/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-06 Wolfgang M. Meier
* wolfgang@exist-db.org
* http://exist.sourceforge.net
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
*/
package org.exist.xquery;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.exist.dom.NodeSet;
import org.exist.memtree.NodeImpl;
import org.exist.xquery.util.ExpressionDumper;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.MemoryNodeSet;
import org.exist.xquery.value.NodeValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceIterator;
import org.exist.xquery.value.ValueSequence;
/**
* FilteredExpression represents a primary expression with a predicate. Examples:
* for $i in (1 to 10)[$i mod 2 = 0], $a[1], (doc("test.xml")//section)[2]. Other predicate
* expressions are handled by class {@link org.exist.xquery.LocationStep}.
*
* @author Wolfgang Meier (wolfgang@exist-db.org)
*/
public class FilteredExpression extends AbstractExpression {
final protected Expression expression;
protected boolean abbreviated = false;
final protected List predicates = new ArrayList(2);
private Expression parent;
/**
* @param context
*/
public FilteredExpression(XQueryContext context, Expression expr) {
super(context);
this.expression = expr;
}
public void addPredicate(Predicate pred) {
predicates.add(pred);
}
public List getPredicates() {
return predicates;
}
public Expression getExpression() {
if (expression instanceof PathExpr)
return ((PathExpr)expression).getExpression(0);
return expression;
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#analyze(org.exist.xquery.AnalyzeContextInfo)
*/
public void analyze(AnalyzeContextInfo contextInfo) throws XPathException {
parent = contextInfo.getParent();
contextInfo.setParent(this);
expression.analyze(contextInfo);
for (Iterator i = predicates.iterator(); i.hasNext();) {
Predicate pred = (Predicate) i.next();
pred.analyze(contextInfo);
}
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#eval(org.exist.dom.DocumentSet, org.exist.xquery.value.Sequence, org.exist.xquery.value.Item)
*/
public Sequence eval(Sequence contextSequence, Item contextItem) throws XPathException {
if (context.getProfiler().isEnabled()) {
context.getProfiler().start(this);
context.getProfiler().message(this, Profiler.DEPENDENCIES, "DEPENDENCIES", Dependency.getDependenciesName(this.getDependencies()));
if (contextSequence != null)
context.getProfiler().message(this, Profiler.START_SEQUENCES, "CONTEXT SEQUENCE", contextSequence);
if (contextItem != null)
context.getProfiler().message(this, Profiler.START_SEQUENCES, "CONTEXT ITEM", contextItem.toSequence());
}
if (contextItem != null)
contextSequence = contextItem.toSequence();
Sequence result;
Sequence seq = expression.eval(contextSequence, contextItem);
if (seq.isEmpty())
result = Sequence.EMPTY_SEQUENCE;
else {
Predicate pred = (Predicate) predicates.get(0);
// If the current step is an // abbreviated step, we have to treat the predicate
// specially to get the context position right. //a[1] translates to /descendant-or-self::node()/a[1],
// so we need to return the 1st a from any parent of a.
//
// If the predicate is known to return a node set, no special treatment is required.
if (abbreviated &&
(pred.getExecutionMode() != Predicate.NODE || !seq.isPersistentSet())) {
result = new ValueSequence();
if (seq.isPersistentSet()) {
NodeSet contextSet = seq.toNodeSet();
Sequence outerSequence = contextSet.getParents(getExpressionId());
for (SequenceIterator i = outerSequence.iterate(); i.hasNext(); ) {
NodeValue node = (NodeValue) i.nextItem();
Sequence newContextSeq =
contextSet.selectParentChild((NodeSet) node, NodeSet.DESCENDANT, getExpressionId());
Sequence temp = processPredicate(outerSequence, newContextSeq);
result.addAll(temp);
}
} else {
MemoryNodeSet nodes = seq.toMemNodeSet();
Sequence outerSequence = nodes.getParents(new AnyNodeTest());
for (SequenceIterator i = outerSequence.iterate(); i.hasNext(); ) {
NodeValue node = (NodeValue) i.nextItem();
Sequence newSet = nodes.getChildrenForParent((NodeImpl) node);
Sequence temp = processPredicate(outerSequence, newSet);
result.addAll(temp);
}
}
} else
result = processPredicate(contextSequence, seq);
}
if (context.getProfiler().isEnabled())
context.getProfiler().end(this, "", result);
return result;
}
private Sequence processPredicate(Sequence contextSequence, Sequence seq) throws XPathException {
for (Iterator i = predicates.iterator(); i.hasNext();) {
Predicate pred = (Predicate) i.next();
seq = pred.evalPredicate(contextSequence, seq, Constants.DESCENDANT_SELF_AXIS);
//subsequent predicates operate on the result of the previous one
contextSequence = null;
}
return seq;
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#dump(org.exist.xquery.util.ExpressionDumper)
*/
public void dump(ExpressionDumper dumper) {
expression.dump(dumper);
for (Iterator i = predicates.iterator(); i.hasNext();) {
((Expression)i.next()).dump(dumper);
}
}
public String toString() {
StringBuilder result = new StringBuilder();
result.append(expression.toString());
for (Iterator i = predicates.iterator(); i.hasNext();) {
result.append(((Expression)i.next()).toString());
}
return result.toString();
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#returnsType()
*/
public int returnsType() {
return expression.returnsType();
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#resetState()
*/
public void resetState(boolean postOptimization) {
super.resetState(postOptimization);
expression.resetState(postOptimization);
for (Iterator i = predicates.iterator(); i.hasNext();) {
Predicate pred = (Predicate) i.next();
pred.resetState(postOptimization);
}
}
/* (non-Javadoc)
* @see org.exist.xquery.AbstractExpression#setPrimaryAxis(int)
*/
public void setPrimaryAxis(int axis) {
expression.setPrimaryAxis(axis);
}
public int getPrimaryAxis() {
return expression.getPrimaryAxis();
}
public void setAbbreviated(boolean abbrev) {
abbreviated = abbrev;
}
/* (non-Javadoc)
* @see org.exist.xquery.AbstractExpression#getDependencies()
*/
public int getDependencies() {
int deps = Dependency.CONTEXT_SET;
for (Iterator i = predicates.iterator(); i.hasNext();) {
deps |= ((Predicate) i.next()).getDependencies();
}
return deps;
}
public void accept(ExpressionVisitor visitor) {
visitor.visitFilteredExpr(this);
}
public Expression getParent() {
return parent;
}
}