/*
* #!
* Ontopia Engine
* #-
* Copyright (C) 2001 - 2013 The Ontopia Project
* #-
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* !#
*/
package net.ontopia.topicmaps.query.impl.basic;
import net.ontopia.topicmaps.query.core.InvalidQueryException;
import net.ontopia.topicmaps.query.impl.utils.PredicateDrivenCostEstimator;
/**
* INTERNAL: Implements the '=' predicate.
*/
public class EqualsPredicate implements BasicPredicateIF {
public String getName() {
return "=";
}
public String getSignature() {
return ". ."; // FIXME: not *quite* accurate; one of them does need to be bound
}
public int getCost(boolean[] boundparams) {
if (boundparams[0] && boundparams[1])
return PredicateDrivenCostEstimator.FILTER_RESULT;
else if (boundparams[0] && !boundparams[1])
return PredicateDrivenCostEstimator.SINGLE_RESULT;
else if (!boundparams[0] && boundparams[1])
return PredicateDrivenCostEstimator.SINGLE_RESULT;
else
return PredicateDrivenCostEstimator.WHOLE_TM_RESULT;
}
public QueryMatches satisfy(QueryMatches matches, Object[] arguments)
throws InvalidQueryException {
int arg1 = matches.getIndex(arguments[0]);
int arg2 = matches.getIndex(arguments[1]);
if (matches.bound(arg1) && matches.bound(arg2))
return PredicateUtils.filter(matches, arg1, arg2, Object.class,
Object.class, PredicateUtils.FILTER_EQUALS);
else if (matches.bound(arg1) && !matches.bound(arg2))
return PredicateUtils.objectToOne(matches, arg1, arg2, Object.class,
PredicateUtils.EQUAL_TO_EQUAL);
else if (!matches.bound(arg1) && matches.bound(arg2))
return PredicateUtils.objectToOne(matches, arg2, arg1, Object.class,
PredicateUtils.EQUAL_TO_EQUAL);
else
throw new InvalidQueryException("At least one argument to = must be bound");
}
}