/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2004-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library 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;
* version 2.1 of the License.
*
* This library 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.
*/
package org.geotools.filter.visitor;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.Stack;
import java.util.logging.Logger;
import org.geotools.factory.CommonFactoryFinder;
import org.geotools.filter.FilterCapabilities;
import org.geotools.filter.IllegalFilterException;
import org.opengis.feature.simple.SimpleFeatureType;
import org.opengis.filter.And;
import org.opengis.filter.BinaryComparisonOperator;
import org.opengis.filter.ExcludeFilter;
import org.opengis.filter.Filter;
import org.opengis.filter.FilterFactory;
import org.opengis.filter.FilterVisitor;
import org.opengis.filter.Id;
import org.opengis.filter.IncludeFilter;
import org.opengis.filter.Not;
import org.opengis.filter.Or;
import org.opengis.filter.PropertyIsBetween;
import org.opengis.filter.PropertyIsEqualTo;
import org.opengis.filter.PropertyIsGreaterThan;
import org.opengis.filter.PropertyIsGreaterThanOrEqualTo;
import org.opengis.filter.PropertyIsLessThan;
import org.opengis.filter.PropertyIsLessThanOrEqualTo;
import org.opengis.filter.PropertyIsLike;
import org.opengis.filter.PropertyIsNotEqualTo;
import org.opengis.filter.PropertyIsNull;
import org.opengis.filter.expression.Add;
import org.opengis.filter.expression.BinaryExpression;
import org.opengis.filter.expression.Divide;
import org.opengis.filter.expression.Expression;
import org.opengis.filter.expression.ExpressionVisitor;
import org.opengis.filter.expression.Function;
import org.opengis.filter.expression.Literal;
import org.opengis.filter.expression.Multiply;
import org.opengis.filter.expression.NilExpression;
import org.opengis.filter.expression.PropertyName;
import org.opengis.filter.expression.Subtract;
import org.opengis.filter.spatial.BBOX;
import org.opengis.filter.spatial.Beyond;
import org.opengis.filter.spatial.BinarySpatialOperator;
import org.opengis.filter.spatial.Contains;
import org.opengis.filter.spatial.Crosses;
import org.opengis.filter.spatial.DWithin;
import org.opengis.filter.spatial.Disjoint;
import org.opengis.filter.spatial.Equals;
import org.opengis.filter.spatial.Intersects;
import org.opengis.filter.spatial.Overlaps;
import org.opengis.filter.spatial.Touches;
import org.opengis.filter.spatial.Within;
/**
* Determines what queries can be processed server side and which can be processed client side.
*
* IMPLEMENTATION NOTE:
* This class is implemented as a stack processor. If you're curious how it works, compare it with
* the old SQLUnpacker class, which did the same thing using recursion in a more straightforward
* way.
*
* Here's a non-implementors best-guess at the algorithm:
* Starting at the top of the filter, split each filter into
* its constituent parts. If the given FilterCapabilities
* support the given operator, then keep checking downwards.
*
* The key is in knowing whether or not something "down the tree"
* from you wound up being supported or not. This is where the
* stacks come in. Right before handing off to accept() the sub-
* filters, we count how many things are currently on the "can
* be proccessed by the underlying datastore" stack (the preStack)
* and we count how many things are currently on the "need to be post-
* processed" stack.
*
* After the accept() call returns, we look again at the preStack.size()
* and postStack.size(). If the postStack has grown, that means that there
* was stuff down in the accept()-ed filter that wasn't supportable.
* Usually this means that our filter isn't supportable, but not always.
*
* In some cases a sub-filter being unsupported isn't necessarily bad,
* as we can 'unpack' OR statements into AND statements
* (DeMorgans rule/modus poens) and still
* see if we can handle the other side of the OR. Same with NOT and
* certain kinds of AND statements.
