
}
default :
{
return m_it . primitive_iterator - other . m_it . primitive_iterator ;
}
}
}
/*!
@ brief access to successor
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
reference operator [ ] ( difference_type n ) const
{
assert ( m_object ! = nullptr ) ;
switch ( m_object - > m_type )
{
case json : : value_t : : object :
{
JSON_THROW ( invalid_iterator : : create ( 208 , " cannot use operator[] for object iterators " ) ) ;
}
case json : : value_t : : array :
{
return * std : : next ( m_it . array_iterator , n ) ;
}
case json : : value_t : : null :
{
JSON_THROW ( invalid_iterator : : create ( 214 , " cannot get value " ) ) ;
}
default :
{
if ( m_it . primitive_iterator . get_value ( ) = = - n )
{
return * m_object ;
}
JSON_THROW ( invalid_iterator : : create ( 214 , " cannot get value " ) ) ;
}
}
}
/*!
@ brief return the key of an object iterator
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
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StringRef key ( ) const
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{
assert ( m_object ! = nullptr ) ;
if ( m_object - > is_object ( ) )
{
return m_it . object_iterator - > first ( ) ;
}
JSON_THROW ( invalid_iterator : : create ( 207 , " cannot use key() for non-object iterators " ) ) ;
}
/*!
@ brief return the value of an iterator
@ pre The iterator is initialized ; i . e . ` m_object ! = nullptr ` .
*/
reference value ( ) const
{
return operator * ( ) ;
}
private :
/// associated JSON instance
pointer m_object ;
/// the actual iterator of the associated instance
struct internal_iterator m_it = internal_iterator ( ) ;
} ;
//////////////////////////////////////////
// binary serialization/deserialization //
//////////////////////////////////////////
/// @name binary serialization/deserialization support
/// @{
public :
/*!
@ brief create a CBOR serialization of a given JSON value
Serializes a given JSON value @ a j to a byte vector using the CBOR ( Concise
Binary Object Representation ) serialization format . CBOR is a binary
serialization format which aims to be more compact than JSON itself , yet
more efficient to parse .
The library uses the following mapping from JSON values types to
CBOR types according to the CBOR specification ( RFC 7049 ) :
JSON value type | value / range | CBOR type | first byte
- - - - - - - - - - - - - - - | - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - | - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - | - - - - - - - - - - - - - - -
null | ` null ` | Null | 0xf6
boolean | ` true ` | True | 0xf5
boolean | ` false ` | False | 0xf4
number_integer | - 9223372036854775808. . - 2147483649 | Negative integer ( 8 bytes follow ) | 0x3b
number_integer | - 2147483648. . - 32769 | Negative integer ( 4 bytes follow ) | 0x3a
number_integer | - 32768. . - 129 | Negative integer ( 2 bytes follow ) | 0x39
number_integer | - 128. . - 25 | Negative integer ( 1 byte follow ) | 0x38
number_integer | - 24. . - 1 | Negative integer | 0x20 . .0 x37
number_integer | 0. .23 | Integer | 0x00 . .0 x17
number_integer | 24. .255 | Unsigned integer ( 1 byte follow ) | 0x18
number_integer | 256. .65535 | Unsigned integer ( 2 bytes follow ) | 0x19
number_integer | 65536. .4294967295 | Unsigned integer ( 4 bytes follow ) | 0x1a
number_integer | 4294967296. .18446744073709551615 | Unsigned integer ( 8 bytes follow ) | 0x1b
number_unsigned | 0. .23 | Integer | 0x00 . .0 x17
number_unsigned | 24. .255 | Unsigned integer ( 1 byte follow ) | 0x18
number_unsigned | 256. .65535 | Unsigned integer ( 2 bytes follow ) | 0x19
number_unsigned | 65536. .4294967295 | Unsigned integer ( 4 bytes follow ) | 0x1a
number_unsigned | 4294967296. .18446744073709551615 | Unsigned integer ( 8 bytes follow ) | 0x1b
number_float | * any value * | Double - Precision Float | 0xfb
string | * length * : 0. .23 | UTF - 8 string | 0x60 . .0 x77
string | * length * : 23. .255 | UTF - 8 string ( 1 byte follow ) | 0x78
string | * length * : 256. .65535 | UTF - 8 string ( 2 bytes follow ) | 0x79
string | * length * : 65536. .4294967295 | UTF - 8 string ( 4 bytes follow ) | 0x7a
string | * length * : 4294967296. .18446744073709551615 | UTF - 8 string ( 8 bytes follow ) | 0x7b
array | * size * : 0. .23 | array | 0x80 . .0 x97
array | * size * : 23. .255 | array ( 1 byte follow ) | 0x98
array | * size * : 256. .65535 | array ( 2 bytes follow ) | 0x99
array | * size * : 65536. .4294967295 | array ( 4 bytes follow ) | 0x9a
array | * size * : 4294967296. .18446744073709551615 | array ( 8 bytes follow ) | 0x9b
object | * size * : 0. .23 | map | 0xa0 . .0 xb7
object | * size * : 23. .255 | map ( 1 byte follow ) | 0xb8
object | * size * : 256. .65535 | map ( 2 bytes follow ) | 0xb9
object | * size * : 65536. .4294967295 | map ( 4 bytes follow ) | 0xba
object | * size * : 4294967296. .18446744073709551615 | map ( 8 bytes follow ) | 0xbb
@ note The mapping is * * complete * * in the sense that any JSON value type
can be converted to a CBOR value .
