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iox::cxx::variant🔗

Variant implementation from the C++17 standard with C++11. The interface is inspired by the C++17 standard but it has changes in get and emplace since we are not allowed to throw exceptions. More...

#include <iceoryx_hoofs/cxx/variant.hpp>

Public Functions🔗

Name
constexpr variant() =default
the default constructor constructs a variant which does not contain an element and returns INVALID_VARIANT_INDEX when .index() is called
template <uint64_t N,typename... CTorArguments>
constexpr
variant(const in_place_index< N > & index, CTorArguments &&... args)
creates a variant and perform an in place construction of the type stored at index N. If the index N is out of bounds you get a compiler error.
template <typename T ,typename... CTorArguments>
constexpr
variant(const in_place_type< T > & type, CTorArguments &&... args)
creates a variant and perform an in place construction of the type T. If T is not part of the variant you get a compiler error.
template <typename T ,typename =std::enable_if_t<!std::is_same, variant>::value>,typename std::enable_if_t<!internal::is_in_place_index< std::decay_t< T >>::value, bool > =false,typename std::enable_if_t<!internal::is_in_place_type< std::decay_t< T >>::value, bool > =false>
constexpr
variant(T && arg)
creates a variant from a user supplied value
constexpr variant(const variant & rhs)
if the variant contains an element the elements copy constructor is called otherwise an empty variant is copied
constexpr variant & operator=(const variant & rhs)
if the variant contains an element the elements copy assignment operator is called otherwise an empty variant is copied
constexpr variant(variant && rhs)
if the variant contains an element the elements move constructor is called otherwise an empty variant is moved
constexpr variant & operator=(variant && rhs)
if the variant contains an element the elements move assignment operator is called otherwise an empty variant is moved
~variant()
if the variant contains an element the elements destructor is called otherwise nothing happens
template <typename T >
std::enable_if<!std::is_same< T, variant< Types... > & >::value, variant< Types... > >::type &
operator=(T && rhs)
if the variant contains an element the elements assignment operator is called otherwise we have undefined behavior. It is important that you make sure that the variant really contains that type T.
template <uint64_t TypeIndex,typename... CTorArguments>
bool
emplace_at_index(CTorArguments &&... args)
calls the constructor of the type at index TypeIndex and perfectly forwards the arguments to this constructor. (not stl compliant)
template <typename T ,typename... CTorArguments>
bool
emplace(CTorArguments &&... args)
calls the constructor of the type T and perfectly forwards the arguments to the constructor of T.
template <uint64_t TypeIndex>
internal::get_type_at_index< 0, TypeIndex, Types... >::type *
get_at_index()
returns a pointer to the type stored at index TypeIndex. (not stl compliant)
template <uint64_t TypeIndex>
const internal::get_type_at_index< 0, TypeIndex, Types... >::type *
get_at_index() const
returns a pointer to the type stored at index TypeIndex. (not stl compliant)
template <typename T >
const T *
get() const
returns a pointer to the type T stored in the variant. (not stl compliant)
template <typename T >
T *
get()
returns a pointer to the type T stored in the variant. (not stl compliant)
template <typename T >
T *
get_if(T * defaultValue)
returns a pointer to the type T if its stored in the variant otherwise it returns the provided defaultValue
template <typename T >
const T *
get_if(const T * defaultValue) const
returns a pointer to the type T if its stored in the variant otherwise it returns the provided defaultValue
constexpr uint64_t index() const
returns the index of the stored type in the variant. if the variant does not contain any type it returns INVALID_VARIANT_INDEX

Detailed Description🔗

template <typename... Types>
class iox::cxx::variant;

Variant implementation from the C++17 standard with C++11. The interface is inspired by the C++17 standard but it has changes in get and emplace since we are not allowed to throw exceptions.

Parameters:

  • Types... variadic list of types which the variant should be able to store
#include "iceoryx_hoofs/cxx/variant.hpp"
#include <iostream>

cxx::variant<int, float, double> someVariant;

// ... do stuff

if ( someVariant.index() == INVALID_VARIANT_INDEX )
{
    someVariant.emplace<float>(123.456f);
}
else if ( someVariant.index() == 1)
{
    auto blubb = someVariant.template get_at_index<1>();
    std::cout << *blubb << std::endl;

    auto sameAsBlubb = someVariant.get<float>();
    std::cout << *sameAsBlubb << std::endl;
}

// .. do stuff

int defaultValue = 123;
int * fuu = someVariant.get_if<int>(&defaultValue);
std::cout << *fuu << std::endl;

Public Functions Documentation🔗

function variant🔗

constexpr variant() =default

the default constructor constructs a variant which does not contain an element and returns INVALID_VARIANT_INDEX when .index() is called

function variant🔗

template <uint64_t N,
typename... CTorArguments>
constexpr variant(
    const in_place_index< N > & index,
    CTorArguments &&... args
)

creates a variant and perform an in place construction of the type stored at index N. If the index N is out of bounds you get a compiler error.

