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: FunctionDescription.java 2716 2007-04-01 13:51:58Z taqua $ 028 * ------------ 029 * (C) Copyright 2006-2007, by Pentaho Corporation. 030 */ 031 package org.jfree.formula.function; 032 033 import java.util.Locale; 034 035 import org.jfree.formula.typing.Type; 036 037 /** 038 * A static definition of the function's parameters, return values etc. 039 * This is a support class with emphasis on GUI tools. 040 * 041 * However, the parameter declarations are also used when filling in the 042 * parameter values. 043 * 044 * Functions have a defined set of known parameters and can have a unlimited 045 * number of optional parameters. If a function declares at least one parameter 046 * and declares that its parameter list is infinite, then the last parameter 047 * type is used on all remaining parameters. 048 * 049 * @author Thomas Morgner 050 */ 051 public interface FunctionDescription 052 { 053 public String getDisplayName (Locale locale); 054 public String getDescription (Locale locale); 055 public boolean isVolatile(); 056 public Type getValueType(); 057 public FunctionCategory getCategory(); 058 059 public int getParameterCount (); 060 public boolean isInfiniteParameterCount(); 061 062 /** 063 * Returns the parameter type at the given position using the function 064 * metadata. The first parameter is at the position 0; 065 * 066 * @param position The parameter index. 067 * @return The parameter type. 068 */ 069 public Type getParameterType(int position); 070 public String getParameterDisplayName(int position, Locale locale); 071 public String getParameterDescription(int position, Locale locale); 072 073 /** 074 * Defines, whether the parameter at the given position is mandatory. A 075 * mandatory parameter must be filled in, while optional parameters need 076 * not to be filled in. 077 * 078 * @return 079 */ 080 public boolean isParameterMandatory(int position); 081 082 /** 083 * Returns the default value for an optional parameter. If the value returned 084 * here is null, then this either means, that the parameter is mandatory or 085 * that the default value is computed by the expression itself. 086 * 087 * @param position 088 * @return 089 */ 090 public Object getDefaultValue (int position); 091 092 }