@ note The following CBOR types are not used in the conversion :
- byte strings ( 0x40 . .0 x5f )
- UTF - 8 strings terminated by " break " ( 0x7f )
- arrays terminated by " break " ( 0x9f )
- maps terminated by " break " ( 0xbf )
- date / time ( 0xc0 . .0 xc1 )
- bignum ( 0xc2 . .0 xc3 )
- decimal fraction ( 0xc4 )
- bigfloat ( 0xc5 )
- tagged items ( 0xc6 . .0 xd4 , 0xd8 . .0 xdb )
- expected conversions ( 0xd5 . .0 xd7 )
- simple values ( 0xe0 . .0 xf3 , 0xf8 )
- undefined ( 0xf7 )
- half and single - precision floats ( 0xf9 - 0xfa )
- break ( 0xff )
@ param [ in , out ] os output stream
@ param [ in ] j JSON value to serialize
@ complexity Linear in the size of the JSON value @ a j .
@ liveexample { The example shows the serialization of a JSON value to a byte
vector in CBOR format . , to_cbor }
@ sa http : //cbor.io
@ sa @ ref from_cbor ( const std : : vector < uint8_t > & , const size_t ) for the
analogous deserialization
@ sa @ ref to_msgpack ( const json & for the related MessagePack format
@ since version 2.0 .9
*/
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static void to_cbor ( raw_ostream & os , const json & j ) ;
static StringRef to_cbor ( const json & j , SmallVectorImpl < char > buf ) ;
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static std : : string to_cbor ( const json & j ) ;
/*!
@ brief create a MessagePack serialization of a given JSON value
Serializes a given JSON value @ a j to a byte vector using the MessagePack
serialization format . MessagePack is a binary serialization format which
aims to be more compact than JSON itself , yet more efficient to parse .
The library uses the following mapping from JSON values types to
MessagePack types according to the MessagePack specification :
JSON value type | value / range | MessagePack type | first byte
- - - - - - - - - - - - - - - | - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - | - - - - - - - - - - - - - - - - | - - - - - - - - - -
null | ` null ` | nil | 0xc0
boolean | ` true ` | true | 0xc3
boolean | ` false ` | false | 0xc2
number_integer | - 9223372036854775808. . - 2147483649 | int64 | 0xd3
number_integer | - 2147483648. . - 32769 | int32 | 0xd2
number_integer | - 32768. . - 129 | int16 | 0xd1
number_integer | - 128. . - 33 | int8 | 0xd0
number_integer | - 32. . - 1 | negative fixint | 0xe0 . .0 xff
number_integer | 0. .127 | positive fixint | 0x00 . .0 x7f
number_integer | 128. .255 | uint 8 | 0xcc
number_integer | 256. .65535 | uint 16 | 0xcd
number_integer | 65536. .4294967295 | uint 32 | 0xce
number_integer | 4294967296. .18446744073709551615 | uint 64 | 0xcf
number_unsigned | 0. .127 | positive fixint | 0x00 . .0 x7f
number_unsigned | 128. .255 | uint 8 | 0xcc
number_unsigned | 256. .65535 | uint 16 | 0xcd
number_unsigned | 65536. .4294967295 | uint 32 | 0xce
number_unsigned | 4294967296. .18446744073709551615 | uint 64 | 0xcf
number_float | * any value * | float 64 | 0xcb
string | * length * : 0. .31 | fixstr | 0xa0 . .0 xbf
string | * length * : 32. .255 | str 8 | 0xd9
string | * length * : 256. .65535 | str 16 | 0xda
string | * length * : 65536. .4294967295 | str 32 | 0xdb
array | * size * : 0. .15 | fixarray | 0x90 . .0 x9f
array | * size * : 16. .65535 | array 16 | 0xdc
array | * size * : 65536. .4294967295 | array 32 | 0xdd
object | * size * : 0. .15 | fix map | 0x80 . .0 x8f
object | * size * : 16. .65535 | map 16 | 0xde
object | * size * : 65536. .4294967295 | map 32 | 0xdf
@ note The mapping is * * complete * * in the sense that any JSON value type
can be converted to a MessagePack value .
