MemCore::Attributes Class Reference

Attributes are a selection of named MemCore::ChunkBase objects, each of them may carry arbitrary data. More...

#include <elementary/memcore/Attributes.hpp>

Inheritance diagram for MemCore::Attributes:

Classes
struct	Iterator
	Attribute iterator base class. More...

Public Member Functions
	Attributes ()
	Default constructor.
MemCore::RefPtr< MemCore::ChunkBase >	getAttribute (const std::string &name) const
	get an attribute by name
const Ageable &	getAttributeAge () const
	Get the age of these attributes.
template<class T >
std::pair< bool, T >	getAttributeValue (const string &AttributeName, size_t ElementNumber=0) const
	Get a single value from an attribute, use structured binding for most compact syntax such as:
attributes_t &	getAttributeValues ()
	allow direct access to internal map
const attributes_t &	getAttributeValues () const
	allow direct access to internal map
size_t	getNumberOfAttributes () const
	Retrieve the number of attributes.
bool	hasAttribute (const std::string &name) const
	Check if an attribute exists.
template<class Functor >
int	Iterate (const Functor &L) const
int	iterate (Iterator &it) const
	Iterate over attributes and apply iterator's apply function for each attribute, i.e.
template<class Functor >
int	iterate_attributes (const Functor &L) const
size_t	NumberOfAttributes () const
	Retrieve the number of attributes.
void	setAttribute (const std::string &name, const MemCore::RefPtr< MemCore::ChunkBase > &AttribData)
	set an attribute
template<class T >
ResizableChunk< T > &	setAttributeValue (const std::string &name, const T &AttribData)
	set a single attribute
template<class T >
ResizableChunk< T > &	setAttributeValues (const std::string &name, const std::initializer_list< T > &AttribData)
	set an attribute
template<class T >
const T &	setValue (const T &AttribData, const std::string &name)
	Convenience function: set an single attribute, return the value itself.
template<class T >
const T &	setValue (const T &AttribData, const std::string &name, const std::string &Comment, const std::string &CommentPrefix="Comment")
	Convenience function: set an single attribute with a comment, return the value itself.
string	toString () const
	Convert attributes to string.
const Ageable &	touchAttributes () const
	Touch the attribute age to indicate some values in the attributes have been changed.
const Ageable &	updateAttributeAge (const Ageable &A) const
	Update the attribute age to another age to indicate some values in the attributes have been changed.
	~Attributes ()
	Destructor.

Detailed Description

Attributes are a selection of named MemCore::ChunkBase objects, each of them may carry arbitrary data.

The Attributes class supports the '<<' streaming operator to set attributes. To set an attribute of type double named "value" the following syntax can be used:

MemCore::Attributes A;
        A << "value" << 3.141593;

An attribute can contain multiple values in the form of an array. They are stored as a Chunk<>, but for initialization via the streaming operator multiple variants are possible, including the usage of a std::initializer_list :

MemCore::Attributes A;
 
        // Bind an initializer list to an auto definition:
auto i = {1,3,5};
        A << "alpha" << i;
 
        // Explicit usage of a std_initializer list:
        A << "alpha" << std::initializer_list<int>( {1,3,5} );
 
        // Dynamic addition of values using push_back()
        // Note that this variant is least favorable as it
        // requires memory re-allocation.
        A << "alpha" << 1 << 2 << 3;

Member Function Documentation

getAttributeValue()

template<class T >

std::pair< bool, T > MemCore::Attributes::getAttributeValue ( const string &  AttributeName, size_t  ElementNumber = 0  ) const

inline

Get a single value from an attribute, use structured binding for most compact syntax such as:

if (auto [valid, value] = Container.getAttributeValue<double>("AttributeName"); valid )
{
        ... do something with value ...
}

hasAttribute()

bool MemCore::Attributes::hasAttribute

(

const std::string &

name

)

const

Check if an attribute exists.

This function will return true even if no data are associated with an attribute.

References getAttribute().

Iterate()

template<class Functor >

int MemCore::Attributes::Iterate ( const Functor &  L ) const

inline

       Lambda iterator, functor must provide signatur

bool operator()( const std::string& attribute_name,
                 const MemCore::RefPtr<MemCore::ChunkBase>& chunk )

iterate()

int MemCore::Attributes::iterate

(

Attributes::Iterator &

it

)

const

Iterate over attributes and apply iterator's apply function for each attribute, i.e.

its name and its chunk.

iterate_attributes()

template<class Functor >

int MemCore::Attributes::iterate_attributes ( const Functor &  L ) const

inline

       Lambda iterator, functor must provide signatur

bool operator()( const std::string& attribute_name,
                 const MemCore::RefPtr<MemCore::ChunkBase>& chunk )