/**
* Copyright 2005 JBoss Inc
*
* 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 org.drools.base;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import org.drools.base.evaluators.Operator;
import org.drools.common.InternalFactHandle;
import org.drools.spi.Evaluator;
import org.drools.time.Interval;
/**
* BaseEvaluator is an Object Comparator that is operator aware
*
* @author mproctor
*
*/
public abstract class BaseEvaluator
implements
Evaluator, Externalizable {
private Operator operator;
private ValueType type;
public BaseEvaluator() {
}
public BaseEvaluator(final ValueType type,
final Operator operator) {
this.type = type;
this.operator = operator;
}
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
operator = (Operator)in.readObject();
type = (ValueType)in.readObject();
if (type != null)
type = ValueType.determineValueType(type.getClassType());
}
public void writeExternal(ObjectOutput out) throws IOException {
out.writeObject(operator);
out.writeObject(type);
}
public Operator getOperator() {
return this.operator;
}
public ValueType getValueType() {
return this.type;
}
public ValueType getCoercedValueType() {
return this.type;
}
/**
* Most evaluators operate on the fact attributes,
* so, by default, the implementation unwraps it,
* but subclasses can override this behaviour.
*/
public Object prepareLeftObject(InternalFactHandle handle) {
return handle.getObject();
}
/**
* Most evaluators operate o symmetrical types of object
* on both sides, i.e., either they operate on facts on
* both sides, or fact handles on both sides. But eventually,
* some operators (like 'after') may differ in behaviour and
* so, they are allowed to override this method.
*/
public Object prepareRightObject(InternalFactHandle handle) {
return prepareLeftObject( handle );
}
public boolean isTemporal() {
return false;
}
public Interval getInterval() {
// returns an open bound interval
return new Interval();
}
public boolean equals(final Object object) {
if ( this == object ) {
return true;
}
if ( object == null || !(object instanceof BaseEvaluator) ) {
return false;
}
final Evaluator other = (Evaluator) object;
return this.getOperator() == other.getOperator() && this.getValueType() == other.getValueType();
}
public int hashCode() {
return (this.getValueType().hashCode()) ^ (this.getOperator().hashCode()) ^ (this.getClass().hashCode());
}
}