@ note The following values can * * not * * be converted to a MessagePack value :
- strings with more than 4294967295 bytes
- arrays with more than 4294967295 elements
- objects with more than 4294967295 elements
@ note The following MessagePack types are not used in the conversion :
- bin 8 - bin 32 ( 0xc4 . .0 xc6 )
- ext 8 - ext 32 ( 0xc7 . .0 xc9 )
- float 32 ( 0xca )
- fixext 1 - fixext 16 ( 0xd4 . .0 xd8 )
@ note Any MessagePack output created @ ref to_msgpack can be successfully
parsed by @ ref from_msgpack .
@ param [ in , out ] os output stream
@ param [ in ] j JSON value to serialize
@ complexity Linear in the size of the JSON value @ a j .
@ liveexample { The example shows the serialization of a JSON value to a byte
vector in MessagePack format . , to_msgpack }
@ sa http : //msgpack.org
@ sa @ ref from_msgpack ( const std : : vector < uint8_t > & , const size_t ) for the
analogous deserialization
@ sa @ ref to_cbor ( const json & for the related CBOR format
@ since version 2.0 .9
*/
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static void to_msgpack ( raw_ostream & os , const json & j ) ;
static StringRef to_msgpack ( const json & j , SmallVectorImpl < char > buf ) ;
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static std : : string to_msgpack ( const json & j ) ;
/*!
@ brief create a JSON value from a byte vector in CBOR format
Deserializes a given byte vector @ a v to a JSON value using the CBOR
( Concise Binary Object Representation ) serialization format .
The library maps CBOR types to JSON value types as follows :
CBOR type | JSON value type | first byte
- - - - - - - - - - - - - - - - - - - - - - | - - - - - - - - - - - - - - - | - - - - - - - - - -
Integer | number_unsigned | 0x00 . .0 x17
Unsigned integer | number_unsigned | 0x18
Unsigned integer | number_unsigned | 0x19
Unsigned integer | number_unsigned | 0x1a
Unsigned integer | number_unsigned | 0x1b
Negative integer | number_integer | 0x20 . .0 x37
Negative integer | number_integer | 0x38
Negative integer | number_integer | 0x39
Negative integer | number_integer | 0x3a
Negative integer | number_integer | 0x3b
Negative integer | number_integer | 0x40 . .0 x57
UTF - 8 string | string | 0x60 . .0 x77
UTF - 8 string | string | 0x78
UTF - 8 string | string | 0x79
UTF - 8 string | string | 0x7a
UTF - 8 string | string | 0x7b
UTF - 8 string | string | 0x7f
array | array | 0x80 . .0 x97
array | array | 0x98
array | array | 0x99
array | array | 0x9a
array | array | 0x9b
array | array | 0x9f
map | object | 0xa0 . .0 xb7
map | object | 0xb8
map | object | 0xb9
map | object | 0xba
map | object | 0xbb
map | object | 0xbf
False | ` false ` | 0xf4
True | ` true ` | 0xf5
Nill | ` null ` | 0xf6
Half - Precision Float | number_float | 0xf9
Single - Precision Float | number_float | 0xfa
Double - Precision Float | number_float | 0xfb
@ warning The mapping is * * incomplete * * in the sense that not all CBOR
types can be converted to a JSON value . The following CBOR types
are not supported and will yield parse errors ( parse_error .112 ) :
- byte strings ( 0x40 . .0 x5f )
- date / time ( 0xc0 . .0 xc1 )
- bignum ( 0xc2 . .0 xc3 )
- decimal fraction ( 0xc4 )
- bigfloat ( 0xc5 )
- tagged items ( 0xc6 . .0 xd4 , 0xd8 . .0 xdb )
- expected conversions ( 0xd5 . .0 xd7 )
- simple values ( 0xe0 . .0 xf3 , 0xf8 )
- undefined ( 0xf7 )
@ warning CBOR allows map keys of any type , whereas JSON only allows
strings as keys in object values . Therefore , CBOR maps with keys
other than UTF - 8 strings are rejected ( parse_error .113 ) .
