python · cedk · Jan 23, 2020 · Jan 23, 2020 · Jan 23, 2020 · Feb 9, 2020
diff --git a/Doc/library/locale.rst b/Doc/library/locale.rst
@@ -279,6 +279,14 @@ The :mod:`locale` module defines the following exception and functions:
       0 to 99.
 
 
+.. function:: getfirstweekday()
+
+   Return the first day of week as integer or ``None`` when unknown.
+   0 is Monday, 6 is Sunday.
+
+   .. versionadded:: 3.11
+
+
 .. function:: getdefaultlocale([envvars])
 
    Tries to determine the default locale settings and returns them as a tuple of

diff --git a/Lib/test/test_locale.py b/Lib/test/test_locale.py
@@ -3,6 +3,7 @@
 from test.support.warnings_helper import check_warnings
 import unittest
 import locale
+import platform
 import sys
 import codecs
 
@@ -583,6 +584,30 @@ def test_invalid_iterable_in_localetuple(self):
             locale.setlocale(locale.LC_ALL, (b'not', b'valid'))
 
 
+class TestGetFirstWeekDay(BaseLocalizedTest):
+
+    locale_type = locale.LC_TIME
+
+    def test_getfirstweekday(self):
+        if platform.libc_ver()[0] == 'glibc':
+            self.assertEqual(locale.getfirstweekday(), 0)
+        elif platform.system() == 'Windows':
+            self.assertEqual(locale.getfirstweekday(), 6)
+        else:
+            self.assertEqual(locale.getfirstweekday(), None)
+
+    @unittest.skipUnless(
+        platform.libc_ver()[0] == 'glibc'
+        or platform.system() == 'Windows',
+        "Implemented and modifiable only with glibc or on Windows")
+    def test_getfirstweekday_fr(self):
+        try:
+            locale.setlocale(self.locale_type, 'fr_FR')
+        except locale.Error:
+            self.skipTest('test needs fr_FR locale')
+        self.assertEqual(locale.getfirstweekday(), 1)
+
+
 class BaseDelocalizeTest(BaseLocalizedTest):
 
     def _test_delocalize(self, value, out):

diff --git a/Misc/NEWS.d/next/Library/2020-01-23-13-05-44.bpo-17659.UfyH00.rst b/Misc/NEWS.d/next/Library/2020-01-23-13-05-44.bpo-17659.UfyH00.rst
@@ -0,0 +1,2 @@
+Provide a :func:`locale.getfirstweekday()` function, which returns the integer
+of the first day of week.
diff --git a/Modules/_localemodule.c b/Modules/_localemodule.c
@@ -623,6 +623,45 @@ _locale_nl_langinfo_impl(PyObject *module, int item)
 }
 #endif /* HAVE_LANGINFO_H */
 
+PyDoc_STRVAR(getfirstweekday__doc__,
+"getfirstweekday() -> integer\n"
+"Return the first day of week. 0 is Monday, 6 is Sunday and None is unknown");
+
+static PyObject*
+PyLocale_getfirstweekday(PyObject* self, PyObject* args)
+{
+    int start = -1;
+#if defined(MS_WINDOWS)
+    char locale[1];
+
+    if (!GetLocaleInfo(LOCALE_USER_DEFAULT,
+                       LOCALE_IFIRSTDAYOFWEEK,
+                       locale, sizeof(locale))) {
+        start = (locale[0] - '0') % 7;
+    }
+#elif defined(HAVE__NL_TIME_FIRST_WEEKDAY)
+    int first_weekday = nl_langinfo(_NL_TIME_FIRST_WEEKDAY)[0];
+    long week_1stday = (long)nl_langinfo(_NL_TIME_WEEK_1STDAY);
+    /* Magic constant is defined by glibc as the third value of the week
+     * keyword of LC_TIME */
+    switch (week_1stday) {
+    default:
+    case 19971130:
+        week_1stday = 0;
+        break;
+    case 19971201:
+        week_1stday = 1;
+        break;
+    }
+    start = (week_1stday + first_weekday - 1) % 7;
+#endif
+    if (0 <= start && start <= 6) {
+        return PyLong_FromLong(start);
+    } else {
+        Py_RETURN_NONE;
+    }
+}
+
 #ifdef HAVE_LIBINTL_H
 
 /*[clinic input]
@@ -801,6 +840,8 @@ static struct PyMethodDef PyLocale_Methods[] = {
 #ifdef HAVE_LANGINFO_H
     _LOCALE_NL_LANGINFO_METHODDEF
 #endif
+  {"getfirstweekday", (PyCFunction) PyLocale_getfirstweekday,
+   METH_NOARGS, getfirstweekday__doc__},
 #ifdef HAVE_LIBINTL_H
     _LOCALE_GETTEXT_METHODDEF
     _LOCALE_DGETTEXT_METHODDEF

@@ -19197,6 +19197,45 @@ then
 
 $as_echo "#define HAVE_STAT_TV_NSEC2 1" >>confdefs.h
 
+fi
+
+# checking for glibc extensions to langinfo.h
+#  _NL_TIME_FIRST_WEEKDAY isn't #define'd, so test it directly
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for _NL_TIME_FIRST_WEEKDAY" >&5
+$as_echo_n "checking for _NL_TIME_FIRST_WEEKDAY... " >&6; }
+if ${ac_cv_have__nl_time_first_weekday+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <langinfo.h>
+int
+main ()
+{
+
+    return !!nl_langinfo(_NL_TIME_FIRST_WEEKDAY);
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  ac_cv_have__nl_time_first_weekday=yes
+else
+  ac_cv_have__nl_time_first_weekday=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_have__nl_time_first_weekday" >&5
+$as_echo "$ac_cv_have__nl_time_first_weekday" >&6; }
+if test "x$ac_cv_have__nl_time_first_weekday" = xyes; then :
+
+
+$as_echo "#define HAVE__NL_TIME_FIRST_WEEKDAY 1" >>confdefs.h
+
+
 fi
 
 # first curses header check

@@ -5476,6 +5476,18 @@ then
   [Define if you have struct stat.st_mtimensec])
 fi
 
+# checking for glibc extensions to langinfo.h
+#  _NL_TIME_FIRST_WEEKDAY isn't #define'd, so test it directly
+AC_CACHE_CHECK([for _NL_TIME_FIRST_WEEKDAY], [ac_cv_have__nl_time_first_weekday], [
+  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <langinfo.h>], [
+    return !!nl_langinfo(_NL_TIME_FIRST_WEEKDAY);
+    ])], [ac_cv_have__nl_time_first_weekday=yes], [ac_cv_have__nl_time_first_weekday=no])
+])
+AS_VAR_IF([ac_cv_have__nl_time_first_weekday], [yes], [
+    AC_DEFINE(HAVE__NL_TIME_FIRST_WEEKDAY, 1,
+    [Define if you have _NL_TIME_FIRST_WEEKDAY in langinfo.h])
+])
+
 # first curses header check
 ac_save_cppflags="$CPPFLAGS"
 if test "$cross_compiling" = no; then

diff --git a/pyconfig.h.in b/pyconfig.h.in
@@ -1426,6 +1426,9 @@
 /* Define to 1 if you have the `_getpty' function. */
 #undef HAVE__GETPTY
 
+/* Define if you have _NL_TIME_FIRST_WEEKDAY in langinfo.h */
+#undef HAVE__NL_TIME_FIRST_WEEKDAY
+
 /* Define to 1 if `major', `minor', and `makedev' are declared in <mkdev.h>.
    */
 #undef MAJOR_IN_MKDEV
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Provide a :func:`locale.getfirstweekday()` function, which returns the integer
		of the first day of week.