Add trim option

README.md

@@ -126,6 +126,14 @@ $slugify = new Slugify(['separator' => '_']);
 $slugify->slugify('Hello World'); // -> "hello_world"
 ```
 
+By default Slugify will remove leading and trailing separators before returning the slug. If you do not want the slug to 
+be trimmed you can set the `trim` option to false.
+
+```php
+$slugify = new Slugify(['trim' => false]);
+$slugify->slugify('Hello World '); // -> "hello-world-"
+```
+
 ### Changing options on the fly
 
 You can overwrite any of the above options on the fly by passing an options array as second argument to the `slugify()`

src/Bridge/Symfony/Configuration.php

@@ -27,6 +27,7 @@ public function getConfigTreeBuilder()
         $rootNode
             ->children()
                 ->booleanNode('lowercase')->end()
+                ->booleanNode('trim')->end()
                 ->scalarNode('separator')->end()
                 ->scalarNode('regexp')->end()
                 ->arrayNode('rulesets')->prototype('scalar')->end()

src/Slugify.php

@@ -45,6 +45,7 @@ class Slugify implements SlugifyInterface
         'regexp'    => self::LOWERCASE_NUMBERS_DASHES,
         'separator' => '-',
         'lowercase' => true,
+        'trim' => true,
         'rulesets'  => [
             'default',
             // Languages are preferred if they appear later, list is ordered by number of
@@ -119,7 +120,9 @@ public function slugify($string, $options = null)
 
         $string = preg_replace($options['regexp'], $options['separator'], $string);
 
-        return trim($string, $options['separator']);
+        return ($options['trim'])
+            ? trim($string, $options['separator'])
+            : $string;
     }
 
     /**

tests/SlugifyTest.php

@@ -207,6 +207,9 @@ public function slugifyOptionsArray()
 
         $this->assertEquals('file-name', $this->slugify->slugify('FILE NAME'));
         $this->assertEquals('FILE-NAME', $this->slugify->slugify('FILE NAME', ['lowercase' => false]));
+
+        $this->assertEquals('file-name', $this->slugify->slugify('file name '));
+        $this->assertEquals('file-name-', $this->slugify->slugify('file name ', ['trim' => false]));
     }
 
     /**