Traits for containers

Simple traits for container classes.Trait classes describing a type have a type member defined after that type. They are also available as template types, in the fashion of C++14. More...

Classes
struct	util::collection_value_type< Coll >
	Trait of value contained in the template collection Coll. More...
struct	util::collection_value_access_type< Coll >
	Trait of type obtained by access to element of collection Coll. More...
struct	util::collection_value_constant_access_type< Coll >
	Trait of type obtained by constant access to element of collection Coll. More...
struct	util::collection_reference_type< Coll >
	Trait of a type that can be used to reference the collection Coll. More...
struct	util::collection_from_reference_type< CollRef >
	Trait with the type of collection referenced by collRef. More...

Typedefs
template<typename Coll >
using	util::collection_value_t = typename collection_value_type< Coll >::type
	Type contained in the collection Coll. More...
template<typename Coll >
using	util::collection_value_access_t = typename collection_value_access_type< Coll >::type
	Type obtained by constant access to element of collection Coll. More...
template<typename Coll >
using	util::collection_value_constant_access_t = typename collection_value_constant_access_type< Coll >::type
	Type obtained by constant access to element of collection Coll. More...
template<typename Coll >
using	util::collection_reference_t = typename collection_reference_type< Coll >::type
	The type contained in util::collection_reference_type trait. More...
template<typename Cont >
using	util::collection_from_reference_t = typename collection_from_reference_type< Cont >::type
	Type contained in util::collection_from_reference_type trait. More...

Functions
template<typename Coll >
auto	util::make_collection_reference (Coll &&coll)
	Returns an object referencing to the data contained in coll. More...
template<typename CollRef >
decltype(auto)	util::collection_from_reference (CollRef &collRef)
	Returns the object referenced by collRef as a C++ reference. More...

Detailed Description

Simple traits for container classes.

Trait classes describing a type have a type member defined after that type. They are also available as template types, in the fashion of C++14.

Trait classes describing a value have a value member (static, constexpr) defined with that value. They are also available as template constants, in the fashion of C++17.

Container value traits

Container classes mimicking the C++ STL interface provide a value_type type detailing the contained object. This is generalised in the util::collection_value_type trait, which can be specialised for containers which do not support that.

Two additional traits are provided, which describe the type obtained by accessing an element of the container. This is a close relative of util::collection_value_type, but it may be decorated by l-value reference or constantness depending on the container. The two traits represent access one to a container that is mutable, the other to one that is constant.

Typedef Documentation

template<typename Cont >

using util::collection_from_reference_t = typedef typename collection_from_reference_type<Cont>::type

Type contained in util::collection_from_reference_type trait.

Definition at line 149 of file ContainerMeta.h.

template<typename Coll >

using util::collection_reference_t = typedef typename collection_reference_type<Coll>::type

The type contained in util::collection_reference_type trait.

Definition at line 110 of file ContainerMeta.h.

template<typename Coll >

using util::collection_value_access_t = typedef typename collection_value_access_type<Coll>::type

Type obtained by constant access to element of collection Coll.

Definition at line 76 of file ContainerMeta.h.

template<typename Coll >

using util::collection_value_constant_access_t = typedef typename collection_value_constant_access_type<Coll>::type

Type obtained by constant access to element of collection Coll.

Definition at line 87 of file ContainerMeta.h.

template<typename Coll >

using util::collection_value_t = typedef typename collection_value_type<Coll>::type

Type contained in the collection Coll.

Definition at line 65 of file ContainerMeta.h.

Function Documentation

template<typename CollRef >

decltype(auto) util::collection_from_reference

(

CollRef &

collRef

)

Returns the object referenced by collRef as a C++ reference.

Template Parameters

CollRef

type of collection of the data

Parameters

collRef

collection of the data to be referenced to

Returns

a reference to the object referenced by collRef

See also

util::make_collection_reference()

The return value is a direct reference to the unwrapped container collRef. For example, a collRef of type std::reference_wrapper will result in a C reference of the wrapped container, while a C pointer is left unchanged and a std::unique_ptr object is turned into the equivalent pointer to its elements.

Definition at line 427 of file ContainerMeta.h.

   { return details::collection_from_reference_impl<CollRef>::get(collRef); }

template<typename Coll >

auto util::make_collection_reference

(

Coll &&

coll

)

Returns an object referencing to the data contained in coll.

Template Parameters

Coll	type of collection of the data

Returns

an object referencing to the data contained in coll

See also

util::collection_from_reference()

The criteria, as well as the type of the returned object, are similar to util::collection_reference_type. Therefore, for example a C pointer is returned unchanged, while a std::vector is returned wrapped into a std::reference_wrapper. A std::unique_ptr is returned as bare pointer, given that the returned object does not own the data.

Definition at line 413 of file ContainerMeta.h.

                                              {
   return details::make_collection_reference_impl<std::remove_reference_t<Coll>>
     ::make(coll)
     ;
  }