diff options
Diffstat (limited to 'Tagset.pm')
| -rw-r--r-- | Tagset.pm | 471 |
1 files changed, 471 insertions, 0 deletions
diff --git a/Tagset.pm b/Tagset.pm new file mode 100644 index 0000000..754137f --- /dev/null +++ b/Tagset.pm @@ -0,0 +1,471 @@ +package HTML::Tagset; + +use strict; + +=head1 NAME + +HTML::Tagset - data tables useful in parsing HTML + +=head1 VERSION + +Version 3.20 + +=cut + +use vars qw( $VERSION ); + +$VERSION = '3.20'; + +=head1 SYNOPSIS + + use HTML::Tagset; + # Then use any of the items in the HTML::Tagset package + # as need arises + +=head1 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.) + +=cut + +use vars qw( + $VERSION + %emptyElement %optionalEndTag %linkElements %boolean_attr + %isHeadElement %isBodyElement %isPhraseMarkup + %is_Possible_Strict_P_Content + %isHeadOrBodyElement + %isList %isTableElement %isFormElement + %isKnown %canTighten + @p_closure_barriers + %isCDATA_Parent +); + +=head1 VARIABLES + +Note that none of these variables are exported. + +=head2 hashset %HTML::Tagset::emptyElement + +This hashset has as values the tag-names (GIs) of elements that cannot +have content. (For example, "base", "br", "hr".) So +C<$HTML::Tagset::emptyElement{'hr'}> exists and is true. +C<$HTML::Tagset::emptyElement{'dl'}> does not exist, and so is not true. + +=cut + +%emptyElement = map {; $_ => 1 } qw(base link meta isindex + img br hr wbr + input area param + embed bgsound spacer + basefont col frame + ~comment ~literal + ~declaration ~pi + ); +# The "~"-initial names are for pseudo-elements used by HTML::Entities +# and TreeBuilder + +=head2 hashset %HTML::Tagset::optionalEndTag + +This hashset lists tag-names for elements that can have content, but whose +end-tags are generally, "safely", omissible. Example: +C<$HTML::Tagset::emptyElement{'li'}> exists and is true. + +=cut + +%optionalEndTag = map {; $_ => 1 } qw(p li dt dd); # option th tr td); + +=head2 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. + +=cut + +%linkElements = +( + 'a' => ['href'], + 'applet' => ['archive', 'codebase', 'code'], + 'area' => ['href'], + 'base' => ['href'], + 'bgsound' => ['src'], + 'blockquote' => ['cite'], + 'body' => ['background'], + 'del' => ['cite'], + 'embed' => ['pluginspage', 'src'], + 'form' => ['action'], + 'frame' => ['src', 'longdesc'], + 'iframe' => ['src', 'longdesc'], + 'ilayer' => ['background'], + 'img' => ['src', 'lowsrc', 'longdesc', 'usemap'], + 'input' => ['src', 'usemap'], + 'ins' => ['cite'], + 'isindex' => ['action'], + 'head' => ['profile'], + 'layer' => ['background', 'src'], + 'link' => ['href'], + 'object' => ['classid', 'codebase', 'data', 'archive', 'usemap'], + 'q' => ['cite'], + 'script' => ['src', 'for'], + 'table' => ['background'], + 'td' => ['background'], + 'th' => ['background'], + 'tr' => ['background'], + 'xmp' => ['href'], +); + +=head2 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. + +=cut + +%boolean_attr = ( +# TODO: make these all hashes + 'area' => 'nohref', + 'dir' => 'compact', + 'dl' => 'compact', + 'hr' => 'noshade', + 'img' => 'ismap', + 'input' => { 'checked' => 1, 'readonly' => 1, 'disabled' => 1 }, + 'menu' => 'compact', + 'ol' => 'compact', + 'option' => 'selected', + 'select' => 'multiple', + 'td' => 'nowrap', + 'th' => 'nowrap', + 'ul' => 'compact', +); + +#========================================================================== +# List of all elements from Extensible HTML version 1.0 Transitional DTD: +# +# a abbr acronym address applet area b base basefont bdo big +# blockquote body br button caption center cite code col colgroup +# dd del dfn dir div dl dt em fieldset font form h1 h2 h3 h4 h5 h6 +# head hr html i iframe img input ins isindex kbd label legend li +# link map menu meta noframes noscript object ol optgroup option p +# param pre q s samp script select small span strike strong style +# sub sup table tbody td textarea tfoot th thead title tr tt u ul +# var +# +# Varia from Mozilla source internal table of tags: +# Implemented: +# xmp listing wbr nobr frame frameset noframes ilayer +# layer nolayer spacer embed multicol +# But these are unimplemented: +# sound?? keygen?? server?? +# Also seen here and there: +# marquee?? app?? (both unimplemented) +#========================================================================== + +=head2 hashset %HTML::Tagset::isPhraseMarkup + +This hashset contains all phrasal-level elements. + +=cut + +%isPhraseMarkup = map {; $_ => 1 } qw( + span abbr acronym q sub sup + cite code em kbd samp strong var dfn strike + b i u s tt small big + a img br + wbr nobr blink + font basefont bdo + spacer embed noembed +); # had: center, hr, table + + +=head2 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. + +=cut + +%is_Possible_Strict_P_Content = ( + %isPhraseMarkup, + %isFormElement, + map {; $_ => 1} qw( object script map ) + # I've no idea why there's these latter exceptions. + # I'm just following the HTML4.01 DTD. +); + +#from html4 strict: +#<!ENTITY % fontstyle "TT | I | B | BIG | SMALL"> +# +#<!ENTITY % phrase "EM | STRONG | DFN | CODE | +# SAMP | KBD | VAR | CITE | ABBR | ACRONYM" > +# +#<!ENTITY % special +# "A | IMG | OBJECT | BR | SCRIPT | MAP | Q | SUB | SUP | SPAN | BDO"> +# +#<!ENTITY % formctrl "INPUT | SELECT | TEXTAREA | LABEL | BUTTON"> +# +#<!