/*
* 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 - 2013 Object Refinery Ltd, Pentaho Corporation and Contributors.. All rights reserved.
*/
package org.pentaho.reporting.engine.classic.core.function;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.pentaho.reporting.engine.classic.core.event.ReportEvent;
import org.pentaho.reporting.engine.classic.core.util.Sequence;
/**
* A report function that calculates the minimum value of one field (column) from the data-row. The function can be used
* in two ways:
* <ul>
* <li>to calculate a minimum value for the entire report;</li>
* <li>to calculate a minimum value within a particular group;</li>
* </ul>
* This function expects its input values to be either java.lang.Number instances or Strings that can be parsed to
* java.lang.Number instances using a java.text.DecimalFormat.
* <p/>
* The function undestands two parameters, the <code>field</code> parameter is required and denotes the name of an
* ItemBand-field which gets summed up.
* <p/>
* The parameter <code>group</code> denotes the name of a group. When this group is started, the counter gets reseted to
* null.
*
* @author Thomas Morgner
*/
public class ItemMinFunction extends AbstractFunction implements FieldAggregationFunction {
private static final Log logger = LogFactory.getLog( ItemMinFunction.class );
/**
* The minimum value.
*/
private Sequence<Comparable> min;
private transient int lastGroupSequenceNumber;
/**
* The name of the group on which to reset the count. This can be set to null to compute the minimum for the whole
* report.
*/
private String group;
/**
* The name of the field from where to read the values.
*/
private String field;
private String crosstabFilterGroup;
/**
* Constructs an unnamed function. Make sure to set a Name or function initialisation will fail.
*/
public ItemMinFunction() {
min = new Sequence<Comparable>();
}
/**
* Constructs a named function.
* <P>
* The field must be defined before using the function.
*
* @param name
* The function name.
*/
public ItemMinFunction( final String name ) {
this();
setName( name );
}
/**
* Receives notification that a new report is about to start.
* <P>
* Does nothing.
*
* @param event
* Information about the event.
*/
public void reportInitialized( final ReportEvent event ) {
clear();
}
protected void clear() {
this.lastGroupSequenceNumber = 0;
this.min.clear();
}
/**
* Receives notification that a new group is about to start. If this is the group defined for the function, then the
* minimum value is reset to zero.
*
* @param event
* Information about the event.
*/
public void groupStarted( final ReportEvent event ) {
if ( FunctionUtilities.isDefinedGroup( getGroup(), event ) ) {
clear();
}
if ( FunctionUtilities.isDefinedGroup( getCrosstabFilterGroup(), event ) ) {
final int groupIndex = event.getState().getCurrentGroupIndex();
this.lastGroupSequenceNumber = (int) event.getState().getCrosstabColumnSequenceCounter( groupIndex );
}
}
/**
* Returns the group name.
*
* @return The group name.
*/
public String getGroup() {
return group;
}
/**
* Sets the group name.
* <P>
* If a group is defined, the minimum value is reset to zero at the start of every instance of this group.
*
* @param name
* the group name (null permitted).
*/
public void setGroup( final String name ) {
this.group = name;
}
/**
* Returns the field used by the function. The field name corresponds to a column name in the report's data-row.
*
* @return The field name.
*/
public String getField() {
return field;
}
/**
* Sets the field name for the function. The field name corresponds to a column name in the report's data-row.
*
* @param field
* the field name.
*/
public void setField( final String field ) {
this.field = field;
}
/**
* Receives notification that a row of data is being processed. Reads the data from the field defined for this
* function and calculates the minimum value.
*
* @param event
* Information about the event.
*/
public void itemsAdvanced( final ReportEvent event ) {
if ( field == null ) {
return;
}
final Object fieldValue = event.getDataRow().get( getField() );
if ( fieldValue instanceof Comparable == false ) {
return;
}
try {
final Comparable compare = (Comparable) fieldValue;
final Comparable oldValue = min.get( lastGroupSequenceNumber );
if ( oldValue == null || oldValue.compareTo( compare ) > 0 ) {
min.set( lastGroupSequenceNumber, compare );
}
} catch ( Exception e ) {
ItemMinFunction.logger.error( "ItemMinFunction.advanceItems(): problem adding number." );
}
}
public void summaryRowSelection( final ReportEvent event ) {
if ( FunctionUtilities.isDefinedGroup( getCrosstabFilterGroup(), event ) ) {
final int groupIndex = event.getState().getCurrentGroupIndex();
this.lastGroupSequenceNumber = (int) event.getState().getCrosstabColumnSequenceCounter( groupIndex );
}
}
/**
* Returns the function value, in this case the running total of a specific column in the report's data row.
*
* @return The function value.
*/
public Object getValue() {
return min.get( lastGroupSequenceNumber );
}
/**
* 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 ItemMinFunction function = (ItemMinFunction) super.getInstance();
function.min = min.clone();
function.lastGroupSequenceNumber = 0;
return function;
}
public Object clone() {
try {
final ItemMinFunction function = (ItemMinFunction) super.clone();
function.min = min.clone();
return function;
} catch ( CloneNotSupportedException e ) {
throw new IllegalStateException();
}
}
public String getCrosstabFilterGroup() {
return crosstabFilterGroup;
}
public void setCrosstabFilterGroup( final String crosstabFilterGroup ) {
this.crosstabFilterGroup = crosstabFilterGroup;
}
}