typelist-manip.hpp File Reference

Metaprogramming: Helpers for manipulating lists-of-types. More...

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Description

Metaprogramming: Helpers for manipulating lists-of-types.

Sometimes, we use metaprogramming to generate a variation of concrete implementations by combining some basic building blocks. Typically, there is a number of similar, but not suitably related types involved. We want to process those types using a common scheme, without being forced to squeeze all those types into a artificial inheritance relationship. Instead, generating some kind of common factory or adapter, while mixing in pieces of code tailored specifically to the individual types, allows still to build a common processing in such situations.

The facilities in this header provide the basics of simple functional list processing (mostly with tail recursion). Usually, there is one template parameter TYPES, which accepts a type-list. The result of the processing step is then accessible as nested type definition named List. Here, all of the „processing“ to calculate this result is performed by the compiler, as a side-effect set off by the need to compute a requested concrete result type. At run time, in the generated code, typically the resulting classes are empty, maybe just exposing a function outfitted for a specific purpose.

Remarks

historically, these functions were developed for the first draft of the render engine, which (for other reasons) did not come to fruition. Over time, some of these functions were used on and off for various purposes; and since (as of 2025) Loki-style type lists are considered an integral part of the Lumiera framework, useful meta-functions are added and documented here, even when not currently in use.

See also

generator.hpp

typelist-manip-test.cpp

TimeControl_test usage example

typelist.hpp

Definition in file typelist-manip.hpp.

#include "lib/meta/typelist.hpp"
#include <sys/types.h>

Namespaces
namespace	lib
	Implementation namespace for support and library code.
namespace	lib::meta

Typedefs
template<class LI , uint l>
using	Prefix = Splice< LI, Nil, l >::Front
	extract prefix of given length
template<class LI , uint p>
using	Suffix = Splice< LI, Nil, p >::Back
	extract suffix starting at given pos

Classes
struct	Pick< TYPES, i >
	pick the n-th element from a typelist More...
struct	Pick< Node< TY, TYPES >, 0 >
struct	Pick< Node< TY, TYPES >, i >
struct	Apply< TY, _TRANS_ >
	apply a transformation (template) to each type in the list More...
struct	Apply< Node< TY, TYPES >, _TRANS_ >
struct	CondNode< bool, T, TAIL >
	conditional node: skip an element based on evaluating a predicate More...
struct	CondNode< true, T, TAIL >
struct	Filter< Nil, _P_ >
struct	Filter< Node< TY, TYPES >, _P_ >
struct	Append< TY1, TY2 >
	append (concatenate) lists-of-types More...
struct	Append< Node< TY, TYPES >, TAIL >
struct	Append< Nil, Node< TY, TYPES > >
struct	Append< Node< TY, TYPES >, Nil >
struct	Append< TY1, Nil >
struct	Append< Nil, TY2 >
struct	Append< Nil, Nil >
struct	PickLast< Nil >
struct	PickLast< Node< TY, Nil > >
struct	PickLast< Node< TY, TYPES > >
struct	Splice< Node< B, BS >, OVERLAY, i >
struct	Splice< Node< B, BS >, Node< O, OS >, 0 >
struct	Splice< Node< B, BS >, Nil, 0 >
struct	Splice< Nil, XX, i >
struct	Dissect< Node< T, TYPES > >
struct	Dissect< Nil >
struct	PrefixAll< T, TY >
	prefix each of the elements, yielding a list-of lists-of-types More...
struct	PrefixAll< T, Nil >
struct	PrefixAll< T, NilNode >
struct	PrefixAll< T, Node< TY, TYPES > >
struct	Distribute< TY1, TY2 >
	build a list-of lists, where each element of the first arg list gets in turn prepended to all elements of the second arg list. More...
struct	Distribute< Nil, TY >
struct	Distribute< Node< TY, TYPES >, TAIL >
struct	Combine< X, _ENUM_ >
	Build all possible combinations, based on a enumeration of the basic cases. More...
struct	Combine< Nil, _ENUM_ >
struct	Combine< Node< TY, TYPES >, _ENUM_ >
struct	FlagOnOff< F >
	enumeration generator for the Combine metafunction, yielding an "on" and "off" case; the latter is represented by a list with a Nil-Entry More...
struct	CombineFlags< FLAGS >
	generate all possible on-off combinations of the given flags. More...

