/
Unique.java
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/
Unique.java
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/*
* Copyright 2013, 2014 Deutsche Nationalbibliothek
*
* 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.metafacture.metamorph.functions;
import org.metafacture.metamorph.api.helpers.AbstractStatefulFunction;
import java.util.HashSet;
import java.util.Set;
/**
* Checks whether the received value was not received before.
*
* @author Markus Michael Geipel
*
*/
public final class Unique extends AbstractStatefulFunction {
public static final String ENTITY = "entity";
public static final String NAME = "name";
public static final String VALUE = "value";
private final Set<String> set = new HashSet<>();
private boolean uniqueInEntity;
private KeyGenerator keyGenerator = new KeyGenerator() {
@Override
public String createKey(final String name, final String value) {
return name + "\0" + value;
}
};
/**
* Creates an instance of {@link Unique}.
*/
public Unique() {
}
@Override
public String process(final String value) {
final String key = keyGenerator.createKey(getLastName(), value);
if (set.contains(key)) {
return null;
}
set.add(key);
return value;
}
@Override
protected void reset() {
set.clear();
}
@Override
protected boolean doResetOnEntityChange() {
return uniqueInEntity;
}
/**
* Flags whether the scope is {@link #ENTITY}.
*
* @param scope the scope
*/
public void setIn(final String scope) {
uniqueInEntity = ENTITY.equals(scope);
}
/**
* Sets the Unique part to be processed. Possible values are {@value #NAME}
* or {@value #VALUE}.
*
* @param part the part
*/
public void setPart(final String part) {
if (NAME.equals(part)) {
keyGenerator = new KeyGenerator() {
@Override
public String createKey(final String name, final String value) {
return name;
}
};
}
else if (VALUE.equals(part)) {
keyGenerator = new KeyGenerator() {
@Override
public String createKey(final String name, final String value) {
return value;
}
};
}
}
/**
* To implement different uniqueness strategies
*/
private interface KeyGenerator {
String createKey(String name, String value);
}
}