Package org.apache.derby.impl.sql.compile

Class ReplaceAggregatesWithCRVisitor

java.lang.Object

org.apache.derby.impl.sql.compile.ReplaceAggregatesWithCRVisitor

All Implemented Interfaces:

Visitor

class ReplaceAggregatesWithCRVisitor
extends java.lang.Object
implements Visitor

Replace all aggregates with result columns.

Field Summary

Fields

Modifier and Type	Field	Description
private ResultColumnList	rcl
private java.lang.Class<?>	skipOverClass
private int	tableNumber

Constructor Summary

Constructors

Constructor	Description
ReplaceAggregatesWithCRVisitor(ResultColumnList rcl, int tableNumber)	Replace all aggregates with column references.
ReplaceAggregatesWithCRVisitor(ResultColumnList rcl, int tableNumber, java.lang.Class<?> skipOverClass)
ReplaceAggregatesWithCRVisitor(ResultColumnList rcl, java.lang.Class<?> nodeToSkip)	Replace all aggregates with column references.

Method Summary

Modifier and Type	Method	Description
boolean	skipChildren(Visitable node)	Don't visit children under the skipOverClass node, if it isn't null.
boolean	stopTraversal()	Method that is called to see if query tree traversal should be stopped before visiting all nodes.
Visitable	visit(Visitable node)	Don't do anything unless we have an aggregate node.
boolean	visitChildrenFirst(Visitable node)	Method that is called to see if visit() should be called on the children of node before it is called on node itself.

Methods inherited from class java.lang.Object

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

Field Detail

rcl

private ResultColumnList rcl

skipOverClass

private java.lang.Class<?> skipOverClass

tableNumber

private int tableNumber

Constructor Detail

ReplaceAggregatesWithCRVisitor

ReplaceAggregatesWithCRVisitor(ResultColumnList rcl,
                               int tableNumber)

Replace all aggregates with column references. Add the reference to the RCL. Delegates most work to AggregateNode.replaceAggregatesWithColumnReferences(rcl, tableNumber).

Parameters:

rcl - the result column list

tableNumber - The tableNumber for the new CRs

ReplaceAggregatesWithCRVisitor

ReplaceAggregatesWithCRVisitor(ResultColumnList rcl,
                               int tableNumber,
                               java.lang.Class<?> skipOverClass)

ReplaceAggregatesWithCRVisitor

ReplaceAggregatesWithCRVisitor(ResultColumnList rcl,
                               java.lang.Class<?> nodeToSkip)

Replace all aggregates with column references. Add the reference to the RCL. Delegates most work to AggregateNode.replaceAggregatesWithColumnReferences(rcl). Doesn't traverse below the passed in class.

Parameters:

rcl - the result column list

nodeToSkip - don't examine anything below nodeToSkip

Method Detail

visit

public Visitable visit(Visitable node)
                throws StandardException

Don't do anything unless we have an aggregate node.

Specified by:

visit in interface Visitor

Parameters:

node - the node to process

Returns:

me

Throws:

StandardException - on error

skipChildren

public boolean skipChildren(Visitable node)

Don't visit children under the skipOverClass node, if it isn't null.

Specified by:

skipChildren in interface Visitor

Parameters:

node - the node to process

Returns:

true/false

visitChildrenFirst

public boolean visitChildrenFirst(Visitable node)

Description copied from interface: Visitor

Method that is called to see if visit() should be called on the children of node before it is called on node itself. If this method always returns true, the visitor will walk the tree bottom-up. If it always returns false, the tree is visited top-down.

Specified by:

visitChildrenFirst in interface Visitor

Parameters:

node - the top node of a sub-tree about to be visited

Returns:

true if node's children should be visited before node, false otherwise

stopTraversal

public boolean stopTraversal()

Description copied from interface: Visitor

Method that is called to see if query tree traversal should be stopped before visiting all nodes. Useful for short circuiting traversal if we already know we are done.

Specified by:

stopTraversal in interface Visitor

Returns:

true/false