org.apache.xpath
Class XPathVisitor

java.lang.Object
  |
  +--org.apache.xpath.XPathVisitor
Direct Known Subclasses:
AbsPathChecker, ExpressionVisitor, HasPositionalPredChecker, VarNameCollector, XSLTVisitor

public class XPathVisitor
extends java.lang.Object

A derivation from this class can be passed to a class that implements the XPathVisitable interface, to have the appropriate method called for each component of the XPath. Aside from possible other uses, the main intention is to provide a reasonable means to perform expression rewriting.

Each method has the form boolean visitComponentType(ExpressionOwner owner, ComponentType compType). The ExpressionOwner argument is the owner of the component, and can be used to reset the expression for rewriting. If a method returns false, the sub hierarchy will not be traversed.

This class is meant to be a base class that will be derived by concrete classes, and doesn't much except return true for each method.


Constructor Summary
XPathVisitor()
           
 
Method Summary
 boolean visitBinaryOperation(ExpressionOwner owner, Operation op)
          Visit a binary operation.
 boolean visitFunction(ExpressionOwner owner, Function func)
          Visit a function.
 boolean visitLocationPath(ExpressionOwner owner, LocPathIterator path)
          Visit a LocationPath.
 boolean visitMatchPattern(ExpressionOwner owner, StepPattern pattern)
          Visit a match pattern.
 boolean visitNumberLiteral(ExpressionOwner owner, XNumber num)
          Visit a number literal.
 boolean visitPredicate(ExpressionOwner owner, Expression pred)
          Visit a predicate within a location path.
 boolean visitStep(ExpressionOwner owner, NodeTest step)
          Visit a step within a location path.
 boolean visitStringLiteral(ExpressionOwner owner, XString str)
          Visit a string literal.
 boolean visitUnaryOperation(ExpressionOwner owner, UnaryOperation op)
          Visit a unary operation.
 boolean visitUnionPath(ExpressionOwner owner, UnionPathIterator path)
          Visit a UnionPath.
 boolean visitUnionPattern(ExpressionOwner owner, UnionPattern pattern)
          Visit a union pattern.
 boolean visitVariableRef(ExpressionOwner owner, Variable var)
          Visit a variable reference.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

XPathVisitor

public XPathVisitor()
Method Detail

visitLocationPath

public boolean visitLocationPath(ExpressionOwner owner,
                                 LocPathIterator path)
Visit a LocationPath.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
path - The LocationPath object.
Returns:
true if the sub expressions should be traversed.

visitUnionPath

public boolean visitUnionPath(ExpressionOwner owner,
                              UnionPathIterator path)
Visit a UnionPath.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
path - The UnionPath object.
Returns:
true if the sub expressions should be traversed.

visitStep

public boolean visitStep(ExpressionOwner owner,
                         NodeTest step)
Visit a step within a location path.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
step - The Step object.
Returns:
true if the sub expressions should be traversed.

visitPredicate

public boolean visitPredicate(ExpressionOwner owner,
                              Expression pred)
Visit a predicate within a location path. Note that there isn't a proper unique component for predicates, and that the expression will be called also for whatever type Expression is.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
pred - The predicate object.
Returns:
true if the sub expressions should be traversed.

visitBinaryOperation

public boolean visitBinaryOperation(ExpressionOwner owner,
                                    Operation op)
Visit a binary operation.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
op - The operation object.
Returns:
true if the sub expressions should be traversed.

visitUnaryOperation

public boolean visitUnaryOperation(ExpressionOwner owner,
                                   UnaryOperation op)
Visit a unary operation.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
op - The operation object.
Returns:
true if the sub expressions should be traversed.

visitVariableRef

public boolean visitVariableRef(ExpressionOwner owner,
                                Variable var)
Visit a variable reference.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
var - The variable reference object.
Returns:
true if the sub expressions should be traversed.

visitFunction

public boolean visitFunction(ExpressionOwner owner,
                             Function func)
Visit a function.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
func - The function reference object.
Returns:
true if the sub expressions should be traversed.

visitMatchPattern

public boolean visitMatchPattern(ExpressionOwner owner,
                                 StepPattern pattern)
Visit a match pattern.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
pattern - The match pattern object.
Returns:
true if the sub expressions should be traversed.

visitUnionPattern

public boolean visitUnionPattern(ExpressionOwner owner,
                                 UnionPattern pattern)
Visit a union pattern.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
pattern - The union pattern object.
Returns:
true if the sub expressions should be traversed.

visitStringLiteral

public boolean visitStringLiteral(ExpressionOwner owner,
                                  XString str)
Visit a string literal.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
str - The string literal object.
Returns:
true if the sub expressions should be traversed.

visitNumberLiteral

public boolean visitNumberLiteral(ExpressionOwner owner,
                                  XNumber num)
Visit a number literal.
Parameters:
owner - The owner of the expression, to which the expression can be reset if rewriting takes place.
num - The number literal object.
Returns:
true if the sub expressions should be traversed.


Copyright 2006 Apache XML Project. All Rights Reserved.