org.exolab.adaptx.xpath.expressions

Class PathExpr

java.lang.Object

org.exolab.adaptx.xpath.expressions.PathExpr

All Implemented Interfaces:

MatchExpression, XPathExpression

public abstract class PathExpr
extends java.lang.Object
implements XPathExpression, MatchExpression

An abstract class representing an XPath Location Path expression.

Version:

$Revision: 3734 $ $Date: 2003-05-13 03:55:04 -0400 (Tue, 13 May 2003) $

Author:

Keith Visco

Field Summary

Fields inherited from interface org.exolab.adaptx.xpath.XPathExpression

BOOLEAN, ERROR, FILTER_EXPR, LOCATION_PATH, NODE_TEST, NUMBER, PATH_EXPR, PRIMARY, STEP, STRING, UNION_EXPR

Constructor Summary

Constructors

Constructor and Description
PathExpr()

Method Summary

Methods

Modifier and Type	Method and Description
abstract XPathResult	evaluate(XPathContext context) Evaluates the expression and returns the XPath result.
abstract double	getDefaultPriority() Determines the priority of a PatternExpr as follows:
short	getExprType() Returns the XPathExpression type
abstract PathComponent	getPathComponent() Returns the PathComponent for the this PathExpr, either a FilterExpr or LocationStep.
abstract PathExpr	getSubPath()
abstract boolean	isAbsolute() Returns true if this PathExpr is an absolute expression, otherwise false (ie.
abstract boolean	matches(XPathNode node, XPathContext context) Determines if the given node is matched by this MatchExpr with respect to the given context.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.exolab.adaptx.xpath.XPathExpression

toString

Constructor Detail

PathExpr

public PathExpr()

Method Detail

evaluate

public abstract XPathResult evaluate(XPathContext context)
                              throws XPathException

Evaluates the expression and returns the XPath result.

Specified by:

evaluate in interface XPathExpression

Parameters:

context - The XPathContext to use during evaluation.

Returns:

The XPathResult (not null).

Throws:

XPathException - if an error occured while evaluating this expression.

getExprType

public final short getExprType()

Returns the XPathExpression type

Specified by:

getExprType in interface XPathExpression

Returns:

the XPathExpression type

See Also:

XPathExpression

getPathComponent

public abstract PathComponent getPathComponent()

Returns the PathComponent for the this PathExpr, either a FilterExpr or LocationStep.

Returns:

the PathComponent for this PathExpr

getSubPath

public abstract PathExpr getSubPath()

getDefaultPriority

public abstract double getDefaultPriority()

Determines the priority of a PatternExpr as follows:

  From the 19991116 XSLT 1.0 Recommendation:
  + If the pattern has the form of a QName preceded by a
    ChildOrAttributeAxisSpecifier or has the form 
    processing-instruction(Literal) then the priority is 0.
  + If the pattern has the form NCName:* preceded by a 
    ChildOrAttributeAxisSpecifier, then the priority is -0.25
  + Otherwise if the pattern consists of just a NodeTest 
    preceded by a ChildOrAttributeAxisSpecifier then the
    priority is -0.5
  + Otherwise the priority is 0.5
 

Returns:

the priority for this PatternExpr

isAbsolute

public abstract boolean isAbsolute()

Returns true if this PathExpr is an absolute expression, otherwise false (ie. it's a relative expression).

Returns:

true if this PathExpr is an absolute expression.

matches

public abstract boolean matches(XPathNode node,
              XPathContext context)
                         throws XPathException

Determines if the given node is matched by this MatchExpr with respect to the given context.

Specified by:

matches in interface MatchExpression

Parameters:

node - the node to determine a match for

context - the XPathContext

Returns:

true if the given node is matched by this MatchExpr

Throws:

XPathException - when an error occurs during evaluation