/**
* Copyright (C) 2012 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.jboss.dashboard.function;
import org.jboss.dashboard.annotation.Install;
import org.jboss.dashboard.profiler.CodeBlockTrace;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* It calculates the number of distinct occurrences inside a given collection.
*/
@Install
public class DistinctFunction extends AbstractFunction {
/**
* The code of the function.
*/
public static final String CODE = "distinct";
protected String code;
public DistinctFunction() {
super();
code = CODE;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public boolean isTypeSupported(Class type) {
return true;
}
public double scalar(Collection values) {
CodeBlockTrace trace = new AbstractFunction.ScalarFunctionTrace(CODE, values).begin();
try {
if (values == null || values.isEmpty()) return 0;
// Return the number of distinct items in the collection.
Set distincts = new HashSet();
Iterator it = values.iterator();
while (it.hasNext()) {
Object o = it.next();
if (distincts.contains(o)) continue;
distincts.add(o);
}
return distincts.size();
} finally {
trace.end();
}
}
}