several.hpp File Reference

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Description

Abstraction interface: array-like random access by subscript.

Design

This is a data structure abstraction suitable for performance critical code. It is used pervasively in the backbone of the Lumiera »Render Node Network«.

• usage is clear and concise, allowing to hide implementation details
• adaption and optimisation for various usage patterns is possible
• suitably fast read access with a limited amount of indirections

  why not std::vector?

  The most prevalent STL container almost fulfils the above mentioned criteria, and thus served as a blueprint for design and implementations. Some drawbacks however prevent its direct use for this purpose. Notably, std::vector leaks implementation details of the contained data and generally exposes way too much operations; it is not possible to abstract away the concrete element type. Moreover, using vector with a custom allocator is surprisingly complicated, requires to embody the concrete allocator type into the container type and requires to store an additional back-link whenever the allocator is not a monostate. The intended use case calls for a large number of small collection elements, which are repeatedly bulk- allocated and deallocated.

  The lib::Several container is a smart front-end and exposes array-style random access through references to a interface type. It can only be created and populated through a builder, and is immutable during lifetime, while it can hold non-const element data. The actual implementation data types and the employed allocator framework are not exposed in the front-end's type signature. The container is single-ownership (move-asignable); some additional metadata and the data storage reside within an ArrayBucket<I>, managed by the allocator. In its simplest form, this storage is heap allocated and automatically deleted.

  See also

  several-builder.hpp

Definition in file several.hpp.

#include "lib/nocopy.hpp"
#include "lib/index-iter.hpp"
#include <cstddef>
#include <functional>

Classes
struct	ArrayBucket< I >
	Metadata record placed immediately before the data storage. More...
class	SelfDestructor< TAR >
class	Several< I >
	Abstraction: Fixed array of elements. More...

Namespaces
	lib
	Implementation namespace for support and library code.