feature #2403 #1802 left/right trim (antonydandrea)

This PR was submitted for the 2.x branch but it was merged into the 1.x branch instead (closes #2403).

Discussion
----------

#1802 left/right trim

It was said in this thread that there was a preference of adding parameters to the trim filter in order to implement this.

So this feature works like:

trim(character_mask, mode), where mode is either "both", "left" or "right". It is by default "both".

This is my first pull request of this project, so I apologise in advance if something is wrong.

Commits
-------

7d8e755 #1802 left/right trim

CHANGELOG

@@ -1,6 +1,7 @@
 * 1.32.0 (2017-XX-XX)
 
  * added a PSR-11 compatible runtime loader
+ * added `side` argument to `trim` to allow left or right trimming only.
 
 * 1.31.0 (2017-01-11)
 

doc/filters/trim.rst

@@ -1,5 +1,8 @@
 ``trim``
 ========
+.. versionadded:: 1.32
+
+    The ``side`` argument was added in Twig 1.32.
 
 .. versionadded:: 1.6.2
     The ``trim`` filter was added in Twig 1.6.2.
@@ -17,13 +20,26 @@ and end of a string:
 
     {# outputs '  I like Twig' #}
 
+    {{ '  I like Twig.  '|trim(side='left') }}
+
+    {# outputs 'I like Twig.  ' #}
+
+    {{ '  I like Twig.  '|trim(' ', 'right') }}
+
+    {# outputs '  I like Twig.' #}
+
 .. note::
 
-    Internally, Twig uses the PHP `trim`_ function.
+    Internally, Twig uses the PHP `trim`_, `ltrim`_, and `rtrim`_ functions.
 
 Arguments
 ---------
 
 * ``character_mask``: The characters to strip
 
+* ``side``: The default is to strip from the left and the right (`both`) sides, but `left`
+  and `right` will strip from either the left side or right side only
+
 .. _`trim`: http://php.net/trim
+.. _`ltrim`: http://php.net/ltrim
+.. _`rtrim`: http://php.net/rtrim

lib/Twig/Extension/Core.php

@@ -163,7 +163,7 @@ public function getFilters()
             new Twig_SimpleFilter('upper', 'strtoupper'),
             new Twig_SimpleFilter('lower', 'strtolower'),
             new Twig_SimpleFilter('striptags', 'strip_tags'),
-            new Twig_SimpleFilter('trim', 'trim'),
+            new Twig_SimpleFilter('trim', 'twig_trim_filter'),
             new Twig_SimpleFilter('nl2br', 'nl2br', array('pre_escape' => 'html', 'is_safe' => array('html'))),
 
             // array helpers
@@ -945,6 +945,31 @@ function twig_in_filter($value, $compare)
     return false;
 }
 
+/** 
+ * Returns a trimmed string.
+ *
+ * @return string
+ *
+ * @throws Twig_Error_Runtime When an invalid trimming side is used (not a string or not 'left', 'right' or 'both')
+ */
+function twig_trim_filter($string, $characterMask = null, $side = 'both')
+{
+    if (null === $characterMask) {
+        $characterMask = " \t\n\r\0\x0B";
+    }
+
+    switch ($side) {
+        case 'both':
+            return trim($string, $characterMask);
+        case 'left':
+            return ltrim($string, $characterMask);
+        case 'right':
+            return rtrim($string, $characterMask);
+        default:
+            throw new Twig_Error_Runtime('Trimming side must be "left", "right" or "both".');
+    }
+}
+
 /**
  * Escapes a string.
  *

test/Twig/Tests/Fixtures/filters/trim.test

@@ -4,9 +4,21 @@
 {{ "  I like Twig.  "|trim }}
 {{ text|trim }}
 {{ "  foo/"|trim("/") }}
+{{ "  I like Twig.  "|trim(side="left") }}
+{{ "  I like Twig.  "|trim(side="right") }}
+{{ "  I like Twig.  "|trim(null, "right") }}
+{{ "/  foo/"|trim("/", "left") }}
+{{ "/  foo/"|trim(character_mask="/", side="left") }}
+{{ "  do nothing.  "|trim("", "right") }}
 --DATA--
 return array('text' => "  If you have some <strong>HTML</strong> it will be escaped.  ")
 --EXPECT--
 I like Twig.
 If you have some &lt;strong&gt;HTML&lt;/strong&gt; it will be escaped.
   foo
+I like Twig.  
+  I like Twig.
+  I like Twig.
+  foo/
+  foo/
+  do nothing.