add old yii-ext twig renderer's function into this. and as per yii2's view…

extensions/yii/twig/TwigSimpleFileLoader.php

+<?php
+
+namespace yii\twig;
+
+/**
+ * Twig view file loader class
+ *
+ * @author dev-mraj <dev.meghraj@gmail.com>
+ * @version 1.0.0
+ */
+class TwigSimpleFileLoader implements \Twig_LoaderInterface {
+
+    /**
+     * Path to directory where all file exists
+     * @param $view string
+     */
+    private $dir;
+
+    public function __construct($dir){
+        $this->dir=$dir;
+    }
+
+    public function isFresh($name, $time){
+        return filemtime($this->getFilePath($name))<=$time;
+    }
+    public function getSource($name){
+        return file_get_contents($this->getFilePath($name));
+    }
+    public function getCacheKey($name){
+        return $this->getFilePath($name);
+    }
+
+    protected  function getFilePath($name){
+        return $this->dir.'/'.$name;
+    }
+}
\ No newline at end of file

extensions/yii/twig/ViewRenderer.php

@@ -28,34 +28,99 @@ class ViewRenderer extends BaseViewRenderer
 	public $cachePath = '@runtime/Twig/cache';
 
 	/**
-	 * @var array extentions list.
-	 */
-	public $extensions = [];
-
-	/**
 	 * @var array Twig options
 	 * @see http://twig.sensiolabs.org/doc/api.html#environment-options
 	 */
 	public $options = [];
 
-	/**
+    /**
+     * @var array Objects or static classes
+     * Keys of array are names to call in template, values - objects or names of static class as string
+     * Example: array('html'=>'\yii\helpers\Html')
+     * Than in template: {{ html.link('Login', 'site/login') }}
+     */
+    public $globals = array();
+
+    /**
+     * @var array Custom functions
+     * Keys of array are names to call in template, values - names of functions or static methods of some class
+     * Example: array('rot13'=>'str_rot13', 'link'=>'\yii\helpers\Html::link')
+     * Than in template: {{ rot13('test') }} or {{ link('Login', 'site/login') }}
+     */
+    public $functions = array();
+
+    /**
+     * @var array Custom filters
+     * Keys of array are names to call in template, values - names of functions or static methods of some class
+     * Example: array('rot13'=>'str_rot13', 'jsonEncode'=>'\yii\helpers\Json::encode')
+     * Then in template: {{ 'test'|rot13 }} or {{ model|jsonEncode }}
+     */
+    public $filters = array();
+
+    /**
+     * @var array Custom extensions
+     * Example: array('Twig_Extension_Sandbox', 'Twig_Extension_Text')
+     */
+    public $extensions = array();
+
+    /**
+     * @var array Twig lexer options
+     * @see http://twig.sensiolabs.org/doc/recipes.html#customizing-the-syntax
+     * Example: Smarty-like syntax
+     * array(
+     *     'tag_comment'  => array('{*', '*}'),
+     *     'tag_block'    => array('{', '}'),
+     *     'tag_variable' => array('{$', '}')
+     * )
+     */
+    public $lexerOptions = array();
+
+    /**
 	 * @var \Twig_Environment
 	 */
 	public $twig;
 
 	public function init()
 	{
-		$loader = new \Twig_Loader_String();
 
-		$this->twig = new \Twig_Environment($loader, array_merge([
+		$this->twig = new \Twig_Environment(null, array_merge([
 			'cache' => Yii::getAlias($this->cachePath),
+            'auto_reload' => true,
+            'charset' => Yii::$app->charset,
 		], $this->options));
-		
+
+        // Adding custom extensions
 		if (!empty($this->extensions)) {
 			foreach ($this->extensions as $extension) {
 				$this->twig->addExtension(new $extension());
 			}
 		}
+        // Adding custom globals (objects or static classes)
+        if (!empty($this->globals)) {
+            $this->addGlobals($this->globals);
+        }
+        // Adding custom functions
+        if (!empty($this->functions)) {
+            $this->addFunctions($this->functions);
+        }
+        // Adding custom filters
+        if (!empty($this->filters)) {
+            $this->addFilters($this->filters);
+        }
+        // Adding custom extensions
+        if (!empty($this->extensions)) {
+            $this->addExtensions($this->extensions);
+        }
+        // Change lexer syntax
+        if (!empty($this->lexerOptions)) {
+            $this->setLexerOptions($this->lexerOptions);
+        }
+
+
+        // Adding global 'void' function (usage: {{void(App.clientScript.registerScriptFile(...))}})
+        $this->twig->addFunction('void', new \Twig_Function_Function(function($argument){
+
+        }));
 
