#!/bin/perl -n -w
use strict;

# global, but could be attached to the parser or passed to the handlers
use vars qw( @results);

# we need those to hold info about the parsing
# @in_element is a stack of open elements, 
# the current element is $in_element[-1]
use vars qw( @in_element $elt_id $child_seen $child_text);  

if(m/^\((.*)$/)                # element start tag (tag
  { push @in_element, $1;
    if( $1 eq 'elt')          # elt start tag
      { $child_seen= 0; }     #   reset the flag
    elsif( $1 eq 'child')     # child start tag
      { $child_seen= 1;       #   set the flag
        $child_text= '';      #   reset the text
      }
  }
elsif( m/^A([^\s]*) (.*)$/)    # attribute Aatt value
  {                           # store the id for elt elements
    $elt_id= $2 if( ($in_element[-1] eq 'elt') && ($1 eq 'id')); 
  }
elsif( m/^-(.*)\n/)            # text -text
  { $child_text.= $1 if( $in_element[-1] eq 'child'); }
elsif( m/\)(.*)$/)             # end tag )tag
  { if( $1 eq 'elt')          
      { if( $child_seen)                      
          { push @results, $child_text; }     
        else
          { push @results, "missing child for elt $elt_id"; }
      }
  }

END
  { print join "\n", @results;
    print "\n";
  }