nt::VM Class Reference

Hosts the first-order logic (FOL) and second-order logic (SOL) cores. More...

#include <VM.h>

Public Member Functions
	VM (CursorManager &cursors)
Tuple *	Next (PlanNode *node)
	Pulls the next tuple from the plan tree (Tarski/FOL core).

Detailed Description

Hosts the first-order logic (FOL) and second-order logic (SOL) cores.

This partitioning exists to ensure retrieval terminates when execution is constrained to first-order logic.

• Tarski runtime (FOL): a relational engine that implements Tarski's relational calculus. It uses a deterministic Volcano-iterator model to perform relational algebra operations such as joins, projections, and selects directly against the CursorManager and a prepared plan.
• Karuta runtime (SOL): an isolated WAM-based environment for higher-order logic programming. It handles recursion, choice points, and other programming constructs that do not guarantee termination.

Remarks

Lazy evaluation and paging strategy

Both the Tarski first-order engine and the Karuta second-order engine are strictly pull-based. Data is streamed lazily from the CursorManager to preserve a constant memory footprint regardless of relation size.

Pipeline dynamics:

• Demand-driven: the Karuta WAM requests a fact only when a goal needs satisfaction. A request propagates down the algebra tree as a chain of Next() calls.
• Short-circuiting: if the Karuta engine finds a solution or reaches a failure that invalidates a branch, the Tarski iterator is discarded or reset without materializing the remaining tuples.
• Resource stewardship: by maintaining laziness up to the highest logical level, the runtime minimizes pressure on ObjectManager and keeps snapshots pinned through LifecycleManager::Monitor only for the minimum time required.

Member Function Documentation

Next()

Tuple * nt::VM::Next

(

PlanNode *

node

)

Pulls the next tuple from the plan tree (Tarski/FOL core).

Propagates a Next() call down the operator tree:

• SCAN delegates to CursorManager::Next.
• JOIN drives the nested-loop: for each outer tuple it resolves scan_args on the inner SCAN, resets the inner cursor, and probes until a match is found or the inner is exhausted.
• TAKE counts emitted tuples and returns nullptr once the limit is reached.
• PROJECT filters an input tuple to the requested attribute names.

Parameters

node	Root of the plan subtree to evaluate.

Returns

Next matching tuple, or nullptr when the plan is exhausted.

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The documentation for this class was generated from the following files:

• VM.h
• VM.cpp