Provided by: libcss-dom-perl_0.17-1_all bug

NAME

       CSS::DOM - Document Object Model for Cascading Style Sheets

VERSION

       Version 0.17

       This is an alpha version. The API is still subject to change. Many features have not been
       implemented yet (but patches would be welcome :-).

       The interface for feeding CSS code to CSS::DOM changed incompatibly in version 0.03.

SYNOPSIS

         use CSS::DOM;

         my $sheet = CSS::DOM::parse( $css_source );

         use CSS::DOM::Style;
         my $style = CSS::DOM::Style::parse(
             'background: red; font-size: large'
         );

         my $other_sheet = new CSS::DOM; # empty
         $other_sheet->insertRule(
            'a{ text-decoration: none }',
             $other_sheet->cssRules->length,
         );
         # etc.

         # access DOM properties
         $other_sheet->cssRules->[0]->selectorText('p'); # change it
         $style->fontSize;          # returns 'large'
         $style->fontSize('small'); # change it

DESCRIPTION

       This set of modules provides the CSS-specific interfaces described in the W3C DOM
       recommendation.

       The CSS::DOM class itself implements the StyleSheet and CSSStyleSheet DOM interfaces.

       This set of modules has two modes:

       1.  It can validate property values, ignoring those that are invalid (just like a real web
           browser), and support shorthand properties. This means you can set font to '13px/15px
           My Font' and have the font-size, line-height, and font-family properties (among
           others) set automatically. Also, "color: green; color: kakariki" will assign 'green'
           to the color property, 'kakariki' not being a recognised color value.

       2.  It can blithely accept all property assignments as being valid. In the case of "color:
           green; color: kakariki", 'kakariki' will be assigned, since it overrides the previous
           assignment.

       These two modes are controlled by the "property_parser" option to the constructors.

CONSTRUCTORS

       CSS::DOM::parse( $string )
           This method parses the $string and returns a style sheet object. If you just have a
           CSS style declaration, e.g., from an HTML "style" attribute, see "parse" in
           CSS::DOM::Style.

       new CSS::DOM
           Creates a new, empty style sheet object. Use this only if you plan to build the style
           sheet piece by piece, instead of parsing a block of CSS code.

       You can pass named arguments to both of those. "parse" accepts all of them; "new"
       understands only the first two, "property_parser" and "url_fetcher".

       property_parser
           Set this to a PropertyParser object to specify which properties are supported and how
           they are parsed.

           If this option is not specified or is set to "undef", all property values are treated
           as valid.

           See CSS::DOM::PropertyParser for more details.

       url_fetcher
           This has to be a code ref that returns the contents of the style sheet at the URL
           passed as the sole argument. E.g.,

             # Disclaimer: This does not work with relative URLs.
             use LWP::Simple;
             use CSS::DOM;
             $css = '@import "file.css"; /* other stuff ... ';
             $ss = CSS::DOM::parse $css, url_fetcher => sub { get shift };
             $ss->cssRules->[0]->styleSheet; # returns a style sheet object
                                             # corresponding to file.css

           The subroutine can choose to return "undef" or an empty list, in which case the
           @import rule's "styleSheet" method will return null (empty list or "undef"), as it
           would if no "url_fetcher" were specified.

           It can also return named items after the CSS code, like this:

             return $css_code, decode => 1, encoding_hint => 'iso-8859-1';

           These correspond to the next two items:

       decode
           If this is specified and set to a true value, then CSS::DOM will treat the CSS code as
           a string of bytes, and try to decode it based on @charset rules and byte order marks.

           By default it assumes that it is already in Unicode (i.e., decoded).

       encoding_hint
           Use this to provide a hint as to what the encoding might be.

           If this is specified, and "decode" is not, then "decode => 1" is assumed.

STYLE SHEET ENCODING

       See the options above. This section explains how and when you should use those options.

       According to the CSS spec, any encoding specified in the 'charset' field on an HTTP
       Content-Type header, or the equivalent in other protocols, takes precedence. In such a
       case, since CSS::DOM doesn't deal with HTTP, you have to decode it yourself.

       Otherwise, you should use "decode => 1" to instruct CSS::DOM to use byte order marks or
       @charset rules.

       If neither of those is present, then encoding data in the referencing document (e.g.,
       <link charset="..."> or an HTML document's own encoding), if available/applicable, should
       be used. In this case, you should use the "encoding_hint" option, so that CSS::DOM has
       something to fall back to.

