/*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* The Original Code is the Kowari Metadata Store.
*
* The Initial Developer of the Original Code is Plugged In Software Pty
* Ltd (http://www.pisoftware.com, mailto:info@pisoftware.com). Portions
* created by Plugged In Software Pty Ltd are Copyright (C) 2001,2002
* Plugged In Software Pty Ltd. All Rights Reserved.
*
* Various modifications to this file copyright:
* The Australian Commonwealth Government
* Department of Defense
* Developed by Netymon Pty Ltd
* under contract 4500430665
* contributed to the Kowari Project under the
* Mozilla Public License version 1.1
* per clause 4.1.3 of the above contract.
*
* Various modifications to this file copyright:
* 2005-2006 Netymon Pty Ltd: mail@netymon.com
*
* Various modifications to this file copyright:
* 2005-2006 Andrae Muys: andrae@muys.id.au
*
* getModel() contributed by Netymon Pty Ltd on behalf of
* The Australian Commonwealth Government under contract 4500507038.
* ConstraintLocalization contributed by Netymon Pty Ltd on behalf of
* The Australian Commonwealth Government under contract 4500507038.
*
* [NOTE: The text of this Exhibit A may differ slightly from the text
* of the notices in the Source Code files of the Original Code. You
* should use the text of this Exhibit A rather than the text found in the
* Original Code Source Code for Your Modifications.]
*
*/
package org.mulgara.resolver;
// Java 2 standard packages
import java.util.*;
// Third party packages
import org.apache.log4j.Logger;
import org.jrdf.graph.Node;
// Local packages
import org.mulgara.query.*;
import org.mulgara.query.rdf.BlankNodeImpl;
import org.mulgara.query.rdf.LiteralImpl;
import org.mulgara.query.rdf.URIReferenceImpl;
import org.mulgara.resolver.spi.GlobalizeException;
import org.mulgara.resolver.spi.LocalizeException;
import org.mulgara.resolver.spi.QueryEvaluationContext;
import org.mulgara.resolver.spi.ResolverSession;
import org.mulgara.store.tuples.RestrictPredicateFactory;
import org.mulgara.store.tuples.Tuples;
import org.mulgara.store.tuples.TuplesOperations;
import org.mulgara.util.StackTrace;
/**
* Localized version of a global {@link Query}.
*
* As well as providing coordinate transformation from global to local
* coordinates, this adds methods to partially resolve the query.
*
* @created 2004-05-06
* @author <a href="http://www.pisoftware.com/raboczi">Simon Raboczi</a>
* @version $Revision: 1.12 $
* @modified $Date: 2005/05/16 11:07:07 $
* @maintenanceAuthor $Author: amuys $
* @company <a href="mailto:info@PIsoftware.com">Plugged In Software</a>
* @copyright ©2004 <a href="http://www.tucanatech.com/">Tucana
* Technology, Inc</a>
* @licence <a href="{@docRoot}/../../LICENCE">Mozilla Public License v1.1</a>
*/
class LocalQueryResolver implements QueryEvaluationContext {
/** Logger. */
private static final Logger logger = Logger.getLogger(LocalQueryResolver.class.getName());
private final DatabaseOperationContext operationContext;
private final ResolverSession resolverSession;
private boolean distinctQuery = false;
// Constructor
LocalQueryResolver(DatabaseOperationContext operationContext, ResolverSession resolverSession) {
if (operationContext == null) {
throw new IllegalArgumentException("Null 'operationContext' parameter");
} else if (resolverSession == null) {
throw new IllegalArgumentException("Null 'resolverSession' parameter");
}
this.operationContext = operationContext;
this.resolverSession = resolverSession;
}
public List<Tuples> resolveConstraintOperation(GraphExpression modelExpr,
ConstraintOperation constraintOper)
throws QueryException {
LinkedList<Tuples> result = new LinkedList<Tuples>();
for (ConstraintExpression constraintExpr: constraintOper.getElements()) {
result.add(ConstraintOperations.resolveConstraintExpression(this, modelExpr, constraintExpr));
}
return result;
}
/**
* Returns either a variable or the LocalNode local equivalent of the
* ConstraintElement.
