Use class_exists instead of require to play nice with inlining

lib/Twig/BaseNodeVisitor.php

@@ -9,8 +9,8 @@
  * file that was distributed with this source code.
  */
 
-require_once __DIR__.'/Environment.php';
-require_once __DIR__.'/Node.php';
+class_exists('Twig_Environment');
+class_exists('Twig_Node');
 
 /**
  * Twig_BaseNodeVisitor can be used to make node visitors compatible with Twig 1.x and 2.x.

lib/Twig/Compiler.php

@@ -10,7 +10,7 @@
  * file that was distributed with this source code.
  */
 
-require_once __DIR__.'/Node.php';
+class_exists('Twig_Node');
 
 /**
  * Compiles a node to PHP code.

lib/Twig/Error.php

@@ -9,7 +9,7 @@
  * file that was distributed with this source code.
  */
 
-require_once __DIR__.'/Source.php';
+class_exists('Twig_Source');
 
 /**
  * Twig base exception.

lib/Twig/Extension.php

@@ -9,7 +9,7 @@
  * file that was distributed with this source code.
  */
 
-require_once __DIR__.'/Environment.php';
+class_exists('Twig_Environment');
 
 abstract class Twig_Extension implements Twig_ExtensionInterface
 {

lib/Twig/Extension/Profiler.php

@@ -9,7 +9,7 @@
  * file that was distributed with this source code.
  */
 
-require_once __DIR__.'/../Profiler/Profile.php';
+class_exists('Twig_Profiler_Profile');
 
 class Twig_Extension_Profiler extends Twig_Extension
 {

lib/Twig/ExtensionInterface.php

@@ -9,7 +9,7 @@
  * file that was distributed with this source code.
  */
 
-require_once __DIR__.'/Environment.php';
+class_exists('Twig_Environment');
 
 /**
  * Interface implemented by extension classes.

lib/Twig/Node.php

@@ -10,7 +10,7 @@
  * file that was distributed with this source code.
  */
 
-require_once __DIR__.'/Compiler.php';
+class_exists('Twig_Compiler');
 
 /**
  * Represents a node in the AST.

lib/Twig/NodeVisitorInterface.php

@@ -9,8 +9,8 @@
  * file that was distributed with this source code.
  */
 
-require_once __DIR__.'/Environment.php';
-require_once __DIR__.'/Node.php';
+class_exists('Twig_Environment');
+class_exists('Twig_Node');
 
 /**
  * Twig_NodeVisitorInterface is the interface the all node visitor classes must implement.

lib/Twig/Parser.php

@@ -10,8 +10,8 @@
  * file that was distributed with this source code.
  */
 
-require_once __DIR__.'/Node.php';
-require_once __DIR__.'/TokenStream.php';
+class_exists('Twig_Node');
+class_exists('Twig_TokenStream');
 
 /**
  * Default parser implementation.

lib/Twig/Test/NodeTestCase.php

@@ -9,8 +9,8 @@
  * file that was distributed with this source code.
  */
 
-require_once __DIR__.'/../Environment.php';
-require_once __DIR__.'/../Node.php';
+class_exists('Twig_Environment');
+class_exists('Twig_Node');
 
 use PHPUnit\Framework\TestCase;
 

lib/Twig/TokenParserInterface.php

@@ -9,8 +9,8 @@
  * file that was distributed with this source code.
  */
 
-require_once __DIR__.'/Parser.php';
-require_once __DIR__.'/Token.php';
+class_exists('Twig_Parser');
+class_exists('Twig_Token');
 
 /**
  * Interface implemented by token parsers.