Selector.php

<?php

namespace Sabberworm\CSS\Property;

use Sabberworm\CSS\Parsing\UnexpectedTokenException;

/**
 * Class representing a single CSS selector. Selectors have to be split by the comma prior to being passed into this class.
 */
class Selector {

	//Regexes for specificity calculations
	const NON_ID_ATTRIBUTES_AND_PSEUDO_CLASSES_RX = '/
	(\.[\w]+)                   # classes
	|
	\[(\w+)                     # attributes
	|
	(\:(                        # pseudo classes
		link|visited|active
		|hover|focus
		|lang
		|target
		|enabled|disabled|checked|indeterminate
		|root
		|nth-child|nth-last-child|nth-of-type|nth-last-of-type
		|first-child|last-child|first-of-type|last-of-type
		|only-child|only-of-type
		|empty|contains
	))
	/ix';

	const ELEMENTS_AND_PSEUDO_ELEMENTS_RX = '/
	((^|[\s\+\>\~]+)[\w]+   # elements
	|
	\:{1,2}(                # pseudo-elements
		after|before|first-letter|first-line|selection
	))
	/ix';

	const SELECTOR_VALIDATION_RX = '/
	^(
		(?:
			[a-zA-Z0-9\x{00A0}-\x{FFFF}_^$|*="\'~\[\]()\-\s\.:#+>]* # any sequence of valid unescaped characters
			(?:\\\\.)?                                              # a single escaped character
			(?:([\'"]).*?(?<!\\\\)\2)?                              # a quoted text like [id="example"]
		)*
	)$
	/ux';

	private $sSelector;
	private $iSpecificity;

	public static function isValid($sSelector) {
		return preg_match(static::SELECTOR_VALIDATION_RX, $sSelector);
	}

	public function __construct($sSelector, $bCalculateSpecificity = false) {
		$this->setSelector($sSelector);
		if ($bCalculateSpecificity) {
			$this->getSpecificity();
		}
	}

	public function getSelector() {
		return $this->sSelector;
	}

	public function setSelector($sSelector) {
		$this->sSelector = trim($sSelector);
		$this->iSpecificity = null;
	}

	public function __toString() {
		return $this->getSelector();
	}

	public function getSpecificity() {
		if ($this->iSpecificity === null) {
			$a = 0;
			/// @todo should exclude \# as well as "#"
			$aMatches = null;
			$b = substr_count($this->sSelector, '#');
			$c = preg_match_all(self::NON_ID_ATTRIBUTES_AND_PSEUDO_CLASSES_RX, $this->sSelector, $aMatches);
			$d = preg_match_all(self::ELEMENTS_AND_PSEUDO_ELEMENTS_RX, $this->sSelector, $aMatches);
			$this->iSpecificity = ($a * 1000) + ($b * 100) + ($c * 10) + $d;
		}
		return $this->iSpecificity;
	}

}