Package org.apache.jena.reasoner.rulesys.impl

Class LPInterpreter

java.lang.Object

org.apache.jena.reasoner.rulesys.impl.LPInterpreter

public class LPInterpreter
extends java.lang.Object

Bytecode interpreter engine for the LP version of the backward chaining rule system. An instance of this is forked off for each parallel query.

Constructor Summary

Constructors

Constructor	Description
LPInterpreter(LPBRuleEngine engine, TriplePattern goal)	Constructor used to construct top level calls.
LPInterpreter(LPBRuleEngine engine, TriplePattern goal, boolean isTop)	Constructor.
LPInterpreter(LPBRuleEngine engine, TriplePattern goal, java.util.List<RuleClauseCode> clauses, boolean isTop)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	bind(Node var, Node val)	Bind a value to a variable, recording the binding in the trail.
void	close()	Stop the current work.
static Node	deref(Node node)	Dereference a node, following any binding trail.
static Triple	deref(TriplePattern t)	Return a dereferenced copy of a triple.
static Node	derefPossFunctor(Node node)	Dereference a node which may be a functor node
FrameObject	getChoiceFrame()	Return the current choice point frame that can be used to restart the interpter at this point.
LPInterpreterContext	getContext()	Return the context in which this interpreter is running, that is either the Generator for a tabled goal or a top level iterator.
LPBRuleEngine	getEngine()	Return the engine which owns this interpreter.
static boolean	isGrounded(Node node)	Check if a node values is now grounded
java.lang.Object	next()	Return the next result from this engine, no further initialization.
void	preserveState(ConsumerChoicePointFrame ccp)	Preserve the current interpter state in the consumer choice point at the top of the choice point tree.
void	restoreState(ConsumerChoicePointFrame ccp)	Restore the interpter state according to the given consumer choice point.
void	setState(LPInterpreterState state)	Start the interpreter running with the given context.
void	setTopInterpreter(LPInterpreterContext context)	Called by top level interpreter to set to execution context for this interpreter to be top level instead of an internal generator.
boolean	unify(Node n1, Node n2)	Unify two nodes.
void	unwindTrail(int mark)	Unwind the trail to given low water mark

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LPInterpreter

public LPInterpreter(LPBRuleEngine engine,
                     TriplePattern goal)

Constructor used to construct top level calls.

Parameters:

engine - the engine which is calling this interpreter

goal - the query to be satisfied

LPInterpreter

public LPInterpreter(LPBRuleEngine engine,
                     TriplePattern goal,
                     boolean isTop)

Constructor.

Parameters:

engine - the engine which is calling this interpreter

goal - the query to be satisfied

isTop - true if this is a top level call from the outside iterator, false means it is an internal generator call which means we don't need to insert an tabled call

LPInterpreter

public LPInterpreter(LPBRuleEngine engine,
                     TriplePattern goal,
                     java.util.List<RuleClauseCode> clauses,
                     boolean isTop)

Constructor.

Parameters:

engine - the engine which is calling this interpreter

goal - the query to be satisfied

clauses - the set of code blocks needed to implement this goal

isTop - true if this is a top level call from the outside iterator, false means it is an internal generator call which means we don't need to insert an tabled call

Method Detail

setTopInterpreter

public void setTopInterpreter(LPInterpreterContext context)

Called by top level interpreter to set to execution context for this interpreter to be top level instead of an internal generator.

close

public void close()

Stop the current work. This is called if the top level results iterator has either finished or the calling application has had enough.

setState

public void setState(LPInterpreterState state)

Start the interpreter running with the given context.

next

public java.lang.Object next()

Return the next result from this engine, no further initialization. Should be called from within an appropriately synchronized block.

getEngine

public LPBRuleEngine getEngine()

Return the engine which owns this interpreter.

getChoiceFrame

public FrameObject getChoiceFrame()

Return the current choice point frame that can be used to restart the interpter at this point.

getContext

public LPInterpreterContext getContext()

Return the context in which this interpreter is running, that is either the Generator for a tabled goal or a top level iterator.

preserveState

public void preserveState(ConsumerChoicePointFrame ccp)

Preserve the current interpter state in the consumer choice point at the top of the choice point tree.

restoreState

public void restoreState(ConsumerChoicePointFrame ccp)

Restore the interpter state according to the given consumer choice point.

unify

public boolean unify(Node n1,
                     Node n2)

Unify two nodes. Current implementation does not support functors.

Returns:

true if the unification succeeds

bind

public void bind(Node var,
                 Node val)

Bind a value to a variable, recording the binding in the trail.

Parameters:

var - the dereferenced variable to be bound

val - the value to bind to it

unwindTrail

public void unwindTrail(int mark)

Unwind the trail to given low water mark

deref

public static Node deref(Node node)

Dereference a node, following any binding trail.

isGrounded

public static boolean isGrounded(Node node)

Check if a node values is now grounded

deref

public static Triple deref(TriplePattern t)

Return a dereferenced copy of a triple.

derefPossFunctor

public static Node derefPossFunctor(Node node)

Dereference a node which may be a functor node