JSON Pointer. More...

#include <json.hpp>

Public Member Functions
	json_pointer (const std::string &s="")
	create JSON pointer More...

std::string	to_string () const
	return a string representation of the JSON pointer More...

	operator std::string () const
	return a string representation of the JSON pointer More...

json_pointer &	operator/= (const json_pointer &ptr)
	append another JSON pointer at the end of this JSON pointer More...

json_pointer &	operator/= (std::string token)
	append an unescaped reference token at the end of this JSON pointer More...

json_pointer &	operator/= (std::size_t array_idx)
	append an array index at the end of this JSON pointer More...

json_pointer	parent_pointer () const
	returns the parent of this JSON pointer More...

void	pop_back ()
	remove last reference token More...

const std::string &	back () const
	return last reference token More...

void	push_back (const std::string &token)
	append an unescaped token at the end of the reference pointer More...

void	push_back (std::string &&token)
	append an unescaped token at the end of the reference pointer More...

bool	empty () const noexcept
	return whether pointer points to the root document More...

Private Member Functions
BasicJsonType &	get_and_create (BasicJsonType &j) const
	create and return a reference to the pointed to value More...

BasicJsonType &	get_unchecked (BasicJsonType *ptr) const
	return a reference to the pointed to value More...

BasicJsonType &	get_checked (BasicJsonType *ptr) const

const BasicJsonType &	get_unchecked (const BasicJsonType *ptr) const
	return a const reference to the pointed to value More...

const BasicJsonType &	get_checked (const BasicJsonType *ptr) const

bool	contains (const BasicJsonType *ptr) const

Static Private Member Functions
static BasicJsonType::size_type	array_index (const std::string &s)

static std::vector< std::string >	split (const std::string &reference_string)
	split the string input to reference tokens More...

static void	replace_substring (std::string &s, const std::string &f, const std::string &t)
	replace all occurrences of a substring by another string More...

static std::string	escape (std::string s)
	escape "~" to "~0" and "/" to "~1"

static void	unescape (std::string &s)
	unescape "~1" to tilde and "~0" to slash (order is important!)

static void	flatten (const std::string &reference_string, const BasicJsonType &value, BasicJsonType &result)

static BasicJsonType	unflatten (const BasicJsonType &value)

Private Attributes
std::vector< std::string >	reference_tokens
	the reference tokens

Friends
json_pointer	operator/ (const json_pointer &lhs, const json_pointer &rhs)
	create a new JSON pointer by appending the right JSON pointer at the end of the left JSON pointer More...

json_pointer	operator/ (const json_pointer &ptr, std::string token)
	create a new JSON pointer by appending the unescaped token at the end of the JSON pointer More...

json_pointer	operator/ (const json_pointer &ptr, std::size_t array_idx)
	create a new JSON pointer by appending the array-index-token at the end of the JSON pointer More...

bool	operator== (json_pointer const &lhs, json_pointer const &rhs) noexcept
	compares two JSON pointers for equality More...

bool	operator!= (json_pointer const &lhs, json_pointer const &rhs) noexcept
	compares two JSON pointers for inequality More...

Detailed Description

template<typename BasicJsonType>
class nlohmann::json_pointer< BasicJsonType >

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.

See also: RFC 6901

Since: version 2.0.0

Constructor & Destructor Documentation

◆ json_pointer()

template<typename BasicJsonType >

nlohmann::json_pointer< BasicJsonType >::json_pointer ( const std::string & s = "" )

inlineexplicit

create JSON pointer

Create a JSON pointer according to the syntax described in Section 3 of RFC6901.

Parameters

[in] s string representing the JSON pointer; if omitted, the empty string is assumed which references the whole JSON value

Exceptions

parse_error.107	if the given JSON pointer s is nonempty and does not begin with a slash (`/`); see example below
parse_error.108	if a tilde (`~`) in the given JSON pointer 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

Member Function Documentation

◆ to_string()

template<typename BasicJsonType >

std::string nlohmann::json_pointer< BasicJsonType >::to_string ( ) const

inline

return a string representation of the JSON pointer

Invariant: For each JSON pointer ptr, it holds:
ptr == json_pointer(ptr.to_string());

Returns: 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

◆ operator std::string()

template<typename BasicJsonType >

nlohmann::json_pointer< BasicJsonType >::operator std::string ( ) const

inline

return a string representation of the JSON pointer

Invariant: For each JSON pointer ptr, it holds:
ptr == json_pointer(ptr.to_string());

Returns: 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

◆ operator/=() [1/3]

template<typename BasicJsonType >

json_pointer& nlohmann::json_pointer< BasicJsonType >::operator/= ( const json_pointer< BasicJsonType > & ptr )

inline

append another JSON pointer at the end of this JSON pointer

Parameters

[in] ptr JSON pointer to append

Returns: JSON pointer with ptr appended

@liveexample{The example shows the usage of operator/=.,json_pointer__operator_add}

@complexity Linear in the length of ptr.