       If you use "decode => 1" with no encoding hint, and no BOM or @charset is to be found,
       UTF-8 is assumed.

SYNTAX ERRORS

       The two constructors above, and also "CSS::DOM::Style::parse", set $@ to the empty string
       upon success. If they encounter a syntax error, they set $@ to the error and return an
       object that represents whatever was parsed up to that point.

       Other methods that parse CSS code might die on encountering syntax errors, and should
       usually be wrapped in an "eval".

       The parser follows the 'future-compatible' syntax described in the CSS 2.1 specification,
       and also the spec's rules for handling parsing errors.  Anything not handled by those two
       is a syntax error.

       In other words, a syntax error is one of the following:

       ·   An unexpected closing bracket, as in these examples

             a { text-decoration: none )
             *[name=~'foo'} {}
             #thing { clip: rect( ]

       ·   An HTML comment delimiter within a rule; e.g.,

             a { text-decoration : none <!-- /* Oops! */ }
             <!-- /*ok*/ @media --> /* bad! */ print { }

       ·   An extra "@" keyword or semicolon where it doesn't belong; e.g.,

             @media @print { .... }
             @import "file.css" @print;
             td, @page { ... }
             #tabbar td; #tab1 { }

OBJECT METHODS

   Attributes
       type
           Returns the string 'text/css'.

       disabled
           Allows one to specify whether the style sheet is used. (This attribute is not actually
           used yet by CSS::DOM.) You can set it by passing an argument.

       ownerNode
           Returns the node that 'owns' this style sheet.

       parentStyleSheet
           If the style sheet belongs to an '@import' rule, this returns the style sheet
           containing that rule. Otherwise it returns an empty list.

       href
           Returns the style sheet's URI, if applicable.

       title
           Returns the value of the owner node's title attribute.

       media
           Returns the MediaList associated with the style sheet (or a plain list in list
           context). This defaults to an empty list. You can pass a comma-delimited string to the
           MediaList's "mediaText" method to initialise it.

           (The medium information is not actually used [yet] by CSS::DOM, but you can put it
           there.)

       ownerRule
           If this style sheet was created by an @import rule, this returns the rule; otherwise
           it returns an empty list (or undef in scalar context).

       cssRules
           In scalar context, this returns a CSS::DOM::RuleList object (simply a blessed array
           reference) of CSS::DOM::Rule objects. In list context it returns a list.

   Methods
       insertRule ( $css_code, $index )
           Parses the rule contained in the $css_code, inserting it in the style sheet's list of
           rules at the given $index.

       deleteRule ( $index )
           Deletes the rule at the given $index.

       hasFeature ( $feature, $version )
           You can call this either as an object or class method.

           This is actually supposed to be a method of the 'DOMImplementation' object.  (See, for
           instance, HTML::DOM::Interface's method of the same name, which delegates to this
           one.) This returns a boolean indicating whether a particular DOM module is
           implemented. Right now it returns true only for the 'CSS2' and 'StyleSheets' features
           (version '2.0').

   Non-DOM Methods
       set_ownerNode
           This allows you to set the value of "ownerNode". Passing an argument to "ownerNode"
           does nothing, because it is supposed to be read-only. But you have to be able to set
           it somehow, so that's why this method is here.

           The style sheet will hold a weak reference to the object passed to this method.

       set_href
           Like "set_ownerNode", but for "href".

       property_parser
       url_fetcher
           These two both return what was passed to the constructor. The second one,
           "url_fetcher" also allows an assignment, but this is not propagated to sub-rules and
           is intended mainly for internal use.

FUNCTIONS

       CSS::DOM::parse
           See "CONSTRUCTORS", above.

       CSS::DOM::compute_style( %options )
           Warning: This is still highly experimental and crawling with bugs.

           This computes the style for a given HTML element. It does not yet calculate actual
           measurements (e.g., converting percentages to pixels), but simply applies the
           cascading rules and selectors. Pseudo-classes are not yet supported (but pseudo-
           elements are).

