tools/lexer/jflex-1.4/examples/interpreter/Main.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 import java.io.File;
  23 import java.io.FileReader;
  24 import java.io.InputStreamReader;
  25 import java.io.Reader;
  26
  27 /**
  28  * Main program of the interpreter for the AS programming language.
  29  * Based on JFlex/CUP.
  30  *
  31  * Steps:
  32  * - scanning                               (Yylex)
  33  * - context free parsing and AST building  (yyparse)
  34  * - build up symbol table                  (setSymtabs)
  35  * - check context conditions               (checkcontext)
  36  * - prepare interpretation                 (prepInterp)
  37  * - start interpretation                   (interpret)
  38  */
  39 public class Main {
  40
  41   public static void main(String [] args) throws Exception {
  42     Reader reader = null;
  43
  44     if (args.length == 1) {
  45       File input = new File(args[0]);
  46       if (!input.canRead()) {
  47         System.out.println("Error: could not read ["+input+"]");
  48       }
  49       reader = new FileReader(input);
  50     }
  51     else {
  52      reader = new InputStreamReader(System.in);
  53     }
  54
  55     Yylex scanner = new Yylex(reader);   // create scanner
  56     SymTab symtab = new SymTab();        // set global symbol table
  57     scanner.setSymtab(symtab);
  58
  59     parser parser = new parser(scanner); // create parser
  60     Tprogram syntaxbaum = null;
  61
  62     try {
  63       syntaxbaum = (Tprogram) parser.parse().value;  // parse
  64     }
  65     catch (Exception e) {
  66       e.printStackTrace();
  67     }
  68
  69     // System.out.println(symtab);
  70     System.out.println(syntaxbaum);
  71
  72     syntaxbaum.setSymtabs();          // set symbol table
  73     // syntaxbaum.printSymtabs();       // print symbol table
  74
  75     syntaxbaum.checkcontext();        // CoCo (DefVar, DefFun, Arity)
  76     if(contexterror>0) return;
  77
  78     syntaxbaum.prepInterp();          // var. indices and function pointers
  79     // im Syntaxbaum setzen
  80     syntaxbaum.interpret();           // interpretation
  81   }
  82
  83   static int contexterror = 0;        // number of errors in context conditions
  84
  85   public static void error(String s) {
  86     System.out.println((contexterror++)+". "+s);
  87   }
  88 }