Template Parameters:


function variant🔗

template <typename T ,
typename... CTorArguments>
constexpr variant(
    const in_place_type< T > & type,
    CTorArguments &&... args
)

creates a variant and perform an in place construction of the type T. If T is not part of the variant you get a compiler error.

Template Parameters:


function variant🔗

template <typename T ,
typename  =std::enable_if_t<!std::is_same<std::decay_t<T>, variant>::value>,
typename std::enable_if_t<!internal::is_in_place_index< std::decay_t< T >>::value, bool >  =false,
typename std::enable_if_t<!internal::is_in_place_type< std::decay_t< T >>::value, bool >  =false>
constexpr variant(
    T && arg
)

creates a variant from a user supplied value

Template Parameters:


function variant🔗

constexpr variant(
    const variant & rhs
)

if the variant contains an element the elements copy constructor is called otherwise an empty variant is copied

Parameters:

  • rhs source of the copy

function operator=🔗

constexpr variant & operator=(
    const variant & rhs
)

if the variant contains an element the elements copy assignment operator is called otherwise an empty variant is copied

Parameters:

  • rhs source of the copy assignment

Return: reference to the variant itself

function variant🔗

constexpr variant(
    variant && rhs
)

if the variant contains an element the elements move constructor is called otherwise an empty variant is moved

Parameters:

  • rhs source of the move

function operator=🔗

constexpr variant & operator=(
    variant && rhs
)

if the variant contains an element the elements move assignment operator is called otherwise an empty variant is moved

Parameters:

  • rhs source of the move assignment

Return: reference to the variant itself

function ~variant🔗

~variant()

if the variant contains an element the elements destructor is called otherwise nothing happens

function operator=🔗

template <typename T >
std::enable_if<!std::is_same< T, variant< Types... > & >::value, variant< Types... > >::type & operator=(
    T && rhs
)

if the variant contains an element the elements assignment operator is called otherwise we have undefined behavior. It is important that you make sure that the variant really contains that type T.

Template Parameters:


function emplace_at_index🔗

template <uint64_t TypeIndex,
typename... CTorArguments>
bool emplace_at_index(
    CTorArguments &&... args
)

calls the constructor of the type at index TypeIndex and perfectly forwards the arguments to this constructor. (not stl compliant)

Parameters:

  • args arguments which will be forwarded to the constructor to the type at TypeIndex

Template Parameters:

  • TypeIndex index of the type which will be created
  • CTorArguments variadic types of the c'tor arguments

Return: if the variant already contains a different type it returns false, if the construction was successful it returns true

function emplace🔗

template <typename T ,
typename... CTorArguments>
bool emplace(
    CTorArguments &&... args
)

calls the constructor of the type T and perfectly forwards the arguments to the constructor of T.

Template Parameters:


function get_at_index🔗

template <uint64_t TypeIndex>
internal::get_type_at_index< 0, TypeIndex, Types... >::type * get_at_index()

returns a pointer to the type stored at index TypeIndex. (not stl compliant)

Template Parameters:


function get_at_index🔗

template <uint64_t TypeIndex>
const internal::get_type_at_index< 0, TypeIndex, Types... >::type * get_at_index() const

returns a pointer to the type stored at index TypeIndex. (not stl compliant)

Template Parameters:


function get🔗

template <typename T >
const T * get() const

returns a pointer to the type T stored in the variant. (not stl compliant)

Template Parameters:


function get🔗

template <typename T >
T * get()

returns a pointer to the type T stored in the variant. (not stl compliant)

Template Parameters:


function get_if🔗

template <typename T >
T * get_if(
    T * defaultValue
)

returns a pointer to the type T if its stored in the variant otherwise it returns the provided defaultValue

Return: pointer to the stored value if it is of type T, otherwise defaultValue

function get_if🔗

template <typename T >
const T * get_if(
    const T * defaultValue
) const

returns a pointer to the type T if its stored in the variant otherwise it returns the provided defaultValue

Template Parameters:


function index🔗

constexpr uint64_t index() const

returns the index of the stored type in the variant. if the variant does not contain any type it returns INVALID_VARIANT_INDEX

Return: index of the stored type


Updated on 2 April 2022 at 16:37:47 CEST