/*
* 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 org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.pentaho.reporting.libraries.base.config.Configuration;
import org.pentaho.reporting.libraries.formula.Formula;
import org.pentaho.reporting.libraries.formula.FormulaContext;
/**
* The formula expression is used to evaluate a LibFormula/OpenFormula expression. There is generally no need to
* reference this class directly, as this expression is used automatically if a formula is specified in a element,
* style-expression or common expression.
*
* @author Thomas Morgner
*/
public final class FormulaExpression extends AbstractExpression
{
private static final Log logger = LogFactory.getLog(FormulaExpression.class);
/**
* A cached version of the compiled formula.
*/
private transient Formula compiledFormula;
/**
* The formula namespace as defined by OpenFormula.
*/
private String formulaNamespace;
/**
* The formula itself.
*/
private String formulaExpression;
/**
* The formula as specified by the user. This is the formula and the namespace.
*/
private String formula;
/**
* A flag indicating that the formula cannot be parsed.
*/
private Exception formulaError;
/**
* Default Constructor.
*/
public FormulaExpression()
{
}
/**
* Returns the defined formula context from the report processing context.
*
* @return the formula context.
*/
private FormulaContext getFormulaContext()
{
final ProcessingContext globalContext = getRuntime().getProcessingContext();
return globalContext.getFormulaContext();
}
/**
* Returns the formula (incuding the optional namespace) as defined by the OpenFormula standard.
*
* @return the formula as text.
*/
public String getFormula()
{
return formula;
}
/**
* Returns the formula namespace. If the formula specified by the user starts with "=", then the namespace "report" is
* assumed.
*
* @return the namespace of the formula.
*/
public String getFormulaNamespace()
{
return formulaNamespace;
}
/**
* Returns the formula expression.
*
* @return the formula expression.
*/
public String getFormulaExpression()
{
return formulaExpression;
}
/**
* Defines the formula (incuding the optional namespace) as defined by the OpenFormula standard.
*
* @param formula the formula as text.
*/
public void setFormula(String formula)
{
this.formula = formula;
if (formula == null)
{
formulaNamespace = null;
formulaExpression = null;
}
else
{
if (formula.endsWith(";"))
{
logger.warn("A formula with a trailing semicolon is not valid. Auto-correcting the formula.");
formula = formula.substring(0, formula.length() - 1);
}
if (formula.length() > 0 && formula.charAt(0) == '=')
{
formulaNamespace = "report";
formulaExpression = formula.substring(1);
}
else
{
final int separator = formula.indexOf(':');
if (separator <= 0 || ((separator + 1) == formula.length()))
{
// error: invalid formula.
formulaNamespace = null;
formulaExpression = null;
}
else
{
formulaNamespace = formula.substring(0, separator);
formulaExpression = formula.substring(separator + 1);
}
}
}
this.compiledFormula = null;
this.formulaError = null;
}
/**
* Computes the value of the formula by evaluating the formula against the current data-row.
*
* @return the computed value or null, if an error occured.
*/
private Object computeRegularValue()
{
if (formulaError != null)
{
return null;
}
if (formulaExpression == null)
{
return null;
}
try
{
if (compiledFormula == null)
{
compiledFormula = new Formula(formulaExpression);
}
final ExpressionRuntime expressionRuntime = getRuntime();
final ReportFormulaContext context =
new ReportFormulaContext(getFormulaContext(), expressionRuntime);
try
{
compiledFormula.initialize(context);
return compiledFormula.evaluate();
}
finally
{
context.close();
}
}
catch (Exception e)
{
formulaError = e;
if (FormulaExpression.logger.isDebugEnabled())
{
final Configuration config = getReportConfiguration();
if ("true".equals(config.getConfigProperty(
"org.pentaho.reporting.engine.classic.core.function.LogFormulaFailureCause")))
{
FormulaExpression.logger.debug("Failed to compute the regular value [" + formulaExpression + ']', e);
}
else
{
FormulaExpression.logger.debug("Failed to compute the regular value [" + formulaExpression + ']');
}
}
return null;
}
}
/**
* Return the computed value of the formula.
*
* @return the value of the function.
*/
public Object getValue()
{
try
{
return computeRegularValue();
}
catch (Exception e)
{
return null;
}
}
public boolean isFormulaError()
{
return formulaError != null;
}
public Exception getFormulaError()
{
return formulaError;
}
/**
* 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 FormulaExpression o = (FormulaExpression) super.getInstance();
o.compiledFormula = null;
return o;
}
}