/*
* 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.
*
* Contributor(s): N/A.
*
* [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.spi;
// Java 2 standard packages
import java.util.*;
// Log4j
import org.apache.log4j.*;
// Locally written packages
import org.mulgara.query.*;
import org.mulgara.store.tuples.*;
/**
* {@link Resolution} from {@link Statements}.
*
* @created 2004-05-05
* @author <a href="http://staff.pisoftware.com/raboczi">Simon Raboczi</a>
* @version $Revision: 1.9 $
* @modified $Date: 2005/02/22 08:16:18 $
* @maintenanceAuthor $Author: newmana $
* @company <a href="mailto:info@PIsoftware.com">Plugged In Software</a>
* @copyright © 2004 <a href="http://www.PIsoftware.com/">Plugged In
* Software Pty Ltd</a>
* @licence <a href="{@docRoot}/../../LICENCE">Mozilla Public License v1.1</a>
*/
public class StatementsWrapperResolution extends AbstractTuples implements
Resolution {
/** Logger. */
private static final Logger logger = Logger.getLogger(StatementsWrapperResolution.class.getName());
/** The constraint this instance resolves. */
private final Constraint constraint;
/** The statements to filter. */
private Statements statements;
/** prefix passed to previous beforeFirst call */
private long[] prefix;
/**
* Which column of the {@link #statements} provides the value of each
* column of the current resolution tuple row.
*/
private final int[] columnIndex;
/** Precalculated return value fot the {@link #isComplete} method. */
private final boolean complete;
//
// Constructors
//
/**
* Construct the resolution to a constraint from a set of statings.
*
* We assume that the <var>statements</var> are a complete resolution to the
* model element of the <var>constraint</var> if that model isn't variable.
*
* @param constraint the constraint to resolve, never <code>null</code>
* @param statements the statements to filter for constraint satisfaction,
* never <code>null</code>
* @param complete whether the <var>statements</var> are the complete and
* definitive solution to the <var>constraint</var>
* @throws IllegalArgumentException if the <var>constraint</var> or
* <var>statements</var> are <code>null</code>
*/
public StatementsWrapperResolution(Constraint constraint,
Statements statements,
boolean complete) {
// Validate "constraint" parameter
if (constraint == null) {
throw new IllegalArgumentException("Null \"constraint\" parameter");
}
// Validate "statements" parameter
if (statements == null) {
throw new IllegalArgumentException("Null \"statements\" parameter");
}
// Initialize fields
this.complete = complete;
this.constraint = constraint;
this.statements = statements;
// Calculate columnIndex and set the variable list
int length = 0;
int[] temp = new int[3];
List<Variable> variableList = new ArrayList<Variable>(3);
for (int i = 0; i < 3; i++) {
if (constraint.getElement(i) instanceof Variable) {
temp[length++] = i;
variableList.add((Variable)constraint.getElement(i));
}
}
columnIndex = new int[length];
for (int i = 0; i < length; i++) {
columnIndex[i] = temp[i];
}
setVariables(variableList);
}
//
// Methods implementing Resolution
//
public Constraint getConstraint() {
return constraint;
}
/**
* @return <code>true</code> only if the constraint specifies a model
*/
public boolean isComplete() {
return complete;
}
//
// Methods implementing Cursor (superinterface of Statements)
//
public void beforeFirst(long[] prefix,
int suffixTruncation) throws TuplesException {
if (logger.isDebugEnabled()) {
logger.debug("Resetting");
}
// Validate "prefix" parameter
if (prefix == null) {
throw new IllegalArgumentException("Null \"prefix\" parameter");
}
// Validate "suffixTruncation" parameter
if (suffixTruncation != 0) {
throw new IllegalArgumentException("Nonzero suffix truncationr");
}
// Reset fields
statements.beforeFirst();
this.prefix = prefix;
if (logger.isDebugEnabled()) {
logger.debug("Reset");
}
}
public Object clone() {
StatementsWrapperResolution cloned =
(StatementsWrapperResolution)super.clone();
// Copy mutable fields by value
cloned.statements = (Statements) statements.clone();
return cloned;
}
/**
* Close the RDF/XML formatted input stream.
*/
public void close() throws TuplesException {
statements.close();
}
/**
* @param column 0 for the subject, 1 for the predicate, 2 for the object
*/
public long getColumnValue(int column) throws TuplesException {
if (column < 0 || column >= columnIndex.length) {
throw new TuplesException("No such column: " + column);
}
switch (columnIndex[column]) {
case 0:
return statements.getSubject();
case 1:
return statements.getPredicate();
case 2:
return statements.getObject();
default:
throw new Error("Bad columnIndex: " + columnIndex[column]);
}
}
public List<Tuples> getOperands() {
return Collections.singletonList((Tuples)statements);
}
public long getRowCount() throws TuplesException {
return statements.getRowCount();
}
public boolean isEmpty() throws TuplesException {
return statements.isEmpty();
}
public long getRowUpperBound() throws TuplesException {
return statements.getRowUpperBound();
}
public long getRowExpectedCount() throws TuplesException {
return statements.getRowExpectedCount();
}
public boolean hasNoDuplicates() throws TuplesException {
return false;
}
public RowComparator getComparator() {
return null;
}
public boolean isColumnEverUnbound(int column) throws TuplesException {
if (column < 0 || column >= columnIndex.length) {
throw new TuplesException("No such column: " + column);
}
return false;
}
public boolean next() throws TuplesException {
// Advance to the next stating that satisfies the constraint
while (statements.next()) {
int prefixIndex = 0;
// Test the subject
if (constraint.getElement(0) instanceof LocalNode) {
long subject = ((LocalNode) constraint.getElement(0)).getValue();
if (subject != statements.getSubject()) {
continue;
}
}
else if (prefix.length > prefixIndex &&
statements.getSubject() != prefix[prefixIndex++]) {
continue;
}
// Test the predicate
if (constraint.getElement(1) instanceof LocalNode) {
long predicate = ((LocalNode) constraint.getElement(1)).getValue();
if (predicate != statements.getPredicate()) {
continue;
}
}
else if (prefix.length > prefixIndex &&
statements.getPredicate() != prefix[prefixIndex++]) {
continue;
}
// Test the subject
if (constraint.getElement(2) instanceof LocalNode) {
long object = ((LocalNode) constraint.getElement(2)).getValue();
if (object != statements.getObject()) {
continue;
}
}
else if (prefix.length > prefixIndex &&
statements.getObject() != prefix[prefixIndex++]) {
continue;
}
// This row satisfies the constraint
return true;
}
// No more statements that satisfy the constraint
if (logger.isDebugEnabled()) {
logger.debug("Complete");
}
return false;
}
}