@ note Any CBOR output created @ ref to_cbor can be successfully parsed by
@ ref from_cbor .
@ param [ in ] is an input stream in CBOR format
@ return deserialized JSON value
@ throw parse_error .110 if the given vector ends prematurely
@ throw parse_error .112 if unsupported features from CBOR were
used in the given vector @ a v or if the input is not valid CBOR
@ throw parse_error .113 if a string was expected as map key , but not found
@ complexity Linear in the size of the byte vector @ a v .
@ liveexample { The example shows the deserialization of a byte vector in CBOR
format to a JSON value . , from_cbor }
@ sa http : //cbor.io
@ sa @ ref to_cbor ( const json & ) for the analogous serialization
@ sa @ ref from_msgpack ( const std : : vector < uint8_t > & , const size_t ) for the
related MessagePack format
@ since version 2.0 .9 , parameter @ a start_index since 2.1 .1
*/
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static json from_cbor ( raw_istream & is ) ;
static json from_cbor ( StringRef s ) ;
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/*!
@ brief create a JSON value from a byte vector in MessagePack format
Deserializes a given byte vector @ a v to a JSON value using the MessagePack
serialization format .
The library maps MessagePack types to JSON value types as follows :
MessagePack type | JSON value type | first byte
- - - - - - - - - - - - - - - - | - - - - - - - - - - - - - - - | - - - - - - - - - -
positive fixint | number_unsigned | 0x00 . .0 x7f
fixmap | object | 0x80 . .0 x8f
fixarray | array | 0x90 . .0 x9f
fixstr | string | 0xa0 . .0 xbf
nil | ` null ` | 0xc0
false | ` false ` | 0xc2
true | ` true ` | 0xc3
float 32 | number_float | 0xca
float 64 | number_float | 0xcb
uint 8 | number_unsigned | 0xcc
uint 16 | number_unsigned | 0xcd
uint 32 | number_unsigned | 0xce
uint 64 | number_unsigned | 0xcf
int 8 | number_integer | 0xd0
int 16 | number_integer | 0xd1
int 32 | number_integer | 0xd2
int 64 | number_integer | 0xd3
str 8 | string | 0xd9
str 16 | string | 0xda
str 32 | string | 0xdb
array 16 | array | 0xdc
array 32 | array | 0xdd
map 16 | object | 0xde
map 32 | object | 0xdf
negative fixint | number_integer | 0xe0 - 0xff
@ warning The mapping is * * incomplete * * in the sense that not all
MessagePack types can be converted to a JSON value . The following
MessagePack types are not supported and will yield parse errors :
- bin 8 - bin 32 ( 0xc4 . .0 xc6 )
- ext 8 - ext 32 ( 0xc7 . .0 xc9 )
- fixext 1 - fixext 16 ( 0xd4 . .0 xd8 )
@ note Any MessagePack output created @ ref to_msgpack can be successfully
parsed by @ ref from_msgpack .
@ param [ in ] is an input stream in MessagePack format
@ return deserialized JSON value
@ throw parse_error .110 if the given vector ends prematurely
@ throw parse_error .112 if unsupported features from MessagePack were
used in the given vector @ a v or if the input is not valid MessagePack
@ throw parse_error .113 if a string was expected as map key , but not found
@ complexity Linear in the size of the byte vector @ a v .
