NAME¶
HTML::Tagset - data tables useful in parsing HTML
VERSION¶
Version 3.20
SYNOPSIS¶
use HTML::Tagset;
# Then use any of the items in the HTML::Tagset package
# as need arises
DESCRIPTION¶
This module contains several data tables useful in various kinds of HTML parsing
operations.
Note that all tag names used are lowercase.
In the following documentation, a "hashset" is a hash being used as a
set -- the hash conveys that its keys are there, and the actual values
associated with the keys are not significant. (But what values are there, are
always true.)
VARIABLES¶
Note that none of these variables are exported.
hashset %HTML::Tagset::emptyElement
This hashset has as values the tag-names (GIs) of elements that cannot have
content. (For example, "base", "br", "hr".) So
$HTML::Tagset::emptyElement{'hr'} exists and is true.
$HTML::Tagset::emptyElement{'dl'} does not exist, and so is not true.
hashset %HTML::Tagset::optionalEndTag
This hashset lists tag-names for elements that can have content, but whose
end-tags are generally, "safely", omissible. Example:
$HTML::Tagset::emptyElement{'li'} exists and is true.
hash %HTML::Tagset::linkElements
Values in this hash are tagnames for elements that might contain links, and the
value for each is a reference to an array of the names of attributes whose
values can be links.
hash %HTML::Tagset::boolean_attr
This hash (not hashset) lists what attributes of what elements can be printed
without showing the value (for example, the "noshade" attribute of
"hr" elements). For elements with only one such attribute, its value
is simply that attribute name. For elements with many such attributes, the
value is a reference to a hashset containing all such attributes.
hashset %HTML::Tagset::isPhraseMarkup
This hashset contains all phrasal-level elements.
hashset %HTML::Tagset::is_Possible_Strict_P_Content
This hashset contains all phrasal-level elements that be content of a P element,
for a strict model of HTML.
hashset %HTML::Tagset::isHeadElement
This hashset contains all elements that elements that should be present only in
the 'head' element of an HTML document.
hashset %HTML::Tagset::isList
This hashset contains all elements that can contain "li" elements.
hashset %HTML::Tagset::isTableElement
This hashset contains all elements that are to be found only in/under a
"table" element.
hashset %HTML::Tagset::isFormElement
This hashset contains all elements that are to be found only in/under a
"form" element.
hashset %HTML::Tagset::isBodyElement
This hashset contains all elements that are to be found only in/under the
"body" element of an HTML document.
hashset %HTML::Tagset::isHeadOrBodyElement
This hashset includes all elements that I notice can fall either in the head or
in the body.
hashset %HTML::Tagset::isKnown
This hashset lists all known HTML elements.
hashset %HTML::Tagset::canTighten
This hashset lists elements that might have ignorable whitespace as children or
siblings.
array @HTML::Tagset::p_closure_barriers
This array has a meaning that I have only seen a need for in
"HTML::TreeBuilder", but I include it here on the off chance that
someone might find it of use:
When we see a "<p>" token, we go lookup up the lineage for a p
element we might have to minimize. At first sight, we might say that if
there's a p anywhere in the lineage of this new p, it should be closed. But
that's wrong. Consider this document:
<html>
<head>
<title>foo</title>
</head>
<body>
<p>foo
<table>
<tr>
<td>
foo
<p>bar
</td>
</tr>
</table>
</p>
</body>
</html>
The second p is quite legally inside a much higher p.
My formalization of the reason why this is legal, but this:
<p>foo<p>bar</p></p>
isn't, is that something about the table constitutes a "barrier" to
the application of the rule about what p must minimize.
So @HTML::Tagset::p_closure_barriers is the list of all such barrier-tags.
hashset %isCDATA_Parent
This hashset includes all elements whose content is CDATA.
CAVEATS¶
You may find it useful to alter the behavior of modules (like
"HTML::Element" or "HTML::TreeBuilder") that use
"HTML::Tagset"'s data tables by altering the data tables themselves.
You are welcome to try, but be careful; and be aware that different modules
may or may react differently to the data tables being changed.
Note that it may be inappropriate to use these tables for
producing HTML
-- for example, %isHeadOrBodyElement lists the tagnames for all elements that
can appear either in the head or in the body, such as "script". That
doesn't mean that I am saying your code that produces HTML should feel free to
put script elements in either place! If you are producing programs that spit
out HTML, you should be
intimately familiar with the DTDs for HTML or
XHTML (available at "
http://www.w3.org/"), and you should slavishly
obey them, not the data tables in this document.
SEE ALSO¶
HTML::Element, HTML::TreeBuilder, HTML::LinkExtor
COPYRIGHT & LICENSE¶
Copyright 1995-2000 Gisle Aas.
Copyright 2000-2005 Sean M. Burke.
Copyright 2005-2008 Andy Lester.
This program is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.
ACKNOWLEDGEMENTS¶
Most of the code/data in this module was adapted from code written by Gisle Aas
for "HTML::Element", "HTML::TreeBuilder", and
"HTML::LinkExtor". Then it was maintained by Sean M. Burke.
AUTHOR¶
Current maintainer: Andy Lester, "<andy at petdance.com>"
BUGS¶
Please report any bugs or feature requests to "bug-html-tagset at
rt.cpan.org", or through the web interface at
<
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=HTML-Tagset>. I will be
notified, and then you'll automatically be notified of progress on your bug as
I make changes.