Strip(3)

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 rapidly and brutally. It could easily be used to strip XML or SGML markup instead; but as removing HTML is a much more common problem, 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). No parsing for quotes is performed within comments, so for instance "<!-- comment with both ' quote types " -->" would be entirely stripped.

2.  Anything the appears within what we term 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.

set_debug()
    Outputs extensive debugging information on internal state during the parse. Not intended to be used by anyone except the module maintainer.

decode_entities()
filter()
auto_reset()
debug()
    Readonly accessors for their respective settings.

  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

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