See also: operator/=(std::string) to append a reference token; operator/=(std::size_t) to append an array index; operator/(const json_pointer&, const json_pointer&) for a binary operator

Since: version 3.6.0

◆ operator/=() [2/3]

template<typename BasicJsonType >

json_pointer& nlohmann::json_pointer< BasicJsonType >::operator/= ( std::string token )

inline

append an unescaped reference token at the end of this JSON pointer

Parameters

[in] token reference token to append

Returns: JSON pointer with token appended without escaping token

@liveexample{The example shows the usage of operator/=.,json_pointer__operator_add}

@complexity Amortized constant.

See also: operator/=(const json_pointer&) to append a JSON pointer; operator/=(std::size_t) to append an array index; operator/(const json_pointer&, std::size_t) for a binary operator

Since: version 3.6.0

◆ operator/=() [3/3]

template<typename BasicJsonType >

json_pointer& nlohmann::json_pointer< BasicJsonType >::operator/= ( std::size_t array_idx )

inline

append an array index at the end of this JSON pointer

Parameters

[in] array_idx array index to append

Returns: JSON pointer with array_idx appended

@liveexample{The example shows the usage of operator/=.,json_pointer__operator_add}

@complexity Amortized constant.

See also: operator/=(const json_pointer&) to append a JSON pointer; operator/=(std::string) to append a reference token; operator/(const json_pointer&, std::string) for a binary operator

Since: version 3.6.0

◆ parent_pointer()

template<typename BasicJsonType >

json_pointer nlohmann::json_pointer< BasicJsonType >::parent_pointer ( ) const

inline

returns the parent of this JSON pointer

Returns: parent of this JSON pointer; in case this JSON pointer is the root, the root itself is returned

@complexity Linear in the length of the JSON pointer.

@liveexample{The example shows the result of parent_pointer for different JSON Pointers.,json_pointer__parent_pointer}

Since: version 3.6.0

◆ pop_back()

template<typename BasicJsonType >

void nlohmann::json_pointer< BasicJsonType >::pop_back ( )

inline

remove last reference token

Precondition: not empty()

@liveexample{The example shows the usage of pop_back.,json_pointer__pop_back}

@complexity Constant.

Exceptions

out_of_range.405 if JSON pointer has no parent

Since: version 3.6.0

◆ back()

template<typename BasicJsonType >

const std::string& nlohmann::json_pointer< BasicJsonType >::back ( ) const

inline

return last reference token

Precondition: not empty()

Returns: last reference token

@liveexample{The example shows the usage of back.,json_pointer__back}

@complexity Constant.

Exceptions

out_of_range.405 if JSON pointer has no parent

Since: version 3.6.0

◆ push_back() [1/2]

template<typename BasicJsonType >

void nlohmann::json_pointer< BasicJsonType >::push_back ( const std::string & token )

inline

append an unescaped token at the end of the reference pointer

Parameters

[in] token token to add

@complexity Amortized constant.

@liveexample{The example shows the result of push_back for different JSON Pointers.,json_pointer__push_back}

Since: version 3.6.0

◆ push_back() [2/2]

template<typename BasicJsonType >

void nlohmann::json_pointer< BasicJsonType >::push_back ( std::string && token )

inline

append an unescaped token at the end of the reference pointer

Parameters

[in] token token to add

@complexity Amortized constant.

@liveexample{The example shows the result of push_back for different JSON Pointers.,json_pointer__push_back}

Since: version 3.6.0

◆ empty()

template<typename BasicJsonType >

bool nlohmann::json_pointer< BasicJsonType >::empty ( ) const

inlinenoexcept

return whether pointer points to the root document

Returns: true iff the JSON pointer points to the root document

@complexity Constant.

@exceptionsafety No-throw guarantee: this function never throws exceptions.