@ liveexample { The example shows the deserialization of a byte vector in
MessagePack format to a JSON value . , from_msgpack }
@ sa http : //msgpack.org
@ sa @ ref to_msgpack ( const json & ) for the analogous serialization
@ sa @ ref from_cbor ( const std : : vector < uint8_t > & , const size_t ) for the
related CBOR format
@ since version 2.0 .9 , parameter @ a start_index since 2.1 .1
*/
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static json from_msgpack ( raw_istream & is ) ;
static json from_msgpack ( StringRef s ) ;
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/// @}
public :
/*!
@ brief JSON Pointer
A JSON pointer defines a string syntax for identifying a specific value
within a JSON document . It can be used with functions ` at ` and
` operator [ ] ` . Furthermore , JSON pointers are the base for JSON patches .
@ sa [ RFC 6901 ] ( https : //tools.ietf.org/html/rfc6901)
@ since version 2.0 .0
*/
class json_pointer
{
/// allow json to access private members
friend class json ;
friend class JsonTest ;
public :
/*!
@ brief create JSON pointer
Create a JSON pointer according to the syntax described in
[ Section 3 of RFC6901 ] ( https : //tools.ietf.org/html/rfc6901#section-3).
@ param [ in ] s string representing the JSON pointer ; if omitted , the
empty string is assumed which references the whole JSON
value
@ throw parse_error .107 if the given JSON pointer @ a s is nonempty and
does not begin with a slash ( ` / ` ) ; see example below
@ throw parse_error .108 if a tilde ( ` ~ ` ) in the given JSON pointer @ a s
is not followed by ` 0 ` ( representing ` ~ ` ) or ` 1 ` ( representing ` / ` ) ;
see example below
@ liveexample { The example shows the construction several valid JSON
pointers as well as the exceptional behavior . , json_pointer }
@ since version 2.0 .0
*/
explicit json_pointer ( const std : : string & s = " " )
: reference_tokens ( split ( s ) )
{ }
/*!
@ brief return a string representation of the JSON pointer
@ invariant For each JSON pointer ` ptr ` , it holds :
@ code { . cpp }
ptr = = json_pointer ( ptr . to_string ( ) ) ;
@ endcode
@ return a string representation of the JSON pointer
@ liveexample { The example shows the result of ` to_string ` . ,
json_pointer__to_string }
@ since version 2.0 .0
*/
std : : string to_string ( ) const noexcept ;
/// @copydoc to_string()
operator std : : string ( ) const
{
return to_string ( ) ;
}
private :
/*!
@ brief remove and return last reference pointer
@ throw out_of_range .405 if JSON pointer has no parent
*/
std : : string pop_back ( )
{
if ( is_root ( ) )
{
JSON_THROW ( out_of_range : : create ( 405 , " JSON pointer has no parent " ) ) ;
}
auto last = reference_tokens . back ( ) ;
reference_tokens . pop_back ( ) ;
return last ;
}
/// return whether pointer points to the root document
bool is_root ( ) const
{
return reference_tokens . empty ( ) ;
}
json_pointer top ( ) const
{
if ( is_root ( ) )
{
JSON_THROW ( out_of_range : : create ( 405 , " JSON pointer has no parent " ) ) ;
}
json_pointer result = * this ;
result . reference_tokens = { reference_tokens [ 0 ] } ;
return result ;
}
/*!
@ brief create and return a reference to the pointed to value
@ complexity Linear in the number of reference tokens .
@ throw parse_error .109 if array index is not a number
@ throw type_error .313 if value cannot be unflattened
*/
reference get_and_create ( reference j ) const ;
/*!
@ brief return a reference to the pointed to value
@ note This version does not throw if a value is not present , but tries
to create nested values instead . For instance , calling this function
with pointer ` " /this/that " ` on a null value is equivalent to calling
` operator [ ] ( " this " ) . operator [ ] ( " that " ) ` on that value , effectively
changing the null value to an object .
@ param [ in ] ptr a JSON value
@ return reference to the JSON value pointed to by the JSON pointer
@ complexity Linear in the length of the JSON pointer .
@ throw parse_error .106 if an array index begins with ' 0 '
@ throw parse_error .109 if an array index was not a number
@ throw out_of_range .404 if the JSON pointer can not be resolved
*/
reference get_unchecked ( pointer ptr ) const ;
/*!
