Debug1.eyp

%{

=head1 SYNOPSIS

See http://search.cpan.org/perldoc?Parse::Eyapp::debuggingtut
This files is almost like Debug.eyp
It only changes the rules

             ds:
                 D ';' ds    
               | D       
for a left-recursive version. 

Be sure C<DebugTail.pm> is reachable
compile it with 

      eyapp -b '' Debug1.eyp

Execute the generated modulino with:

      ./Debug1.pm -t

There is an error in the lexical analyzer.
Can you find it?

Try first with input "D;S" and then 
with input "D; S" 


=head1 See also

    Debug1.eyp Debug2.eyp DebugLookForward.eyp DebugDynamicResolution.eyp

=cut

our $VERSION = '0.01';
use base q{DebugTail}; 

# This is an exercise:
# There is an error somewhere below ...
# Can you find it?

%}

%token D S

%lexer {
        s{^(\s)}{} and $self->tokenline($1 =~ tr{\n}{});

        return ($1, $1) if s/^(.)//;
    }

%tree 

%%
p:
    %name P
      ds ';' ss  
  | %name SS
      ss
;


ds:
    %name D2
      ds ';' D
  | %name D1
      D       
;

ss:
    %name S2
    S ';' ss      
  | %name S1
    S       
;

%%

my $prompt = 'Try first "D;S" and then "D; D;  S" '.
             '(press <CR><CTRL-D> to finish): ';
__PACKAGE__->main($prompt) unless caller();