| HTML::Truncate(3pm) | User Contributed Perl Documentation | HTML::Truncate(3pm) |
HTML::Truncate - (beta software) truncate HTML by percentage or character count while preserving well-formedness.
0.20
When working with text it is common to want to truncate strings to make them fit a desired context. E.g., you might have a menu that is only 100px wide and prefer text doesn't wrap so you'd truncate it around 15-30 characters, depending on preference and typeface size. This is trivial with plain text using substr but with HTML it is somewhat difficult because whitespace has fluid significance and open tags that are not properly closed destroy well-formedness and can wreck an entire layout.
HTML::Truncate attempts to account for those two problems by padding truncation for spacing and entities and closing any tags that remain open at the point of truncation.
use strict;
use HTML::Truncate;
my $html = '<p><i>We</i> have to test <b>something</b>.</p>';
my $readmore = '... <a href="/full-article">[readmore]</a>';
my $html_truncate = HTML::Truncate->new();
$html_truncate->chars(20);
$html_truncate->ellipsis($readmore);
print $html_truncate->truncate($html);
# or
use Encode;
my $ht = HTML::Truncate->new( utf8_mode => 1,
chars => 1_000,
);
print Encode::encode_utf8( $ht->truncate($html) );
This module is designed to work with XHTML-style nested tags. More below.
Repeated natural whitespace (i.e., "\s+" and not " ") in HTML -- with rare exception (pre tags or user defined styles) -- is not meaningful. Therefore it is normalized when truncating. Entities are also normalized. The following is only counted 14 chars long.
\n<p>\nthis is ‘text’\n\n</p> ^^^^^^^12345----678--9------01234------^^^^^^^^
my $ht = HTML::Truncate->new(utf8_mode => 1,
chars => 500, # default is 100
);
Entities are counted as single characters. E.g., "©" is one character for truncation counts.
Default is "100." Side-effect: clears any "percent" that has been set.
Side-effect: clears any "chars" that has been set.
The omission of a word or phrase necessary for a complete
syntactical construction but not necessary for understanding.
http://www.answers.com/topic/ellipsis
What it will probably mean in most real applications is "read more." The default is "…" which if the utf8 flag is true will render as a literal ellipsis, "chr(8230)".
The reason the default is "…" and not "..." is this is meant for use in HTML environments, not plain text, and "..." (dot-dot-dot) is not typographically correct or equivalent to a real horizontal ellipsis character.
my $truncated = $ht->truncate($html);
It will truncate the string in place if no return value is expected (wantarray is not defined).
$ht->truncate($html);
print $html;
Also can be called with inline arguments-
print $ht->truncate( $html,
$chars_or_percent,
$ellipsis );
No arguments are strictly required. Without HTML to operate upon it returns undef. The two optional arguments may be preset with the methods "chars" (or "percent") and "ellipsis".
Valid nesting of tags is required (alla XHTML). Therefore some old HTML habits like <p> without a </p> are not supported and may cause a fatal error. See "repair" for help with badly formed HTML.
Certain tags are omitted by default from the truncated output.
These will not be included in truncated output by default.
<head>...</head> <script>...</script> <form>...</form>
<iframe></iframe> <title>...</title> <style>...</style>
<base/> <link/> <meta/>
See emptyElement in HTML::Tagset.
$ht->add_skip_tags( 'h1' );
For excerpting HTML in your Templates. Note the "add_skip_tags" which is set to drop any images from the truncated output.
use Template;
use HTML::Truncate;
my %config =
(
FILTERS => {
truncate_html => [ \&truncate_html_filter_factory, 1 ],
},
);
my $tt = Template->new(\%config) or die $Template::ERROR;
# ... etc ...
sub truncate_html_filter_factory {
my ( $context, $len, $ellipsis ) = @_;
$len = 32 unless $len;
$ellipsis = chr(8230) unless defined $ellipsis;
my $ht = HTML::Truncate->new();
$ht->add_skip_tags(qw( img ));
return sub {
my $html = shift || return '';
return $ht->truncate( $html, $len, $ellipsis );
}
}
Then in your templates you can do things like this:
[% FOR item IN search_results %]
<div class="searchResult">
<a href="[% item.uri %]">[% item.title %]</a><br />
[% item.body | truncate_html(200) %]
</div>
[% END %]
See also Template::Filters.
Ashley Pond V, "<ashley@cpan.org>".
There may be places where this will break down right now. I'll pad out possible edge cases as I find them or they are sent to me via the CPAN bug ticket system.
Although this happens to do some crude HTML filtering to achieve its end, it is not a fully featured filter. If you are looking for one, check out HTML::Scrubber and HTML::Sanitizer.
Please report any bugs or feature requests to "bug-html-truncate@rt.cpan.org", or through the web interface at <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=HTML-Truncate>. I will get the ticket, and then you'll automatically be notified of progress as I make changes.
Write a couple more tests (percent and skip stuff) then take out beta notice. Try to make the 5.6 stuff work without decode...? Try a "drop_tags" method?
Write an XML::LibXML based version to load when possible...? Or make that part of XHTML::Util?
Kevin Riggle for the "repair" functionality; patch, Pod, and tests.
Lorenzo Iannuzzi for the "on_space" functionality.
HTML::Entities, HTML::TokeParser, the "truncate" filter in Template, and Text::Truncate.
HTML::Scrubber and HTML::Sanitizer.
Copyright (©) 2005-2009 Ashley Pond V.
This program is free software; you can redistribute it or modify it or both under the same terms as Perl itself.
Because this software is licensed free of charge, there is no warranty for the software, to the extent permitted by applicable law. Except when otherwise stated in writing the copyright holders or other parties provide the software "as is" without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. The entire risk as to the quality and performance of the software is with you. Should the software prove defective, you assume the cost of all necessary servicing, repair, or correction.
In no event unless required by applicable law or agreed to in writing will any copyright holder, or any other party who may modify and/or redistribute the software as permitted by the above licence, be liable to you for damages, including any general, special, incidental, or consequential damages arising out of the use or inability to use the software (including but not limited to loss of data or data being rendered inaccurate or losses sustained by you or third parties or a failure of the software to operate with any other software), even if such holder or other party has been advised of the possibility of such damages.
| 2022-06-14 | perl v5.34.0 |