PHP CSS Parser

A Parser for CSS Files written in PHP. Allows extraction of CSS files into a data structure, manipulation of said structure and output as (optimized) CSS.

Usage

Installation using Composer

composer require sabberworm/php-css-parser

Extraction

To use the CSS Parser, create a new instance. The constructor takes the following form:

new \Sabberworm\CSS\Parser($css);

To read a file, for example, you’d do the following:

$parser = new \Sabberworm\CSS\Parser(file_get_contents('somefile.css'));
$cssDocument = $parser->parse();

The resulting CSS document structure can be manipulated prior to being output.

Options

Charset

The charset option will only be used if the CSS file does not contain an @charset declaration. UTF-8 is the default, so you won’t have to create a settings object at all if you don’t intend to change that.

$settings = \Sabberworm\CSS\Settings::create()
    ->withDefaultCharset('windows-1252');
$parser = new \Sabberworm\CSS\Parser($css, $settings);

Strict parsing

To have the parser throw an exception when encountering invalid/unknown constructs (as opposed to trying to ignore them and carry on parsing), supply a thusly configured \Sabberworm\CSS\Settings object:

$parser = new \Sabberworm\CSS\Parser(
    file_get_contents('somefile.css'),
    \Sabberworm\CSS\Settings::create()->beStrict()
);

Note that this will also disable a workaround for parsing the unquoted variant of the legacy IE-specific filter rule.

Disable multibyte functions

To achieve faster parsing, you can choose to have PHP-CSS-Parser use regular string functions instead of mb_* functions. This should work fine in most cases, even for UTF-8 files, as all the multibyte characters are in string literals. Still it’s not recommended using this with input you have no control over as it’s not thoroughly covered by test cases.

$settings = \Sabberworm\CSS\Settings::create()->withMultibyteSupport(false);
$parser = new \Sabberworm\CSS\Parser($css, $settings);

Manipulation

The resulting data structure consists mainly of five basic types: CSSList, RuleSet, Rule, Selector and Value. There are two additional types used: Import and Charset, which you won’t use often.

CSSList

CSSList represents a generic CSS container, most likely containing declaration blocks (rule sets with a selector), but it may also contain at-rules, charset declarations, etc.

To access the items stored in a CSSList – like the document you got back when calling $parser->parse() –, use getContents(), then iterate over that collection and use instanceof to check whether you’re dealing with another CSSList, a RuleSet, a Import or a Charset.

To append a new item (selector, media query, etc.) to an existing CSSList, construct it using the constructor for this class and use the append($oItem) method.

RuleSet

RuleSet is a container for individual rules. The most common form of a rule set is one constrained by a selector. The following concrete subtypes exist:

• AtRuleSet – for generic at-rules for generic at-rules which are not covered by specific classes, i.e., not @import, @charset or @media. A common example for this is @font-face.
• DeclarationBlock – a RuleSet constrained by a Selector; contains an array of selector objects (comma-separated in the CSS) as well as the rules to be applied to the matching elements.

Note: A CSSList can contain other CSSLists (and Imports as well as a Charset), while a RuleSet can only contain Rules.

If you want to manipulate a RuleSet, use the methods addRule(Rule $rule), getRules() and removeRule($rule) (which accepts either a Rule or a rule name; optionally suffixed by a dash to remove all related rules).

Rule

Rules just have a string key (the rule) and a Value.

Value

Value is an abstract class that only defines the render method. The concrete subclasses for atomic value types are:

• Size – consists of a numeric size value and a unit.
• Color – colors can be input in the form #rrggbb, #rgb or schema(val1, val2, …) but are always stored as an array of ('s' => val1, 'c' => val2, 'h' => val3, …) and output in the second form.
• CSSString – this is just a wrapper for quoted strings to distinguish them from keywords; always output with double quotes.
• URL – URLs in CSS; always output in URL("") notation.

There is another abstract subclass of Value, ValueList: A ValueList represents a lists of Values, separated by some separation character (mostly ,, whitespace, or /).

There are two types of ValueLists:

• RuleValueList – The default type, used to represent all multivalued rules like font: bold 12px/3 Helvetica, Verdana, sans-serif; (where the value would be a whitespace-separated list of the primitive value bold, a slash-separated list and a comma-separated list).
• CSSFunction – A special kind of value that also contains a function name and where the values are the function’s arguments. Also handles equals-sign-separated argument lists like filter: alpha(opacity=90);.

Convenience methods

There are a few convenience methods on Document to ease finding, manipulating and deleting rules:

• getAllDeclarationBlocks() – does what it says; no matter how deeply nested the selectors are. Aliased as getAllSelectors().
• getAllRuleSets() – does what it says; no matter how deeply nested the rule sets are.
• getAllValues() – finds all Value objects inside Rules.

