Json_scalar_holder Class Reference

A class that is capable of holding objects of any sub-type of Json_scalar. More...

#include <json_dom.h>

Classes
union	Any_json_scalar
	Union of all concrete subclasses of Json_scalar. More...

Public Member Functions
Json_scalar *	get ()
	Get a pointer to the held object, or nullptr if there is none. More...
template<typename T , typename... Args>
void	emplace (Args &&... args)
	Construct a new Json_scalar value in this Json_scalar_holder. More...

Private Attributes
Any_json_scalar	m_buffer
	The buffer in which the Json_scalar value is stored. More...
Json_scalar *	m_scalar_ptr {nullptr}
	Pointer to the held scalar, or nullptr if no value is held. More...

Detailed Description

A class that is capable of holding objects of any sub-type of Json_scalar.

Used for pre-allocating space in query-duration memory for JSON scalars that are to be returned by get_json_atom_wrapper().

This class should be replaced by std::variant when moving to C++17.

Member Function Documentation

emplace()

template<typename T , typename... Args>

void Json_scalar_holder::emplace ( Args &&...  args )

inline

Construct a new Json_scalar value in this Json_scalar_holder.

If a value is already held, the old value is destroyed and replaced.

Template Parameters

T	which type of Json_scalar to create

Parameters

args	the arguments to T's constructor

get()

Json_scalar * Json_scalar_holder::get ( )

inline

Get a pointer to the held object, or nullptr if there is none.

Member Data Documentation

m_buffer

Any_json_scalar Json_scalar_holder::m_buffer

private

The buffer in which the Json_scalar value is stored.

m_scalar_ptr

Json_scalar* Json_scalar_holder::m_scalar_ptr {nullptr}

private

Pointer to the held scalar, or nullptr if no value is held.

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The documentation for this class was generated from the following file:

• sql-common/json_dom.h