Add getpreferredencoding. Support @euro modifiers. Fixes #554676.

The @euro part is backported to 2.2.3.

Lib/locale.py

@@ -264,6 +264,15 @@ def _parse_localename(localename):
 
     """
     code = normalize(localename)
+    if '@' in localename:
+        # Deal with locale modifiers
+        code, modifier = code.split('@')
+        if modifier == 'euro' and '.' not in code:
+            # Assume Latin-9 for @euro locales. This is bogus,
+            # since some systems may use other encodings for these
+            # locales. Also, we ignore other modifiers.
+            return code, 'iso-8859-15'
+            
     if '.' in code:
         return code.split('.')[:2]
     elif code == 'C':
@@ -381,6 +390,38 @@ def resetlocale(category=LC_ALL):
     """
     _setlocale(category, _build_localename(getdefaultlocale()))
 
+if sys.platform in ('win32', 'darwin', 'mac'):
+    # On Win32, this will return the ANSI code page
+    # On the Mac, it should return the system encoding;
+    # it might return "ascii" instead
+    def getpreferredencoding(do_setlocale = True):
+        """Return the charset that the user is likely using."""
+        import _locale
+        return _locale.getdefaultlocale()[1]
+else:
+    # On Unix, if CODESET is available, use that.
+    try:
+        CODESET
+    except NameError:
+        # Fall back to parsing environment variables :-(
+        def getpreferredencoding(do_setlocale = True):
+            """Return the charset that the user is likely using,
+            by looking at environment variables."""
+            return getdefaultlocale()[1]
+    else:
+        def getpreferredencoding(do_setlocale = True):
+            """Return the charset that the user is likely using,
+            according to the system configuration."""
+            if do_setlocale:
+                oldloc = setlocale(LC_CTYPE)
+                setlocale(LC_CTYPE, "")
+                result = nl_langinfo(CODESET)
+                setlocale(LC_CTYPE, oldloc)
+                return result
+            else:
+                return nl_langinfo(CODESET)
+                
+
 ### Database
 #
 # The following data was extracted from the locale.alias file which