*
* In addition this class supports the case where we're doing an split
* in the middle of a client-side transaction. I.e. imagine doing a
* <Transaction> against a WFS-T where you have to filter against
* actions that happened previously in the transaction. That's what
* the ClientTransactionAccessor interface does, and this class splits
* filters while respecting the information about deletes and updates
* that have happened previously in the Transaction. I can't say with
* certainty exactly how the logic for that part of this works, but
* the test suite does seem to test it and the tests do pass.
*
*
* @author dzwiers
* @author commented and ported from gt to ogc filters by saul.farber
*
* @source $URL$
* @deprecated use {@link CapabilitiesFilterSplitter} instead for geoapi FilterCapabilities
*/
public class PostPreProcessFilterSplittingVisitor implements FilterVisitor, ExpressionVisitor {
private static final Logger logger=org.geotools.util.logging.Logging.getLogger("org.geotools.filter");
/**
* The stack holding the bits of the filter that are not processable
* by something with the given {@link FilterCapabilities}
*/
private Stack postStack = new Stack();
/**
* The stack holding the bits of the filter that <b>are</b> processable
* by something with the given {@link FilterCapabilities}
*/
private Stack preStack = new Stack();
/**
* Operates similar to postStack. When a update is determined to affect an attribute expression the update
* filter is pushed on to the stack, then ored with the filter that contains the expression.
*/
private Set changedStack=new HashSet();
/**
* The given filterCapabilities that we're splitting on.
*/
private FilterCapabilities fcs = null;
private SimpleFeatureType parent = null;
private Filter original = null;
/**
* If we're in the middle of a client-side transaction, this object
* will help us figure out what we need to handle from updates/deletes
* that we're tracking client-side.
*/
private ClientTransactionAccessor transactionAccessor;
private FilterFactory ff = CommonFactoryFinder.getFilterFactory(null);
private PostPreProcessFilterSplittingVisitor() {
// do nothing
}
/**
* Create a new instance.
* @param fcs The FilterCapabilties that describes what Filters/Expressions the server can process.
* @param parent The FeatureType that this filter involves. Why is this needed?
* @param transactionAccessor If the transaction is handled on the client and not the server then different filters
* must be sent to the server. This class provides a generic way of obtaining the information from the transaction.
*/
public PostPreProcessFilterSplittingVisitor(FilterCapabilities fcs, SimpleFeatureType parent, ClientTransactionAccessor transactionAccessor) {
this.fcs = fcs;
this.parent = parent;
this.transactionAccessor = transactionAccessor;
}
/**
* Gets the filter that cannot be sent to the server and must be post-processed on the client by geotools.
*
* @return the filter that cannot be sent to the server and must be post-processed on the client by geotools.
*/
public Filter getFilterPost() {
if (!changedStack.isEmpty())
// Return the original filter to ensure that
// correct features are filtered
return original ;
if (postStack.size() > 1) {
logger.warning("Too many post stack items after run: "
+ postStack.size());
}
// JE: Changed to peek because get implies that the value can be retrieved multiple times
Filter f = postStack.isEmpty() ? Filter.INCLUDE : (Filter) postStack.peek();
return f;
}
/**
* Gets the filter that can be sent to the server for pre-processing.
*
* @return the filter that can be sent to the server for pre-processing.
*/
public Filter getFilterPre() {
FilterFactory ff = CommonFactoryFinder.getFilterFactory(null);
if (preStack.isEmpty()) {
return Filter.INCLUDE;
}
if (preStack.size() > 1) {
logger.warning("Too many pre stack items after run: "
+ preStack.size());
}
// JE: Changed to peek because get implies that the value can be retrieved multiple times
Filter f = preStack.isEmpty() ? Filter.INCLUDE : (Filter) preStack.peek();
// deal with deletes here !!!
