str_utils: added common non-ascii replacer

rhodecode/lib/str_utils.py

@@ -20,6 +20,7 b''
 
 import logging
 import rhodecode
+import unicodedata
 from rhodecode.lib.type_utils import aslist
 
 log = logging.getLogger(__name__)
@@ -133,3 +134,14 b' def ascii_str(str_):'
     if not isinstance(str_, bytes):
         raise ValueError('ascii_str cannot convert other types than bytes: got: {}'.format(type(str_)))
     return str_.decode('ascii')
+
+
+def convert_special_chars(str_):
+    """
+        trie to replace non-ascii letters to their ascii representation eg::
+
+            `żołw` converts into `zolw`
+    """
+    value = safe_str(str_)
+    converted_value = unicodedata.normalize('NFKD', value).encode('ascii', 'ignore').decode()
+    return converted_value