           The precedence rules for normal vs important declarations in the CSS 2 specification
           are used. (CSS 2.1 is unclear.) The precedence is as follows, from lowest to highest:

            user agent normal declarations
            user normal declarations
            author normal     "
            user agent !important declarations
            author !important "
            user      "       "

           The %options are as follows. They are all optional except for "element".

           ua_sheet
               The user agent style sheet

           user_sheet
               The user style sheet

           author_sheets
               Array ref of style sheets that the HTML document defines or links to.

           element
               The element, as an HTML::DOM::Element object.

           pseudo
               The pseudo-element (e.g., 'first-line'). This can be specified with no colons (the
               way Opera requires it) or with one or two colons (the way Firefox requires it).

           medium
           height
           width
           ppi (To be implemented)

           The

CLASSES AND DOM INTERFACES

       Here are the inheritance hierarchy of CSS::DOM's various classes and the DOM interfaces
       those classes implement. For brevity's sake, a simple '::' at the beginning of a class
       name in the left column is used for 'CSS::DOM::'. Items in brackets do not exist yet. (See
       also CSS::DOM::Interface for a machine-readable list of standard methods.)

         Class Inheritance Hierarchy  Interfaces
         ---------------------------  ----------

         CSS::DOM                     StyleSheet, CSSStyleSheet
         ::Array
             ::MediaList              MediaList
             ::StyleSheetList         StyleSheetList
             ::RuleList               CSSRuleList
         ::Rule                       CSSRule, CSSUnknownRule
             ::Rule::Style            CSSStyleRule
             ::Rule::Media            CSSMediaRule
             ::Rule::FontFace         CSSFontFaceRule
             ::Rule::Page             CSSPageRule
             ::Rule::Import           CSSImportRule
             ::Rule::Charset          CSSCharsetRule
         ::Style                      CSSStyleDeclaration, CSS2Properties
         ::Value                      CSSValue
         ::Value::Primitive           CSSPrimitiveValue, RGBColor, Rect
         ::Value::List                CSSValueList
        [::Counter                    Counter]

       CSS::DOM does not implement the following interfaces (see HTML::DOM for these):

         LinkStyle
         DocumentStyle
         ViewCSS
         DocumentCSS
         DOMImplementationCSS
         ElementCSSInlineStyle

IMPLEMENTATION NOTES

       ·   Attributes of objects are accessed via methods of the same name. When the method is
           invoked, the current value is returned. If an argument is supplied, the attribute is
           set (unless it is read-only) and its old value returned.

       ·   Where the DOM spec. says to use null, undef or an empty list is used.

       ·   Instead of UTF-16 strings, CSS::DOM uses Perl's Unicode strings.

       ·   Each method that the specification says returns an array-like object (e.g., a
           RuleList) will return such an object in scalar context, or a simple list in list
           context. You can use the object as an array ref in addition to calling its "item" and
           "length" methods.

PREREQUISITES

       perl 5.8.2 or higher

       Exporter 5.57 or later

       Encode 2.10 or higher

       Clone 0.09 or higher

BUGS

       The parser has not been updated to conform to the April 2009 revision of the CSS 2.1
       candidate recommendation. Specifically, unexpected closing brackets are not ignored, but
       cause syntax errors; and @media rules containing unrecognised statements are themselves
       currently treated as unrecognised (the unrecognised inner statements should be ignored,
       rendering the outer @media rule itself valid).

       If you create a custom property parser that defines 'list-style-type' to include multiple
       tokens, then counters will become "CSS_CUSTOM" CSSValue objects instead of "CSS_COUNTER"
       CSSPrimitiveValue objects.

       If you change a property parser's property definitions such that a primitive value becomes
       a list, or vice versa, and then try to modify the "cssText" property of an existing value
       object belonging to that property, things will go awry.

       Whitespace and comments are sometimes preserved in serialised CSS and sometimes not.
       Expect inconsistency.

       To report bugs, please e-mail the author.

ACKNOWLEDGEMENTS

       Thanks to Ville Skyttä, Nicholas Bamber and Gregor Herrmann for their contributions.

AUTHOR & COPYRIGHT

       Copyright (C) 2007-18 Father Chrysostomos <sprout [at] cpan [dot] org>

       This program is free software; you may redistribute it and/or modify it under the same
       terms as perl. The full text of the license can be found in the LICENSE file included with
       this module.

SEE ALSO

       All the classes listed above under "CLASSES AND DOM INTERFACES".

       CSS::SAC, CSS.pm and HTML::DOM

       The DOM Level 2 Style specification at <http://www.w3.org/TR/DOM-Level-2-Style>

       The CSS 2.1 specification at <http://www.w3.org/TR/CSS21/>