diff --git a/framework/yii/helpers/StringHelperBase.php b/framework/yii/helpers/StringHelperBase.php
index 54dabda..cbb696e 100644
--- a/framework/yii/helpers/StringHelperBase.php
+++ b/framework/yii/helpers/StringHelperBase.php
@@ -47,8 +47,8 @@ class StringHelperBase
 
 	/**
 	 * Returns the trailing name component of a path.
-	 * This method does the same as the php function `basename()` except that it will
-	 * always use \ and / as directory separators, independent of the operating system.
+	 * This method is similar to the php function `basename()` except that it will
+	 * treat both \ and / as directory separators, independent of the operating system.
 	 * This method was mainly created to work on php namespaces. When working with real
 	 * file paths, php's `basename()` should work fine for you.
 	 * Note: this method is not aware of the actual filesystem, or path components such as "..".
@@ -70,6 +70,24 @@ class StringHelperBase
 	}
 
 	/**
+	 * Returns parent directory's path.
+	 * This method is similar to `dirname()` except that it will treat
+	 * both \ and / as directory separators, independent of the operating system.
+	 * @param string $path A path string.
+	 * @return string the parent directory's path.
+	 * @see http://www.php.net/manual/en/function.basename.php
+	 */
+	public static function dirname($path)
+	{
+		$pos = mb_strrpos(str_replace('\\', '/', $path), '/');
+		if ($pos !== false) {
+			return mb_substr($path, 0, $pos);
+		} else {
+			return $path;
+		}
+	}
+
+	/**
 	 * Compares two strings or string arrays, and return their differences.
 	 * This is a wrapper of the [phpspec/php-diff](https://packagist.org/packages/phpspec/php-diff) package.
 	 * @param string|array $lines1 the first string or string array to be compared. If it is a string,