org.exist.xpath
Class Predicate

java.lang.Object
  extended byorg.exist.xpath.PathExpr
      extended byorg.exist.xpath.Predicate
All Implemented Interfaces:
Expression

public class Predicate
extends PathExpr

Handles predicate expressions.

Author:
Wolfgang Meier

Field Summary
protected static org.apache.log4j.Logger LOG
           
 
Fields inherited from class org.exist.xpath.PathExpr
docs, inPredicate, keepVirtual, pool, steps
 
Constructor Summary
Predicate(BrokerPool pool)
           
 
Method Summary
 Value eval(DocumentSet docs, NodeSet context, NodeProxy node)
          Evaluate the expression represented by this object.
 Value evalBody(DocumentSet docs, NodeSet context, NodeProxy node)
           
 DocumentSet preselect(DocumentSet in_docs)
          Determine the documents, taken from in_docs, for which this expression will possibly yield a result.
 
Methods inherited from class org.exist.xpath.PathExpr
add, add, addDocument, addPath, addPredicate, getDocumentSet, getExpression, getLength, pprint, preselect, returnsType, setDocumentSet, setFirstExpression, setInPredicate
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

LOG

protected static org.apache.log4j.Logger LOG
Constructor Detail

Predicate

public Predicate(BrokerPool pool)
Method Detail

eval

public Value eval(DocumentSet docs,
                  NodeSet context,
                  NodeProxy node)
Description copied from interface: Expression
Evaluate the expression represented by this object. Depending on the context in which this expression is executed, either context, node or both of them may be set. An implementing class should know how to handle this. Most classes only expect context to contain a list of nodes which represents the current context of this expression.

Specified by:
eval in interface Expression
Overrides:
eval in class PathExpr

preselect

public DocumentSet preselect(DocumentSet in_docs)
Description copied from interface: Expression
Determine the documents, taken from in_docs, for which this expression will possibly yield a result. An expression does not have to do anything here. It may simply return in_docs. This method is used to restrict the range of documents in question for a given xpath-expression. It is called before the xpath-expression is actually executed.

Specified by:
preselect in interface Expression
Overrides:
preselect in class PathExpr

evalBody

public Value evalBody(DocumentSet docs,
                      NodeSet context,
                      NodeProxy node)


Copyright (C) Wolfgang Meier. All rights reserved.