/*
* JBoss, Home of Professional Open Source.
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership. Some portions may be licensed
* to Red Hat, Inc. under one or more contributor license agreements.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA.
*/
package org.teiid.query.function.aggregate;
import java.math.BigDecimal;
import java.util.List;
import org.teiid.api.exception.query.ExpressionEvaluationException;
import org.teiid.api.exception.query.FunctionExecutionException;
import org.teiid.core.TeiidComponentException;
import org.teiid.core.types.DataTypeManager;
import org.teiid.query.QueryPlugin;
/**
* Accumulates (per tuple) and calculates the average of the values
* of a column. The type of the result varies depending on the type
* of the input {@see AggregateSymbol} - the type will not be an
* integral type but will always be some kind of decimal type.
*/
public class Avg extends Sum {
private static final int AVG_SCALE = 9;
private int count = 0;
/**
* @see org.teiid.query.function.aggregate.AggregateFunction#initialize(String, Class)
*/
public void initialize(Class<?> dataType, Class<?> inputType) {
if (dataType.equals(DataTypeManager.DefaultDataClasses.BIG_DECIMAL)) {
this.accumulatorType = BIG_DECIMAL;
} else {
this.accumulatorType = DOUBLE;
}
}
public void reset() {
super.reset();
count = 0;
}
/**
* @see org.teiid.query.function.aggregate.AggregateFunction#addInputDirect(Object, List)
*/
public void addInputDirect(Object input, List<?> tuple)
throws FunctionExecutionException, ExpressionEvaluationException, TeiidComponentException {
super.addInputDirect(input, tuple);
count++;
}
/**
* @see org.teiid.query.function.aggregate.AggregateFunction#getResult()
*/
public Object getResult()
throws FunctionExecutionException, ExpressionEvaluationException, TeiidComponentException {
Object sum = super.getResult();
if (count == 0 || sum == null) {
return null;
}
switch(getAccumulatorType()) {
case DOUBLE:
return new Double( ((Double)sum).doubleValue() / count );
case BIG_DECIMAL:
try {
return ((BigDecimal)sum).divide(new BigDecimal(count), AVG_SCALE, BigDecimal.ROUND_HALF_UP);
} catch(ArithmeticException e) {
throw new FunctionExecutionException(e, "ERR.015.001.0048", QueryPlugin.Util.getString("ERR.015.001.0048", sum, new Integer(count))); //$NON-NLS-1$ //$NON-NLS-2$
}
default:
throw new AssertionError("unknown accumulator type"); //$NON-NLS-1$
}
}
}