The custom when dealing with line numbers is to make the attribute associated with the token somewhat more complex: an anonymous array or hash.

The following is an example of a Lexer for a C-like language written in Parse::Eyapp. The token attribute is an array having the value and the line number. Thus, for a number we return

('INUM',[$1, $tokenbegin])
[download]

$ sed -ne '513,567p' Types.eyp | cat -n
 1  sub _Lexer {
 2    my($parser)=shift;
 3
 4    my $token;
 5    for ($parser->YYData->{INPUT}) { # warn! false for
 6        return('',undef) if !defined($_) or $_ eq '';
 7
 8        #Skip blanks
 9        s{\A
10           ((?:
11                \s+       # any white space char
12            |   /\*.*?\*/ # C like comments
13            )+
14           )
15         }
16         {}xs
17        and do { # Count line numbers
18              my($blanks)=$1;
19
20              #Maybe At EOF
21              return('', undef) if $_ eq '';
22              $tokenend += $blanks =~ tr/\n//;
23          };
24
25       $tokenbegin = $tokenend;
26
27        s/^('.')//
28                and return('CHARCONSTANT', [$1, $tokenbegin]);
29
30        s/^([0-9]+(?:\.[0-9]+)?)//
31                and return('INUM',[$1, $tokenbegin]);
32
33        s/^([A-Za-z][A-Za-z0-9_]*)//
34          and do {
35            my $word = $1;
36            my $r;
37            return ($r, [$r, $tokenbegin]) if defined($r = $reserved
+{$word});
38            return('ID',[$word, $tokenbegin]);
39        };
40
41        m/^(\S\S)/ and  defined($token = $1) and exists($lexeme{$tok
+en})
42          and do {
43            s/..//;
44            return ($token, [$token, $tokenbegin]);
45          }; # do
46
47        m/^(\S)/ and defined($token = $1) and  exists($lexeme{$token
+})
48          and do {
49            s/.//;
50            return ($token, [$token, $tokenbegin]);
51          }; # do
52
53        die "Unexpected character at $tokenbegin\n";
54    } # for
55  }
[download]

my %lexeme = (
  '='  => "ASSIGN",
  .................
  ']'  => "RIGHTBRACKET",
  '==' => "EQ",
  '+=' => "PLUSASSIGN",
  ...................
  '--' => "DEC",
  '**' => "EXP"
);
[download]

Hope it helps

Casiano