Refactor specificity

CssToInlineStyles.php

@@ -146,39 +146,6 @@ private function buildXPathQuery($selector)
         return str_replace('] *', ']//*', $xPath);
     }
 
-    /**
-     * Calculate the specifity for the CSS-selector
-     *
-     * @return int
-     * @param  string $selector The selector to calculate the specifity for.
-     */
-    private function calculateCSSSpecifity($selector)
-    {
-        // cleanup selector
-        $selector = str_replace(array('>', '+'), array(' > ', ' + '), $selector);
-
-        // init var
-        $specifity = 0;
-
-        // split the selector into chunks based on spaces
-        $chunks = explode(' ', $selector);
-
-        // loop chunks
-        foreach ($chunks as $chunk) {
-            // an ID is important, so give it a high specifity
-            if(strstr($chunk, '#') !== false) $specifity += 100;
-
-            // classes are more important than a tag, but less important then an ID
-            elseif(strstr($chunk, '.')) $specifity += 10;
-
-            // anything else isn't that important
-            else $specifity += 1;
-        }
-
-        // return
-        return $specifity;
-    }
-
 
     /**
      * Cleanup the generated HTML
@@ -547,10 +514,11 @@ private function processCSS()
                     $cssProperties
                 );
 
-                // calculate specifity
-                $ruleSet['specifity'] = $this->calculateCSSSpecifity(
-                    $selector
-                ) + $i;
+                // calculate specificity
+                $ruleSet['specificity'] = Specificity::fromSelector($selector);
+
+                // remember the order in which the rules appear
+                $ruleSet['order'] = $i;
 
                 // add into global rules
                 $this->cssRules[] = $ruleSet;
@@ -560,9 +528,9 @@ private function processCSS()
             $i++;
         }
 
-        // sort based on specifity
+        // sort based on specificity
         if (!empty($this->cssRules)) {
-            usort($this->cssRules, array(__CLASS__, 'sortOnSpecifity'));
+            usort($this->cssRules, array(__CLASS__, 'sortOnSpecificity'));
         }
     }
 
@@ -699,17 +667,22 @@ private function stripOriginalStyleTags($html)
     }
 
     /**
-     * Sort an array on the specifity element
+     * Sort an array on the specificity element
      *
      * @return int
      * @param  array $e1 The first element.
      * @param  array $e2 The second element.
      */
-    private static function sortOnSpecifity($e1, $e2)
+    private static function sortOnSpecificity($e1, $e2)
     {
-        if ($e1['specifity'] == $e2['specifity']) {
-            return 0;
+        // Compare the specificity
+        $value = $e1['specificity']->compare($e2['specificity']);
+
+        // if the specificity is the same, use the order in which the element appeared
+        if ($value === 0) {
+            $value = $e1['order'] - $e2['order'];
         }
-        return ($e1['specifity'] < $e2['specifity']) ? -1 : 1;
+
+        return $value;
     }
 }

Specificity.php

@@ -0,0 +1,112 @@
+<?php
+namespace TijsVerkoyen\CssToInlineStyles;
+
+/**
+ * CSS to Inline Styles Specificity class.
+ *
+ * Compare specificity based on the CSS3 spec.
+ *
+ * @see http://www.w3.org/TR/selectors/#specificity
+ *
+ */
+class Specificity{
+
+    /**
+     * The number of ID selectors in the selector
+     *
+     * @var int
+     */
+    private $a;
+
+    /**
+     *
+     * The number of class selectors, attributes selectors, and pseudo-classes in the selector
+     *
+     * @var int
+     */
+    private $b;
+
+    /**
+     * The number of type selectors and pseudo-elements in the selector
+     *
+     * @var int
+     */
+    private $c;
+
+    /**
+     * @param int $a The number of ID selectors in the selector
+     * @param int $b The number of class selectors, attributes selectors, and pseudo-classes in the selector
+     * @param int $c The number of type selectors and pseudo-elements in the selector
+     */
+    public function __construct($a=0, $b=0, $c=0)
+    {
+        $this->a = $a;
+        $this->b = $b;
+        $this->c = $c;
+    }
+
+    /**
+     * Increase the current specificity by adding the three values
+     *
+     * @param int $a The number of ID selectors in the selector
+     * @param int $b The number of class selectors, attributes selectors, and pseudo-classes in the selector
+     * @param int $c The number of type selectors and pseudo-elements in the selector
+     */
+    public function increase($a, $b, $c)
+    {
+        $this->a += $a;
+        $this->b += $b;
+        $this->c += $c;
+    }
+
+    /**
+     * Calculate the specificity based on a CSS Selector string
+     *
+     * @param string $selector
+     * @return static
+     */
+    public static function fromSelector($selector)
+    {
+        // cleanup selector
+        $selector = str_replace(array('>', '+'), array(' > ', ' + '), $selector);
+
+        // create a new instance
+        $specificity = new static;
+
+        // split the selector into chunks based on spaces
+        $chunks = explode(' ', $selector);
+
+        // loop chunks
+        foreach ($chunks as $chunk) {
+            // an ID is important, so give it a high specificity
+            if(strstr($chunk, '#') !== false) $specificity->increase(1,0,0);
+
+            // classes are more important than a tag, but less important then an ID
+            elseif(strstr($chunk, '.')) $specificity->increase(0,1,0);
+
+            // anything else isn't that important
+            else $specificity->increase(0,0,1);
+        }
+
+        // return
+        return $specificity;
+
+    }
+
+    /**
+     * Returns <0 when $specificity is greater, 0 when equal, >0 when smaller
+     *
+     * @param Specificity $specificity
+     * @return int
+     */
+    public function compare(Specificity $specificity)
+    {
+        if ($this->a !== $specificity->a) {
+            return $this->a - $specificity->a;
+        } elseif ($this->b !== $specificity->b) {
+            return $this->b - $specificity->b;
+        } else {
+            return $this->c - $specificity->c;
+        }
+    }
+}