Provided by: libhtml-simpleparse-perl_0.12-5_all bug

NAME

       HTML::SimpleParse - a bare-bones HTML parser

SYNOPSIS

        use HTML::SimpleParse;

        # Parse the text into a simple tree
        my $p = new HTML::SimpleParse( $html_text );
        $p->output;                 # Output the HTML verbatim

        $p->text( $new_text );      # Give it some new HTML to chew on
        $p->parse                   # Parse the new HTML
        $p->output;

        my %attrs = HTML::SimpleParse->parse_args('A="xx" B=3');
        # %attrs is now ('A' => 'xx', 'B' => '3')

DESCRIPTION

       This module is a simple HTML parser.  It is similar in concept to HTML::Parser, but it
       differs from HTML::TreeBuilder in a couple of important ways.

       First, HTML::TreeBuilder knows which tags can contain other tags, which start tags have
       corresponding end tags, which tags can exist only in the <HEAD> portion of the document,
       and so forth.  HTML::SimpleParse does not know any of these things.  It just finds tags
       and text in the HTML you give it, it does not care about the specific content of these
       tags (though it does distiguish between different _types_ of tags, such as comments,
       starting tags like <b>, ending tags like </b>, and so on).

       Second, HTML::SimpleParse does not create a hierarchical tree of HTML content, but rather
       a simple linear list.  It does not pay any attention to balancing start tags with
       corresponding end tags, or which pairs of tags are inside other pairs of tags.

       Because of these characteristics, you can make a very effective HTML filter by sub-
       classing HTML::SimpleParse.  For example, to remove all comments from HTML:

        package NoComment;
        use HTML::SimpleParse;
        @ISA = qw(HTML::SimpleParse);
        sub output_comment {}

        package main;
        NoComment->new($some_html)->output;

       Historically, I started the HTML::SimpleParse project in part because of a
       misunderstanding about HTML::Parser's functionality.  Many aspects of these two modules
       actually overlap.  I continue to maintain the HTML::SimpleParse module because people seem
       to be depending on it, and because beginners sometimes find HTML::SimpleParse to be
       simpler than HTML::Parser's more powerful interface.  People also seem to get a fair
       amount of usage out of the "parse_args()" method directly.

   Methods
       •   new

            $p = new HTML::SimpleParse( $some_html );

           Creates a new HTML::SimpleParse object.  Optionally takes one argument, a string
           containing some HTML with which to initialize the object.  If you give it a non-empty
           string, the HTML will be parsed into a tree and ready for outputting.

           Can also take a list of attributes, such as

            $p = new HTML::SimpleParse( $some_html, 'fix_case' => -1);

           See the "parse_args()" method below for an explanation of this attribute.

       •   text

            $text = $p->text;
            $p->text( $new_text );

           Get or set the contents of the HTML to be parsed.

       •   tree

            foreach ($p->tree) { ... }

           Returns a list of all the nodes in the tree, in case you want to step through them
           manually or something.  Each node in the tree is an anonymous hash with (at least)
           three data members, $node->{type} (is this a comment, a start tag, an end tag, etc.),
           $node->{content} (all the text between the angle brackets, verbatim), and
           $node->{offset} (number of bytes from the beginning of the string).

           The possible values of $node->{type} are "text", "starttag", "endtag", "ssi", and
           "markup".

       •   parse

            $p->parse;

           Once an object has been initialized with some text, call $p->parse and a tree will be
           created.  After the tree is created, you can call $p->output.  If you feed some text
           to the new() method, parse will be called automatically during your object's
           construction.

       •   parse_args

            %hash = $p->parse_args( $arg_string );

           This routine is handy for parsing the contents of an HTML tag into key=value pairs.
           For instance:

             $text = 'type=checkbox checked name=flavor value="chocolate or strawberry"';
             %hash = $p->parse_args( $text );
             # %hash is ( TYPE=>'checkbox', CHECKED=>undef, NAME=>'flavor',
             #            VALUE=>'chocolate or strawberry' )

           Note that the position of the last m//g search on the string (the value returned by
           Perl's pos() function) will be altered by the parse_args function, so make sure you
           take that into account if (in the above example) you do "$text =~ m/something/g".