if(transactionAccessor != null){
if(f != null && f!=Filter.EXCLUDE){
Filter deleteFilter = transactionAccessor.getDeleteFilter();
if( deleteFilter!=null ){
if (deleteFilter == Filter.EXCLUDE)
f=Filter.EXCLUDE;
else
f=ff.and(f,ff.not(deleteFilter));
}
}
}
if( changedStack.isEmpty())
return f;
Iterator iter=changedStack.iterator();
Filter updateFilter=(Filter) iter.next();
while( iter.hasNext() ){
Filter next=(Filter) iter.next();
if( next == Filter.INCLUDE){
updateFilter=next;
break;
}else{
updateFilter=(Filter) ff.or(updateFilter,next);
}
}
if( updateFilter == Filter.INCLUDE || f==Filter.INCLUDE )
return Filter.INCLUDE;
return ff.or(f,updateFilter);
}
/**
* @see FilterVisitor#visit(IncludeFilter, Object)
*
* @param filter the {@link Filter} to visit
*/
public void visit( IncludeFilter filter ) {
return;
}
/**
* @see FilterVisitor#visit(ExcludeFilter, Object)
*
* @param filter the {@link Filter} to visit
*/
public void visit( ExcludeFilter filter ) {
if (fcs.supports(Filter.EXCLUDE)) {
preStack.push(filter);
} else {
postStack.push(filter);
}
}
/**
* @see FilterVisitor#visit(PropertyIsBetween, Object)
*
* NOTE: This method is extra documented as an example of how
* all the other methods are implemented. If you want to know how this
* class works read this method first!
*
* @param filter the {@link Filter} to visit
*/
public Object visit(PropertyIsBetween filter, Object extradata) {
if( original==null )
original=filter;
// Do we support this filter type at all?
if (fcs.supports(PropertyIsBetween.class)) {
//Yes, we do. Now, can we support the sub-filters?
//first, remember how big the current list of "I can't support these"
// filters is.
int i = postStack.size();
Expression lowerBound = filter.getLowerBoundary();
Expression expr = filter.getExpression();
Expression upperBound = filter.getUpperBoundary();
if(lowerBound==null ||
upperBound==null ||
expr==null ){
//Well, one of the boundaries is null, so I guess
// we're saying that *no* datastore could support this.
postStack.push(filter);
return null;
}
//Ok, here's the magic. We know how big our list of "can't support"
//filters is. Now we send off the lowerBound Expression to see if
//it can be supported.
lowerBound.accept(this, null);
//Now we're back, and we check. Did the postStack get bigger?
if (i < postStack.size()) {
//Yes, it did. Well, that means we can't support
//this particular filter. Let's back out anything that was
//added by the lowerBound.accept() and add ourselves.
postStack.pop(); //lowerBound.accept()'s bum filter
postStack.push(filter);
return null;
}
//Aha! The postStack didn't get any bigger, so we're still
//all good. Now try again with the middle expression itself...
expr.accept(this, null);
//Did postStack get bigger?
if (i < postStack.size()) {
//Yes, it did. So that means we can't support
//this particular filter. We need to back out what we've
//done, which is BOTH the lowerbounds filter *and* the
//thing that was added by expr.accept() when it failed.
preStack.pop(); // lowerBound.accept()'s success
postStack.pop(); // expr.accept()'s bum filter
postStack.push(filter);
return null;
}
//Same deal again...
upperBound.accept(this, null);
if (i < postStack.size()) {
// post process it
postStack.pop(); // upperBound.accept()'s bum filter
preStack.pop(); // expr.accept()'s success
preStack.pop(); // lowerBound.accept()'s success
postStack.push(filter);
return null;
}
//Well, by getting here it means that postStack didn't get
//taller, even after accepting all three middle filters. This
//means that this whole filter is totally pre-filterable.
//Let's clean up the pre-stack (which got one added to it
//for the success at each of the three above .accept() calls)
//and add us to the stack.
preStack.pop(); // upperBounds.accept()'s success
preStack.pop(); // expr.accept()'s success
preStack.pop(); // lowerBounds.accept()'s success
//finally we add ourselves to the "can be pre-proccessed" filter
//stack. Now when we return we've added exactly one thing to
//the preStack...namely, the given filter.
preStack.push(filter);
} else {
// No, we don't support this filter.
// So we push it onto the postStack, saying
// "Hey, here's one more filter that we don't support.
