NAME
HTML::Truncate - (beta software) truncate HTML by percentage or
character count while preserving well-formedness.
VERSION
0.20
ABSTRACT
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.
SYNOPSIS
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) );
XHTML
This module is designed to work with XHTML-style nested tags. More
below.
WHITESPACE AND ENTITIES
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------^^^^^^^^
METHODS
new Can take all the methods as hash style args. "percent" and "chars"
are incompatible so don't use them both. Whichever is set most
recently will erase the other.
my $ht = HTML::Truncate->new(utf8_mode => 1,
chars => 500, # default is 100
);
utf8_mode
Set/get, true/false. If "utf8_mode" is set, utf8_mode(1) is also set
in the underlying HTML::Parser, entities will be transformed with
decode and the default ellipsis will be a literal ellipsis and not
the default of "…".
chars
Set/get. The number of characters remaining after truncation,
excluding the "ellipsis".
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.
percent
Set/get. A percentage to keep while truncating the rest. For a
document of 1,000 chars, percent('15%') and chars(150) would be
equivalent. The actual amount of character that the percent
represents cannot be known until the given HTML is parsed.
Side-effect: clears any "chars" that has been set.
ellipsis
Set/get. Ellipsis in this case means --
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.
truncate
It returns the truncated XHTML if asked for a return value.
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.
* Skipped tags
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/>
* Tags allowed to self-close
See emptyElement in HTML::Tagset.
add_skip_tags( qw( tag list ) )
Put one or more new tags into the list of those to be omitted from
truncated output. An example of when you might like to use this is
if you're thumb-nailing articles and they start with
"<h1>title</h1>" or such before the article body. The heading level
would be absurd with a list of excerpts so you could drop it
completely this way--
$ht->add_skip_tags( 'h1' );
dont_skip_tags( qw( tag list ) )
Takes tags out of the current list to be omitted from truncated
output.
repair
Set/get, true/false. If true, will attempt to repair unclosed HTML
tags by adding close-tags as late as possible (eg.
"<i><b>foobar</i>" becomes "<i><b>foobar</b></i>"). Unmatched close
tags are dropped ("foobar</b>" becomes "foobar").
on_space
This will make the truncation back up to the first space it finds so
it doesn't truncate in the the middle of a word. "on_space" runs
before "cleanly" if both are set.
cleanly
Set/get -- a regular expression. This is on by default and the
default cleaning regular expression is
"cleanly(qr/[\s[:punct:]]+\z/)". It will make the truncation strip
any trailing spacing and punctuation so you don't get things like
"The End...." or "What? ..." You can cancel it with
"$ht->cleanly(undef)" or provide your own regular expression.
COOKBOOK (well, a recipe)
Template Toolkit filter
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.
AUTHOR
Ashley Pond V, "<ashley@cpan.org>".
LIMITATIONS
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.
This is not an HTML filter
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.
BUGS, FEEDBACK, PATCHES
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.
TO DO
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?
THANKS TO
Kevin Riggle for the "repair" functionality; patch, Pod, and tests.
Lorenzo Iannuzzi for the "on_space" functionality.
SEE ALSO
HTML::Entities, HTML::TokeParser, the "truncate" filter in Template, and
Text::Truncate.
HTML::Scrubber and HTML::Sanitizer.
COPYRIGHT & LICENSE
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.
DISCLAIMER OF WARRANTY
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.