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Class Documentation

lib::meta::Pick

struct lib::meta::Pick

Class Members
typedef Nil	Type

Collaboration diagram for Pick< TYPES, i >:

lib::meta::Pick< Node< TY, TYPES >, 0 >

struct lib::meta::Pick< Node< TY, TYPES >, 0 >

Class Members
typedef TY	Type

Collaboration diagram for Pick< Node< TY, TYPES >, 0 >:

lib::meta::Pick< Node< TY, TYPES >, i >

struct lib::meta::Pick< Node< TY, TYPES >, i >

Class Members
typedef Type	Type

Collaboration diagram for Pick< Node< TY, TYPES >, i >:

lib::meta::Apply

struct lib::meta::Apply

Class Members
typedef TY	List

Collaboration diagram for Apply< TY, _TRANS_ >:

lib::meta::Apply< Node< TY, TYPES >, _TRANS_ >

struct lib::meta::Apply< Node< TY, TYPES >, _TRANS_ >

Class Members
typedef Type, typename List >	List

Collaboration diagram for Apply< Node< TY, TYPES >, _TRANS_ >:

lib::meta::CondNode

struct lib::meta::CondNode

Class Members
typedef TAIL	Next

Collaboration diagram for CondNode< bool, T, TAIL >:

lib::meta::CondNode< true, T, TAIL >

struct lib::meta::CondNode< true, T, TAIL >

Class Members
typedef Node< T, TAIL >	Next

Collaboration diagram for CondNode< true, T, TAIL >:

lib::meta::Filter< Nil, _P_ >

struct lib::meta::Filter< Nil, _P_ >

Class Members
typedef Nil	List

Collaboration diagram for Filter< Nil, _P_ >:

lib::meta::Filter< Node< TY, TYPES >, _P_ >

struct lib::meta::Filter< Node< TY, TYPES >, _P_ >

Class Members
typedef value, TY, typename List >::Next	List

Collaboration diagram for Filter< Node< TY, TYPES >, _P_ >:

lib::meta::Append

struct lib::meta::Append

Class Members
typedef List >	List

Collaboration diagram for Append< TY1, TY2 >:

lib::meta::Append< Node< TY, TYPES >, TAIL >

struct lib::meta::Append< Node< TY, TYPES >, TAIL >

Class Members
typedef List >	List

Collaboration diagram for Append< Node< TY, TYPES >, TAIL >:

lib::meta::Append< Nil, Node< TY, TYPES > >

struct lib::meta::Append< Nil, Node< TY, TYPES > >

Class Members
typedef Node< TY, TYPES >	List

Collaboration diagram for Append< Nil, Node< TY, TYPES > >:

lib::meta::Append< Node< TY, TYPES >, Nil >

struct lib::meta::Append< Node< TY, TYPES >, Nil >

Class Members
typedef Node< TY, TYPES >	List

Collaboration diagram for Append< Node< TY, TYPES >, Nil >:

lib::meta::Append< TY1, Nil >

struct lib::meta::Append< TY1, Nil >

Class Members
typedef Node< TY1, Nil >	List

Collaboration diagram for Append< TY1, Nil >:

lib::meta::Append< Nil, TY2 >

struct lib::meta::Append< Nil, TY2 >

Class Members
typedef Node< TY2, Nil >	List

Collaboration diagram for Append< Nil, TY2 >:

lib::meta::Append< Nil, Nil >

struct lib::meta::Append< Nil, Nil >

Class Members
typedef Nil	List

Collaboration diagram for Append< Nil, Nil >:

lib::meta::PickLast< Nil >

struct lib::meta::PickLast< Nil >

Class Members
typedef Nil	Type
typedef Nil	List

Collaboration diagram for PickLast< Nil >:

lib::meta::PickLast< Node< TY, Nil > >

struct lib::meta::PickLast< Node< TY, Nil > >

Class Members
typedef TY	Type
typedef Nil	List

Collaboration diagram for PickLast< Node< TY, Nil > >:

lib::meta::PickLast< Node< TY, TYPES > >

struct lib::meta::PickLast< Node< TY, TYPES > >

Class Members
typedef Type	Type
typedef List >::List	List

Collaboration diagram for PickLast< Node< TY, TYPES > >:

lib::meta::Splice< Node< B, BS >, OVERLAY, i >

struct lib::meta::Splice< Node< B, BS >, OVERLAY, i >

Class Members
typedef List >	List
typedef Front >	Front
typedef typename Back	Back