// Someone who called us may look at this and say,
// "Hmm, I called accept() on this filter and now
// the postStack is taller than it was...I guess this
// filter wasn't accepted.
postStack.push(filter);
}
return null;
}
public Object visit(PropertyIsEqualTo filter, Object notUsed) {
visitBinaryComparisonOperator(filter);
return null;
}
public Object visit(PropertyIsGreaterThan filter, Object notUsed) {
visitBinaryComparisonOperator(filter);
return null;
}
public Object visit(PropertyIsGreaterThanOrEqualTo filter, Object notUsed) {
visitBinaryComparisonOperator(filter);
return null;
}
public Object visit(PropertyIsLessThan filter, Object notUsed) {
visitBinaryComparisonOperator(filter);
return null;
}
public Object visit(PropertyIsLessThanOrEqualTo filter, Object notUsed) {
visitBinaryComparisonOperator(filter);
return null;
}
public Object visit(PropertyIsNotEqualTo filter, Object notUsed) {
visitBinaryComparisonOperator(filter);
return null;
}
private void visitBinaryComparisonOperator(BinaryComparisonOperator filter) {
if( original==null )
original=filter;
// supports it as a group -- no need to check the type
if (!fcs.supports(FilterCapabilities.SIMPLE_COMPARISONS_OPENGIS) ) {
postStack.push(filter);
return;
}
int i = postStack.size();
Expression leftValue = filter.getExpression1();
Expression rightValue = filter.getExpression2();
if( leftValue==null || rightValue==null ){
postStack.push(filter);
return;
}
leftValue.accept(this, null);
if (i < postStack.size()) {
postStack.pop();
postStack.push(filter);
return;
}
rightValue.accept(this, null);
if (i < postStack.size()) {
preStack.pop(); // left
postStack.pop();
postStack.push(filter);
return;
}
preStack.pop(); // left side
preStack.pop(); // right side
preStack.push(filter);
}
public Object visit(BBOX filter, Object notUsed) {
if (!fcs.supports(BBOX.class)) {
postStack.push(filter);
} else {
preStack.push(filter);
}
return null;
}
public Object visit(Beyond filter, Object notUsed) {
visitBinarySpatialOperator(filter);
return null;
}
public Object visit(Contains filter, Object notUsed) {
visitBinarySpatialOperator(filter);
return null;
}
public Object visit(Crosses filter, Object notUsed) {
visitBinarySpatialOperator(filter);
return null;
}
public Object visit(Disjoint filter, Object notUsed) {
visitBinarySpatialOperator(filter);
return null;
}
public Object visit(DWithin filter, Object notUsed) {
visitBinarySpatialOperator(filter);
return null;
}
public Object visit(Equals filter, Object notUsed) {
visitBinarySpatialOperator(filter);
return null;
}
public Object visit(Intersects filter, Object notUsed) {
visitBinarySpatialOperator(filter);
return null;
}
public Object visit(Overlaps filter, Object notUsed) {
visitBinarySpatialOperator(filter);
return null;
}
public Object visit(Touches filter, Object notUsed) {
visitBinarySpatialOperator(filter);
return null;
}
public Object visit(Within filter, Object notUsed) {
visitBinarySpatialOperator(filter);
return null;
}
private void visitBinarySpatialOperator(BinarySpatialOperator filter) {
if( original==null )
original=filter;
Class [] spatialOps = new Class[] { Beyond.class,
Contains.class, Crosses.class, Disjoint.class, DWithin.class,
Equals.class, Intersects.class, Overlaps.class, Touches.class,
Within.class };
for (int i = 0; i < spatialOps.length; i++) {
if (spatialOps[i].isAssignableFrom(filter.getClass())) {
if (!fcs.supports(spatialOps[i])) {
postStack.push(filter);
return;
} else {
//fcs supports this filter, no need to check the rest
break;
}
}
}
// TODO check against tranasaction ?
