truncate-html.pl

#!/usr/bin/env perl

use strict;
use warnings;

use HTML::Parser;

my $len = 0;
my $max = 85;
my (@close, @open);

my $parser = HTML::Parser->new(
  start_h => [\&start_tag, 'tag,text'],
  text_h  => [\&tag_text, 'text'],
  end_h   => [\&end_tag, 'text'],
);

$parser->parse($_) while <STDIN>;
$parser->eof;

sub start_tag {
  my ($tag, $text) = @_;
  push @open, $text;
  push @close, $tag;
}

sub tag_text {
  my $text = shift;
  my @words = split /\b/, $text;

  while (my $word = shift @words) {
    if (length($word) + $len > $max) {
      print " &hellip;";
      print "</$_>" for @close;
      exit 0;
    }
    
    if (@open) {
      print join "", @open;
      @open = ();
    }

    $len += length $word;
    print $word;
  }
}

sub end_tag {
  print shift;
  pop @close;
}