@ throw parse_error .106 if an array index begins with ' 0 '
@ throw parse_error .109 if an array index was not a number
@ throw out_of_range .402 if the array index ' - ' is used
@ throw out_of_range .404 if the JSON pointer can not be resolved
*/
reference get_checked ( pointer ptr ) const ;
/*!
@ brief return a const reference to the pointed to value
@ param [ in ] ptr a JSON value
@ return const reference to the JSON value pointed to by the JSON
pointer
@ throw parse_error .106 if an array index begins with ' 0 '
@ throw parse_error .109 if an array index was not a number
@ throw out_of_range .402 if the array index ' - ' is used
@ throw out_of_range .404 if the JSON pointer can not be resolved
*/
const_reference get_unchecked ( const_pointer ptr ) const ;
/*!
@ throw parse_error .106 if an array index begins with ' 0 '
@ throw parse_error .109 if an array index was not a number
@ throw out_of_range .402 if the array index ' - ' is used
@ throw out_of_range .404 if the JSON pointer can not be resolved
*/
const_reference get_checked ( const_pointer ptr ) const ;
/*!
@ brief split the string input to reference tokens
@ note This function is only called by the json_pointer constructor .
All exceptions below are documented there .
@ throw parse_error .107 if the pointer is not empty or begins with ' / '
@ throw parse_error .108 if character ' ~ ' is not followed by ' 0 ' or ' 1 '
*/
static std : : vector < std : : string > split ( const std : : string & reference_string ) ;
/*!
@ brief replace all occurrences of a substring by another string
@ param [ in , out ] s the string to manipulate ; changed so that all
occurrences of @ a f are replaced with @ a t
@ param [ in ] f the substring to replace with @ a t
@ param [ in ] t the string to replace @ a f
@ pre The search string @ a f must not be empty . * * This precondition is
enforced with an assertion . * *
@ since version 2.0 .0
*/
static void replace_substring ( std : : string & s ,
const std : : string & f ,
const std : : string & t ) ;
/// escape tilde and slash
static std : : string escape ( std : : string s ) ;
/// unescape tilde and slash
static void unescape ( std : : string & s ) ;
/*!
@ param [ in ] reference_string the reference string to the current value
@ param [ in ] value the value to consider
@ param [ in , out ] result the result object to insert values to
@ note Empty objects or arrays are flattened to ` null ` .
*/
static void flatten ( const std : : string & reference_string ,
const json & value ,
json & result ) ;
/*!
@ param [ in ] value flattened JSON
@ return unflattened JSON
@ throw parse_error .109 if array index is not a number
@ throw type_error .314 if value is not an object
@ throw type_error .315 if object values are not primitive
@ throw type_error .313 if value cannot be unflattened
*/
static json unflatten ( const json & value ) ;
friend bool operator = = ( json_pointer const & lhs ,
json_pointer const & rhs ) noexcept
{
return lhs . reference_tokens = = rhs . reference_tokens ;
}
friend bool operator ! = ( json_pointer const & lhs ,
json_pointer const & rhs ) noexcept
{
return ! ( lhs = = rhs ) ;
}
/// the reference tokens
std : : vector < std : : string > reference_tokens { } ;
} ;
//////////////////////////
// JSON Pointer support //
//////////////////////////
/// @name JSON Pointer functions
/// @{
/*!
@ brief access specified element via JSON Pointer
Uses a JSON pointer to retrieve a reference to the respective JSON value .
No bound checking is performed . Similar to @ ref operator [ ] (
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StringRef ) , ` null ` values are created in arrays and objects if
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necessary .
In particular :
- If the JSON pointer points to an object key that does not exist , it
is created an filled with a ` null ` value before a reference to it
is returned .
- If the JSON pointer points to an array index that does not exist , it
is created an filled with a ` null ` value before a reference to it
is returned . All indices between the current maximum and the given
index are also filled with ` null ` .
- The special value ` - ` is treated as a synonym for the index past the
end .
@ param [ in ] ptr a JSON pointer
@ return reference to the element pointed to by @ a ptr
@ complexity Constant .
