NAME¶
HTML::Strip - Perl extension for stripping HTML markup from text.
SYNOPSIS¶
use HTML::Strip;
my $hs = HTML::Strip->new();
my $clean_text = $hs->parse( $raw_html );
$hs->eof;
DESCRIPTION¶
This module simply strips HTML-like markup from text in a very quick and brutal
manner. It could quite easily be used to strip XML or SGML from text as well;
but removing HTML markup is a much more common problem, hence this module
lives in the HTML:: namespace.
It is written in XS, and thus about five times quicker than using regular
expressions for the same task.
It does
not do any syntax checking (if you want that, use HTML::Parser),
instead it merely applies the following rules:
- 1.
- Anything that looks like a tag, or group of tags will be replaced with a
single space character. Tags are considered to be anything that starts
with a "<" and ends with a ">"; with the caveat
that a ">" character may appear in either of the following
without ending the tag:
- Quote
- Quotes are considered to start with either a "'" or a
""" character, and end with a matching character not
preceded by an even number or escaping slashes (i.e. "\""
does not end the quote but "\\\\"" does).
- Comment
- If the tag starts with an exclamation mark, it is assumed to be a
declaration or a comment. Within such tags, ">" characters do
not end the tag if they appear within pairs of double dashes (e.g.
"<!-- <a href="old.htm">old page</a>
-->" would be stripped completely). Inside a comment, no parsing
for quotes is done as well. (That means "<!-- comment with ' quote
" -->" are entirely stripped.)
- 2.
- Anything the appears within so-called strip tags is stripped as
well. By default, these tags are "title", "script",
"style" and "applet".
HTML::Strip maintains state between calls, so you can parse a document in chunks
should you wish. If one chunk ends half-way through a tag, quote, comment, or
whatever; it will remember this, and expect the next call to parse to start
with the remains of said tag.
If this is not going to be the case, be sure to call $hs->
eof()
between calls to $hs->
parse(). Alternatively, you may set
"auto_reset" to true on the constructor or any time after with
"set_auto_reset", so that the parser will always operate in one-shot
basis (resetting after each parsed chunk).
METHODS¶
- new()
- Constructor. Can optionally take a hash of settings (with keys
corresponsing to the "set_" methods below).
For example, the following is a valid constructor:
my $hs = HTML::Strip->new(
striptags => [ 'script', 'iframe' ],
emit_spaces => 0
);
- parse()
- Takes a string as an argument, returns it stripped of HTML.
- eof()
- Resets the current state information, ready to parse a new block of
HTML.
- clear_striptags()
- Clears the current set of strip tags.
- add_striptag()
- Adds the string passed as an argument to the current set of strip
tags.
- set_striptags()
- Takes a reference to an array of strings, which replace the current set of
strip tags.
- set_emit_spaces()
- Takes a boolean value. If set to false, HTML::Strip will not attempt any
conversion of tags into spaces. Set to true by default.
- set_decode_entities()
- Takes a boolean value. If set to false, HTML::Strip will decode HTML
entities. Set to true by default.
- filter_entities()
- If HTML::Entities is available, this method behaves just like invoking
HTML::Entities::decode_entities, except that it respects the current
setting of 'decode_entities'.
- set_filter()
- Sets a filter to be applied after tags were stripped. It may accept the
name of a method (like 'filter_entities') or a code ref. By default, its
value is 'filter_entities' if HTML::Entities is available or
"undef" otherwise.
- set_auto_reset()
- Takes a boolean value. If set to true, "parse" resets after each
call (equivalent to calling "eof"). Otherwise, the parser
remembers its state from one call to "parse" to another, until
you call "eof" explicitly. Set to false by default.
LIMITATIONS¶
- Whitespace
- Despite only outputting one space character per group of tags, and
avoiding doing so when tags are bordered by spaces or the start or end of
strings, HTML::Strip can often output more than desired; such as with the
following HTML:
<h1> HTML::Strip </h1> <p> <em> <strong> fast, and brutal </strong> </em> </p>
Which gives the following output:
" HTML::Strip fast, and
brutal "
Thus, you may want to post-filter the output of HTML::Strip to remove excess
whitespace (for example, using "tr/ / /s;"). (This has been
improved since previous releases, but is still an issue)
- HTML Entities
- HTML::Strip will only attempt decoding of HTML entities if HTML::Entities
is installed.
EXPORT¶
None by default.
AUTHOR¶
Alex Bowley <kilinrax@cpan.org>
SEE ALSO¶
perl, HTML::Parser, HTML::Entities