int i = postStack.size();
Expression leftGeometry, rightGeometry;
leftGeometry = ((BinarySpatialOperator)filter).getExpression1();
rightGeometry = ((BinarySpatialOperator)filter).getExpression2();
if( leftGeometry==null || rightGeometry==null ){
postStack.push(filter);
return;
}
leftGeometry.accept(this,null);
if (i < postStack.size()) {
postStack.pop();
postStack.push(filter);
return;
}
rightGeometry.accept(this,null);
if (i < postStack.size()) {
preStack.pop(); // left
postStack.pop();
postStack.push(filter);
return;
}
preStack.pop(); // left side
preStack.pop(); // right side
preStack.push(filter);
}
public Object visit(PropertyIsLike filter, Object notUsed) {
if( original==null )
original=filter;
if (!fcs.supports(PropertyIsLike.class) ) {
postStack.push(filter);
return null;
}
int i = postStack.size();
filter.getExpression().accept(this, null);
if (i < postStack.size()) {
postStack.pop();
postStack.push(filter);
return null;
}
preStack.pop(); // value
preStack.push(filter);
return null;
}
public Object visit(And filter, Object notUsed) {
visitLogicOperator(filter, And.class);
return null;
}
public Object visit(Not filter, Object notUsed) {
visitLogicOperator(filter, Not.class);
return null;
}
public Object visit(Or filter, Object notUsed) {
visitLogicOperator(filter, Or.class);
return null;
}
private void visitLogicOperator(Filter filter, Class filterInterface) {
if( original==null )
original=filter;
if (!fcs.supports(filterInterface)) {
postStack.push(filter);
return;
}
int i = postStack.size();
int j = preStack.size();
if (filter instanceof Not) {
if (((Not)filter).getFilter() != null) {
Filter next = ((Not)filter).getFilter();
next.accept(this, null);
if (i < postStack.size()) {
// since and can split filter into both pre and post parts
// the parts have to be combined since ~(A^B) == ~A | ~B
// combining is easy since filter==combined result however both post and pre stacks
// must be cleared since both may have components of the filter
popToSize(postStack,i);
popToSize(preStack, j);
postStack.push(filter);
}else{
popToSize(preStack,j);
preStack.push(filter);
}
}
} else {
if (filter instanceof Or) {
Filter orReplacement;
try {
orReplacement = translateOr((Or)filter);
orReplacement.accept(this, null);
} catch (IllegalFilterException e) {
popToSize(preStack,j);
postStack.push(filter);
return;
}
if( postStack.size()>i ){
popToSize(postStack,i);
postStack.push(filter);
return;
}
preStack.pop();
preStack.push(filter);
} else {
// it's an AND
Iterator it = ((And)filter).getChildren().iterator();
while (it.hasNext()) {
Filter next = (Filter) it.next();
next.accept(this, null);
}
//combine the unsupported and add to the top
if (i < postStack.size()) {
if (filter instanceof And) {
Filter f = (Filter) postStack.pop();
while (postStack.size() > i)
f= ff.and(f, (Filter) postStack.pop());
postStack.push(f);
if(j<preStack.size()){
f = (Filter)preStack.pop();
while (preStack.size() > j)
f=ff.and(f, (Filter) preStack.pop());
preStack.push(f);
}
} else {
logger.warning(
"LogicFilter found which is not 'and, or, not");
popToSize(postStack, i);
popToSize(preStack, j);
postStack.push(filter);
}
} else {
popToSize(preStack,j);
preStack.push(filter);
}
}
}
}
private void popToSize(Stack stack, int j) {
while( j<stack.size() ){
stack.pop();
}
}
public Object visitNullFilter(Object notUsed) {
return null;
}
public Object visit(IncludeFilter filter, Object notUsed) {
return null;
}
public Object visit(ExcludeFilter filter, Object notUsed) {
if (fcs.supports(Filter.EXCLUDE)) {
preStack.push(filter);
} else {
postStack.push(filter);
}
return null;
}
public Object visit(PropertyIsNull filter, Object notUsed) {
if( original==null )
original=filter;
if (!fcs.supports( PropertyIsNull.class) ) {
postStack.push(filter);
return null;
}
int i = postStack.size();
((PropertyIsNull)filter).getExpression().accept(this, null);
if (i < postStack.size()) {
postStack.pop();
postStack.push(filter);
}
preStack.pop(); // null
preStack.push(filter);
return null;
}
public Object visit(Id filter, Object notUsed) {
if( original==null )
original=filter;
// figure out how to check that this is top level.
