/*
* This program is free software; you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
* Foundation.
*
* You should have received a copy of the GNU Lesser General Public License along with this
* program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* or from the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* This program 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.
*
* Copyright (c) 2001 - 2009 Object Refinery Ltd, Pentaho Corporation and Contributors.. All rights reserved.
*/
package org.pentaho.reporting.engine.classic.core.function;
import java.util.ArrayList;
import java.util.Arrays;
import org.pentaho.reporting.engine.classic.core.DataRow;
/**
* The base-class for all expressions that aggregate values from multiple columns.
*
* @author Thomas Morgner
*/
public abstract class ColumnAggregationExpression extends AbstractExpression
{
/**
* An ordered list containing the fieldnames used in the expression.
*/
private ArrayList fields;
/**
* A temporary array to reduce the number of object creations.
*/
private transient Object[] fieldValues;
/**
* Default Constructor.
*/
protected ColumnAggregationExpression()
{
fields = new ArrayList();
}
/**
* Collects the values of all fields defined in the fieldList.
*
* @return an Object-array containing all defined values from the datarow
*/
protected Object[] getFieldValues()
{
final int size = fields.size();
if (fieldValues == null || fieldValues.length != size)
{
fieldValues = new Object[size];
}
final DataRow dataRow = getDataRow();
for (int i = 0; i < size; i++)
{
final String field = (String) fields.get(i);
if (field != null)
{
fieldValues[i] = dataRow.get(field);
}
}
return fieldValues;
}
/**
* Defines the field in the field-list at the given index.
*
* @param index the position in the list, where the field should be defined.
* @param field the name of the field.
*/
public void setField(final int index, final String field)
{
if (fields.size() == index)
{
fields.add(field);
}
else
{
fields.set(index, field);
}
this.fieldValues = null;
}
/**
* Returns the defined field at the given index-position.
*
* @param index the position of the field name that should be queried.
* @return the field name at the given position.
*/
public String getField(final int index)
{
return (String) fields.get(index);
}
/**
* Returns the number of fields defined in this expression.
*
* @return the number of fields.
*/
public int getFieldCount()
{
return fields.size();
}
/**
* Returns all defined fields as array of strings.
*
* @return all the fields.
*/
public String[] getField()
{
return (String[]) fields.toArray(new String[fields.size()]);
}
/**
* Defines all fields as array. This completely replaces any previously defined fields.
*
* @param fields the new list of fields.
*/
public void setField(final String[] fields)
{
this.fields.clear();
this.fields.addAll(Arrays.asList(fields));
this.fieldValues = null;
}
/**
* Return a completly separated copy of this function. The copy does no longer share any changeable objects with the
* original function.
*
* @return a copy of this function.
*/
public Expression getInstance()
{
final ColumnAggregationExpression cae = (ColumnAggregationExpression) super.getInstance();
cae.fields = (ArrayList) fields.clone();
return cae;
}
}