shamalgs::ImplVariantGlobal< Alts > Class Template Reference

Drop-in replacement for the hand-rolled "global variable + enum + name mapping. More...

#include <shamalgs/include/shamalgs/ImplVariant.hpp>

Inheritance diagram for shamalgs::ImplVariantGlobal< Alts >:

Collaboration diagram for shamalgs::ImplVariantGlobal< Alts >:

Public Types
using	Variant = std::variant<Alts...>
using	AutoselectFn = std::function<void(const sham::DeviceScheduler_ptr &, ImplVariantGlobal &)>
	Callable selecting the default implementation, by calling set() on the selector.

Public Member Functions
	ImplVariantGlobal (AutoselectFn fn)
	Construct an unset selector, whose default implementation is picked by fn.
bool	is_set () const override
	Whether an implementation has been selected yet.
void	autoselect (const sham::DeviceScheduler_ptr &sched) override
	Select the algorithm's default implementation for the device behind sched.
const Variant &	get () const
	Get the currently selected implementation. Requires is_set().
std::string	get_current_config () const override
std::vector< std::string >	get_default_config_list () const override
void	set (Variant v)
	Directly select an alternative (e.g. to seed a default at the call site).
void	set (std::string_view config_json) override
	Select an implementation from a {"implementation": ..., "parameters": ...} json string.

Detailed Description

template<class... Alts>
class shamalgs::ImplVariantGlobal< Alts >

Drop-in replacement for the hand-rolled "global variable + enum + name mapping.

• 3 free functions" implementation-selection pattern. Holds the currently selected implementation as a std::variant<Alts...> and exposes it through a single config json string ABI, so that an algorithm's get_default_impl_list_X / get_current_impl_X / set_impl_X free functions become one-liners: - get_current_config() / get_default_config_list() / set(string_view) : a single <tt>{\"implementation\": ..., \"parameters\": ...}

json string ABI.

No implementation is selected at construction: is_set() reports whether one has been picked yet. The rule picking the algorithm's default is however given at construction, as a callable of signature void(const sham::DeviceScheduler_ptr &, ImplVariantGlobal &) that calls set() on the selector it is handed. autoselect(sched) runs it, so that the default may depend on the device behind sched (see e.g. compute_histogram.hpp), or ignore it when it is a compile-time choice:

shamalgs::ImplVariantGlobal<AltA, AltB> my_algo_impl{
    [](const sham::DeviceScheduler_ptr &, auto &self) {
        self.set(AltA{});
    }};

Call sites typically check is_set() and call autoselect() right before dispatching (see e.g. segmented_sort_in_place.cpp). get() assumes is_set(); get_current_config() is the one exception and safely returns a json null instead of dereferencing an unset selection.

Template Parameters

Alts	the alternative types, each requiring a static constexpr std::string_view variant_type_name

Definition at line 265 of file ImplVariant.hpp.

Member Typedef Documentation

AutoselectFn

template<class... Alts>

using shamalgs::ImplVariantGlobal< Alts >::AutoselectFn = std::function<void(const sham::DeviceScheduler_ptr &, ImplVariantGlobal &)>

Callable selecting the default implementation, by calling set() on the selector.

Definition at line 270 of file ImplVariant.hpp.

Variant

template<class... Alts>

using shamalgs::ImplVariantGlobal< Alts >::Variant = std::variant<Alts...>

Definition at line 267 of file ImplVariant.hpp.

Constructor & Destructor Documentation

ImplVariantGlobal()

template<class... Alts>

shamalgs::ImplVariantGlobal< Alts >::ImplVariantGlobal ( AutoselectFn fn )

inlineexplicit

Construct an unset selector, whose default implementation is picked by fn.

Definition at line 273 of file ImplVariant.hpp.

Member Function Documentation

autoselect()

template<class... Alts>

void shamalgs::ImplVariantGlobal< Alts >::autoselect ( const sham::DeviceScheduler_ptr & sched )

inlineoverridevirtual

Select the algorithm's default implementation for the device behind sched.

Implements shamalgs::IImplVariant.

Definition at line 279 of file ImplVariant.hpp.

get()

template<class... Alts>

const Variant & shamalgs::ImplVariantGlobal< Alts >::get ( ) const

inline

Get the currently selected implementation. Requires is_set().

Definition at line 284 of file ImplVariant.hpp.

get_current_config()

template<class... Alts>

std::string shamalgs::ImplVariantGlobal< Alts >::get_current_config ( ) const

inlineoverridevirtual

Get the currently selected implementation as a single config json string, or a json null if no implementation has been selected yet (see is_set())

Implements shamalgs::IImplVariant.

Definition at line 288 of file ImplVariant.hpp.

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get_default_config_list()

template<class... Alts>

std::vector< std::string > shamalgs::ImplVariantGlobal< Alts >::get_default_config_list ( ) const

inlineoverridevirtual

List the available implementations as config json strings. Most alternatives contribute exactly one entry; alternatives opting into HasCustomDefaults contribute one entry per instance in their variant_custom_defaults() list.

Implements shamalgs::IImplVariant.

Definition at line 298 of file ImplVariant.hpp.

is_set()

template<class... Alts>

bool shamalgs::ImplVariantGlobal< Alts >::is_set ( ) const

inlineoverridevirtual

Whether an implementation has been selected yet.

Implements shamalgs::IImplVariant.

Definition at line 276 of file ImplVariant.hpp.

set() [1/2]

template<class... Alts>

void shamalgs::ImplVariantGlobal< Alts >::set ( std::string_view config_json )

inlineoverridevirtual

Select an implementation from a {"implementation": ..., "parameters": ...} json string.

Implements shamalgs::IImplVariant.

Definition at line 306 of file ImplVariant.hpp.

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set() [2/2]

template<class... Alts>

void shamalgs::ImplVariantGlobal< Alts >::set ( Variant v )

inline

Directly select an alternative (e.g. to seed a default at the call site).

Definition at line 303 of file ImplVariant.hpp.

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

• shamalgs/include/shamalgs/ImplVariant.hpp