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livetrax/libs/pbd/locale_guard.cc

132 lines
4.8 KiB
C++

/*
Copyright (C) 2012 Paul Davis
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <locale.h>
#include "pbd/compose.h"
#include "pbd/debug.h"
#include "pbd/error.h"
#include "pbd/locale_guard.h"
using namespace PBD;
/* Neither C nor C++ pick up a user's preferred locale choice without the
* application actively taking steps to make this happen.
*
* For C: setlocale (LC_ALL, "");
* For C++ (assuming that the C version was called):
* std::locale::global (std::locale (setlocale (LC_ALL, 0)));
*
* The application needs to make these calls, probably in main().
*
* Setting the C++ locale will change the C locale, but not the other way 'round.
* and some plugin may change either behind our back.
*/
LocaleGuard::LocaleGuard ()
: old_c_locale (0)
{
/* A LocaleGuard object ensures that the
* LC_NUMERIC/std::locale::numeric aspect of the C and C++ locales are
* set to "C" during its lifetime, so that printf/iostreams use a
* portable format for numeric output (i.e. 1234.5 is always 1234.5 and
* not sometimes 1234,5, as it would be in fr or de locales)
*/
char const * const current_c_locale = setlocale (LC_NUMERIC, 0);
if (strcmp ("C", current_c_locale) != 0) {
old_c_locale = strdup (current_c_locale);
try {
/* set the C++ global/default locale to whatever we are using
* now, but with "C" numeric handling.
*
* this also sets the C locale, so no additional call to setlocale() is required.
*/
std::locale::global (std::locale (old_cpp_locale, "C", std::locale::numeric));
pre_cpp_locale = std::locale();
DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: change C & C++ locale from '%1' => %2\n", old_cpp_locale.name(), pre_cpp_locale.name()));
} catch (...) {
/* Apple in particular have historically done a
* terrible job supporting setlocale and even more so
* with the C++ API. Using any locale other than "C" or
* "POSIX" will fail, and in the case of the C++ API,
* will throw an exception. In that case, just try to
* use setlocale() to reset *only* the numeric aspect
* of the current locale settings back to "C", which is
* likely to work everywhere.
*/
setlocale (LC_NUMERIC, "C");
pre_cpp_locale = std::locale();
DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: C++ locale API failed, change just C locale from '%1' => 'C' (C++ locale is %2)\n", old_c_locale, pre_cpp_locale.name()));
}
}
}
LocaleGuard::~LocaleGuard ()
{
char const * current_c_locale = setlocale (LC_NUMERIC, 0);
std::locale current_cpp_locale;
if (current_cpp_locale != pre_cpp_locale) {
PBD::warning << string_compose ("LocaleGuard: someone (a plugin) changed the C++ locale from\n\t%1\nto\n\t%2\n, expect non-portable session files. Decimal OK ? %2",
old_cpp_locale.name(), current_cpp_locale.name(),
(std::use_facet<std::numpunct<char> >(std::locale()).decimal_point() == '.'))
<< endmsg;
try {
/* this resets C & C++ locales */
std::locale::global (old_cpp_locale);
DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: restore C & C++ locale: '%1'\n", std::locale().name()));
} catch (...) {
/* see comments in the constructor regarding the
* exception.
*
* This should restore restore numeric handling back to
* the default (which may reflect user
* preferences). This probably can't fail, because
* old_c_locale was already in use during the
* constructor for this object.
*
* Still ... Apple ... locale support ... just sayin' ....
*/
setlocale (LC_NUMERIC, old_c_locale);
DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: C++ locale API failed, restore C locale from %1 to\n'%2'\n(C++ is '%3')\n", current_c_locale, old_c_locale, std::locale().name()));
}
} else if (old_c_locale && (strcmp (current_c_locale, old_c_locale) != 0)) {
/* reset only the C locale */
setlocale (LC_NUMERIC, old_c_locale);
DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: restore C locale from %1 to\n'%2'\n(C++ is '%3')\n", current_c_locale, old_c_locale, std::locale().name()));
}
free (const_cast<char*> (old_c_locale));
}