@ throw parse_error .106 if an array index begins with ' 0 '
@ throw parse_error .109 if an array index was not a number
@ throw out_of_range .404 if the JSON pointer can not be resolved
@ liveexample { The behavior is shown in the example . , operatorjson_pointer }
@ since version 2.0 .0
*/
reference operator [ ] ( const json_pointer & ptr )
{
return ptr . get_unchecked ( this ) ;
}
/*!
@ brief access specified element via JSON Pointer
Uses a JSON pointer to retrieve a reference to the respective JSON value .
No bound checking is performed . The function does not change the JSON
value ; no ` null ` values are created . In particular , the the special value
` - ` yields an exception .
@ param [ in ] ptr JSON pointer to the desired element
@ return const reference to the element pointed to by @ a ptr
@ complexity Constant .
@ throw parse_error .106 if an array index begins with ' 0 '
@ throw parse_error .109 if an array index was not a number
@ throw out_of_range .402 if the array index ' - ' is used
@ throw out_of_range .404 if the JSON pointer can not be resolved
@ liveexample { The behavior is shown in the example . , operatorjson_pointer_const }
@ since version 2.0 .0
*/
const_reference operator [ ] ( const json_pointer & ptr ) const
{
return ptr . get_unchecked ( this ) ;
}
/*!
@ brief access specified element via JSON Pointer
Returns a reference to the element at with specified JSON pointer @ a ptr ,
with bounds checking .
@ param [ in ] ptr JSON pointer to the desired element
@ return reference to the element pointed to by @ a ptr
@ throw parse_error .106 if an array index in the passed JSON pointer @ a ptr
begins with ' 0 ' . See example below .
@ throw parse_error .109 if an array index in the passed JSON pointer @ a ptr
is not a number . See example below .
@ throw out_of_range .401 if an array index in the passed JSON pointer @ a ptr
is out of range . See example below .
@ throw out_of_range .402 if the array index ' - ' is used in the passed JSON
pointer @ a ptr . As ` at ` provides checked access ( and no elements are
implicitly inserted ) , the index ' - ' is always invalid . See example below .
@ throw out_of_range .404 if the JSON pointer @ a ptr can not be resolved .
See example below .
@ exceptionsafety Strong guarantee : if an exception is thrown , there are no
changes in the JSON value .
@ complexity Constant .
@ since version 2.0 .0
@ liveexample { The behavior is shown in the example . , at_json_pointer }
*/
reference at ( const json_pointer & ptr )
{
return ptr . get_checked ( this ) ;
}
/*!
@ brief access specified element via JSON Pointer
Returns a const reference to the element at with specified JSON pointer @ a
ptr , with bounds checking .
@ param [ in ] ptr JSON pointer to the desired element
@ return reference to the element pointed to by @ a ptr
@ throw parse_error .106 if an array index in the passed JSON pointer @ a ptr
begins with ' 0 ' . See example below .
@ throw parse_error .109 if an array index in the passed JSON pointer @ a ptr
is not a number . See example below .
@ throw out_of_range .401 if an array index in the passed JSON pointer @ a ptr
is out of range . See example below .
@ throw out_of_range .402 if the array index ' - ' is used in the passed JSON
pointer @ a ptr . As ` at ` provides checked access ( and no elements are
implicitly inserted ) , the index ' - ' is always invalid . See example below .
@ throw out_of_range .404 if the JSON pointer @ a ptr can not be resolved .
See example below .
@ exceptionsafety Strong guarantee : if an exception is thrown , there are no
changes in the JSON value .
@ complexity Constant .
@ since version 2.0 .0
@ liveexample { The behavior is shown in the example . , at_json_pointer_const }
*/
const_reference at ( const json_pointer & ptr ) const
{
return ptr . get_checked ( this ) ;
}
/*!
@ brief return flattened JSON value
The function creates a JSON object whose keys are JSON pointers ( see [ RFC
6901 ] ( https : //tools.ietf.org/html/rfc6901)) and whose values are all
primitive . The original JSON value can be restored using the @ ref
unflatten ( ) function .
@ return an object that maps JSON pointers to primitive values
@ note Empty objects and arrays are flattened to ` null ` and will not be
reconstructed correctly by the @ ref unflatten ( ) function .
@ complexity Linear in the size the JSON value .
