Fixed #18269 -- Applied unicode_literals for Python 3 compatibility.

Thanks Vinay Sajip for the support of his django3 branch and
Jannis Leidel for the review.

django/utils/text.py

@@ -1,3 +1,5 @@
+from __future__ import unicode_literals
+
 import re
 import unicodedata
 import warnings
@@ -43,7 +45,7 @@ def wrap(text, width):
                 if len(lines) > 1:
                     pos = len(lines[-1])
             yield word
-    return u''.join(_generator())
+    return ''.join(_generator())
 wrap = allow_lazy(wrap, unicode)
 
 
@@ -58,7 +60,7 @@ class Truncator(SimpleLazyObject):
         if truncate is None:
             truncate = pgettext(
                 'String to return when truncating text',
-                u'%(truncated_text)s...')
+                '%(truncated_text)s...')
         truncate = force_unicode(truncate)
         if '%(truncated_text)s' in truncate:
             return truncate % {'truncated_text': text}
@@ -130,8 +132,8 @@ class Truncator(SimpleLazyObject):
         words = self._wrapped.split()
         if len(words) > length:
             words = words[:length]
-            return self.add_truncation_text(u' '.join(words), truncate)
-        return u' '.join(words)
+            return self.add_truncation_text(' '.join(words), truncate)
+        return ' '.join(words)
 
     def _html_words(self, length, truncate):
         """
@@ -142,7 +144,7 @@ class Truncator(SimpleLazyObject):
         Newlines in the HTML are preserved.
         """
         if length <= 0:
-            return u''
+            return ''
         html4_singlets = (
             'br', 'col', 'link', 'base', 'img',
             'param', 'area', 'hr', 'input'
@@ -221,28 +223,28 @@ def get_valid_filename(s):
     spaces are converted to underscores; and anything that is not a unicode
     alphanumeric, dash, underscore, or dot, is removed.
     >>> get_valid_filename("john's portrait in 2004.jpg")
-    u'johns_portrait_in_2004.jpg'
+    'johns_portrait_in_2004.jpg'
     """
     s = force_unicode(s).strip().replace(' ', '_')
     return re.sub(r'(?u)[^-\w.]', '', s)
 get_valid_filename = allow_lazy(get_valid_filename, unicode)
 
-def get_text_list(list_, last_word=ugettext_lazy(u'or')):
+def get_text_list(list_, last_word=ugettext_lazy('or')):
     """
     >>> get_text_list(['a', 'b', 'c', 'd'])
-    u'a, b, c or d'
+    'a, b, c or d'
     >>> get_text_list(['a', 'b', 'c'], 'and')
-    u'a, b and c'
+    'a, b and c'
     >>> get_text_list(['a', 'b'], 'and')
-    u'a and b'
+    'a and b'
     >>> get_text_list(['a'])
-    u'a'
+    'a'
     >>> get_text_list([])
-    u''
+    ''
     """
-    if len(list_) == 0: return u''
+    if len(list_) == 0: return ''
     if len(list_) == 1: return force_unicode(list_[0])
-    return u'%s %s %s' % (
+    return '%s %s %s' % (
         # Translators: This string is used as a separator between list elements
         _(', ').join([force_unicode(i) for i in list_][:-1]),
         force_unicode(last_word), force_unicode(list_[-1]))
@@ -267,7 +269,7 @@ def phone2numeric(phone):
          'n': '6', 'o': '6', 'p': '7', 'q': '7', 'r': '7', 's': '7', 't': '8',
          'u': '8', 'v': '8', 'w': '9', 'x': '9', 'y': '9', 'z': '9',
         }
-    return u''.join(char2number.get(c, c) for c in phone.lower())
+    return ''.join(char2number.get(c, c) for c in phone.lower())
 phone2numeric = allow_lazy(phone2numeric)
 
 # From http://www.xhaus.com/alan/python/httpcomp.html#gzip
@@ -279,12 +281,12 @@ def compress_string(s):
     zfile.close()
     return zbuf.getvalue()
 
-ustring_re = re.compile(u"([\u0080-\uffff])")
+ustring_re = re.compile("([\u0080-\uffff])")
 
 def javascript_quote(s, quote_double_quotes=False):
 
     def fix(match):
-        return r"\u%04x" % ord(match.group(1))
+        return b"\u%04x" % ord(match.group(1))
 
     if type(s) == str:
         s = s.decode('utf-8')
@@ -321,11 +323,11 @@ def smart_split(text):
     be further processed with unescape_string_literal()).
 
     >>> list(smart_split(r'This is "a person\'s" test.'))
-    [u'This', u'is', u'"a person\\\'s"', u'test.']
+    ['This', 'is', '"a person\\\'s"', 'test.']
     >>> list(smart_split(r"Another 'person\'s' test."))
-    [u'Another', u"'person\\'s'", u'test.']
+    ['Another', "'person\\'s'", 'test.']
     >>> list(smart_split(r'A "\"funky\" style" test.'))
-    [u'A', u'"\\"funky\\" style"', u'test.']
+    ['A', '"\\"funky\\" style"', 'test.']
     """
     text = force_unicode(text)
     for bit in smart_split_re.finditer(text):
@@ -334,10 +336,10 @@ smart_split = allow_lazy(smart_split, unicode)
 
 def _replace_entity(match):
     text = match.group(1)
-    if text[0] == u'#':
+    if text[0] == '#':
         text = text[1:]
         try:
-            if text[0] in u'xX':
+            if text[0] in 'xX':
                 c = int(text[1:], 16)
             else:
                 c = int(text)