Add supported adapters static method

src/AdapterInterface.php

@@ -8,6 +8,13 @@
 interface AdapterInterface
 {
     const CREATION_MODE = 'rwxrw----';
+
+    /**
+     * Checks whether the current installation supports the adapter.
+     *
+     * @return boolean
+     */
+    public static function isSupported();
 
     /**
      * Return the loop associated with this adapter.

src/ChildProcess/Adapter.php

@@ -90,6 +90,14 @@ protected function setUpPool($options)
         });
     }
 
+    /**
+     * @return boolean
+     */
+    public static function isSupported()
+    {
+        return substr(strtolower(PHP_OS), 0, 3) !== 'win' && function_exists('proc_open');
+    }
+
     /**
      * @return LoopInterface
      */

src/Eio/Adapter.php

@@ -102,6 +102,14 @@ protected function applyConfiguration(array $options)
         $this->options = array_merge_recursive($this->options, $options);
     }
 
+    /**
+     * @return boolean
+     */
+    public static function isSupported()
+    {
+        return extension_loaded('eio');
+    }
+
     /**
      * {@inheritDoc}
      */

src/Filesystem.php

@@ -2,6 +2,7 @@
 
 namespace React\Filesystem;
 
+use RuntimeException;
 use React\EventLoop\LoopInterface;
 use React\Filesystem\Node;
 
@@ -16,14 +17,18 @@ class Filesystem implements FilesystemInterface
      * @param LoopInterface $loop
      * @param array $options
      * @return FilesystemInterface
+     * @throws RuntimeException
      */
     public static function create(LoopInterface $loop, array $options = [])
     {
-        if (extension_loaded('eio')) {
-            return static::setFilesystemOnAdapter(static::createFromAdapter(new Eio\Adapter($loop, $options)));
+        $adapters = static::getSupportedAdapters();
+
+        if (!empty($adapters)) {
+            $adapter = "\\React\\Filesystem\\".$adapters[0]."\\Adapter";
+            return static::setFilesystemOnAdapter(static::createFromAdapter(new $adapter($loop, $options)));
         }
 
-        return static::setFilesystemOnAdapter(static::createFromAdapter(new ChildProcess\Adapter($loop, $options)));
+        throw new RuntimeException('No supported adapter found for this installation');
     }
 
     /**
@@ -45,6 +50,24 @@ protected static function setFilesystemOnAdapter(FilesystemInterface $filesystem
         return $filesystem;
     }
 
+    /**
+     * @return string[]
+     */
+    public static function getSupportedAdapters()
+    {
+        $adapters = [];
+
+        if (Eio\Adapter::isSupported()) {
+            $adapters[] = 'Eio';
+        }
+
+        if (ChildProcess\Adapter::isSupported()) {
+            $adapters[] = 'ChildProcess';
+        }
+
+        return $adapters;
+    }
+
     /**
      * Filesystem constructor.
      * @param AdapterInterface $adapter

src/FilesystemInterface.php

@@ -2,6 +2,7 @@
 
 namespace React\Filesystem;
 
+use RuntimeException;
 use React\EventLoop\LoopInterface;
 use React\Filesystem\Node;
 
@@ -11,6 +12,7 @@ interface FilesystemInterface
      * @param LoopInterface $loop
      * @param array $options
      * @return FilesystemInterface
+     * @throws RuntimeException
      */
     public static function create(LoopInterface $loop, array $options = []);
 
@@ -20,6 +22,11 @@ public static function create(LoopInterface $loop, array $options = []);
      */
     public static function createFromAdapter(AdapterInterface $adapter);
 
+    /**
+     * @return string[]
+     */
+    public static function getSupportedAdapters();
+
     /**
      * @return AdapterInterface
      */

tests/TestCase.php

@@ -27,6 +27,7 @@ protected function mockAdapter(LoopInterface $loop = null)
             'setFilesystem',
             'setInvoker',
             'callFilesystem',
+            'isSupported',
             'mkdir',
             'rmdir',
             'unlink',