*
* @param constraintElement a global constraint element
* @return the localized equivalent to the global <var>constraintElement</var>
*/
public ConstraintElement localize(ConstraintElement constraintElement)
throws LocalizeException
{
if (constraintElement instanceof Node) {
return new LocalNode(resolverSession.localize((Node)constraintElement));
} else if (constraintElement instanceof Variable) {
return constraintElement;
} else if (constraintElement instanceof LocalNode) {
return (LocalNode)constraintElement;
} else {
throw new IllegalArgumentException("Not a global constraint element: " + constraintElement +
"::" + constraintElement.getClass());
}
}
public ConstraintElement globalize(ConstraintElement constraintElement)
throws GlobalizeException
{
Node node;
if (constraintElement instanceof LocalNode) {
node = resolverSession.globalize(((LocalNode)constraintElement).getValue());
if (node instanceof URIReferenceImpl ||
node instanceof LiteralImpl ||
node instanceof BlankNodeImpl) {
return (Value)node;
} else {
throw new GlobalizeException(((LocalNode)constraintElement).getValue(),
"Globalize of non-internal Nodes not supported by LocalQueryResolver: " + constraintElement + " -> " + node);
}
} else {
return constraintElement; // Either Variable or GlobalNode
}
}
/**
* Localize and resolve the leaf node of the <code>FROM</code> and
* <code>WHERE</code> clause product.
*
* @param graphResource the <code>FROM<code> clause to resolve, never
* <code>null</codE>
* @param constraint the <code>WHERE</code> clause to resolve, which must
* have {@link Variable#FROM} as its fourth element, and never be
* <code>null</code>
* @throws QueryException if resolution can't be obtained
*/
public Tuples resolve(GraphResource graphResource, Constraint constraint) throws QueryException
{
assert graphResource != null || !constraint.getModel().equals(Variable.FROM);
assert constraint != null;
// Delegate constraint resolution back to the database session
try {
Constraint localized = ConstraintOperations.localize(this, constraint);
if (localized.getModel().equals(Variable.FROM)) {
// create the URIReferenceImpl without checking if it is absolute
localized = ConstraintOperations.rewriteConstraintModel(
localize(new URIReferenceImpl(graphResource.getURI(), false)), localized);
}
Tuples result = operationContext.resolve(localized);
return result;
} catch (LocalizeException e) {
throw new QueryException("Unable to resolve FROM " + graphResource +
" WHERE " + constraint, e);
} catch (QueryException eq) {
throw new QueryException("Error resolving " + constraint + " from " + graphResource, eq);
} catch (Exception e) {
throw new QueryException("Unexpected error resolving " + constraint + " from " + graphResource, e);
}
}
public Tuples resolve(GraphExpression graphExpression, ConstraintExpression constraintExpression) throws QueryException {
return ConstraintOperations.resolveConstraintExpression(this, graphExpression, constraintExpression);
}
public ResolverSession getResolverSession() {
return resolverSession;
}
/**
* Indicates that the query being run in this context should return distinct results.
* @return If <code>true</code>, then return distinct results. Otherwise allow for duplicates.
*/
public boolean isDistinctQuery() {
return distinctQuery;
}
/**
* Sets the "distinct" status of a query context, returning the previous value.
* @param newValue The new value to set the distinct status to.
* @return The previous value of the distinct status.
*/
public boolean setDistinctQuery(boolean newValue) {
boolean oldValue = distinctQuery;
distinctQuery = newValue;
return oldValue;
}
Tuples resolveMap(Query query, Map<Variable,Value> outerBindings) throws QueryException {
try {
Query newQuery = new Query(
query.getVariableList(),
query.getModelExpression(),
new ConstraintConjunction(
ConstraintOperations.bindVariables(outerBindings, query.getConstraintExpression()),
constrainBindings(outerBindings)),
query.getHavingExpression(),
query.getOrderList(),
query.getLimit(),
query.getOffset(),
query.isDistinct(),
(Answer)query.getGiven().clone());
return operationContext.innerCount(newQuery);
} catch (LocalizeException el) {
throw new QueryException("Failed to resolve inner local query", el);
}
}
// FIXME: This method should be using a LiteralTuples. Also I believe MULGARA_IS is now preallocated.