Collaboration diagram for Splice< Node< B, BS >, OVERLAY, i >:

lib::meta::Splice< Node< B, BS >, Node< O, OS >, 0 >

struct lib::meta::Splice< Node< B, BS >, Node< O, OS >, 0 >

Class Members
typedef List >	List
typedef Nil	Front
typedef typename Back	Back

Collaboration diagram for Splice< Node< B, BS >, Node< O, OS >, 0 >:

lib::meta::Splice< Node< B, BS >, Nil, 0 >

struct lib::meta::Splice< Node< B, BS >, Nil, 0 >

Class Members
typedef Node< B, BS >	List
typedef Nil	Front
typedef Node< B, BS >	Back

Collaboration diagram for Splice< Node< B, BS >, Nil, 0 >:

lib::meta::Splice< Nil, XX, i >

struct lib::meta::Splice< Nil, XX, i >

Class Members
typedef Nil	List
typedef Nil	Front
typedef Nil	Back

Collaboration diagram for Splice< Nil, XX, i >:

lib::meta::Dissect< Node< T, TYPES > >

struct lib::meta::Dissect< Node< T, TYPES > >

Class Members
typedef Node< T, TYPES >	List	the complete list
typedef T	Head	first element
typedef Node< T, Nil >	First	a list containing the first element
typedef TYPES	Tail	remainder of the list starting with the second elm.
typedef List	Prefix	all of the list, up to but excluding the last element
typedef Type	End	the last element
typedef Node< End, Nil >	Last	a list containing the last element

Collaboration diagram for Dissect< Node< T, TYPES > >:

lib::meta::Dissect< Nil >

struct lib::meta::Dissect< Nil >

Class Members
typedef Nil	List
typedef Nil	Head
typedef Nil	First
typedef Nil	Tail
typedef Nil	Prefix
typedef Nil	End
typedef Nil	Last

Collaboration diagram for Dissect< Nil >:

lib::meta::PrefixAll

struct lib::meta::PrefixAll

Class Members
typedef List, Nil >	List

Collaboration diagram for PrefixAll< T, TY >:

lib::meta::PrefixAll< T, Nil >

struct lib::meta::PrefixAll< T, Nil >

Class Members
typedef Nil	List

Collaboration diagram for PrefixAll< T, Nil >:

lib::meta::PrefixAll< T, NilNode >

struct lib::meta::PrefixAll< T, NilNode >

Class Members
typedef List, Nil >	List

Collaboration diagram for PrefixAll< T, NilNode >:

lib::meta::PrefixAll< T, Node< TY, TYPES > >

struct lib::meta::PrefixAll< T, Node< TY, TYPES > >

Class Members
typedef List, typename List >	List

Collaboration diagram for PrefixAll< T, Node< TY, TYPES > >:

lib::meta::Distribute

struct lib::meta::Distribute

Class Members
typedef List	List

Inheritance diagram for Distribute< TY1, TY2 >:

Collaboration diagram for Distribute< TY1, TY2 >:

lib::meta::Distribute< Nil, TY >

struct lib::meta::Distribute< Nil, TY >

Class Members
typedef Nil	List

Collaboration diagram for Distribute< Nil, TY >:

lib::meta::Distribute< Node< TY, TYPES >, TAIL >

struct lib::meta::Distribute< Node< TY, TYPES >, TAIL >

Class Members
typedef List, typename List >::List	List

Collaboration diagram for Distribute< Node< TY, TYPES >, TAIL >:

lib::meta::Combine

struct lib::meta::Combine

Class Members
typedef List, NilNode >::List	List

Collaboration diagram for Combine< X, _ENUM_ >:

lib::meta::Combine< Nil, _ENUM_ >

struct lib::meta::Combine< Nil, _ENUM_ >

Class Members
typedef NilNode	List

Collaboration diagram for Combine< Nil, _ENUM_ >:

lib::meta::Combine< Node< TY, TYPES >, _ENUM_ >

struct lib::meta::Combine< Node< TY, TYPES >, _ENUM_ >

Class Members
typedef List, typename List >::List	List

Collaboration diagram for Combine< Node< TY, TYPES >, _ENUM_ >:

lib::meta::FlagOnOff

struct lib::meta::FlagOnOff

Class Members
typedef Node< F, NilNode >	List

Collaboration diagram for FlagOnOff< F >:

lib::meta::CombineFlags

struct lib::meta::CombineFlags

Class Members
typedef List	List

Collaboration diagram for CombineFlags< FLAGS >: