1Tagset(3) User Contributed Perl Documentation Tagset(3)
2
6 HTML::Tagset - data tables useful in parsing HTML
7
9 Version 3.20
10
12 use HTML::Tagset;
13 # Then use any of the items in the HTML::Tagset package
14 # as need arises
15
17 This module contains several data tables useful in various kinds of
18 HTML parsing operations.
19 Note that all tag names used are lowercase.
21 In the following documentation, a "hashset" is a hash being used as a
23 set -- the hash conveys that its keys are there, and the actual values
24 associated with the keys are not significant. (But what values are
25 there, are always true.)
26
28 Note that none of these variables are exported.
29 hashset %HTML::Tagset::emptyElement
31 This hashset has as values the tag-names (GIs) of elements that cannot
32 have content. (For example, "base", "br", "hr".) So
33 $HTML::Tagset::emptyElement{'hr'} exists and is true.
34 $HTML::Tagset::emptyElement{'dl'} does not exist, and so is not true.
35 hashset %HTML::Tagset::optionalEndTag
37 This hashset lists tag-names for elements that can have content, but
38 whose end-tags are generally, "safely", omissible. Example:
39 $HTML::Tagset::emptyElement{'li'} exists and is true.
40 hash %HTML::Tagset::linkElements
42 Values in this hash are tagnames for elements that might contain links,
43 and the value for each is a reference to an array of the names of
44 attributes whose values can be links.
45 hash %HTML::Tagset::boolean_attr
47 This hash (not hashset) lists what attributes of what elements can be
48 printed without showing the value (for example, the "noshade" attribute
49 of "hr" elements). For elements with only one such attribute, its
50 value is simply that attribute name. For elements with many such
51 attributes, the value is a reference to a hashset containing all such
52 attributes.
53 hashset %HTML::Tagset::isPhraseMarkup
55 This hashset contains all phrasal-level elements.
56 hashset %HTML::Tagset::is_Possible_Strict_P_Content
58 This hashset contains all phrasal-level elements that be content of a P
59 element, for a strict model of HTML.
60 hashset %HTML::Tagset::isHeadElement
62 This hashset contains all elements that elements that should be present
63 only in the 'head' element of an HTML document.
64 hashset %HTML::Tagset::isList
66 This hashset contains all elements that can contain "li" elements.
67 hashset %HTML::Tagset::isTableElement
69 This hashset contains all elements that are to be found only in/under a
70 "table" element.
71 hashset %HTML::Tagset::isFormElement
73 This hashset contains all elements that are to be found only in/under a
74 "form" element.
75 hashset %HTML::Tagset::isBodyMarkup
77 This hashset contains all elements that are to be found only in/under
78 the "body" element of an HTML document.
79 hashset %HTML::Tagset::isHeadOrBodyElement
81 This hashset includes all elements that I notice can fall either in the
82 head or in the body.
83 hashset %HTML::Tagset::isKnown
85 This hashset lists all known HTML elements.
86 hashset %HTML::Tagset::canTighten
88 This hashset lists elements that might have ignorable whitespace as
89 children or siblings.
90 array @HTML::Tagset::p_closure_barriers
92 This array has a meaning that I have only seen a need for in
93 "HTML::TreeBuilder", but I include it here on the off chance that
94 someone might find it of use:
95 When we see a "<p>" token, we go lookup up the lineage for a p element
97 we might have to minimize. At first sight, we might say that if
98 there's a p anywhere in the lineage of this new p, it should be closed.
99 But that's wrong. Consider this document:
100 <html>
102 <head>
103 <title>foo</title>
104 </head>
105 <body>
106 <p>foo
107 <table>
108 <tr>
109 <td>
110 foo
111 <p>bar
112 </td>
113 </tr>
114 </table>
115 </p>
116 </body>
117 </html>
118 The second p is quite legally inside a much higher p.
120 My formalization of the reason why this is legal, but this:
122 <p>foo<p>bar</p></p>
124 isn't, is that something about the table constitutes a "barrier" to the
126 application of the rule about what p must minimize.
127 So @HTML::Tagset::p_closure_barriers is the list of all such barrier-
129 tags.
130 hashset %isCDATA_Parent
132 This hashset includes all elements whose content is CDATA.
133
135 You may find it useful to alter the behavior of modules (like
136 "HTML::Element" or "HTML::TreeBuilder") that use "HTML::Tagset"'s data
137 tables by altering the data tables themselves. You are welcome to try,
138 but be careful; and be aware that different modules may or may react
139 differently to the data tables being changed.
140 Note that it may be inappropriate to use these tables for producing
142 HTML -- for example, %isHeadOrBodyElement lists the tagnames for all
143 elements that can appear either in the head or in the body, such as
144 "script". That doesn't mean that I am saying your code that produces
145 HTML should feel free to put script elements in either place! If you
146 are producing programs that spit out HTML, you should be intimately
147 familiar with the DTDs for HTML or XHTML (available at
148 "http://www.w3.org/"), and you should slavishly obey them, not the data
149 tables in this document.
150
152 HTML::Element, HTML::TreeBuilder, HTML::LinkExtor
153
155 Copyright 1995-2000 Gisle Aas.
156 Copyright 2000-2005 Sean M. Burke.
158 Copyright 2005-2008 Andy Lester.
160 This program is free software; you can redistribute it and/or modify it
162 under the same terms as Perl itself.
163
165 Most of the code/data in this module was adapted from code written by
166 Gisle Aas for "HTML::Element", "HTML::TreeBuilder", and
167 "HTML::LinkExtor". Then it was maintained by Sean M. Burke.
168
170 Current maintainer: Andy Lester, "<andy at petdance.com>"
171
173 Please report any bugs or feature requests to "bug-html-tagset at
174 rt.cpan.org", or through the web interface at
175 <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=HTML-Tagset>. I will
176 be notified, and then you'll automatically be notified of progress on
177 your bug as I make changes.
178perl v5.30.1 2020-01-30 Tagset(3)