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/*
 *************************************************************************
 * Copyright (c) 2004, 2008 Actuate Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *  Actuate Corporation  - initial API and implementation
 *  
 *************************************************************************
 */

package org.eclipse.birt.data.aggregation.impl;

import org.eclipse.birt.core.data.DataType;
import org.eclipse.birt.data.aggregation.api.IBuildInAggregation;
import org.eclipse.birt.data.aggregation.i18n.Messages;
import org.eclipse.birt.data.engine.api.aggregation.Accumulator;
import org.eclipse.birt.data.engine.api.aggregation.IParameterDefn;

/**
 * Implements the built-in Total.count aggregation
 */
public class TotalCount extends AggrFunction
{

	public String getName( )
	{
		return IBuildInAggregation.TOTAL_COUNT_FUNC;
	}

	public int getType( )
	{
		return SUMMARY_AGGR;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.data.engine.api.aggregation.IAggregation#getDateType()
	 */
	public int getDataType( )
	{
		return DataType.INTEGER_TYPE;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.data.engine.api.aggregation.IAggrFunction#getParameterDefn()
	 */
	public IParameterDefn[] getParameterDefn( )
	{
    	// one parameter definition
		return new IParameterDefn[]{
			new ParameterDefn( Constants.EXPRESSION_NAME,
					Constants.EXPRESSION_DISPLAY_NAME,
					true,
					true,
					SupportedDataTypes.ANY,
					"" )
		};
    }
    
	public Accumulator newAccumulator( )
	{
		return new MyAccumulator( );
	}

	private static class MyAccumulator extends SummaryAccumulator
	{

		private int count = 0;
		boolean countByColumn = true;

		public void start( )
		{
			super.start( );
			count = 0;
		}

		public void onRow( Object[] args )
		{
        	if ( !countByColumn || args == null || args.length == 0 )
			{
        		if( countByColumn )
				{
        			countByColumn = false;
				}
				++count;
			}
			else if ( args.length > 0 && args[0] != null )
			{
				++count;
			}
		}

		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.birt.data.engine.aggregation.SummaryAccumulator#getSummaryValue()
		 */
		public Object getSummaryValue( )
		{
			return Integer.valueOf( count );
		}
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.data.engine.api.aggregation.IAggrFunction#getDescription()
	 */
	public String getDescription( )
	{
		return Messages.getString( "TotalCount.description" ); //$NON-NLS-1$
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.data.engine.api.aggregation.IAggrFunction#getDisplayName()
	 */
	public String getDisplayName( )
	{
		return Messages.getString( "TotalCount.displayName" ); //$NON-NLS-1$
	}

	/* (non-Javadoc)
	 * @see org.eclipse.birt.data.engine.api.aggregation.AggrFunction#getDefaultValue()
	 */
	public Object getDefaultValue( )
	{
		return Integer.valueOf( 0 );
	}
}