/*
* 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.filter;
import java.text.Format;
import java.text.ParseException;
import org.pentaho.reporting.engine.classic.core.Element;
import org.pentaho.reporting.engine.classic.core.function.ExpressionRuntime;
/**
* A format parser tries to parse a string into an object. If the value returned by the datasource is no string, a
* string is formed using String.valueOf (Object). This string is fed into the java.text.Format of this FormatParser and
* the parsed object is returned.
* <p/>
* What class of object is returned, is determined by the given format. If parsing failed, the defined NullValue is
* returned.
*
* @author Thomas Morgner
*/
public class FormatParser implements DataFilter
{
/**
* The format used to create the string representation of the data.
*/
private Format format;
/**
* The datasource from where the data is obtained.
*/
private DataSource datasource;
/**
* The object used to represent null.
*/
private Object nullvalue;
/**
* DefaultConstructor.
*/
public FormatParser()
{
}
/**
* Sets the format for the filter.
*
* @param format The format.
* @throws NullPointerException if the given format is null
*/
public void setFormatter(final Format format)
{
if (format == null)
{
throw new NullPointerException();
}
this.format = format;
}
/**
* Returns the format for the filter.
*
* @return The format.
*/
public Format getFormatter()
{
return this.format;
}
/**
* Returns the parsed object. The value is read using the data source given and parsed using the formatter of this
* object. The parsing is guaranteed to completly form the target object or to return the defined NullValue.
* <p/>
* If the given datasource does not return a string, the returned object is transformed into a string using
* String.valueOf (Object) and then parsed.
* <p/>
* If format, datasource or object are null, the NullValue is returned.
*
* @param runtime the expression runtime that is used to evaluate formulas and expressions when computing the value of
* this filter.
* @param element
* @return The formatted value.
*/
public Object getValue(final ExpressionRuntime runtime, final Element element)
{
final Format f = getFormatter();
if (f == null)
{
return getNullValue();
}
final DataSource ds = getDataSource();
if (ds == null)
{
return getNullValue();
}
final Object o = ds.getValue(runtime, element);
if (o == null)
{
return getNullValue();
}
if (isValidOutput(o))
{
return o;
}
try
{
return f.parseObject(String.valueOf(o));
}
catch (ParseException e)
{
return null;
}
}
/**
* Checks whether the given value is already a valid result. IF the datasource already returned a valid value, and no
* parsing is required, a parser can skip the parsing process by returning true in this function.
*
* @param o the object to parse.
* @return false as this class does not know anything about the format of input or result objects.
*/
protected boolean isValidOutput(final Object o)
{
return false;
}
/**
* Returns the data source for the filter.
*
* @return The data source.
*/
public DataSource getDataSource()
{
return datasource;
}
/**
* Sets the data source.
*
* @param ds The data source.
*/
public void setDataSource(final DataSource ds)
{
if (ds == null)
{
throw new NullPointerException();
}
this.datasource = ds;
}
/**
* Sets the value that will be displayed if the data source supplies a null value. The nullValue itself can be null to
* cover the case when no reasonable default value can be defined.
*
* @param nullvalue The value returned when the parsing failed.
*/
public void setNullValue(final Object nullvalue)
{
this.nullvalue = nullvalue;
}
/**
* Returns the object representing a null value from the data source. This value will also be returned when parsing
* failed or no parser or datasource is set at all.
*
* @return The value returned when the parsing failed.
*/
public Object getNullValue()
{
return nullvalue;
}
/**
* Clones the parser.
*
* @return a clone.
* @throws CloneNotSupportedException this should never happen.
*/
public Object clone()
throws CloneNotSupportedException
{
final FormatParser p = (FormatParser) super.clone();
if (datasource != null)
{
p.datasource = (DataSource) datasource.clone();
}
if (format != null)
{
p.format = (Format) format.clone();
}
return p;
}
}