[TASK] Stop caching the selector specificity

This avoids additional state that makes it hard to compare
selectors for equality.

Author: oliverklee

config/phpstan-baseline.neon

@@ -222,6 +222,12 @@ parameters:
 			count: 1
 			path: ../src/Property/Import.php
 
+		-
+			message: '#^Constructor of class Sabberworm\\CSS\\Property\\Selector has an unused parameter \$calculateSpecificity\.$#'
+			identifier: constructor.unusedParameter
+			count: 1
+			path: ../src/Property/Selector.php
+
 		-
 			message: '#^Call to an undefined method Sabberworm\\CSS\\OutputFormat\:\:comments\(\)\.$#'
 			identifier: method.notFound

src/Property/Selector.php

@@ -69,11 +69,6 @@ class Selector
      */
     private $selector;
 
-    /**
-     * @var int|null
-     */
-    private $specificity;
-
     /**
      * @param string $selector
      *
@@ -93,9 +88,6 @@ public static function isValid($selector)
     public function __construct($selector, $calculateSpecificity = false)
     {
         $this->setSelector($selector);
-        if ($calculateSpecificity) {
-            $this->getSpecificity();
-        }
     }
 
     /**
@@ -112,7 +104,6 @@ public function getSelector()
     public function setSelector($selector): void
     {
         $this->selector = \trim($selector);
-        $this->specificity = null;
     }
 
     /**
@@ -124,19 +115,16 @@ public function __toString(): string
     }
 
     /**
-     * @return int
+     * @return int<0, max>
      */
-    public function getSpecificity()
+    public function getSpecificity(): int
     {
-        if ($this->specificity === null) {
-            $a = 0;
-            /// @todo should exclude \# as well as "#"
-            $aMatches = null;
-            $b = \substr_count($this->selector, '#');
-            $c = \preg_match_all(self::NON_ID_ATTRIBUTES_AND_PSEUDO_CLASSES_RX, $this->selector, $aMatches);
-            $d = \preg_match_all(self::ELEMENTS_AND_PSEUDO_ELEMENTS_RX, $this->selector, $aMatches);
-            $this->specificity = ($a * 1000) + ($b * 100) + ($c * 10) + $d;
-        }
-        return $this->specificity;
+        $a = 0;
+        /// @todo should exclude \# as well as "#"
+        $aMatches = null;
+        $b = \substr_count($this->selector, '#');
+        $c = \preg_match_all(self::NON_ID_ATTRIBUTES_AND_PSEUDO_CLASSES_RX, $this->selector, $aMatches);
+        $d = \preg_match_all(self::ELEMENTS_AND_PSEUDO_ELEMENTS_RX, $this->selector, $aMatches);
+        return ($a * 1000) + ($b * 100) + ($c * 10) + $d;
     }
 }