如何处理解析器javacc中的错误

Question

在附件中，我的解析器在eclipse中使用javacc生成。我不知道在解析器中处理sintax的错误。 我该怎么办？有什么方法？ 如果您可以发布显示它的代码，我更喜欢。 非常感谢你的进步。

    /**
 * JavaCC template file created by SF JavaCC plugin 1.5.17+ wizard for JavaCC 1.5.0+
 */
options
{
  JDK_VERSION = "1.5";
  IGNORE_CASE = true;
  LOOKAHEAD = 2;
  static = true;
}

PARSER_BEGIN(MyParser)
import java.io.* ;

public class MyParser
{  
  public static void main(String args []) throws ParseException
  {
    Token t;
        MyParserTokenManager tm;
        int numToken = 0;

        if (args.length<1) {
            System.out.println("Sorgente non specificato");
            System.exit(1);
        }

        try {
            java.io.InputStream infile;
            infile = new java.io.FileInputStream(args[0]);
            tm = new MyParserTokenManager(new SimpleCharStream(infile));
        }
        catch (java.io.FileNotFoundException e) {
            System.out.println("File "+args[0]+" non trovato");
            return; 
        } // catch

        t = tm.getNextToken();
        numToken++;
        while(t.kind != MyParserConstants.EOF){
            t = tm.getNextToken();
            System.out.printf("%s\t %s\n",tokenImage[t.kind],t.image);
            numToken++;
        }// while
  }

  static void error_skipto(int kind) {
  ParseException e = generateParseException();  // generate the exception object.
  System.out.println(e.toString());  // print the error message
  Token t;
  do {
    t = getNextToken();
  } while (t.kind != kind);
}
}

PARSER_END(MyParser)

void Stm() :
{}
{
  try {
    (
      SE()
    |
      MENTRE()
    |
      DO()
    |
      PER()
    |
      condizione()
    |
      espressione()
    |
      expres()
    )
  }catch (ParseException e) {
    error_skipto(PV);
  }
}

SKIP :
{
  " "
| "\r"
| "\t"
| "\n"
}

TOKEN : /* OPERATORS */
{
    <PIU: "+">
|   <MENO: "-">
|   <PER: "*">
|   <DIV: "/">
}

TOKEN :
{
    <PAR_SIN: "(">
|   <PAR_DES: ")">
|   <QUAD_SIN: "[">
|   <QUAD_DES: "]">
|   <UGUALE: "==">
|   <VIRGOLA: ","> 
|   <ASS: "=">
|   <NEG: "?=">
|   <PV: ";">
|   <FOR: "da">
|   <TO: "a">
|   <IF: "se">
|   <ELSE: "altrimenti">
|   <END_IF: "fine">
|   <WHILE: "mentre">
|   <DO: "esegui">
|   <COST_INT: (["0"-"9"])+>
|   <ID: ["a"-"z","A"-"Z"]>

}


void SE() :
{}
{
  (<IF> <QUAD_SIN> condizione() <QUAD_DES> <PAR_SIN> espressione() <PV> <PAR_DES> <END_IF>)
|  (<IF> <QUAD_SIN> condizione() <QUAD_DES> <PAR_SIN> espressione() <PV> <PAR_DES> <ELSE> <PAR_SIN>
    espressione() <PV> <PAR_DES> <END_IF>)
}

void MENTRE() :
{}
{
  <WHILE> <QUAD_SIN> condizione() <QUAD_DES> <PAR_SIN> espressione() <PV> <PAR_DES>
}

void DO() :
{}
{
  <DO> <PAR_SIN> espressione() <PV> <PAR_DES> <WHILE> <QUAD_SIN> condizione() <QUAD_DES> <PV>
}

void PER() :
{}
{
  <FOR> (<ID>)+ <ASS> <COST_INT> <TO> (<COST_INT>)+ <PAR_SIN> espressione() <PV> <PAR_DES>
}

void condizione():
{ }
{
  (<ID>)+ (<NEG> | <UGUALE>) ((<ID>)+ | (<COST_INT>)+)
}

void espressione ():
{}
{
  (<ID>)+ <ASS> ((<ID>)+ | (<COST_INT>)+ | expres() )
}

void expres() :
{}
{
  ((<ID>)+ <PIU> ((<ID>)+ | (<COST_INT>)+))
| ((<ID>)+ <MENO> ((<ID>)+ | (<COST_INT>)+))
| ((<ID>)+ <PER> ((<ID>)+ | (<COST_INT>)+))
| ((<ID>)+ <DIV> ((<ID>)+ | (<COST_INT>)+))

}