/*
BEGIN LICENSE BLOCK
Copyright 2010-2011, Heiko Mueller, Sam Lindley, James Cheney and
University of Edinburgh
This file is part of Database Wiki.
Database Wiki is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Database Wiki 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with Database Wiki. If not, see <http://www.gnu.org/licenses/>.
END LICENSE BLOCK
*/
package org.dbwiki.data.query.xaql;
/** A COINCIDES expression in a XAQL WHERE clause.
*
* @author hmueller
*
*/
import java.util.Vector;
import org.dbwiki.data.query.condition.AttributeConditionListing;
import org.dbwiki.data.query.condition.TimestampEvaluationResult;
import org.dbwiki.data.query.handler.QueryNodeSet;
import org.dbwiki.data.time.TimeSequence;
public class CoincidesExpression implements WhereExpression {
/*
* Private Variables
*/
private Vector<WhereCondition> _conditions;
private boolean _negated;
/*
* Constructors
*/
public CoincidesExpression(boolean negated) {
_negated = negated;
_conditions = new Vector<WhereCondition>();
}
/*
* Public Methods
*/
public void add(WhereCondition condition) {
_conditions.add(condition);
}
public boolean eval(QueryNodeSet nodeSet) {
TimestampEvaluationResult evalResult = this.getEvalResult(nodeSet);
if (evalResult != null) {
if (evalResult.timestamp() != null) {
boolean emptyResult = evalResult.timestamp().isEmpty();
if (_negated) {
return emptyResult;
} else
return !emptyResult;
} else {
return _negated;
}
} else {
return _negated;
}
}
public TimeSequence evalTimestamp(QueryNodeSet nodeSet) {
TimestampEvaluationResult evalResult = this.getEvalResult(nodeSet);
if (evalResult != null) {
if (evalResult.timestamp() != null) {
return evalResult.timestamp();
} else {
return null;
}
} else {
return null;
}
}
public void listConditions(AttributeConditionListing listing) {
for (WhereCondition condition : _conditions) {
condition.listConditions(listing);
}
}
/*
* Private Methods
*/
private TimestampEvaluationResult getEvalResult(QueryNodeSet nodeSet) {
TimestampEvaluationResult evalResult = new TimestampEvaluationResult();
for (WhereCondition condition : _conditions) {
TimeSequence timestamp = condition.evalTimestamp(nodeSet);
if (timestamp != null) {
evalResult.intersect(timestamp);
if (evalResult.timestamp().isEmpty()) {
return null;
}
} else {
return null;
}
}
return evalResult;
}
}