%token NUM = /(\d+)/
%token OP  = /([-+*\/])/

%{

my $nxr = 0;
my $nxs = 0;
%}

%conflict isInTheMiddle {


  $nxs++;

  warn "nxr = $nxr nxs = $nxs\n";
  if ($nxs == $nxr+1) { 
    warn "Reducing by :MIDx nxs = $nxs nxr = $nxr input: '".unexpendedInput()."'\n";
    $self->YYSetReduce(':MIDx' );
    
    $nxr = $nxs = 0; 
  }
  else { 
     warn "Shifting input: '".unexpendedInput()."'\n";
     $self->YYSetShift() 
     ##$self->YYSetShift(['NUM',]  ) 
  } 
}

%%

T: isInTheMiddle S 'other' 'things'
;

isInTheMiddle: /* empty */
   {
     ($nxr) = $_[0]->YYPreParse('ExpList'); 
     warn "Number of x's = $nxr\n";
     $nxr = int ($nxr/2);
   }
;

S:
     x  %PREC isInTheMiddle S x  
  |  %name :MIDx 
     x  %PREC isInTheMiddle 
;

x:
     NUM
  |  NUM OP x
;
%%

=head1 SYNOPSIS

This grammar is similar to the one in file C<nopackrat.eyp>.
It can't be parsed by LR(k) nor LL(k) algorithms.
Backtracking LR and GLR algorithms can but will perform poorly.

Compile it with:

   $ eyapp ExpList.eyp 
   $ eyapp -TC noPackratSolvedExpRG2.eyp

Run it with:

   $ ./noPackratSolvedExpRG2.pm -t -i -m 1 -c '2-3 3*4 5+2 other things'

=head1 SEE ALSO

Files C<nopackrat.eyp>, C<noLRk_exp.eyp>, C<noLRk_expSolved.eyp>

=cut