parse last line

Aaron Wohl <>
Fri, 17 Feb 1995 13:10:26 GMT

          From comp.compilers

Related articles
parse last line (Aaron Wohl) (1995-02-17)
Re: parse last line (Zerksis D. Umrigar) (1995-02-21)
Re: parse last line (1995-02-21)
| List of all articles for this month |

Newsgroups: comp.compilers
From: Aaron Wohl <>
Keywords: lex, parse, question
Organization: Systems Group 97, Carnegie Mellon, Pittsburgh, PA
Date: Fri, 17 Feb 1995 13:10:26 GMT

How do folks handle parsing the last line of input?

I am using lex/yacc for a new compiler for an obscure basic dialect that
up until now has only been interpreted. It is fairly common for the
basic programs to not have and end of line character on the last line.
My grammar looks like:

  | program stmt

  | ID ':' stmt
  | ID '=' exp EOL

All the stuff I tried to allow the last EOL to be optional ended up with
shift/reduce conflicts on ID. I tried replacing the lex character
input to return an extra eol before eof. But different versions of
yacc/bison/etc override the character input differently. What I ended
up doing was putting a function between yacc and lex. When lex returns
EOF it returns EOL once then EOF.

Is there a good way to allow EOL to be a statement terminator but
optional at EOF that is portable to different yacc/lex dialects?

Aaron Wohl / ham callsign N3LIW / 412-731-3691 / 412-268-5032

Post a followup to this message

Return to the comp.compilers page.
Search the comp.compilers archives again.