/*
* 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.List;
import org.exist.dom.persistent.NodeSet;
import org.exist.dom.memtree.NodeImpl;
import org.exist.xquery.util.ExpressionDumper;
import org.exist.xquery.value.*;
/**
* 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<Predicate> predicates = new ArrayList<Predicate>(2);
private Expression parent;
/**
* @param context
*/
public FilteredExpression(XQueryContext context, Expression expr) {
super(context);
this.expression = expr.simplify();
}
public void addPredicate(Predicate pred) {
predicates.add(pred);
}
public List<Predicate> 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);
if (predicates.size() > 0) {
final AnalyzeContextInfo newContext = new AnalyzeContextInfo(contextInfo);
newContext.setParent(this);
newContext.setContextStep(this);
newContext.setStaticType(expression.returnsType());
for (final Predicate pred : predicates) {
pred.analyze(newContext);
}
}
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#eval(org.exist.dom.persistent.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;
final Sequence seq = expression.eval(contextSequence, contextItem);
if (seq.isEmpty())
{result = Sequence.EMPTY_SEQUENCE;}
else {
final Predicate pred = predicates.get(0);
context.setContextSequencePosition(0, seq);
// 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()) {
final NodeSet contextSet = seq.toNodeSet();
final Sequence outerSequence = contextSet.getParents(getExpressionId());
for (final SequenceIterator i = outerSequence.iterate(); i.hasNext(); ) {
final NodeValue node = (NodeValue) i.nextItem();
final Sequence newContextSeq =
contextSet.selectParentChild((NodeSet) node, NodeSet.DESCENDANT,
getExpressionId());
final Sequence temp = processPredicate(outerSequence, newContextSeq);
result.addAll(temp);
}
} else {
final MemoryNodeSet nodes = seq.toMemNodeSet();
final Sequence outerSequence = nodes.getParents(new AnyNodeTest());
for (final SequenceIterator i = outerSequence.iterate(); i.hasNext(); ) {
final NodeValue node = (NodeValue) i.nextItem();
final Sequence newSet = nodes.getChildrenForParent((NodeImpl) node);
final 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 (final Predicate pred : predicates) {
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 (final Predicate pred : predicates) {
pred.dump(dumper);
}
}
public String toString() {
final StringBuilder result = new StringBuilder();
result.append(expression.toString());
for (final Predicate pred : predicates) {
result.append(pred.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 (final Predicate pred : predicates) {
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;
deps |= expression.getDependencies();
for (final Predicate pred : predicates) {
deps |= pred.getDependencies();
}
return deps;
}
public void accept(ExpressionVisitor visitor) {
visitor.visitFilteredExpr(this);
}
public Expression getParent() {
return parent;
}
}