saffron.rel
Class SingleRel

java.lang.Object
  |
  +--saffron.rel.Rel
        |
        +--saffron.rel.SingleRel

Direct Known Subclasses:

Aggregate, Converter, Distinct, Filter, Project, SingleTerminator

public abstract class SingleRel

extends Rel

A SingleRel is a base class single-input relational expressions.

Since:

23 September, 2001

Version:

$Id: //open/saffron/src/main/saffron/rel/SingleRel.java#4 $

Author:

jhyde

Nested Class Summary

Nested classes inherited from class saffron.rel.Rel

Field Summary

Rel

child

Fields inherited from class saffron.rel.Rel

cluster, digest, emptyArray, id, nextId, rowType

Constructor Summary

protected

SingleRel(Cluster cluster, Rel child) Creates a SingleRel.

Method Summary

void	childrenAccept(RelVisitor visitor)
protected Type	deriveRowType()
void	explain(PlanWriter pw)
Rel[]	getInputs() Returns an array of this Rel's inputs.
void	replaceInput(int ordinalInParent, Rel rel) Replaces the ordinalInParentth input.

Methods inherited from class saffron.rel.Rel

clone, computeDigest, computeSelfCost, getChildExps, getCluster, getConvention, getCorelVariable, getEnvironment, getId, getInput, getOrCreateCorelVariable, getParentEnv, getQualifier, getQuery, getRelTypeName, getRows, getRowType, getTable, getType, getVariablesStopped, implement, implementExp, implementExps, implementFieldAccess, implementSelf, isAccessTo, isDistinct, onRegister, recomputeDigest, register, registerCorelVariable, setCorelVariable, toString

Methods inherited from class java.lang.Object

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

Field Detail

child

public Rel child

Constructor Detail

SingleRel

protected SingleRel(Cluster cluster,
                    Rel child)

Creates a SingleRel.

Parameters:

cluster - Cluster this relational expression belongs to

child - input relational expression

Method Detail

getInputs

public Rel[] getInputs()

Description copied from class: Rel

Returns an array of this Rel's inputs. If there are no inputs, returns an empty array, not null.

Overrides:

getInputs in class Rel

replaceInput

public void replaceInput(int ordinalInParent,
                         Rel rel)

Description copied from class: Rel

Replaces the ordinalInParent^th input. You must override this method if you override Rel.getInputs().

Overrides:

replaceInput in class Rel

deriveRowType

protected Type deriveRowType()

Specified by:

deriveRowType in class Rel

childrenAccept

public void childrenAccept(RelVisitor visitor)

Overrides:

childrenAccept in class Rel

explain

public void explain(PlanWriter pw)

Overrides:

explain in class Rel