           The parse_args() method can be run as either an object method or as a class method,
           i.e. as either $p->parse_args(...) or HTML::SimpleParse->parse_args(...).

           HTML attribute lists are supposed to be case-insensitive with respect to attribute
           names.  To achieve this behavior, parse_args() respects the 'fix_case' flag, which can
           be set either as a package global $FIX_CASE, or as a class member datum 'fix_case'.
           If set to 0, no case conversion is done.  If set to 1, all keys are converted to upper
           case.  If set to -1, all keys are converted to lower case.  The default is 1, i.e. all
           keys are uppercased.

           If an attribute takes no value (like "checked" in the above example) then it will
           still have an entry in the returned hash, but its value will be "undef".  For example:

             %hash = $p->parse_args('type=checkbox checked name=banana value=""');
             # $hash{CHECKED} is undef, but $hash{VALUE} is ""

           This method actually returns a list (not a hash), so duplicate attributes and order
           will be preserved if you want them to be:

            @hash = $p->parse_args("name=family value=gwen value=mom value=pop");
            # @hash is qw(NAME family VALUE gwen VALUE mom VALUE pop)

       •   output

            $p->output;

           This will output the contents of the HTML, passing the real work off to the
           output_text, output_comment, etc. functions.  If you do not override any of these
           methods, this module will output the exact text that it parsed into a tree in the
           first place.

       •   get_output

            print $p->get_output

           Similar to $p->output(), but returns its result instead of printing it.

       •   execute

            foreach ($p->tree) {
               print $p->execute($_);
            }

           Executes a single node in the HTML parse tree.  Useful if you want to loop through the
           nodes and output them individually.

       The following methods do the actual outputting of the various parts of the HTML.  Override
       some of them if you want to change the way the HTML is output.  For instance, to strip
       comments from the HTML, override the output_comment method like so:

        # In subclass:
        sub output_comment { }  # Does nothing

       •   output_text

       •   output_comment

       •   output_endtag

       •   output_starttag

       •   output_markup

       •   output_ssi

CAVEATS

       Please do not assume that the interface here is stable.  This is a first pass, and I'm
       still trying to incorporate suggestions from the community.  If you employ this module
       somewhere, make doubly sure before upgrading that none of your code breaks when you use
       the newer version.

BUGS

       •   Embedded >s are broken

           Won't handle tags with embedded >s in them, like <input name=expr value="x > y">.
           This will be fixed in a future version, probably by using the parse_args method.
           Suggestions are welcome.

TO DO

       •   extensibility

           Based on a suggestion from Randy Harmon (thanks), I'd like to make it easier for
           subclasses of SimpleParse to pick out other kinds of HTML blocks, i.e.  extend the set
           {text, comment, endtag, starttag, markup, ssi} to include more members.  Currently the
           only easy way to do that is by overriding the "parse" method:

            sub parse {  # In subclass
               my $self = $_[0];
               $self->SUPER::parse(@_);
               foreach ($self->tree) {
                  if ($_->{content} =~ m#^a\s+#i) {
                     $_->{type} = 'anchor_start';
                  }
               }
            }

            sub output_anchor_start {
               # Whatever you want...
            }

           Alternatively, this feature might be implemented by hanging attatchments onto the
           parsing loop, like this:

            my $parser = new SimpleParse( $html_text );
            $regex = '<(a\s+.*?)>';
            $parser->watch_for( 'anchor_start', $regex );

            sub SimpleParse::output_anchor_start {
               # Whatever you want...
            }

           I think I like that idea better.  If you wanted to, you could make a subclass with
           output_anchor_start as one of its methods, and put the ->watch_for stuff in the
           constructor.

       •   reading from filehandles

           It would be nice if you could initialize an object by giving it a filehandle or
           filename instead of the text itself.

       •   tests

           I need to write a few tests that run under "make test".

AUTHOR

       Ken Williams <ken@forum.swarthmore.edu>

COPYRIGHT

       Copyright 1998 Swarthmore College.  All rights reserved.

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