@liveexample{The example shows the result of empty for different JSON Pointers.,json_pointer__empty}

Since: version 3.6.0

◆ array_index()

template<typename BasicJsonType >

static BasicJsonType::size_type nlohmann::json_pointer< BasicJsonType >::array_index ( const std::string & s )

inlinestaticprivate

Parameters

[in] s reference token to be converted into an array index

Returns: integer representation of s

Exceptions

parse_error.106	if an array index begins with '0'
parse_error.109	if an array index begins not with a digit
out_of_range.404	if string s could not be converted to an integer
out_of_range.410	if an array index exceeds size_type

◆ get_and_create()

template<typename BasicJsonType >

BasicJsonType& nlohmann::json_pointer< BasicJsonType >::get_and_create ( BasicJsonType & j ) const

inlineprivate

create and return a reference to the pointed to value

@complexity Linear in the number of reference tokens.

Exceptions

parse_error.109	if array index is not a number
type_error.313	if value cannot be unflattened

◆ get_unchecked() [1/2]

template<typename BasicJsonType >

BasicJsonType& nlohmann::json_pointer< BasicJsonType >::get_unchecked ( BasicJsonType * ptr ) const

inlineprivate

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.

Parameters

[in] ptr a JSON value

Returns: reference to the JSON value pointed to by the JSON pointer

@complexity Linear in the length of the JSON pointer.

Exceptions

parse_error.106	if an array index begins with '0'
parse_error.109	if an array index was not a number
out_of_range.404	if the JSON pointer can not be resolved

◆ get_checked() [1/2]

template<typename BasicJsonType >

BasicJsonType& nlohmann::json_pointer< BasicJsonType >::get_checked ( BasicJsonType * ptr ) const

inlineprivate

Exceptions

parse_error.106	if an array index begins with '0'
parse_error.109	if an array index was not a number
out_of_range.402	if the array index '-' is used
out_of_range.404	if the JSON pointer can not be resolved

◆ get_unchecked() [2/2]

template<typename BasicJsonType >

const BasicJsonType& nlohmann::json_pointer< BasicJsonType >::get_unchecked ( const BasicJsonType * ptr ) const

inlineprivate

return a const reference to the pointed to value

Parameters

[in] ptr a JSON value

Returns: const reference to the JSON value pointed to by the JSON pointer

Exceptions

parse_error.106	if an array index begins with '0'
parse_error.109	if an array index was not a number
out_of_range.402	if the array index '-' is used
out_of_range.404	if the JSON pointer can not be resolved

◆ get_checked() [2/2]

template<typename BasicJsonType >

const BasicJsonType& nlohmann::json_pointer< BasicJsonType >::get_checked ( const BasicJsonType * ptr ) const

inlineprivate

Exceptions

parse_error.106	if an array index begins with '0'
parse_error.109	if an array index was not a number
out_of_range.402	if the array index '-' is used
out_of_range.404	if the JSON pointer can not be resolved

◆ contains()

template<typename BasicJsonType >

bool nlohmann::json_pointer< BasicJsonType >::contains ( const BasicJsonType * ptr ) const

inlineprivate

Exceptions

parse_error.106	if an array index begins with '0'
parse_error.109	if an array index was not a number

◆ split()

template<typename BasicJsonType >

static std::vector<std::string> nlohmann::json_pointer< BasicJsonType >::split ( const std::string & reference_string )

inlinestaticprivate

split the string input to reference tokens

Note: This function is only called by the json_pointer constructor. All exceptions below are documented there.

Exceptions

parse_error.107	if the pointer is not empty or begins with '/'
parse_error.108	if character '~' is not followed by '0' or '1'

◆ replace_substring()

template<typename BasicJsonType >

static void nlohmann::json_pointer< BasicJsonType >::replace_substring	(	std::string &	s,
		const std::string &	f,
		const std::string &	t
	)

inlinestaticprivate

replace all occurrences of a substring by another string

Parameters

[in,out]	s	the string to manipulate; changed so that all occurrences of f are replaced with t
[in]	f	the substring to replace with t
[in]	t	the string to replace f

Precondition: The search string f must not be empty. This precondition is enforced with an assertion.

Since: version 2.0.0

◆ flatten()

template<typename BasicJsonType >

static void nlohmann::json_pointer< BasicJsonType >::flatten	(	const std::string &	reference_string,
		const BasicJsonType &	value,
		BasicJsonType &	result
	)

inlinestaticprivate

Parameters

[in]	reference_string	the reference string to the current value
[in]	value	the value to consider
[in,out]	result	the result object to insert values to

Note: Empty objects or arrays are flattened to null.