@ liveexample { The following code shows how a JSON object is flattened to an
object whose keys consist of JSON pointers . , flatten }
@ sa @ ref unflatten ( ) for the reverse function
@ since version 2.0 .0
*/
json flatten ( ) const
{
json result ( value_t : : object ) ;
json_pointer : : flatten ( " " , * this , result ) ;
return result ;
}
/*!
@ brief unflatten a previously flattened JSON value
The function restores the arbitrary nesting of a JSON value that has been
flattened before using the @ ref flatten ( ) function . The JSON value must
meet certain constraints :
1. The value must be an object .
2. The keys must be JSON pointers ( see
[ RFC 6901 ] ( https : //tools.ietf.org/html/rfc6901))
3. The mapped values must be primitive JSON types .
@ return the original JSON from a flattened version
@ note Empty objects and arrays are flattened by @ ref flatten ( ) to ` null `
values and can not unflattened to their original type . Apart from
this example , for a JSON value ` j ` , the following is always true :
` j = = j . flatten ( ) . unflatten ( ) ` .
@ complexity Linear in the size the JSON value .
@ throw type_error .314 if value is not an object
@ throw type_error .315 if object values are not primitve
@ liveexample { The following code shows how a flattened JSON object is
unflattened into the original nested JSON object . , unflatten }
@ sa @ ref flatten ( ) for the reverse function
@ since version 2.0 .0
*/
json unflatten ( ) const
{
return json_pointer : : unflatten ( * this ) ;
}
/// @}
} ;
} // namespace wpi
///////////////////////
// nonmember support //
///////////////////////
// specialization of std::swap, and std::hash
namespace std
{
/*!
@ brief exchanges the values of two JSON objects
@ since version 1.0 .0
*/
template < >
inline void swap ( wpi : : json & j1 ,
wpi : : json & j2 ) noexcept (
is_nothrow_move_constructible < wpi : : json > : : value & &
is_nothrow_move_assignable < wpi : : json > : : value
)
{
j1 . swap ( j2 ) ;
}
/// hash value for JSON objects
template < >
struct hash < wpi : : json >
{
/*!
@ brief return a hash value for a JSON object
@ since version 1.0 .0
*/
std : : size_t operator ( ) ( const wpi : : json & j ) const ;
} ;
/// specialization for std::less<value_t>
template < >
struct less < : : wpi : : detail : : value_t >
{
/*!
@ brief compare two value_t enum values
@ since version 3.0 .0
*/
bool operator ( ) ( wpi : : detail : : value_t lhs ,
wpi : : detail : : value_t rhs ) const noexcept
{
return wpi : : detail : : operator < ( lhs , rhs ) ;
}
} ;
} // namespace std
/*!
@ brief user - defined string literal for JSON values
This operator implements a user - defined string literal for JSON objects . It
can be used by adding ` " _json " ` to a string literal and returns a JSON object
if no parse error occurred .
@ param [ in ] s a string representation of a JSON object
@ param [ in ] n the length of string @ a s
@ return a JSON object
@ since version 1.0 .0
*/
inline wpi : : json operator " " _json ( const char * s , std : : size_t n )
{
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return wpi : : json : : parse ( wpi : : StringRef ( s , n ) ) ;
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}
/*!
@ brief user - defined string literal for JSON pointer
This operator implements a user - defined string literal for JSON Pointers . It
can be used by adding ` " _json_pointer " ` to a string literal and returns a JSON pointer
object if no parse error occurred .
@ param [ in ] s a string representation of a JSON Pointer
@ param [ in ] n the length of string @ a s
@ return a JSON pointer object
@ since version 2.0 .0
*/
inline wpi : : json : : json_pointer operator " " _json_pointer ( const char * s , std : : size_t n )
{
return wpi : : json : : json_pointer ( std : : string ( s , n ) ) ;
}
# ifndef WPI_JSON_IMPLEMENTATION
// restore GCC/clang diagnostic settings
# if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
# pragma GCC diagnostic pop
# endif
# if defined(__clang__)
# pragma GCC diagnostic pop
# endif
// clean up
# undef JSON_CATCH
# undef JSON_THROW
# undef JSON_TRY
# undef JSON_LIKELY
# undef JSON_UNLIKELY
# endif // WPI_JSON_IMPLEMENTATION
# endif