com.hp.hpl.jena.sparql.algebra.optimize
Class TransformExtendCombine

java.lang.Object
  com.hp.hpl.jena.sparql.algebra.TransformCopy
      com.hp.hpl.jena.sparql.algebra.optimize.TransformExtendCombine

All Implemented Interfaces:

Transform

public class TransformExtendCombine
extends TransformCopy

An optimizer that aims to combine multiple extend clauses together.

Since the semantics of extend are such that the expressions are expected to be evaluated in order we can combine extends together. This can make evaluation more efficient because all the assignments are done in a single step though depending on the underlying store this may make little or no difference.

Note that standard algebra construction will cause much of this to happen naturally but sometimes it is useful to apply this as an additional independent transform.

Field Summary

Fields inherited from class com.hp.hpl.jena.sparql.algebra.TransformCopy

COPY_ALWAYS, COPY_ONLY_ON_CHANGE

Constructor Summary

TransformExtendCombine()

Method Summary

Op	transform(OpAssign opAssign, Op subOp)
Op	transform(OpExtend opExtend, Op subOp)

Methods inherited from class com.hp.hpl.jena.sparql.algebra.TransformCopy

transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform, transform

Methods inherited from class java.lang.Object

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

Constructor Detail

TransformExtendCombine

public TransformExtendCombine()

Method Detail

transform

public Op transform(OpAssign opAssign,
                    Op subOp)

Specified by:

transform in interface Transform

Overrides:

transform in class TransformCopy

transform

public Op transform(OpExtend opExtend,
                    Op subOp)

Specified by:

transform in interface Transform

Overrides:

transform in class TransformCopy