texplist.java

java语法解释器生成器

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright (C) 2001       Gerwin Klein <[e-mail]>                    *
 * Copyright (C) 2001       Bernhard Rumpe <[e-mail]>               *
 * All rights reserved.                                                    *
 *                                                                         *
 * This program is free software; you can redistribute it and/or modify    *
 * it under the terms of the GNU General Public License. See the file      *
 * COPYRIGHT for more information.                                         *
 *                                                                         *
 * This program is distributed in the hope that it will be useful,         *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of          *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           *
 * GNU General Public License for more details.                            *
 *                                                                         *
 * You should have received a copy of the GNU General Public License along *
 * with this program; if not, write to the Free Software Foundation, Inc., *
 * 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA                 *
 *                                                                         *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */


/**
 * AST node for a list of expressions.
 * 
 * The interpretation of a list of expressions stores the
 * results of the expressions in an array that can be used
 * as parameter list for function calls.
 */ 
class Texplist implements AST {
  Texplist explist;           // next list element (optional null)
  Texp exp;                   // expression of this list node

  public Texplist(Texplist p, Texp e) {
    explist=p;
    exp=e;
  }

  public Texplist(Texp e) {
    explist=null;
    exp=e;
  }

  public String toString() {
    if (explist!=null)
      return explist+","+exp;
    else 
      return exp.toString();
  }

  public void checkcontext(SymTab st) {
    if (explist!=null) 
      explist.checkcontext(st);
    exp.checkcontext(st);             // CoCo (DefFun,DefVar,Arity)
  }                                   // in expression

  public int length() {
    if (explist!=null) 
      return 1+explist.length();
    else 
      return 1;
  }
  
  public void prepInterp(SymTab st) {  // set pointers and indices
    exp.prepInterp(st);
    if (explist!=null) explist.prepInterp(st);
  }
  
  public void interpret(int[] in, int[] par, int[] res, int index) {
    res[index] = exp.interpret(in,par);
    if (explist!=null) explist.interpret(in,par,res,index+1);
  }
}