--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/tools/common/regex.py	Tue Mar 22 22:46:04 2016 +0100
@@ -0,0 +1,62 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# Salut à Toi: an XMPP client
+# Copyright (C) 2009-2016 Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+""" regex tools common to backend and frontends """
+
+import re
+path_escape = {'%': '%25', '/': '%2F', '\\': '%5c'}
+path_escape_rev = {re.escape(v):k for k, v in path_escape.iteritems()}
+path_escape = {re.escape(k):v for k, v in path_escape.iteritems()}
+
+
+def reJoin(exps):
+    """Join (OR) various regexes"""
+    return re.compile('|'.join(exps))
+
+
+def reSubDict(pattern, repl_dict, string):
+    """Replace key, value found in dict according to pattern
+
+    @param pattern(basestr): pattern using keys found in repl_dict
+    @repl_dict(dict): keys found in this dict will be replaced by
+        corresponding values
+    @param string(basestr): string to use for the replacement
+    """
+    return pattern.sub(lambda m: repl_dict[re.escape(m.group(0))], string)
+
+path_escape_re = reJoin(path_escape.keys())
+path_escape_rev_re = reJoin(path_escape_rev.keys())
+
+
+def pathEscape(string):
+    """Escape string so it can be use in a file path
+
+    @param string(basestr): string to escape
+    @return (str, unicode): escaped string, usable in a file path
+    """
+    return reSubDict(path_escape_re, path_escape, string)
+
+
+def pathUnescape(string):
+    """Unescape string from value found in file path
+
+    @param string(basestr): string found in file path
+    @return (str, unicode): unescaped string
+    """
+    return reSubDict(path_escape_rev_re, path_escape_rev, string)