meta::util::optional< T > Class Template Reference

A class for representing optional values. More...

#include <optional.h>

Inheritance diagram for meta::util::optional< T >:

Public Member Functions
	optional ()
	Default constructor, creates a disengaged optional value.
	optional (nullopt_t)
	Conversion constructor from nullopt, creates a disengaged optional value.
	optional (const T &value)
	Creates an optional value with the given contents. More...
	optional (T &&value)
	Creates an optional value with the given contents via move construction. More...
	optional (const optional &)
	Copy constructor.
	optional (optional &&)
	Move constructor.
optional &	operator= (optional)
	Assignment operator.
	~optional ()
	Destructor. More...
void	swap (optional &other)
	Swaps the current optional instance with the parameter. More...
const T &	operator* () const
	Obtains the value contained in the optional. More...
T &	operator* ()
	Obtains the value contained in the optional. More...
const T *	operator-> () const
	Member access operator to the value contained in the optional. More...
T *	operator-> ()
	Member access operator to the value contained in the optional. More...
	operator bool () const
void	clear ()
	Empties the optional.

Private Member Functions
const T *	dataptr () const
	Helper function to obtain the address of the contained value. More...
T *	dataptr ()
	Helper function to obtain the address of the contained value. More...

Private Attributes
bool	initialized_
	Whether or not this optional is engaged.
optional_storage< T >	storage_
	The storage for this optional.

Detailed Description

template<class T>
class meta::util::optional< T >

A class for representing optional values.

This is a very naiive approach based on the design given in the WG21 paper and the reference implementation. Many features of the real optional<T> design there are not supported here—this is a lightweight replacement until C++14 is completed and implemented in compilers.

See also

http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2013/n3527.html

https://github.com/akrzemi1/Optional/

Constructor & Destructor Documentation

template<class T>

meta::util::optional< T >::optional

(

const T &

value

)

Creates an optional value with the given contents.

Parameters

value

the desired value to be contained in the optional

template<class T>

meta::util::optional< T >::optional

(

T &&

value

)

Creates an optional value with the given contents via move construction.

Parameters

value

the desired value to be moved into the optional

template<class T >

meta::util::optional< T >::~optional

(

)

Destructor.

Responsible for ensuring the proper destruction of the contained type, if it is engaged.

Member Function Documentation

template<class T >

void meta::util::optional< T >::swap

(

optional< T > &

other

)

Swaps the current optional instance with the parameter.

Parameters

other

the optional to swap with

template<class T >

const T & meta::util::optional< T >::operator*

(

)

const

Obtains the value contained in the optional.

Const version.

Returns

the value in the optional

template<class T >

T & meta::util::optional< T >::operator*

(

)

Obtains the value contained in the optional.

Non-const version.

Returns

the value in the optional

template<class T >

const T * meta::util::optional< T >::operator->

(

)

const

Member access operator to the value contained in the optional.

Const version.

Returns

a pointer to the current value in the optional (member access)

template<class T >

T * meta::util::optional< T >::operator->

(

)

Member access operator to the value contained in the optional.

Non-const version.

Returns

a pointer to the current value in the optional (member access)

template<class T >

meta::util::optional< T >::operator bool ( ) const

explicit

Returns

whether the optional is engaged

template<class T >

const T * meta::util::optional< T >::dataptr ( ) const

private

Helper function to obtain the address of the contained value.

const version.

Returns

the address of the contained value

template<class T >

T * meta::util::optional< T >::dataptr ( )

private

Helper function to obtain the address of the contained value.

non-const version.

Returns

the address of the contained value

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

• /home/chase/projects/meta/include/index/vocabulary_map.h
• /home/chase/projects/meta/include/util/optional.h
• /home/chase/projects/meta/include/util/optional.tcc