org.exolab.adaptx.xpath.engine
Class AbstractPathComponent

java.lang.Object
  org.exolab.adaptx.xpath.engine.AbstractPathComponent

All Implemented Interfaces:

MatchExpression, PathComponent, XPathExpression

public abstract class AbstractPathComponent
extends java.lang.Object
implements PathComponent

The base class for paths (now basically called paths)

Version:

$Revision: 4055 $ $Date: 2004-01-13 01:08:41 -0500 (Tue, 13 Jan 2004) $

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

AbstractPathComponent()
Creates a new AbstractPathComponent

Method Summary

void	addPredicate(org.exolab.adaptx.xpath.engine.PredicateExprImpl predicate) Adds the given Expression to this PathComponent's predicate List.
void	addPredicate(XPathExpression expr) Adds the given Expression to this PathComponent's predicate List.
abstract XPathResult	evaluate(XPathContext context) Evaluates the expression and returns the XPath result.
void	evaluatePredicates(NodeSet nodes, XPathContext context) Evaluates the PredicateExpr of this PathComponent against the given Node.
abstract double	getDefaultPriority() Determines the priority of a PatternExpr as follows:
abstract short	getExprType() Returns the type of this expression.
PredicateExpr	getPredicate() Returns the PredicateExpr of this PathComponent
abstract XPathExpression	getSubExpression() Returns the sub-expression encapsulated by this PathComponent.
boolean	hasPredicates() Returns true if this FilterBase has predicates expressions.
abstract boolean	isFilterExpr() Returns true if this PathComponent is a FilterExpr.
abstract boolean	isLocationStep() Returns true if this PathComponent is a LocationStep.
abstract boolean	matches(XPathNode node, XPathContext context) Determines if the given node is matched by this MatchExpr with respect to the given context.
java.lang.String	toString() Returns the String representation of this PathComponent

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractPathComponent

public AbstractPathComponent()

Creates a new AbstractPathComponent

Method Detail

addPredicate

public void addPredicate(XPathExpression expr)
                  throws XPathException

Adds the given Expression to this PathComponent's predicate List.

Parameters:

expr - the Expr to add to the predicate list

Throws:

XPathException

addPredicate

public void addPredicate(org.exolab.adaptx.xpath.engine.PredicateExprImpl predicate)
                  throws XPathException

Adds the given Expression to this PathComponent's predicate List.

Parameters:

expr - the Expr to add to the predicate list

Throws:

XPathException

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
 

Specified by:

getDefaultPriority in interface PathComponent

Returns:

the priority for this PatternExpr

getSubExpression

public abstract XPathExpression getSubExpression()

Returns the sub-expression encapsulated by this PathComponent. the sub-expression will either be a PrimaryExpr if this PathComponent is a FilterExpr, or a NodeExpression if this Pathcomponent is a LocationStep. This method may return null if no such sub-expression exists for the PathComponent.

Specified by:

getSubExpression in interface PathComponent

Returns:

the sub-expression encapsulated by this PathComponent.

getExprType

public abstract short getExprType()

Description copied from interface: XPathExpression

Returns the type of this expression.

Specified by:

getExprType in interface XPathExpression

Returns:

The type of this expression

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.

getPredicate

public PredicateExpr getPredicate()

Returns the PredicateExpr of this PathComponent

Specified by:

getPredicate in interface PathComponent

Returns:

the PredicateExpr of this PathComponent

hasPredicates

public boolean hasPredicates()

Returns true if this FilterBase has predicates expressions.

Specified by:

hasPredicates in interface PathComponent

Returns:

true if this FilterBase has predicates expressions.

evaluatePredicates

public void evaluatePredicates(NodeSet nodes,
                               XPathContext context)
                        throws XPathException

Evaluates the PredicateExpr of this PathComponent against the given Node.

Specified by:

evaluatePredicates in interface PathComponent

Parameters:

nodes - the current NodeSet

contextInfo - provides a way to retrieve additional context information needed to evaluate some expressions

Throws:

XPathException

isFilterExpr

public abstract boolean isFilterExpr()

Returns true if this PathComponent is a FilterExpr. Note that if this method returns true, then a call to #isLocationStep must return false.

Specified by:

isFilterExpr in interface PathComponent

Returns:

true if this PathComponent is a FilterExpr

See Also:

isLocationStep

isLocationStep

public abstract boolean isLocationStep()

Returns true if this PathComponent is a LocationStep. Note that if this method returns true, then a call to #isFilterExpr must return false.

Specified by:

isLocationStep in interface PathComponent

Returns:

true if this PathComponent is a LocationStep

See Also:

isFilterExpr

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

toString

public java.lang.String toString()

Returns the String representation of this PathComponent

Specified by:

toString in interface XPathExpression

Overrides:

toString in class java.lang.Object

Returns:

the String representation of this PathComponent