To-Do

• More convenience methods (like selectorsWithElement($sId/Class/TagName), attributesOfType($type), removeAttributesOfType($type))
• Real multibyte support. Currently, only multibyte charsets whose first 255 code points take up only one byte and are identical with ASCII are supported (yes, UTF-8 fits this description).
• Named color support (using Color instead of an anonymous string literal)

Use cases

Use Parser to prepend an ID to all selectors

$myId = "#my_id";
$parser = new \Sabberworm\CSS\Parser($css);
$cssDocument = $parser->parse();
foreach ($cssDocument->getAllDeclarationBlocks() as $block) {
    foreach ($block->getSelectors() as $selector) {
        // Loop over all selector parts (the comma-separated strings in a
        // selector) and prepend the ID.
        $selector->setSelector($myId.' '.$selector->getSelector());
    }
}

Shrink all absolute sizes to half

$parser = new \Sabberworm\CSS\Parser($css);
$cssDocument = $parser->parse();
foreach ($cssDocument->getAllValues() as $value) {
    if ($value instanceof CSSSize && !$value->isRelative()) {
        $value->setSize($value->getSize() / 2);
    }
}

Remove unwanted rules

$parser = new \Sabberworm\CSS\Parser($css);
$cssDocument = $parser->parse();
foreach($cssDocument->getAllRuleSets() as $oRuleSet) {
    // Note that the added dash will make this remove all rules starting with
    // `font-` (like `font-size`, `font-weight`, etc.) as well as a potential
    // `font` rule.
    $oRuleSet->removeRule('font-');
    $oRuleSet->removeRule('cursor');
}

Output

To output the entire CSS document into a variable, just use ->render():

$parser = new \Sabberworm\CSS\Parser(file_get_contents('somefile.css'));
$cssDocument = $parser->parse();
print $cssDocument->render();

If you want to format the output, pass an instance of type \Sabberworm\CSS\OutputFormat:

$format = \Sabberworm\CSS\OutputFormat::create()
    ->indentWithSpaces(4)->setSpaceBetweenRules("\n");
print $cssDocument->render($format);

Or use one of the predefined formats:

print $cssDocument->render(Sabberworm\CSS\OutputFormat::createPretty());
print $cssDocument->render(Sabberworm\CSS\OutputFormat::createCompact());

To see what you can do with output formatting, look at the tests in tests/OutputFormatTest.php.

Examples

Example 1 (At-Rules)

Input

@charset "utf-8";

@font-face {
  font-family: "CrassRoots";
  src: url("../media/cr.ttf");
}

html, body {
    font-size: 1.6em;
}

@keyframes mymove {
    from { top: 0px; }
    to { top: 200px; }
}

class Sabberworm\CSS\CSSList\Document#4 (2) {
  protected $contents =>
  array(4) {
    [0] =>
    class Sabberworm\CSS\Property\Charset#6 (2) {
      private $charset =>
      class Sabberworm\CSS\Value\CSSString#5 (2) {
        private $string =>
        string(5) "utf-8"
        protected $lineNumber =>
        int(1)
      }
      protected $lineNumber =>
      int(1)
    }
    [1] =>
    class Sabberworm\CSS\RuleSet\AtRuleSet#7 (4) {
      private $type =>
      string(9) "font-face"
      private $arguments =>
      string(0) ""
      private $rules =>
      array(2) {
        'font-family' =>
        array(1) {
          [0] =>
          class Sabberworm\CSS\Rule\Rule#8 (4) {
            private $rule =>
            string(11) "font-family"
            private $value =>
            class Sabberworm\CSS\Value\CSSString#9 (2) {
              private $string =>
              string(10) "CrassRoots"
              protected $lineNumber =>
              int(4)
            }
            private $isImportant =>
            bool(false)
            protected $lineNumber =>
            int(4)
          }
        }
        'src' =>
        array(1) {
          [0] =>
          class Sabberworm\CSS\Rule\Rule#10 (4) {
            private $rule =>
            string(3) "src"
            private $value =>
            class Sabberworm\CSS\Value\URL#11 (2) {
              private $url =>
              class Sabberworm\CSS\Value\CSSString#12 (2) {
                private $string =>
                string(15) "../media/cr.ttf"
                protected $lineNumber =>
                int(5)
              }
              protected $lineNumber =>
              int(5)
            }
            private $isImportant =>
            bool(false)
            protected $lineNumber =>
            int(5)
          }
        }
      }
      protected $lineNumber =>
      int(3)
    }
    [2] =>
    class Sabberworm\CSS\RuleSet\DeclarationBlock#13 (3) {
      private $selectors =>
      array(2) {
        [0] =>
        class Sabberworm\CSS\Property\Selector#14 (2) {
          private $selector =>
          string(4) "html"
          private $specificity =>
          NULL
        }
        [1] =>
        class Sabberworm\CSS\Property\Selector#15 (2) {
          private $selector =>
          string(4) "body"
          private $specificity =>
          NULL
        }
      }
      private $rules =>
      array(1) {
        'font-size' =>
        array(1) {
          [0] =>
          class Sabberworm\CSS\Rule\Rule#16 (4) {
            private $rule =>
            string(9) "font-size"
            private $value =>
            class Sabberworm\CSS\Value\Size#17 (4) {
              private $size =>
              double(1.6)
              private $unit =>
              string(2) "em"
              private $isColorComponent =>
              bool(false)
              protected $lineNumber =>
              int(9)
            }
            private $isImportant =>
            bool(false)
            protected $lineNumber =>
            int(9)
          }
        }
      }
      protected $lineNumber =>
      int(8)
    }
    [3] =>
    class Sabberworm\CSS\CSSList\KeyFrame#18 (4) {
      private $vendorKeyFrame =>
      string(9) "keyframes"
      private $animationName =>