org.exolab.adaptx.xpath.expressions

Class PathExpr

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

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

Method Summary

abstract XPathResult
evaluate(XPathContext context)
Evaluates the expression and returns the XPath result.
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.
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.

Method Details

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.

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

getExprType

public final short getExprType()
Returns the XPathExpression type
Specified by:
getExprType in interface XPathExpression
Returns:
the XPathExpression type

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()

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