org.apache.jena.reasoner.rulesys.impl

Class BindingVector

java.lang.Object

org.apache.jena.reasoner.rulesys.impl.BindingVector

All Implemented Interfaces:

BindingEnvironment

public class BindingVector
extends Object
implements BindingEnvironment

An implementation of a binding environment that maintains a single array of bound values for the variables in a rule. Stack management is done externally. This is intended for use in the Brule system and so also supports variable-variable bindings by use of reference chains.

Constructor Summary

Constructors

Constructor and Description
BindingVector(BindingVector clone) Constructor - create a binding environment which is a copy of the given environment
BindingVector(int size) Constructor - create an empty binding environment
BindingVector(Node[] env) Constructor - create a binding environment from a vector of bindings

Method Summary

Modifier and Type	Method and Description
boolean	bind(int i, Node value) Bind the ith variable in the current environment to the given value.
boolean	bind(Node var, Node value) Bind a variable in the current environment to the given value.
boolean	equals(Object o) Equality override
Node	getBinding(Node node) If the node is a variable then return the current binding (null if not bound) otherwise return the node itself.
Node[]	getEnvironment() Return the current array of bindings.
Node	getGroundVersion(Node node) Return the most ground version of the node.
int	hashCode() hash function override
Triple	instantiate(TriplePattern pattern) Instantiate a triple pattern against the current environment.
TriplePattern	partInstantiate(TriplePattern goal) Bind the variables in a goal pattern using the binding environment, to generate a more specialized goal
String	toString() Printable form
static BindingVector	unify(TriplePattern goal, TriplePattern head, int numRuleVars) Unify a goal with the head of a rule.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

BindingVector

public BindingVector(int size)

Constructor - create an empty binding environment

BindingVector

public BindingVector(Node[] env)

Constructor - create a binding environment from a vector of bindings

BindingVector

public BindingVector(BindingVector clone)

Constructor - create a binding environment which is a copy of the given environment

Method Detail

getEnvironment

public Node[] getEnvironment()

Return the current array of bindings. Useful for fast access to several bindings, not useful for doing updates.

getBinding

public Node getBinding(Node node)

If the node is a variable then return the current binding (null if not bound) otherwise return the node itself.

getGroundVersion

public Node getGroundVersion(Node node)

Return the most ground version of the node. If the node is not a variable just return it, if it is a variable bound in this environment return the binding, if it is an unbound variable return the variable.

Specified by:

getGroundVersion in interface BindingEnvironment

bind

public boolean bind(int i,
                    Node value)

Bind the ith variable in the current environment to the given value. Checks that the new binding is compatible with any current binding. Handles aliased variables.

Returns:

false if the binding fails

bind

public boolean bind(Node var,
                    Node value)

Bind a variable in the current environment to the given value. Checks that the new binding is compatible with any current binding.

Specified by:

bind in interface BindingEnvironment

Parameters:

var - a Node_RuleVariable defining the variable to bind

value - the value to bind

Returns:

false if the binding fails

partInstantiate

public TriplePattern partInstantiate(TriplePattern goal)

Bind the variables in a goal pattern using the binding environment, to generate a more specialized goal

Parameters:

goal - the TriplePattern to be instantiated

Returns:

a TriplePattern obtained from the goal by substituting current bindings

instantiate

public Triple instantiate(TriplePattern pattern)

Instantiate a triple pattern against the current environment. This version handles unbound variables by turning them into bNodes.

Specified by:

instantiate in interface BindingEnvironment

Parameters:

pattern - the triple pattern to match

Returns:

a new, instantiated triple

toString

public String toString()

Printable form

Overrides:

toString in class Object

unify

public static BindingVector unify(TriplePattern goal,
                                  TriplePattern head,
                                  int numRuleVars)

Unify a goal with the head of a rule. This is a poor-man's unification, we should try switching to a more conventional global-variables-with-trail implementation in the future.

Parameters:

goal - the goal pattern which it being matched to a rule

head - the head pattern of the rule which is being instantiated

numRuleVars - the length of the environment to allocate.

Returns:

An initialized binding environment for the rule variables or null if the unification fails. If a variable in the environment becomes aliased to another variable through the unification this is represented by having its value in the environment be the variable to which it is aliased.

equals

public boolean equals(Object o)

Equality override

Overrides:

equals in class Object

hashCode

public int hashCode()

hash function override

Overrides:

hashCode in class Object