com.metamatrix.jdbc.api
Class PlanVisitor

java.lang.Object
  com.metamatrix.jdbc.api.PlanVisitor

Direct Known Subclasses:

TextOutputVisitor

public abstract class PlanVisitor
extends java.lang.Object

A helper class to walk a query plan and execute some action at each node. Subclasses should override the appropriate visit() methods to get notification when a node of each type is visited.

Constructor Summary

PlanVisitor()
Construct the visitor with a reference to the root node.

Method Summary

void	visit(PlanNode rootNode) This method controls how a tree is visited from the rootNode.
protected abstract void	visitContainerProperty(PlanNode node, java.lang.String propertyName, java.util.Collection propertyValue) Visit a container property - the container property will be visited, then each particular value of the container will be visited.
protected abstract void	visitNode(PlanNode node) Visit a node.
protected abstract void	visitPropertyValue(PlanNode node, java.lang.String propertyName, java.lang.Object propertyValue) Visit a property value.

Methods inherited from class java.lang.Object

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

Constructor Detail

PlanVisitor

public PlanVisitor()

Construct the visitor with a reference to the root node.

Method Detail

visit

public void visit(PlanNode rootNode)

This method controls how a tree is visited from the rootNode. This implementation will walk the tree in pre-order (a node is visited before it's children) and will visit a particular node in the following order: node itself, each property of the node, and finally the children of the node, in order.

Subclasses may override this method to manipulate the visitor order if desired.

Parameters:

rootNode - The rootNode of the tree

visitNode

protected abstract void visitNode(PlanNode node)

Visit a node.

Parameters:

node - The node being visited

visitPropertyValue

protected abstract void visitPropertyValue(PlanNode node,
                                           java.lang.String propertyName,
                                           java.lang.Object propertyValue)

Visit a property value.

Parameters:

node - The node being visited

propertyName - The property name being visited

propertyValue - The property value being visited

visitContainerProperty

protected abstract void visitContainerProperty(PlanNode node,
                                               java.lang.String propertyName,
                                               java.util.Collection propertyValue)

Visit a container property - the container property will be visited, then each particular value of the container will be visited.

Parameters:

node - The node being visited

propertyName - The property name being visited

propertyValue - The collection value being visited