state_traits< StateT > Struct Template Reference

Interface for a type specializing the State concept. More...

#include <atria/xform/state_traits.hpp>

Static Public Member Functions
template<typename T >
static auto	is_reduced (T &&) -> bool
	Returns whether the value is idempotent, and thus, the reduction can finish. More...
template<typename T , typename D >
static auto	data (T &&, D &&d) -> decltype(std::forward< D >(d)())
	Returns the associated from the current state. More...
template<typename T >
static auto	complete (T &&state) -> decltype(std::forward< T >(state))
	Unwraps all the layers of state wrappers returning the deepmost. More...
template<typename T >
static auto	unwrap (T &&state) -> decltype(std::forward< T >(state))
	Unwraps this layers of state wrappers, returning the nested state for the next reducing function. More...
template<typename T >
static auto	unwrap_all (T &&state) -> decltype(std::forward< T >(state))
	Unwraps all layers of state wrappers, returning the most nested state for the innermost reducing function. More...
template<typename T , typename U >
static auto	rewrap (T &&, U &&x) -> decltype(std::forward< U >(x))
	Copies all layers of state wrappers but replaces the innermost state with substate. More...

Detailed Description

template<typename StateT>
struct atria::xform::state_traits< StateT >

Interface for a type specializing the State concept.

A State is the first parameter of a reducing function, also known as the accumulator. Every type is a model of State, with the following default implementation. However, one might want to specialize the state it for a particular accumulator type, such that transducers can operate with it. A transducer should not make assumptions about the state it receives, instead, it can only wrap it using wrap_state to attach additional data.

For an example of a stateful reducing function, see take.

See also

wrap_state

take

Definition at line 53 of file state_traits.hpp.

Member Function Documentation

static auto complete ( T &&  state ) -> decltype( std::forward<T>(state) )

inlinestatic

Unwraps all the layers of state wrappers returning the deepmost.

Definition at line 75 of file state_traits.hpp.

static auto data ( T &&  , D &&  d  ) -> decltype( std::forward<D>(d)() )

inlinestatic

Returns the associated from the current state.

If the state contains no associated data, the default_data will be returned.

Definition at line 68 of file state_traits.hpp.

static auto is_reduced ( T &&  ) -> bool

inlinestatic

Returns whether the value is idempotent, and thus, the reduction can finish.

Definition at line 60 of file state_traits.hpp.

static auto rewrap ( T &&  , U &&  x  ) -> decltype( std::forward<U>(x) )

inlinestatic

Copies all layers of state wrappers but replaces the innermost state with substate.

Definition at line 99 of file state_traits.hpp.

static auto unwrap ( T &&  state ) -> decltype( std::forward<T>(state) )

inlinestatic

Unwraps this layers of state wrappers, returning the nested state for the next reducing function.

Definition at line 83 of file state_traits.hpp.

static auto unwrap_all ( T &&  state ) -> decltype( std::forward<T>(state) )

inlinestatic

Unwraps all layers of state wrappers, returning the most nested state for the innermost reducing function.

Definition at line 91 of file state_traits.hpp.

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

• src/atria/xform/state_traits.hpp