Do not replace strftime placehoders escaped with double %

trytond/trytond/ir/lang.py

@@ -4,6 +4,7 @@
 import datetime
 from ast import literal_eval
 from decimal import Decimal
+from itertools import takewhile
 from locale import CHAR_MAX
 
 from sql import Table
@@ -41,6 +42,27 @@ class DeleteDefaultError(UserError):
 NO_BREAKING_SPACE = '\u00A0'
 
 
+def _replace(src, old, new, escape='%'):
+    """Return a copy of src with all occurrences of substring old replaced
+    by new if not escaped using double escape"""
+    def is_escape(x):
+        return x == escape
+    assert old.startswith(escape)
+    start = 0
+    while start < len(src):
+        i = src.find(old, start)
+        if i < 0:
+            break
+        # if there is an odd number of percentage before the
+        # placeholder then it is not escaped
+        if len(list(takewhile(is_escape, reversed(src[:i])))) % 2:
+            start = i + len(old)
+        else:
+            src = src[:i] + new + src[i + len(old):]
+            start = i + len(new)
+    return src
+
+
 class Lang(DeactivableMixin, ModelSQL, ModelView):
     "Language"
     __name__ = "ir.lang"
@@ -547,15 +569,15 @@ class Lang(DeactivableMixin, ModelSQL, ModelView):
             if isinstance(value, datetime.datetime):
                 format += ' %H:%M:%S'
         if '%x' in format:
-            format = format.replace('%x', self.date)
-        format = format.replace('%X', '%H:%M:%S')
+            format = _replace(format, '%x', self.date)
+        format = _replace(format, '%X', '%H:%M:%S')
         if isinstance(value, datetime.date):
             for f, i, klass in (('%A', 6, Day), ('%B', 1, Month)):
                 for field, f in [('name', f), ('abbreviation', f.lower())]:
                     if f in format:
                         locale = klass.locale(self, field=field)
-                        format = format.replace(
-                            f, locale[value.timetuple()[i]])
+                        format = _replace(
+                            format, f, locale[value.timetuple()[i]])
         if '%p' in format:
             if isinstance(value, datetime.time):
                 time = value
@@ -569,7 +591,7 @@ class Lang(DeactivableMixin, ModelSQL, ModelView):
                     p = self.am or 'AM'
                 else:
                     p = self.pm or 'PM'
-                format = format.replace('%p', p)
+                format = _replace(format, '%p', p)
         return value.strftime(format).replace(' ', NO_BREAKING_SPACE)
 
     def format_number(self, value, digits=None, grouping=True, monetary=None):

trytond/trytond/tests/test_ir.py

@@ -13,6 +13,7 @@ except ImportError:
 from dateutil.relativedelta import relativedelta
 
 from trytond.config import config
+from trytond.ir.lang import _replace
 from trytond.pool import Pool
 from trytond.pyson import Eval, If, PYSONEncoder
 from trytond.tools import timezone
@@ -174,6 +175,17 @@ class IrTestCase(ModuleTestCase):
             self.assertEqual(
                 lang.format(percent, value, grouping, monetary, *add), result)
 
+    def test_lang_replace(self):
+        "Test string _replace"
+        for src, result in [
+                ('%x', 'foo'),
+                ('%%x', '%%x'),
+                ('%x %x', 'foo foo'),
+                ('%x %y %x %%x', 'foo %y foo %%x'),
+                ]:
+            with self.subTest(src=src):
+                self.assertEqual(_replace(src, '%x', 'foo'), result)
+
     @with_transaction()
     def test_lang_strftime(self):
         "Test Lang.strftime"
@@ -192,9 +204,14 @@ class IrTestCase(ModuleTestCase):
                 '%H:%M:%S', "14:30:12"),
             (datetime.datetime(2018, 11, 1, 14, 30, 12), None,
                 "11/01/2018 14:30:12"),
+            (datetime.date(2016, 8, 3), '%d %%m %Y', "03 %m 2016"),
+            (datetime.date(2018, 11, 1), '%d %%x', "01 %x"),
+            (datetime.date(2018, 11, 1), '%d %%a', "01 %a"),
+            (datetime.datetime(2018, 11, 1, 14, 30, 12), '%d %%p', "01 %p"),
             ]
         for date, format_, result in test_data:
-            self.assertEqual(lang.strftime(date, format_), result)
+            with self.subTest(date=date, format=format_):
+                self.assertEqual(lang.strftime(date, format_), result)
 
     @with_transaction()
     def test_lang_format_number(self):