[antlr-interest] Syntaxerror not found if first symbol is wrong

[Oliver B. Fischer]

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Hello,

my grammar is not able to recognize an syntax error if already the first
~ symbol found is not an expected one:

My grammar looks like this:

INT : 'int' ;

ID : ('a'..'z')+ ;

WS : (' '|'\t'|'\n'|'\r')+ { $channel=HIDDEN; };

program : (a b ';')+ ;

a : INT ;

b : ID ;

So, any valid input must start with 'int', but if the first symbol found
by the lexer is an ID, the generated parser does not recognize the error.

ANTLR generates the following code:
public final void program() throws RecognitionException {
~  try {
~    {
~      int cnt1 = 0;
~      loop1:
~      do {
~        int alt1 = 2;
~        int LA1_0 = input.LA(1);

~        if ((LA1_0 == INT)) {
~          alt1 = 1;
~        }


~        switch (alt1) {
~          case 1: {
~            pushFollow(FOLLOW_a_in_program154);
~            a();
~            _fsp--;

~            pushFollow(FOLLOW_b_in_program156);
~            b();
~            _fsp--;

~            match(input, SEM, FOLLOW_SEM_in_program158);

~          }
~          break;

~          default:
~            if (cnt1 >= 1) break loop1;
~            EarlyExitException eee =
~                    new EarlyExitException(1, input);
~            throw eee;
~        }
~        cnt1++;
~      } while (true);


~    }

~  }

~  catch (RecognitionException e) {
~    throw e;
~  }
~  finally {
~  }
~  return;
}

So, the ID token falls through the switch-statement. How can I avoid this?

Thank you for your help!

Bye

Oliver



- --
Oliver B. Fischer, Schönhauser Allee 64, 10437 Berlin
Tel. +49 30 44793251, Mobil: +49 178 7903538
Mail: o.b.fischer at gmx.de Blog: http://www.sw-blog.net
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