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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: FunctionDescription.java 2716 2007-04-01 13:51:58Z taqua $ 28: * ------------ 29: * (C) Copyright 2006-2007, by Pentaho Corporation. 30: */ 31: package org.jfree.formula.function; 32: 33: import java.util.Locale; 34: 35: import org.jfree.formula.typing.Type; 36: 37: /** 38: * A static definition of the function's parameters, return values etc. 39: * This is a support class with emphasis on GUI tools. 40: * 41: * However, the parameter declarations are also used when filling in the 42: * parameter values. 43: * 44: * Functions have a defined set of known parameters and can have a unlimited 45: * number of optional parameters. If a function declares at least one parameter 46: * and declares that its parameter list is infinite, then the last parameter 47: * type is used on all remaining parameters. 48: * 49: * @author Thomas Morgner 50: */ 51: public interface FunctionDescription 52: { 53: public String getDisplayName (Locale locale); 54: public String getDescription (Locale locale); 55: public boolean isVolatile(); 56: public Type getValueType(); 57: public FunctionCategory getCategory(); 58: 59: public int getParameterCount (); 60: public boolean isInfiniteParameterCount(); 61: 62: /** 63: * Returns the parameter type at the given position using the function 64: * metadata. The first parameter is at the position 0; 65: * 66: * @param position The parameter index. 67: * @return The parameter type. 68: */ 69: public Type getParameterType(int position); 70: public String getParameterDisplayName(int position, Locale locale); 71: public String getParameterDescription(int position, Locale locale); 72: 73: /** 74: * Defines, whether the parameter at the given position is mandatory. A 75: * mandatory parameter must be filled in, while optional parameters need 76: * not to be filled in. 77: * 78: * @return 79: */ 80: public boolean isParameterMandatory(int position); 81: 82: /** 83: * Returns the default value for an optional parameter. If the value returned 84: * here is null, then this either means, that the parameter is mandatory or 85: * that the default value is computed by the expression itself. 86: * 87: * @param position 88: * @return 89: */ 90: public Object getDefaultValue (int position); 91: 92: }