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'databene commons' is an open source Java library by Volker Bergmann.
It provides extensions to the Java core library by utility classes, abstract concepts
and concrete implementations.
/*
* Copyright (C) 2004-2014 Volker Bergmann ([email protected]).
* All rights reserved.
*
* 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.databene.commons.mutator;
import org.databene.commons.Accessor;
import org.databene.commons.Mutator;
import org.databene.commons.NullSafeComparator;
import org.databene.commons.ComparableComparator;
import org.databene.commons.StringUtil;
import org.databene.commons.UpdateFailedException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Comparator;
/**
* Mutator that is only applied if a condition is true.
*
* Created: 08.05.2005 06:47:17
*/
@SuppressWarnings("unchecked")
public class ConditionalMutator extends MutatorProxy {
public static final int ASSERT_EQUALS = 0;
public static final int OVERWRITE = 1;
public static final int SET_IF_UNDEFINED = 2;
public static final int SET_IF_GREATER = 3;
protected int mode;
@SuppressWarnings("rawtypes")
private Comparator comparator;
@SuppressWarnings("rawtypes")
private Accessor accessor;
private static Logger logger = LoggerFactory.getLogger(ConditionalMutator.class);
@SuppressWarnings("rawtypes")
public ConditionalMutator(Mutator realMutator, Accessor accessor, int mode) {
super(realMutator);
this.accessor = accessor;
this.mode = mode;
comparator = new ComparableComparator();
}
@Override
public void setValue(Object target, Object value) throws UpdateFailedException {
Object oldValue = accessor.getValue(target);
switch (mode) {
case OVERWRITE:
realMutator.setValue(target, value);
break;
case ASSERT_EQUALS:
if (isEmpty(oldValue)) {
realMutator.setValue(target, value);
} else if (!NullSafeComparator.equals(oldValue, value))
throw new UpdateFailedException("Mutator " + realMutator + " expected '" + oldValue + "', "
+ "but found '" + value + "'");
else
logger.debug("no update needed by " + realMutator);
break;
case SET_IF_UNDEFINED:
if (isEmpty(oldValue))
realMutator.setValue(target, value);
else
logger.debug("no update needed by " + realMutator);
break;
case SET_IF_GREATER:
if (isEmpty(oldValue))
realMutator.setValue(target, value);
else if (comparator.compare(oldValue, value) == -1)
realMutator.setValue(target, value);
else
logger.debug("no update needed by " + realMutator);
break;
default:
throw new RuntimeException("Illegal mode");
}
}
// private helpers -------------------------------------------------------------------------------------------------
private static boolean isEmpty(Object value) {
return (value instanceof String ? StringUtil.isEmpty((String)value) : value == null);
}
}