Wikimedia CSS Parser & Sanitizer

This library implements a CSS tokenizer, parser and grammar matcher in PHP.

Usage

use Wikimedia\CSS\Parser\Parser;
use Wikimedia\CSS\Sanitizer\StylesheetSanitizer;

/** Parse a stylesheet from a string **/

$parser = Parser::newFromString( $cssText );
$stylesheet = $parser->parseStylesheet();

/** Report any parser errors **/

foreach ( $parser->getParseErrors() as list( $code, $line, $pos ) ) {
	// $code is a string that should be suitable as a key for an i18n library.
	// See errors.md for details.
	$error = lookupI18nMessage( "css-parse-error-$code" );
	echo "Parse error: $error at line $line character $pos\n";
}

/** Apply sanitization to the stylesheet **/

// If you need to customize the defaults, copy the code of this method and
// modify it.
$sanitizer = StylesheetSanitizer::newDefault();
$newStylesheet = $sanitizer->sanitize( $stylesheet );

/** Report any sanitizer errors **/

foreach ( $sanitizer->getSanitizationErrors() as list( $code, $line, $pos ) ) {
	// $code is a string that should be suitable as a key for an i18n library.
	// See errors.md for details.
	$error = lookupI18nMessage( "css-sanitization-error-$code" );
	echo "Sanitization error: $error at line $line character $pos\n";
}

/** Convert the sanitized stylesheet back to text **/

$newText = (string)$newStylesheet;

// Or if you'd rather have it minified too
$minifiedText = Wikimedia\CSS\Util::stringify( $newStylesheet, [ 'minify' => true ] );

Conformance

The library follows the following grammar specifications:

• CSS Syntax Level 3, 2019-07-16
• CSS Values and Units Module Level 3, 2019-06-06
• CSS Selectors Level 3, 2018-11-06

The sanitizer recognizes the following CSS modules:

• Align Level 3, 2018-12-06
• Animations Level 1, 2018-10-11
• Backgrounds Level 3, 2017-10-17
• Break Level 3, 2018-12-04
• Cascade Level 4, 2018-08-28
• Color Level 3, 2018-06-19
• Compositing Level 1, 2015-01-13
• CSS Level 2, 2011-06-07
• Display Level 3, 2019-07-11
• Filter Effects Level 1, 2018-12-18
• Flexbox Level 1, 2018-11-19
• Fonts Level 3, 2018-09-20
• Grid Level 1, 2017-12-14
• Images Level 3, 2019-10-10
• Masking Level 1, 2014-08-26
• Multicol Level 1, 2019-10-15
• Overflow Level 3, 2018-07-31
• Page Level 3, 2018-10-18
• Position Level 3, 2016-05-17
• Shapes Level 1, 2014-03-20
• Sizing Level 3, 2019-05-22
• Text Level 3, 2019-11-13
• Text Decorations Level 3, 2019-08-13
• Easing Level 1, 2019-04-30
• Transforms Level 1, 2019-02-14
• Transitions Level 1, 2018-10-11
• UI 3 Level 3, 2018-06-21
• UI 4 Level 4, 2020-01-02
• Writing Modes Level 4, 2019-07-30
• Selectors Level 4, 2019-02-25
• Logical Properties and Values Level 1, 2018-08-27

And also,

• The touch-action property from Pointer Events Level 2, 2019-04-04
• :dir() pseudo-class from Selectors Level 4, 2022-11-11

Running tests

composer install --prefer-dist
composer test

Releasing a new version

This package uses wikimedia/update-history and its conventions.

See https://www.mediawiki.org/wiki/UpdateHistory for details.

History

We required a CSS sanitizer with several properties:

• Strict parsing according to modern standards.
• Includes line and character position for all errors.
• Configurable to limit unsafe constructs such as external URL references.
• Errors are easily localizable.

We could not find a library that fit these requirements, so we created one.

Additional release history is in HISTORY.md.

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