[ClassLoader] ordered ClassCollectionLoader writing to avoid redeclaration at runtime

src/Symfony/Component/ClassLoader/ClassCollectionLoader.php

@@ -19,6 +19,7 @@ namespace Symfony\Component\ClassLoader;
 class ClassCollectionLoader
 {
     static private $loaded;
+    static private $baseClassesCountMap;
 
     /**
      * Loads a list of classes and caches them in one big file.
@@ -61,6 +62,9 @@ class ClassCollectionLoader
                 $time = filemtime($cache);
                 $meta = unserialize(file_get_contents($metadata));
 
+                sort($meta[1]);
+                sort($classes);
+
                 if ($meta[1] != $classes) {
                     $reload = true;
                 } else {
@@ -81,6 +85,9 @@ class ClassCollectionLoader
             return;
         }
 
+        // order classes to avoid redeclaration at runtime (class declared before its parent)
+        self::orderClasses($classes);
+
         $files = array();
         $content = '';
         foreach ($classes as $class) {
@@ -220,4 +227,49 @@ class ClassCollectionLoader
 
         return $output;
     }
+
+    /**
+     * Orders a set of classes according to their number of parents.
+     *
+     * @param array $classes
+     *
+     * @throws \InvalidArgumentException When a class can't be loaded
+     */
+    static private function orderClasses(array &$classes)
+    {
+        foreach ($classes as $class) {
+            if (isset(self::$baseClassesCountMap[$class])) {
+                continue;
+            }
+
+            try {
+                $reflectionClass = new \ReflectionClass($class);
+            } catch (\ReflectionException $e) {
+                throw new \InvalidArgumentException(sprintf('Unable to load class "%s"', $class));
+            }
+
+            // The counter is cached to avoid reflection if the same class is asked again later
+            self::$baseClassesCountMap[$class] = self::countParentClasses($reflectionClass) + count($reflectionClass->getInterfaces());
+        }
+
+        asort(self::$baseClassesCountMap);
+
+        $classes = array_intersect(array_keys(self::$baseClassesCountMap), $classes);
+    }
+
+    /**
+     * Counts the number of parent classes in userland.
+     *
+     * @param  \ReflectionClass $class
+     * @param  integer          $count If exists, the current counter
+     * @return integer
+     */
+    static private function countParentClasses(\ReflectionClass $class, $count = 0)
+    {
+        if (($parent = $class->getParentClass()) && $parent->isUserDefined()) {
+            $count = self::countParentClasses($parent, ++$count);
+        }
+
+        return $count;
+    }
 }

src/Symfony/Component/ClassLoader/Tests/ClassCollectionLoaderTest.php

@@ -12,9 +12,74 @@
 namespace Symfony\Component\ClassLoader\Tests;
 
 use Symfony\Component\ClassLoader\ClassCollectionLoader;
+use Symfony\Component\ClassLoader\UniversalClassLoader;
 
 class ClassCollectionLoaderTest extends \PHPUnit_Framework_TestCase
 {
+    /**
+     * @dataProvider getDifferentOrders
+     */
+    public function testClassReordering(array $classes)
+    {
+        $loader = new UniversalClassLoader();
+        $loader->registerNamespace('ClassesWithParents', __DIR__.'/Fixtures');
+        $loader->register();
+
+        $expected = <<<EOF
+<?php  
+
+namespace ClassesWithParents
+{
+
+interface CInterface {}
+}
+ 
+
+namespace ClassesWithParents
+{
+
+class B implements CInterface {}
+}
+ 
+
+namespace ClassesWithParents
+{
+
+class A extends B {}
+}
+
+EOF;
+
+        $dir = sys_get_temp_dir();
+        $fileName = uniqid('symfony_');
+
+        ClassCollectionLoader::load($classes, $dir, $fileName, true);
+        $cachedContent = @file_get_contents($dir.'/'.$fileName.'.php');
+
+        $this->assertEquals($expected, $cachedContent);
+    }
+    
+    public function getDifferentOrders()
+    {
+        return array(
+            array(array(
+                'ClassesWithParents\\A',
+                'ClassesWithParents\\CInterface',
+                'ClassesWithParents\\B',
+            )),
+            array(array(
+                'ClassesWithParents\\B',
+                'ClassesWithParents\\A',
+                'ClassesWithParents\\CInterface',
+            )),
+            array(array(
+                'ClassesWithParents\\CInterface',
+                'ClassesWithParents\\B',
+                'ClassesWithParents\\A',
+            )),
+        );
+    }
+
     public function testFixNamespaceDeclarations()
     {
         $source = <<<EOF

src/Symfony/Component/ClassLoader/Tests/Fixtures/ClassesWithParents/A.php

@@ -0,0 +1,5 @@
+<?php
+
+namespace ClassesWithParents;
+
+class A extends B {}

src/Symfony/Component/ClassLoader/Tests/Fixtures/ClassesWithParents/B.php

@@ -0,0 +1,5 @@
+<?php
+
+namespace ClassesWithParents;
+
+class B implements CInterface {}

src/Symfony/Component/ClassLoader/Tests/Fixtures/ClassesWithParents/CInterface.php

@@ -0,0 +1,5 @@
+<?php
+
+namespace ClassesWithParents;
+
+interface CInterface {}