com.bigdata.relation.rule

Class EmptyAccessPathExpander<E>

java.lang.Object

com.bigdata.relation.rule.EmptyAccessPathExpander<E>

All Implemented Interfaces:

IAccessPathExpander<E>, Serializable

public class EmptyAccessPathExpander<E>
extends Object
implements IAccessPathExpander<E>

An "expander" which replaces the access path with an EmptyAccessPath.

Version:

$Id$

Author:

Bryan Thompson

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static EmptyAccessPathExpander	INSTANCE

Constructor Summary

Constructors

Constructor and Description
EmptyAccessPathExpander()

Method Summary

Methods

Modifier and Type	Method and Description
boolean	backchain() Add the backchainer on top of the expander.
IAccessPath<E>	getAccessPath(IAccessPath<E> accessPath) Return the IAccessPath that will be used to evaluate the IPredicate.
boolean	runFirst() If true, the predicate for this expander will be given priority in the join order.

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

public static final transient EmptyAccessPathExpander INSTANCE

Constructor Detail

EmptyAccessPathExpander

public EmptyAccessPathExpander()

Method Detail

getAccessPath

public IAccessPath<E> getAccessPath(IAccessPath<E> accessPath)

Description copied from interface: IAccessPathExpander

Return the IAccessPath that will be used to evaluate the IPredicate.

Specified by:

getAccessPath in interface IAccessPathExpander<E>

Parameters:

accessPath - The IAccessPath that will be used by default.

Returns:

The IAccessPath that will be used. You can return the given accessPath or you can layer additional semantics onto or otherwise override the given IAccessPath.

runFirst

public boolean runFirst()

Description copied from interface: IAccessPathExpander

If true, the predicate for this expander will be given priority in the join order.

Specified by:

runFirst in interface IAccessPathExpander<E>

Returns:

true if the predicate should be run first

backchain

public boolean backchain()

Description copied from interface: IAccessPathExpander

Add the backchainer on top of the expander.

Specified by:

backchain in interface IAccessPathExpander<E>

Returns:

true if the backchainer should run