org.apache.directory.api.ldap.model.filter
Interface FilterVisitor

All Known Implementing Classes:

BranchNormalizedVisitor

public interface FilterVisitor

Filter expression tree node visitor interface. Note that this is a variation of the extrinsic visitor variation. It has the following advantages over the standard visitor pattern:

• Visitor takes responsibility that a visitor can visit a node
• Each visitor knows which types of concrete classes it can visit
• New visitors can be created without changing the node class
• New node classes can be added without having to change old visitors
• Visitation order can be controled in every respect:
• Visitation rejection with canVisit() and/or getOrder()
• Recursive visitation ordering with isPrefix()
• Child visitation ordering with getOrder()

Author:

Apache Directory Project

Method Summary

boolean	canVisit(ExprNode node) Checks to see if a node can be visited.
List<ExprNode>	getOrder(BranchNode node, List<ExprNode> children) Get the array of children to visit sequentially to determine the order of child visitations.
boolean	isPrefix() Determines whether the visitation order is prefix or postfix.
Object	visit(ExprNode node) Visits a filter expression AST using a specific visitation order.

Method Detail

visit

Object visit(ExprNode node)

Visits a filter expression AST using a specific visitation order.

Parameters:

node - the node to visit

Returns:

node the resulting modified node

canVisit

boolean canVisit(ExprNode node)

Checks to see if a node can be visited.

Parameters:

node - the node to be visited

Returns:

whether or node the node should be visited

isPrefix

boolean isPrefix()

Determines whether the visitation order is prefix or postfix.

Returns:

true if the visitation is in prefix order, false otherwise.

getOrder

List<ExprNode> getOrder(BranchNode node,
                        List<ExprNode> children)

Get the array of children to visit sequentially to determine the order of child visitations. Some children may not be returned at all if canVisit() returns false on them.

Parameters:

node - the parent branch node

children - the child node array

Returns:

the new reordered array of children