flyweight::flyweight< T, Args > Class Template Reference

#include <flyweight.hpp>

Public Types
using	value = T
using	autorelease_value = autorelease_value< T, flyweight, std::tuple< Args... > >

Public Member Functions
	flyweight ()
template<typename Creator >
	flyweight (Creator &&creator)
template<typename Creator , typename Deleter >
	flyweight (Creator &&creator, Deleter &&deleter)
T &	get (const std::tuple< Args... > &arg_tuple)
template<bool uses_multiple_args = (sizeof...(Args) > 1)>
auto	get (Args &&... args) -> typename std::enable_if< uses_multiple_args, T & >::type
	Alternative to flyweight::get with the arguments unpacked.
autorelease_value	get_autorelease (const std::tuple< Args... > &arg_tuple)
template<bool uses_multiple_args = (sizeof...(Args) > 1)>
auto	get_autorelease (Args &&... args) -> typename std::enable_if< uses_multiple_args, autorelease_value >::type
	Alternative to flyweight::get_autorelease with the arguments unpacked.
bool	is_loaded (const std::tuple< Args... > &arg_tuple) const
	Check whether the value mapped to the passed arguments is loaded.
template<bool uses_multiple_args = (sizeof...(Args) > 1)>
auto	is_loaded (Args &&... args) const -> typename std::enable_if< uses_multiple_args, bool >::type
	Alternative to flyweight::is_loaded with the arguments unpacked.
bool	release (const std::tuple< Args... > &arg_tuple)
template<bool uses_multiple_args = (sizeof...(Args) > 1)>
auto	release (Args &&... args) -> typename std::enable_if< uses_multiple_args, bool >::type
	Alternative to flyweight::release with the arguments unpacked.

Protected Attributes
std::unordered_map< std::tuple< Args... >, T, detail::tuple_hasher< Args... > >	map
std::function< T(Args &&...)>	creator
std::function< void(T &)>	deleter

Detailed Description

template<typename T, typename... Args>
class flyweight::flyweight< T, Args >

Factory for flyweight objects of type T, created with arguments of type Args....

When getting a value, the flyweight first checks for an existing value associated with the passed arguments, returning a reference to it if found. Otherwise, a new value is created and cached for future requests. When no longer needed, an existing value may be released by calling flyweight::release.

Flyweights are useful as a way to load heavy objects only once and sharing them whenever necessary, for example images used as icons in an interactive app. Flyweights can also be used to implement function result memoization.

Template Parameters

T	Value type.
Args	Arguments mapped to loaded values.

Constructor & Destructor Documentation

flyweight() [1/3]

template<typename T , typename... Args>

flyweight::flyweight< T, Args >::flyweight ( )

inline

Default constructor. Uses default_creator as the value creator and default_deleter as the value deleter.

flyweight() [2/3]

template<typename T , typename... Args>

template<typename Creator >

flyweight::flyweight< T, Args >::flyweight ( Creator &&  creator )

inline

Constructor with custom value creator functor.

Parameters

creator

Creator functor that will be called when creating a mapped value for the first time. It will be called with the arguments passed to flyweight::get or flyweight::get_tuple.

flyweight() [3/3]

template<typename T , typename... Args>

template<typename Creator , typename Deleter >

flyweight::flyweight< T, Args >::flyweight ( Creator &&  creator, Deleter &&  deleter  )

inline

Constructor with custom value creator functor and deleter functor.

Parameters

creator	Creator functor that will be called when creating a mapped value for the first time. It will be called with the arguments passed to flyweight::get or flyweight::get_tuple.
deleter	Deleter functor that will be called when releasing a mapped value. It will be called by flyweight::release or flyweight::release_tuple with a reference to the value.

Member Function Documentation

get() [1/2]

template<typename T , typename... Args>

T & flyweight::flyweight< T, Args >::get ( const std::tuple< Args... > &  arg_tuple )

inline

Gets the value associated to the passed arguments. If the value was already created, a reference to the existing value is returned. Otherwise, the value is created using the creator functor passed on the flyweight's constructor.

Parameters

args	Arguments that represent a value. These will be forwarded to the creator functor if the value is not loaded yet.

Returns

Reference to the value mapped to the passed arguments.

get() [2/2]

template<typename T , typename... Args>

template<bool uses_multiple_args = (sizeof...(Args) > 1)>

auto flyweight::flyweight< T, Args >::get ( Args &&...  args ) -> typename std::enable_if<uses_multiple_args, T&>::type

inline

Alternative to flyweight::get with the arguments unpacked.

get_autorelease() [1/2]

template<typename T , typename... Args>

autorelease_value flyweight::flyweight< T, Args >::get_autorelease ( const std::tuple< Args... > &  arg_tuple )

inline

Alternative to flyweight::get that returns an autorelease_value. This enables the RAII idiom for automatically releasing values.

See also

get

get_autorelease() [2/2]

template<typename T , typename... Args>

template<bool uses_multiple_args = (sizeof...(Args) > 1)>

auto flyweight::flyweight< T, Args >::get_autorelease ( Args &&...  args ) -> typename std::enable_if<uses_multiple_args, autorelease_value>::type

inline

Alternative to flyweight::get_autorelease with the arguments unpacked.

is_loaded() [1/2]

template<typename T , typename... Args>

bool flyweight::flyweight< T, Args >::is_loaded ( const std::tuple< Args... > &  arg_tuple ) const

inline

Check whether the value mapped to the passed arguments is loaded.

is_loaded() [2/2]

template<typename T , typename... Args>

template<bool uses_multiple_args = (sizeof...(Args) > 1)>

auto flyweight::flyweight< T, Args >::is_loaded ( Args &&...  args ) const -> typename std::enable_if<uses_multiple_args, bool>::type

inline

Alternative to flyweight::is_loaded with the arguments unpacked.

release() [1/2]

template<typename T , typename... Args>

bool flyweight::flyweight< T, Args >::release ( const std::tuple< Args... > &  arg_tuple )

inline

Release the value mapped to the passed arguments. Trying to release a value that is not loaded is a no-op.

Returns

true if a loaded value was released, false otherwise.

release() [2/2]

template<typename T , typename... Args>

template<bool uses_multiple_args = (sizeof...(Args) > 1)>

auto flyweight::flyweight< T, Args >::release ( Args &&...  args ) -> typename std::enable_if<uses_multiple_args, bool>::type

inline

Alternative to flyweight::release with the arguments unpacked.

Member Data Documentation

map

template<typename T , typename... Args>

std::unordered_map<std::tuple<Args...>, T, detail::tuple_hasher<Args...> > flyweight::flyweight< T, Args >::map

protected

Value map. Maps the tuple of arguments to an already loaded value of type T.

creator

template<typename T , typename... Args>

std::function<T(Args&&...)> flyweight::flyweight< T, Args >::creator

protected

Creator function. Wraps the creator functor passed when constructing the flyweight, if any.

deleter

template<typename T , typename... Args>

std::function<void(T&)> flyweight::flyweight< T, Args >::deleter

protected

Deleter function. Wraps the deleter functor passed when constructing the flyweight, if any.

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

• flyweight.hpp