// Someone needs to try making the change and testing.
private ConstraintExpression constrainBindings(Map<Variable,Value> bindings) throws LocalizeException {
List<ConstraintExpression> args = new ArrayList<ConstraintExpression>();
Iterator<Map.Entry<Variable,Value>> i = bindings.entrySet().iterator();
logger.info("FIXME:localize should be lookup, need to preallocate MULGARA_IS");
while (i.hasNext()) {
Map.Entry<Variable,Value> entry = i.next();
args.add(ConstraintIs.newLocalConstraintIs(
entry.getKey(),
new LocalNode(resolverSession.localize(ConstraintIs.MULGARA_IS)),
entry.getValue(),
null));
}
return new ConstraintConjunction(args);
}
/**
* @return the solution to this query
* @throws QueryException if resolution can't be obtained
*/
Tuples resolveE(Query query) throws QueryException
{
if (query == null) {
throw new IllegalArgumentException("Query null in LocalQuery::resolveE");
}
try {
if (logger.isDebugEnabled()) {
logger.debug("Resolving query " + query);
}
if (logger.isDebugEnabled()) {
logger.debug(new StackTrace().toString());
}
distinctQuery = query.isDistinct();
Tuples result = ConstraintOperations.resolveConstraintExpression(this,
query.getModelExpression(), query.getConstraintExpression());
if (logger.isDebugEnabled()) {
logger.debug("Tuples result = " + TuplesOperations.formatTuplesTree(result));
}
result = projectSelectClause(query, result);
result = appendAggregates(query, result);
result = applyHaving(query, result);
result = orderResult(query, result);
result = offsetResult(query, result);
result = limitResult(query, result);
return result;
} catch (TuplesException et) {
throw new QueryException("Failed to resolve query", et);
}
}
private Tuples projectSelectClause(Query query, Tuples result) throws TuplesException
{
if (!result.isEmpty()) {
Tuples tmp = result;
try {
List<Variable> variables = new ArrayList<Variable>();
/*
* Note that this code need not concern itself with the order of the select-list,
* only the contents. The mapping is handled by the subsequent Answer object,
* and only becomes important if the row-order is important and is therefore
* deferred to order-by resolution.
*/
Variable[] vars = result.getVariables();
for (int i = 0; i < vars.length; i++) {
if (query.getVariableList().contains(vars[i])) {
variables.add(vars[i]);
}
}
result = TuplesOperations.project(result, variables, query.isDistinct());
} catch (TuplesException t) {
try {
tmp.close();
} catch (TuplesException e) { /* Already throwing an exception. Ignore. */ }
throw t;
}
tmp.close();
}
return result;
}
private Tuples appendAggregates(Query query, Tuples result) throws TuplesException
{
if (!result.isEmpty()) {
Tuples tmp = result;
result = new AppendAggregateTuples(resolverSession, this, result,
filterSubqueries(query.getVariableList()));
tmp.close();
}
return result;
}
private List<SelectElement> filterSubqueries(List<SelectElement> select) {
List<SelectElement> result = new ArrayList<SelectElement>();
for (SelectElement o : select) {
if (!(o instanceof Subquery)) {
result.add(o);
}
}
return result;
}
private Tuples applyHaving(Query query, Tuples result) throws TuplesException {
ConstraintHaving having = query.getHavingExpression();
Tuples tmp = result;
if (having != null) {
result = TuplesOperations.restrict(
result, RestrictPredicateFactory.getPredicate(having, resolverSession));
tmp.close();
}
return result;
}
private Tuples orderResult(Query query, Tuples result) throws TuplesException, QueryException {
List<Order> orderList = query.getOrderList();
if (orderList.size() > 0 && result.getRowCardinality() > Cursor.ONE) {
Tuples tmp = result;
result = TuplesOperations.sort(result,
new OrderByRowComparator(result, orderList, resolverSession));
tmp.close();
}
return result;
}
private Tuples offsetResult(Query query, Tuples result) throws TuplesException
{
int offset = query.getOffset();
if (offset > 0) {
Tuples tmp = result;
result = TuplesOperations.offset(result, offset);
tmp.close();
}
return result;
}
private Tuples limitResult(Query query, Tuples result) throws TuplesException
{
Integer limit = query.getLimit();
if (limit != null) {
Tuples tmp = result;
result = TuplesOperations.limit(result, limit.intValue());
tmp.close();
}
return result;
}
}