◆ unflatten()

template<typename BasicJsonType >

static BasicJsonType nlohmann::json_pointer< BasicJsonType >::unflatten ( const BasicJsonType & value )

inlinestaticprivate

Parameters

[in] value flattened JSON

Returns: unflattened JSON

Exceptions

parse_error.109	if array index is not a number
type_error.314	if value is not an object
type_error.315	if object values are not primitive
type_error.313	if value cannot be unflattened

Friends And Related Function Documentation

◆ operator/ [1/3]

template<typename BasicJsonType >

json_pointer operator/	(	const json_pointer< BasicJsonType > &	lhs,
		const json_pointer< BasicJsonType > &	rhs
	)

friend

create a new JSON pointer by appending the right JSON pointer at the end of the left JSON pointer

Parameters

[in]	lhs	JSON pointer
[in]	rhs	JSON pointer

Returns: a new JSON pointer with rhs appended to lhs

@liveexample{The example shows the usage of operator/.,json_pointer__operator_add_binary}

@complexity Linear in the length of lhs and rhs.

See also: operator/=(const json_pointer&) to append a JSON pointer

Since: version 3.6.0

◆ operator/ [2/3]

template<typename BasicJsonType >

json_pointer operator/	(	const json_pointer< BasicJsonType > &	ptr,
		std::string	token
	)

friend

create a new JSON pointer by appending the unescaped token at the end of the JSON pointer

Parameters

[in]	ptr	JSON pointer
[in]	token	reference token

Returns: a new JSON pointer with unescaped token appended to ptr

@liveexample{The example shows the usage of operator/.,json_pointer__operator_add_binary}

@complexity Linear in the length of ptr.

See also: operator/=(std::string) to append a reference token

Since: version 3.6.0

◆ operator/ [3/3]

template<typename BasicJsonType >

json_pointer operator/	(	const json_pointer< BasicJsonType > &	ptr,
		std::size_t	array_idx
	)

friend

create a new JSON pointer by appending the array-index-token at the end of the JSON pointer

Parameters

[in]	ptr	JSON pointer
[in]	array_idx	array index

Returns: a new JSON pointer with array_idx appended to ptr

@liveexample{The example shows the usage of operator/.,json_pointer__operator_add_binary}

@complexity Linear in the length of ptr.

See also: operator/=(std::size_t) to append an array index

Since: version 3.6.0

◆ operator==

template<typename BasicJsonType >

bool operator==	(	json_pointer< BasicJsonType > const &	lhs,
		json_pointer< BasicJsonType > const &	rhs
	)

friend

compares two JSON pointers for equality

Parameters

[in]	lhs	JSON pointer to compare
[in]	rhs	JSON pointer to compare

Returns: whether lhs is equal to rhs

@complexity Linear in the length of the JSON pointer

@exceptionsafety No-throw guarantee: this function never throws exceptions.

◆ operator!=

template<typename BasicJsonType >

bool operator!=	(	json_pointer< BasicJsonType > const &	lhs,
		json_pointer< BasicJsonType > const &	rhs
	)

friend

compares two JSON pointers for inequality

Parameters

[in]	lhs	JSON pointer to compare
[in]	rhs	JSON pointer to compare

Returns: whether lhs is not equal rhs

@complexity Linear in the length of the JSON pointer

@exceptionsafety No-throw guarantee: this function never throws exceptions.

Public Member Functions

Private Member Functions

Static Private Member Functions

Private Attributes

Friends

Detailed Description

template<typename BasicJsonType> class nlohmann::json_pointer< BasicJsonType >

Constructor & Destructor Documentation

◆ json_pointer()

Member Function Documentation

◆ to_string()

◆ operator std::string()

◆ operator/=() [1/3]

◆ operator/=() [2/3]

◆ operator/=() [3/3]

◆ parent_pointer()

◆ pop_back()

◆ back()

◆ push_back() [1/2]

◆ push_back() [2/2]

◆ empty()

◆ array_index()

◆ get_and_create()

◆ get_unchecked() [1/2]

◆ get_checked() [1/2]

◆ get_unchecked() [2/2]

◆ get_checked() [2/2]

◆ contains()

◆ split()

◆ replace_substring()

◆ flatten()

◆ unflatten()

Friends And Related Function Documentation

◆ operator/ [1/3]

◆ operator/ [2/3]

◆ operator/ [3/3]

◆ operator==

◆ operator!=

template<typename BasicJsonType>
class nlohmann::json_pointer< BasicJsonType >