-- %inline; covers inline or "text-level" elements --> +#<!ENTITY % inline "#PCDATA | %fontstyle; | %phrase; | %special; | %formctrl;"> + +=head2 hashset %HTML::Tagset::isHeadElement + +This hashset contains all elements that elements that should be +present only in the 'head' element of an HTML document. + +=cut + +%isHeadElement = map {; $_ => 1 } + qw(title base link meta isindex script style object bgsound); + +=head2 hashset %HTML::Tagset::isList + +This hashset contains all elements that can contain "li" elements. + +=cut + +%isList = map {; $_ => 1 } qw(ul ol dir menu); + +=head2 hashset %HTML::Tagset::isTableElement + +This hashset contains all elements that are to be found only in/under +a "table" element. + +=cut + +%isTableElement = map {; $_ => 1 } + qw(tr td th thead tbody tfoot caption col colgroup); + +=head2 hashset %HTML::Tagset::isFormElement + +This hashset contains all elements that are to be found only in/under +a "form" element. + +=cut + +%isFormElement = map {; $_ => 1 } + qw(input select option optgroup textarea button label); + +=head2 hashset %HTML::Tagset::isBodyMarkup + +This hashset contains all elements that are to be found only in/under +the "body" element of an HTML document. + +=cut + +%isBodyElement = map {; $_ => 1 } qw( + h1 h2 h3 h4 h5 h6 + p div pre plaintext address blockquote + xmp listing + center + + multicol + iframe ilayer nolayer + bgsound + + hr + ol ul dir menu li + dl dt dd + ins del + + fieldset legend + + map area + applet param object + isindex script noscript + table + center + form + ), + keys %isFormElement, + keys %isPhraseMarkup, # And everything phrasal + keys %isTableElement, +; + + +=head2 hashset %HTML::Tagset::isHeadOrBodyElement + +This hashset includes all elements that I notice can fall either in +the head or in the body. + +=cut + +%isHeadOrBodyElement = map {; $_ => 1 } + qw(script isindex style object map area param noscript bgsound); + # i.e., if we find 'script' in the 'body' or the 'head', don't freak out. + + +=head2 hashset %HTML::Tagset::isKnown + +This hashset lists all known HTML elements. + +=cut + +%isKnown = (%isHeadElement, %isBodyElement, + map{; $_=>1 } + qw( head body html + frame frameset noframes + ~comment ~pi ~directive ~literal +)); + # that should be all known tags ever ever + + +=head2 hashset %HTML::Tagset::canTighten + +This hashset lists elements that might have ignorable whitespace as +children or siblings. + +=cut + +%canTighten = %isKnown; +delete @canTighten{ + keys(%isPhraseMarkup), 'input', 'select', + 'xmp', 'listing', 'plaintext', 'pre', +}; + # xmp, listing, plaintext, and pre are untightenable, and + # in a really special way. +@canTighten{'hr','br'} = (1,1); + # exceptional 'phrasal' things that ARE subject to tightening. + +# The one case where I can think of my tightening rules failing is: +# <p>foo bar<center> <em>baz quux</em> ... +# ^-- that would get deleted. +# But that's pretty gruesome code anyhow. You gets what you pays for. + +#========================================================================== + +=head2 array @HTML::Tagset::p_closure_barriers + +This array has a meaning that I have only seen a need for in +C<HTML::TreeBuilder>, but I include it here on the off chance that someone +might find it of use: + +When we see a "E<lt>pE<gt>" 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 C<@HTML::Tagset::p_closure_barriers> is the list of all such +barrier-tags. + +=cut + +@p_closure_barriers = qw( + li blockquote + ul ol menu dir + dl dt dd + td th tr table caption + div + ); + +# In an ideal world (i.e., XHTML) we wouldn't have to bother with any of this +# monkey business of barriers to minimization! + +=head2 hashset %isCDATA_Parent + +This hashset includes all elements whose content is CDATA. + +=cut + +%isCDATA_Parent = map {; $_ => 1 } + qw(script style xmp listing plaintext); + +# TODO: there's nothing else that takes CDATA children, right? + +# As the HTML3 DTD (Raggett 1995-04-24) noted: +# The XMP, LISTING and PLAINTEXT tags are incompatible with SGML +# and derive from very early versions of HTML. They require non- +# standard parsers and will cause problems for processing +# documents with standard SGML tools. + + +=head1 CAVEATS + +You may find it useful to alter the behavior of modules (like +C<HTML::Element> or C<HTML::TreeBuilder>) that use C<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 I<producing> +HTML -- for example, C<%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 +I<intimately> familiar with the DTDs for HTML or XHTML (available at +C<http://www.w3.org/>), and you should slavishly obey them, not +the data tables in this document. + +=head1 SEE ALSO + +L<HTML::Element>, L<HTML::TreeBuilder>, L<HTML::LinkExtor> + +=head1 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. + +=head1 ACKNOWLEDGEMENTS + +Most of the code/data in this module was adapted from code written +by Gisle Aas for C<HTML::Element>, C<HTML::TreeBuilder>, and +C<HTML::LinkExtor>. Then it was maintained by Sean M. Burke. + +=head1 AUTHOR + +Current maintainer: Andy Lester, C<< <andy at petdance.com> >> + +=head1 BUGS + +Please report any bugs or feature requests to +C<bug-html-tagset at rt.cpan.org>, or through the web interface at +L<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. + +=cut + +1; |