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org.exolab.adaptx.xpath.engine

Class AbstractPathComponent

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 07:08:41 +0100 (Tue, 13 Jan 2004) $
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

Constructor Summary

AbstractPathComponent()
Creates a new AbstractPathComponent

Method Summary

void
addPredicate(XPathExpression expr)
Adds the given Expression to this PathComponent's predicate List.
void
addPredicate(org.exolab.adaptx.xpath.engine.PredicateExprImpl predicate)
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: 
  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.
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.
String
toString()
Returns the String representation of this PathComponent

Constructor Details

AbstractPathComponent

public AbstractPathComponent()
Creates a new AbstractPathComponent

Method Details

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

addPredicate

public void addPredicate(org.exolab.adaptx.xpath.engine.PredicateExprImpl predicate)
            throws XPathException
Adds the given Expression to this PathComponent's predicate List.
Parameters:

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.

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

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

getExprType

public abstract short getExprType()
Returns the type of this expression.
Specified by:
getExprType in interface XPathExpression
Returns:
The type of this expression

getPredicate

public PredicateExpr getPredicate()
Returns the PredicateExpr of this PathComponent
Specified by:
getPredicate in interface PathComponent
Returns:
the PredicateExpr of this PathComponent

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.

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.

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 String toString()
Returns the String representation of this PathComponent
Specified by:
toString in interface XPathExpression
Returns:
the String representation of this PathComponent

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