// otherwise this is fine
if (!postStack.isEmpty()) {
postStack.push(filter);
}
preStack.push(filter);
return null;
}
public Object visit(PropertyName expression, Object notUsed) {
//JD: use an expression to get at the attribute type intead of accessing directly
if (parent != null && expression.evaluate( parent ) == null ) {
throw new IllegalArgumentException("Property '" + expression.getPropertyName()
+ "' could not be found in " + parent.getTypeName());
}
if(transactionAccessor!=null){
Filter updateFilter= (Filter) transactionAccessor.getUpdateFilter(expression.getPropertyName());
if( updateFilter!=null ){
changedStack.add(updateFilter);
preStack.push(updateFilter);
}else
preStack.push(expression);
} else{
preStack.push(expression);
}
return null;
}
public Object visit(Literal expression, Object notUsed) {
if (expression.getValue() == null) {
postStack.push(expression);
}
preStack.push(expression);
return null;
}
public Object visit(Add filter, Object notUsed) {
visitMathExpression(filter);
return null;
}
public Object visit(Divide filter, Object notUsed) {
visitMathExpression(filter);
return null;
}
public Object visit(Multiply filter, Object notUsed) {
visitMathExpression(filter);
return null;
}
public Object visit(Subtract filter, Object notUsed) {
visitMathExpression(filter);
return null;
}
private void visitMathExpression(BinaryExpression expression) {
if (!fcs.supports(Add.class) && !fcs.supports(Subtract.class)
&& !fcs.supports(Multiply.class) && !fcs.supports(Divide.class)) {
postStack.push(expression);
return;
}
int i = postStack.size();
Expression leftValue = expression.getExpression1();
Expression rightValue = expression.getExpression2();
if( leftValue==null || rightValue==null ){
postStack.push(expression);
return;
}
leftValue.accept(this, null);
if (i < postStack.size()) {
postStack.pop();
postStack.push(expression);
return;
}
rightValue.accept(this, null);
if (i < postStack.size()) {
preStack.pop(); // left
postStack.pop();
postStack.push(expression);
return;
}
preStack.pop(); // left side
preStack.pop(); // right side
preStack.push(expression);
}
/**
*
* @see org.geotools.filter.FilterVisitor#visit(org.geotools.filter.FunctionExpression)
*/
public Object visit(Function expression, Object notUsed) {
if (!fcs.supports(expression.getClass()) ) {
postStack.push(expression);
return null;
}
if (expression.getName() == null) {
postStack.push(expression);
return null;
}
int i = postStack.size();
int j = preStack.size();
for (int k = 0; k < expression.getParameters().size(); k++) {
((Expression)expression.getParameters().get(i)).accept(this, null);
if (i < postStack.size()) {
while(j<preStack.size())
preStack.pop();
postStack.pop();
postStack.push(expression);
return null;
}
}
while(j<preStack.size())
preStack.pop();
preStack.push(expression);
return null;
}
public Object visit(NilExpression nilExpression, Object notUsed) {
postStack.push(nilExpression);
return null;
}
private Filter translateOr(Or filter)
throws IllegalFilterException {
if (!(filter instanceof Or)) {
return filter;
}
// a|b == ~~(a|b) negative introduction
// ~(a|b) == (~a + ~b) modus ponens
// ~~(a|b) == ~(~a + ~b) substitution
// a|b == ~(~a + ~b) negative simpilification
Iterator i = filter.getChildren().iterator();
List translated = new ArrayList();
while (i.hasNext()) {
Filter f = (Filter) i.next();
if (f instanceof Not) {
// simplify it
Not logic = (Not) f;
Filter next = logic.getFilter();
translated.add(next);
} else {
translated.add(ff.not(f));
}
}
Filter and = ff.and(translated);
return ff.not(and);
}
}