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1: /** 2: * ========================================= 3: * LibFormula : a free Java formula library 4: * ========================================= 5: * 6: * Project Info: http://reporting.pentaho.org/libformula/ 7: * 8: * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors. 9: * 10: * This library is free software; you can redistribute it and/or modify it under the terms 11: * of the GNU Lesser General Public License as published by the Free Software Foundation; 12: * either version 2.1 of the License, or (at your option) any later version. 13: * 14: * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 15: * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 16: * See the GNU Lesser General Public License for more details. 17: * 18: * You should have received a copy of the GNU Lesser General Public License along with this 19: * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, 20: * Boston, MA 02111-1307, USA. 21: * 22: * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 23: * in the United States and other countries.] 24: * 25: * 26: * ------------ 27: * $Id: Function.java 2752 2007-04-10 14:10:41Z taqua $ 28: * ------------ 29: * (C) Copyright 2006-2007, by Pentaho Corporation. 30: */ 31: package org.jfree.formula.function; 32: 33: import java.io.Serializable; 34: 35: import org.jfree.formula.lvalues.TypeValuePair; 36: import org.jfree.formula.FormulaContext; 37: import org.jfree.formula.EvaluationException; 38: import org.jfree.formula.typing.TypeConversionException; 39: 40: /** 41: * A function is an arbitary computation. A return value type is not available 42: * unless the function has been evaluated. 43: * 44: * Functions must be stateless, that means: Calling the same function with 45: * exactly the same parameters must always result in the same computed value. 46: * 47: * @author Thomas Morgner 48: */ 49: public interface Function extends Serializable 50: { 51: public String getCanonicalName(); 52: public TypeValuePair evaluate (FormulaContext context, 53: ParameterCallback parameters) 54: throws EvaluationException, TypeConversionException; 55: }