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/*
Derby - Class org.apache.derbyTesting.functionTests.tests.lang.LobMode
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to you 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.apache.derbyTesting.functionTests.tests.lang;
import java.sql.Clob;
import java.sql.Blob;
import java.sql.Date;
import java.sql.Time;
import java.sql.Timestamp;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import org.apache.derby.agg.Aggregator;
/**
* <p>
* This is a version of GenericMode for use with types which are not Comparable.
* The class started out for use with Blob and Clob but was pressed into service
* for other types also.
* </p>
*
* <p>
* In particular, this is a mode aggregator for use with the
* JDBC date/time classes too. You can't use GenericMode with those types
* because they do not satisfy its type bounds. That is because they inherit the
* Comparable implementation of java.util.Date rather than implementing
* their own more specific version of Comparable. That is,
* java.sql.Date implements Comparable<java.util.Date> rather than
* Comparable<java.sql.Date>.
* </p>
*/
public class LobMode<V> implements Aggregator<V,V,LobMode<V>>
{
///////////////////////////////////////////////////////////////////////////////////
//
// NESTED CLASSES
//
///////////////////////////////////////////////////////////////////////////////////
public static final class ClobMode extends LobMode<Clob> {}
public static final class BlobMode extends LobMode<Blob> {}
public static final class BinaryMode extends LobMode<byte[]> {}
public static final class DateMode extends LobMode<Date> {}
public static final class TimeMode extends LobMode<Time> {}
public static final class TimestampMode extends LobMode<Timestamp> {}
///////////////////////////////////////////////////////////////////////////////////
//
// STATE
//
///////////////////////////////////////////////////////////////////////////////////
private HashMap<String,Accumulator<V>> _accumulators;
///////////////////////////////////////////////////////////////////////////////////
//
// CONSTRUCTOR
//
///////////////////////////////////////////////////////////////////////////////////
public LobMode() {}
public void init()
{
_accumulators = new HashMap<String,Accumulator<V>>();
}
public void accumulate( V value )
{
getAccumulator( value ).add( 1 );
}
public void merge( LobMode<V> otherAggregator )
{
HashMap<String,Accumulator<V>> otherAccumulators = otherAggregator._accumulators;
for ( Accumulator<V> accumulator : otherAccumulators.values() )
{
V value = accumulator.getValue();
getAccumulator( value ).add( accumulator.getCount() );
}
}
public V terminate()
{
return _accumulators.isEmpty() ? null : Collections.max( _accumulators.values() ).getValue();
}
private Accumulator<V> getAccumulator( V value )
{
String key = toString( value );
Accumulator<V> retval = _accumulators.get( key );
if ( retval == null )
{
retval = new Accumulator<V>( value );
_accumulators.put( key, retval );
}
return retval;
}
static String toString( Object raw )
{
try {
if ( raw instanceof Clob )
{
Clob clob = (Clob) raw;
return clob.getSubString( 1L, (int) clob.length() );
}
else if ( raw instanceof Blob )
{
Blob blob = (Blob) raw;
byte[] bytes = blob.getBytes( 1L, (int) blob.length() );
return new String( bytes, "UTF-8" );
}
else if ( raw instanceof Date ) { return raw.toString(); }
else if ( raw instanceof Time ) { return raw.toString(); }
else if ( raw instanceof Timestamp ) { return raw.toString(); }
else if ( raw instanceof byte[] )
{
byte[] bytes = (byte[]) raw;
return new String( bytes, "UTF-8" );
}
} catch (Exception e) { throw new IllegalArgumentException( e ); }
throw new IllegalArgumentException( "Unsupported object type: " + raw.getClass().getName() );
}
///////////////////////////////////////////////////////////////////////////////////
//
// NESTED CLASSES
//
///////////////////////////////////////////////////////////////////////////////////
public static final class Accumulator<V> implements Comparable<Accumulator<V>>
{
private V _value;
private int _count;
public Accumulator( V value )
{
_value = value;
_count = 0;
}
public void add( int increment ) { _count += increment; }
public V getValue() { return _value; }
public int getCount() { return _count; }
// Comparable behavior
public int compareTo( Accumulator<V> that )
{
int retval = this._count - that._count;
if ( retval != 0 ) { return retval; }
else { return LobMode.toString( this._value ).compareTo( LobMode.toString( that._value ) ); }
}
}
}
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