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 }