 		$this->twig->addFunction('path', new \Twig_Function_Function(function ($path, $args = []) {
 			return Html::url(array_merge([$path], $args));
@@ -64,6 +129,7 @@ class ViewRenderer extends BaseViewRenderer
 		$this->twig->addGlobal('app', \Yii::$app);
 	}
 
+
 	/**
 	 * Renders a view file.
 	 *
@@ -79,6 +145,95 @@ class ViewRenderer extends BaseViewRenderer
 	public function render($view, $file, $params)
 	{
 		$this->twig->addGlobal('this', $view);
-		return $this->twig->render(file_get_contents($file), $params);
+        $this->twig->setLoader(new TwigSimpleFileLoader(dirname($file)));
+		return $this->twig->render(pathinfo($file,PATHINFO_BASENAME), $params);
 	}
+
+    /**
+     * Adds global objects or static classes
+     * @param array $globals @see self::$globals
+     */
+    public function addGlobals($globals)
+    {
+        foreach ($globals as $name => $value) {
+            if (!is_object($value)) {
+                $value = new ViewRendererStaticClassProxy($value);
+            }
+            $this->twig->addGlobal($name, $value);
+        }
+    }
+
+    /**
+     * Adds custom functions
+     * @param array $functions @see self::$functions
+     */
+    public function addFunctions($functions)
+    {
+        $this->_addCustom('Function', $functions);
+    }
+
+    /**
+     * Adds custom filters
+     * @param array $filters @see self::$filters
+     */
+    public function addFilters($filters)
+    {
+        $this->_addCustom('Filter', $filters);
+    }
+
+    /**
+     * Adds custom extensions
+     * @param array $extensions @see self::$extensions
+     */
+    public function addExtensions($extensions)
+    {
+        foreach ($extensions as $extName) {
+            $this->twig->addExtension(new $extName());
+        }
+    }
+
+    /**
+     * Sets Twig lexer options to change templates syntax
+     * @param array $options @see self::$lexerOptions
+     */
+    public function setLexerOptions($options)
+    {
+        $lexer = new \Twig_Lexer($this->twig, $options);
+        $this->twig->setLexer($lexer);
+    }
+
+    /**
+     * Adds custom function or filter
+     * @param string $classType 'Function' or 'Filter'
+     * @param array $elements Parameters of elements to add
+     * @throws \Exception
+     */
+    private function _addCustom($classType, $elements)
+    {
+        $classFunction = 'Twig_'.$classType.'_Function';
+
+        foreach ($elements as $name => $func) {
+            $twigElement = null;
+
+            switch ($func) {
+                // Just a name of function
+                case is_string($func):
+                    $twigElement = new $classFunction($func);
+                    break;
+                // Name of function + options array
+                case is_array($func) && is_string($func[0]) && isset($func[1]) && is_array($func[1]):
+                    $twigElement = new $classFunction($func[0], $func[1]);
+                    break;
+            }
+
+            if ($twigElement !== null) {
+                $this->twig->{'add'.$classType}($name, $twigElement);
+            } else {
+                throw new \Exception(Yii::t('yiiext',
+                    'Incorrect options for "{classType}" [{name}]',
+                    array('{classType}'=>$classType, '{name}'=>$name)));
+            }
+        }
+    }
 }
+

extensions/yii/twig/ViewRendererStaticClassProxy.php

+<?php
+
+namespace yii\twig;
+
+/**
+ * Class-proxy for static classes
+ * Needed because you can't pass static class to Twig other way
+ *
+ * @author Leonid Svyatov <leonid@svyatov.ru>
+ * @version 1.0.0
+ */
+class ViewRendererStaticClassProxy
+{
+    private $_staticClassName;
+
+    public function __construct($staticClassName) {
+        $this->_staticClassName = $staticClassName;
+    }
+
+    public function __get($property)
+    {
+        $class = new \ReflectionClass($this->_staticClassName);
+        return $class->getStaticPropertyValue($property);
+    }
+
+    public function __set($property, $value)
+    {
+        $class = new \ReflectionClass($this->_staticClassName);
+        $class->setStaticPropertyValue($property, $value);
+        return $value;
+    }
+
+    public function __call($method, $arguments)
+    {
+        return call_user_func_array(array($this->_staticClassName, $method), $arguments);
+    }
+}
\ No newline at end of file