nt::ObjectManager::ephemeral_object_type Struct Reference

Object type descriptor for EPHEMERAL_RELATION objects. More...

#include <ObjectManager.h>

Inheritance diagram for nt::ObjectManager::ephemeral_object_type:

Public Types
enum class	Cardinality { Finite , ConstrainedFinite , AlephZero , Continuum }
using	Generator
	Produces a page of tuples for the given bound arguments.

Public Attributes
Cardinality	cardinality
Generator	generator
Public Attributes inherited from nt::ObjectManager::object_type
OBJECT_TYPE	label
	Object category label.
bool	disposable
	True when the object is not durable.
std::set< METHOD >	methods
	Methods supported by this object type.
bool	exclusive = false
	When true, only one write-mode handle may be open at a time.

Detailed Description

Object type descriptor for EPHEMERAL_RELATION objects.

An ephemeral relation has no physical storage. Its tuples are produced on demand by a generator function. Cardinality may be finite (e.g. a projected stored relation) or AlephZero (e.g. the eq/lt builtins).

The generator receives the bound argument values that were written into the cursor by the JOIN operator before each probe, together with a pagination offset and limit. It must return at most limit tuples starting at logical position offset.

For membership-probe builtins (all args ground), the generator returns at most one tuple. For enumeration over AlephZero relations the generator maps offset to the appropriate pair via a bijective enumeration scheme (e.g. Cantor pairing); callers must bound such scans with a TAKE node.

Member Typedef Documentation

Generator

using nt::ObjectManager::ephemeral_object_type::Generator

Initial value:

std::function<std::vector<Tuple>(
               const std::vector<std::string>& args, std::size_t offset, std::size_t limit)>

Produces a page of tuples for the given bound arguments.

Parameters

args	Bound argument values written by the JOIN before probing.
offset	Zero-based logical tuple offset (for pagination).
limit	Maximum number of tuples to return.

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

• ObjectManager.h