HTML::Filter::Callbacks - modify HTML with callbacks

  use HTML::Filter::Callbacks;

  # Case 1: remove script tags
  my $filter = HTML::Filter::Callbacks->new;
  $filter->add_callbacks(
    script => {
      start => sub { shift->remove_text_and_tag },
      end   => sub { shift->remove_text_and_tag },
    },
  );
  my $new_html = $filter->process($html);

  # Case 2: remove on_* attributes
  my $filter = HTML::Filter::Callbacks->new;
  $filter->add_callbacks(
    '*' => {
      start => sub { shift->remove_attr(qr/^on_/) },
    },
  );
  my $new_html = $filter->process($html);

  # Case 3: replace url of <img src="...">
  my $filter = HTML::Filter::Callbacks->new;
  $filter->add_callbacks(
    'img' => {
      start => sub {
        shift->replace_attr(src => sub { URI->new(shift)->canonical })
      },
    },
  );
  my $new_html = $filter->process($html);

  # Case 4: more complex example to enforce a submit button
  my $filter = HTML::Filter::Callbacks->new;
  $filter->add_callbacks(
    'form' => {
      start => sub {
        my ($tag, $c) = @_;
        $c->stash->{__form_has_submit} = 0;
      },
      end => sub {
        my ($tag, $c) = @_;
        $tag->prepend(qq/<input type="submit">\n/)
          unless $c->stash->{__form_has_submit};
        delete $c->stash->{__form_has_submit};
      }
    },
    'input' => {
      start => sub {
        my ($tag, $c) = @_;
        $c->stash->{__form_has_submit} = 1
          if $tag->attr('type') eq 'submit';
      }
    },
  );
  my $new_html = $filter->process($html);

This is a rather simple HTML filter, based on HTML::Parser. It only looks for tags you add callbacks to modify something that is related to the tags (i.e. tag attributes and related comments and texts that it looked and skipped). If you want finer control, you can add extra handlers to the filter. See the SYNOPSIS and tests for usage.

creates an object.

takes an (X)HTML, applies all the callbacks, and returns the result.

takes an array of callbacks, which typically have a tag name, and a hash reference which holds a callback for the open tag of the name (start = {...}>), and a callback for the close tag of the name (end = {...}>). The callbacks will take a HTML::Filter::Callbacks::Tag object, and the filter object itself as a context holder (stash).

is just a hash reference which you can use freely in the callbacks.

used internally to register default callbacks.

HTML::Parser

Kenichi Ishigaki, <ishigaki@cpan.org>

Copyright (C) 2009 by Kenichi Ishigaki.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.