/*
* $Header: /cvsroot/jaxen/jaxen/src/java/main/org/jaxen/expr/PredicateSet.java,v 1.11 2002/04/26 17:17:34 jstrachan Exp $
* $Revision: 1.11 $
* $Date: 2002/04/26 17:17:34 $
*
* ====================================================================
*
* Copyright (C) 2000-2002 bob mcwhirter & James Strachan.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions, and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions, and the disclaimer that follows
* these conditions in the documentation and/or other materials
* provided with the distribution.
*
* 3. The name "Jaxen" must not be used to endorse or promote products
* derived from this software without prior written permission. For
* written permission, please contact license@jaxen.org.
*
* 4. Products derived from this software may not be called "Jaxen", nor
* may "Jaxen" appear in their name, without prior written permission
* from the Jaxen Project Management (pm@jaxen.org).
*
* In addition, we request (but do not require) that you include in the
* end-user documentation provided with the redistribution and/or in the
* software itself an acknowledgement equivalent to the following:
* "This product includes software developed by the
* Jaxen Project (http://www.jaxen.org/)."
* Alternatively, the acknowledgment may be graphical using the logos
* available at http://www.jaxen.org/
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* ====================================================================
* This software consists of voluntary contributions made by many
* individuals on behalf of the Jaxen Project and was originally
* created by bob mcwhirter <bob@werken.com> and
* James Strachan <jstrachan@apache.org>. For more information on the
* Jaxen Project, please see <http://www.jaxen.org/>.
*
* $Id: PredicateSet.java,v 1.11 2002/04/26 17:17:34 jstrachan Exp $
*/
package org.jaxen.expr;
import org.jaxen.Context;
import org.jaxen.ContextSupport;
import org.jaxen.JaxenException;
import org.jaxen.function.BooleanFunction;
import java.io.Serializable;
import java.util.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
class PredicateSet implements Serializable
{
private List predicates;
public PredicateSet()
{
this.predicates = Collections.EMPTY_LIST;
}
public void addPredicate(Predicate predicate)
{
if ( this.predicates == Collections.EMPTY_LIST )
{
this.predicates = new ArrayList();
}
this.predicates.add( predicate );
}
public List getPredicates()
{
return this.predicates;
}
public void simplify()
{
Iterator predIter = this.predicates.iterator();
Predicate eachPred = null;
while ( predIter.hasNext() )
{
eachPred = (Predicate) predIter.next();
eachPred.simplify();
}
}
public String getText()
{
StringBuffer buf = new StringBuffer();
Iterator predIter = this.predicates.iterator();
Predicate eachPred = null;
while ( predIter.hasNext() )
{
eachPred = (Predicate) predIter.next();
buf.append( eachPred.getText() );
}
return buf.toString();
}
// XXXX: Note - this could be *MUCH* more efficient
// currently this creates many redundant collections and should halt
// evaluation on the first matching item.
protected boolean evaluateAsBoolean(List contextNodeSet,
ContextSupport support) throws JaxenException
{
List result = evaluatePredicates( contextNodeSet, support );
return ! result.isEmpty();
}
protected List evaluatePredicates(List contextNodeSet,
ContextSupport support) throws JaxenException
{
// Easy way out (necessary)
if (predicates.size()==0) return contextNodeSet;
List newNodeSet = new ArrayList();
List filterSet = contextNodeSet;
List predicates = getPredicates();
Iterator predIter = predicates.iterator();
Predicate eachPred = null;
Object contextNode = null;
Object predResult = null;
Context predContext = new Context( support );
// Filter the 'filterSet' against all predicates. This has been
// tuned for performance, so there are two separate loops
// In the first run, all nodes matching the first predicate will
// be copied from contextNodeSet to newNodeSet
// In the second loop, newNodeSet is filtered progressively against
// the remaining predicates, eliminating any non-matching nodes
if ( predIter.hasNext() )
{
eachPred = (Predicate) predIter.next();
int filterSize = filterSet.size();
for ( int i = 0 ; i < filterSize ; ++i )
{
contextNode = filterSet.get( i );
List list = new ArrayList( 1 );
list.add( contextNode );
predContext.setNodeSet( list );
predContext.setPosition( i + 1 );
predContext.setSize( filterSize );
predResult = eachPred.evaluate( predContext );
if ( predResult instanceof Number )
{
int proximity = ((Number)predResult).intValue();
if ( proximity == ( i + 1 ) )
{
newNodeSet.add( contextNode );
}
}
else
{
Boolean includes = BooleanFunction.evaluate( predResult, predContext.getNavigator() );
if ( includes.booleanValue() )
{
newNodeSet.add( contextNode );
}
}
}
}
// This will be true if any filtering takes place from here on
boolean nodesFiltered = false;
// Second loop: Filter filterSet until no more predicates are left
filterSet = newNodeSet;
while ( predIter.hasNext() )
{
eachPred = (Predicate) predIter.next();
int filterSize = filterSet.size();
for ( int i = 0 ; i < filterSize ; ++i )
{
contextNode = filterSet.get(i);
// Check if a node has been eliminated already
if (contextNode == null) continue;
List list = new ArrayList( 1 );
list.add( contextNode );
predContext.setNodeSet( list );
predContext.setPosition( i + 1 );
predContext.setSize( filterSize );
predResult = eachPred.evaluate( predContext );
if ( predResult instanceof Number )
{
int proximity = ((Number)predResult).intValue();
if ( proximity != ( i + 1 ) )
{
filterSet.set(i,null);
nodesFiltered = true;
}
}
else
{
Boolean includes = BooleanFunction.evaluate( predResult, predContext.getNavigator() );
if ( !includes.booleanValue() )
{
filterSet.set(i,null);
nodesFiltered = true;
}
}
}
}
// Go through the filtered set and delete any null nodes (if necessary)
if (nodesFiltered)
{
// System.err.println("FILTERING");
Iterator iter=filterSet.iterator();
while (iter.hasNext()) {
Object obj=iter.next();
if (obj==null)
iter.remove();
}
}
return filterSet;
}
}