Source for org.jfree.formula.function.FunctionDescription

   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: }