trait.hpp File Reference

Helpers for type detection, type rewriting and metaprogramming. More...

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Description

Helpers for type detection, type rewriting and metaprogramming.

This header is a collection of frequently used templates for working with types. It incurs only modest header inclusion overhead

Warning

be sure not to jeopardise that!

unwrapping

Strip away all kinds of type adornments, like const, reference, pointer, smart-ptr. The accompanying lib::meta::unwrap() function can be used to accept "stuff packaged in various forms". The Strip template packages this ability in various degrees for metaprogramming

Warning

these helpers can be quite dangerous, as they silently break any protective barriers (including lifecycle managing smart-ptrs)

string conversion

a set of trait templates to categorise arbitrary types with respect to the ability for string conversions

ability to iterate

these traits can be used to build the notion of a generic container – basically anything that can be enumerated. Within Lumiera, we frequently use our own concept of "iterability", known as "Lumiera Forward Iterator". These helpers here allow to unify this concept with the "Range" concept from the standard library (begin() and end())

See also

MetaUtils_test

format-obj.hpp string representation for anything

meta/util.hpp very basic metaprogramming helpers

typelist.hpp

Definition in file trait.hpp.

#include "lib/meta/util.hpp"
#include "lib/meta/duck-detector.hpp"
#include <type_traits>

Namespaces
namespace	boost
namespace	std
	STL namespace.
namespace	lib
	Implementation namespace for support and library code.
namespace	lib::hash
	Hash implementations usable for the HashIndexed mixin as well as key within std::unordered_map.
namespace	lib::time
namespace	steam
	Steam-Layer implementation namespace root.
namespace	steam::mobject
	Media-Objects, edit operations and high-level session.
namespace	lib::meta

Macros
#define	TRAIT_IS_NARROWING(_SRC_, _TAR_)

Classes
struct	Unwrap< X >
	Helper for type analysis and convenience accessors: attempts to extract a base type from various wrappers. More...
struct	Unwrap< void >
	< More...
struct	Unwrap< X * >
struct	Unwrap< boost::reference_wrapper< X > >
struct	Unwrap< std::reference_wrapper< X > >
struct	Unwrap< std::unique_ptr< X, D > >
struct	Unwrap< std::shared_ptr< X > >
struct	Unwrap< P< X, B > >
struct	Strip< X >
	Helper for type analysis: tries to strip all kinds of type adornments. More...
struct	RefTraits< TY >
	Type definition helper for pointer and reference types. More...
struct	RefTraits< TY * >
struct	RefTraits< TY & >
struct	RefTraits< TY && >
struct	is_basicallySame< T, U >
	compare unadorned types, disregarding const and references More...
struct	is_Subclass< S, I >
	verify compliance to an interface by subtype check More...
struct	is_basically< S, I >
	compare for unadorned base type, disregarding const and references More...
struct	can_StandIn< S, G >
	verify the first (special) type can stand-in for the second More...
struct	is_StringLike< X >
	detect various flavours of string / text data More...
struct	can_lexical2string< X >
	types able to be lexically converted to string representation More...
struct	use_LexicalConversion< X >
struct	is_StreamSource< X >
struct	use_StringConversion4Stream< X >
	when to use custom string conversions for output streams More...
struct	is_smart_ptr< X >
	detect smart pointers More...
struct	is_smart_ptr< std::shared_ptr< T > >
struct	is_smart_ptr< std::unique_ptr< T, D > >
struct	is_nonFloat< NUM >
struct	is_narrowingInit< SRC, TAR >
	temporary workaround for GCC Bug-63723, necessary until CGG-5 More...
struct	is_narrowingInit< lib::hash::LuidH, TAR >
class	can_IterForEach< T >
	Trait template to detect a type usable immediately as "Lumiera Forward Iterator" in a specialised for-each loop This is just a heuristic, based on some common properties of such iterators; it is enough to distinguish it from an STL container, but can certainly be refined. More...
class	is_StateCore< T >
	Trait template to detect a type exposing a »state core« API. More...
class	can_STL_ForEach< T >
	Trait template to detect a type usable with the STL for-each loop. More...
struct	can_STL_ForEach< T >::is_iterable
struct	can_STL_ForEach< T >::is_noexcept_iterable
struct	can_STL_ForEach< T >::is_const_iterable
struct	can_STL_ForEach< T >::is_const_noexcept_iterable
class	can_STL_backIteration< T >
	Trait template to detect a type also supporting STL-style backwards iteration. More...
struct	can_STL_backIteration< T >::is_backIterable
struct	can_STL_backIteration< T >::is_noexcept_backIterable
struct	can_STL_backIteration< T >::is_const_backIterable
struct	can_STL_backIteration< T >::is_const_noexcept_backIterable

Functions
template<typename X >
Unwrap< X >::Type &	unwrap (X const &wrapped)
	convenience shortcut: unwrapping free function.

Variables
template<typename T >
static constexpr bool	isConst_v = std::is_const_v<remove_reference_t<T>>
template<typename T >
static constexpr bool	isLRef_v = std::is_lvalue_reference_v<T>
template<typename T >
static constexpr bool	isRRef_v = std::is_rvalue_reference_v<T>
template<typename T >
static constexpr bool	isRef_v = std::is_reference_v<T>

Macro Definition Documentation

TRAIT_IS_NARROWING

#define TRAIT_IS_NARROWING	(		_SRC_,
			_TAR_
	)

Value:

  template<>                              \
  struct is_narrowingInit<_SRC_, _TAR_>    \
    : std::true_type                        \
    { };

Definition at line 464 of file trait.hpp.

---

Class Documentation

lib::meta::Strip

struct lib::meta::Strip

Class Members
typedef conditional_t< is_reference_v< X >, conditional_t< is_rvalue_reference_v< X >, remove_cv_t< remove_reference_t< X > > &&, remove_cv_t< remove_reference_t< X > > & >, remove_cv_t< X > >	TypeUnconst
typedef remove_reference_t< TypeUnconst >	TypeReferred
typedef remove_pointer_t< TypeReferred >	TypePointee
typedef remove_cv_t< TypePointee >	TypePlain
typedef Type	Type

Inheritance diagram for Strip< X >:

Collaboration diagram for Strip< X >:

lib::meta::RefTraits

struct lib::meta::RefTraits

Class Members
typedef TY	Value
typedef TY *	Pointer
typedef TY &	Reference

Collaboration diagram for RefTraits< TY >:

lib::meta::RefTraits< TY * >

struct lib::meta::RefTraits< TY * >

Class Members
typedef TY *	Value
typedef TY **	Pointer
typedef TY *&	Reference

Collaboration diagram for RefTraits< TY * >:

lib::meta::RefTraits< TY & >

struct lib::meta::RefTraits< TY & >

Class Members
typedef TY	Value
typedef TY *	Pointer
typedef TY &	Reference

Collaboration diagram for RefTraits< TY & >:

lib::meta::RefTraits< TY && >

struct lib::meta::RefTraits< TY && >

Class Members
typedef TY	Value
typedef TY *	Pointer
typedef TY &	Reference

Collaboration diagram for RefTraits< TY && >: