001 /** 002 * ========================================= 003 * LibFormula : a free Java formula library 004 * ========================================= 005 * 006 * Project Info: http://reporting.pentaho.org/libformula/ 007 * 008 * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors. 009 * 010 * This library is free software; you can redistribute it and/or modify it under the terms 011 * of the GNU Lesser General Public License as published by the Free Software Foundation; 012 * either version 2.1 of the License, or (at your option) any later version. 013 * 014 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 015 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 016 * See the GNU Lesser General Public License for more details. 017 * 018 * You should have received a copy of the GNU Lesser General Public License along with this 019 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, 020 * Boston, MA 02111-1307, USA. 021 * 022 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 023 * in the United States and other countries.] 024 * 025 * 026 * ------------ 027 * $Id: Function.java 2752 2007-04-10 14:10:41Z taqua $ 028 * ------------ 029 * (C) Copyright 2006-2007, by Pentaho Corporation. 030 */ 031 package org.jfree.formula.function; 032 033 import java.io.Serializable; 034 035 import org.jfree.formula.lvalues.TypeValuePair; 036 import org.jfree.formula.FormulaContext; 037 import org.jfree.formula.EvaluationException; 038 import org.jfree.formula.typing.TypeConversionException; 039 040 /** 041 * A function is an arbitary computation. A return value type is not available 042 * unless the function has been evaluated. 043 * 044 * Functions must be stateless, that means: Calling the same function with 045 * exactly the same parameters must always result in the same computed value. 046 * 047 * @author Thomas Morgner 048 */ 049 public interface Function extends Serializable 050 { 051 public String getCanonicalName(); 052 public TypeValuePair evaluate (FormulaContext context, 053 ParameterCallback parameters) 054 throws EvaluationException, TypeConversionException; 055 }