tools/lexer/jflex-1.4/examples/interpreter/Texp.java

   1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
   2  * Copyright (C) 2001       Gerwin Klein <lsf@jflex.de>                    *
   3  * Copyright (C) 2001       Bernhard Rumpe <rumpe@in.tum.de>               *
   4  * All rights reserved.                                                    *
   5  *                                                                         *
   6  * This program is free software; you can redistribute it and/or modify    *
   7  * it under the terms of the GNU General Public License. See the file      *
   8  * COPYRIGHT for more information.                                         *
   9  *                                                                         *
  10  * This program is distributed in the hope that it will be useful,         *
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of          *
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           *
  13  * GNU General Public License for more details.                            *
  14  *                                                                         *
  15  * You should have received a copy of the GNU General Public License along *
  16  * with this program; if not, write to the Free Software Foundation, Inc., *
  17  * 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA                 *
  18  *                                                                         *
  19  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  20
  21
  22 /**
  23  * AST node for an integer expression.
  24  *
  25  * The non terminal exp is the sum of multiple variants and
  26  * therefore modeled as an abstract class.
  27  *
  28  * The interpretation function <tt>interpret</tt> is called with
  29  * valuations of input variables <tt>in</tt> and parameters
  30  * <tt>par</tt>. Before interpret can be called, pointers
  31  * and variable indices must be set with <tt>prepInterp</tt>.
  32  */
  33 abstract class Texp implements AST {
  34   // test context conditions (DefFun,DefVar,Arity)
  35   abstract public void checkcontext(SymTab st);
  36
  37   // set pointers and indices for variables and functions
  38   abstract public void prepInterp(SymTab st);
  39
  40   // interpretation
  41   abstract public int interpret(int[] in, int[] par);
  42 }
  43