fix #218: consider locale while serialization

.github/workflows/main.yml

@@ -20,6 +20,7 @@ jobs:
             sudo apt-add-repository ppa:ubuntu-toolchain-r/test
             sudo apt-get update
             sudo apt-get install libboost-test-dev
+            sudo apt-get install language-pack-fr # test serializer w/ locale
             sudo apt-get install ${{ matrix.compiler }}
       - name: Configure
         run: |
@@ -48,6 +49,7 @@ jobs:
             sudo apt-add-repository ppa:ubuntu-toolchain-r/test
             sudo apt-get update
             sudo apt-get install libboost-test-dev
+            sudo apt-get install language-pack-fr # test serializer w/ locale
             sudo apt-get install clang-${{ matrix.compiler }}
       - name: Configure
         run: |
@@ -80,6 +82,7 @@ jobs:
             sudo apt-add-repository ppa:mhier/libboost-latest
             sudo apt-get update
             sudo apt-get install boost1.70
+            sudo apt-get install language-pack-fr # test serializer w/ locale
             sudo apt-get install ${{ matrix.compiler }}
       - name: Configure
         run: |
@@ -119,6 +122,7 @@ jobs:
             sudo apt-add-repository ppa:mhier/libboost-latest
             sudo apt-get update
             sudo apt-get install boost1.70
+            sudo apt-get install language-pack-fr # test serializer w/ locale
             sudo apt-get install clang-${{ matrix.compiler }}
       - name: Configure
         run: |
@@ -216,7 +220,6 @@ jobs:
       - name: Test
         working-directory: ./build
         run: |
-            ./tests/test_literals --log_level=all
             file --mime-encoding tests/toml/tests/example.toml
             file --mime-encoding tests/toml/tests/fruit.toml
             file --mime-encoding tests/toml/tests/hard_example.toml

tests/test_serialize_file.cpp

@@ -8,6 +8,8 @@
 #include <map>
 #include <sstream>
 
+#include <clocale>
+
 template<typename Comment,
          template<typename ...> class Table,
          template<typename ...> class Array>
@@ -357,3 +359,47 @@ array_of_table = [
     BOOST_TEST(parsed.at("array_of_table").at(0).comments().size()  == 1u);
     BOOST_TEST(parsed.at("array_of_table").at(0).comments().front() == " comment about the first element (table)");
 }
+
+
+BOOST_AUTO_TEST_CASE(test_serialize_under_locale)
+{
+    // avoid null init (setlocale returns null when it failed)
+    std::string setloc(std::setlocale(LC_ALL, nullptr));
+
+    // fr_FR is a one of locales that uses `,` as a decimal separator.
+    if(const char* try_hyphen = std::setlocale(LC_ALL, "fr_FR.UTF-8"))
+    {
+        setloc = std::string(try_hyphen);
+    }
+    else if(const char* try_nohyphen = std::setlocale(LC_ALL, "fr_FR.utf8"))
+    {
+        setloc = std::string(try_nohyphen);
+    }
+    // In some envs, fr_FR locale has not been installed. Tests must work even in such a case.
+//     else
+//     {
+//         BOOST_TEST(false);
+//     }
+    BOOST_TEST_MESSAGE("current locale at the beginning of the test = " << setloc);
+
+    const std::string str = R"(
+pi        = 3.14159
+large_int = 1234567890
+)";
+    std::istringstream iss(str);
+    const auto ref = toml::parse(iss);
+    const auto serialized_str = toml::format(ref, /*width = */ 80);
+
+    BOOST_TEST_MESSAGE("serialized = " << serialized_str);
+
+    std::istringstream serialized_iss(serialized_str);
+    const auto serialized_ref = toml::parse(serialized_iss);
+
+    BOOST_TEST(serialized_ref.at("pi").as_floating() == ref.at("pi").as_floating());
+    BOOST_TEST(serialized_ref.at("large_int").as_integer() == ref.at("large_int").as_integer());
+
+    const std::string endloc(std::setlocale(LC_ALL, nullptr));
+    BOOST_TEST_MESSAGE("current locale at the end of the test = " << endloc);
+    // check if serializer change global locale
+    BOOST_TEST(setloc == endloc);
+}

toml/serializer.hpp

@@ -7,6 +7,14 @@
 
 #include <limits>
 
+#if defined(_WIN32)
+#include <locale.h>
+#elif defined(__APPLE__) || defined(__FreeBSD__)
+#include <xlocale.h>
+#elif defined(__linux__)
+#include <locale.h>
+#endif
+
 #include "lexer.hpp"
 #include "value.hpp"
 
@@ -120,7 +128,31 @@ struct serializer
     }
     std::string operator()(const integer_type i) const
     {
-        return std::to_string(i);
+#if defined(_WIN32)
+        _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);
+        const std::string original_locale(setlocale(LC_NUMERIC, nullptr));
+        setlocale(LC_NUMERIC, "C");
+#elif defined(__APPLE__) || defined(__FreeBSD__) || defined(__linux__)
+        const auto c_locale = newlocale(LC_NUMERIC_MASK, "C", locale_t(0));
+        locale_t original_locale(0);
+        if(c_locale != locale_t(0))
+        {
+            original_locale = uselocale(c_locale);
+        }
+#endif
+
+        const auto str = std::to_string(i);
+
+#if defined(_WIN32)
+        setlocale(LC_NUMERIC, original_locale.c_str());
+        _configthreadlocale(_DISABLE_PER_THREAD_LOCALE);
+#elif defined(__APPLE__) || defined(__FreeBSD__) || defined(__linux__)
+        if(original_locale != locale_t(0))
+        {
+            uselocale(original_locale);
+        }
+#endif
+        return str;
     }
     std::string operator()(const floating_type f) const
     {
@@ -147,12 +179,40 @@ struct serializer
             }
         }
 
+        // set locale to "C".
+        // To make it thread-local, we use OS-specific features.
+        // If we set process-global locale, it can break other thread that also
+        // outputs something simultaneously.
+#if defined(_WIN32)
+        _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);
+        const std::string original_locale(setlocale(LC_NUMERIC, nullptr));
+        setlocale(LC_NUMERIC, "C");
+#elif defined(__APPLE__) || defined(__FreeBSD__) || defined(__linux__)
+        const auto c_locale = newlocale(LC_NUMERIC_MASK, "C", locale_t(0));
+        locale_t original_locale(0);
+        if(c_locale != locale_t(0))
+        {
+            original_locale = uselocale(c_locale);
+        }
+#endif
+
         const auto fmt = "%.*g";
         const auto bsz = std::snprintf(nullptr, 0, fmt, this->float_prec_, f);
         // +1 for null character(\0)
         std::vector<char> buf(static_cast<std::size_t>(bsz + 1), '\0');
         std::snprintf(buf.data(), buf.size(), fmt, this->float_prec_, f);
 
+        // restore the original locale
+#if defined(_WIN32)
+        setlocale(LC_NUMERIC, original_locale.c_str());
+        _configthreadlocale(_DISABLE_PER_THREAD_LOCALE);
+#elif defined(__APPLE__) || defined(__FreeBSD__) || defined(__linux__)
+        if(original_locale != locale_t(0))
+        {
+            uselocale(original_locale);
+        }
+#endif
+
         std::string token(buf.begin(), std::prev(buf.end()));
         if(!token.empty() && token.back() == '.') // 1. => 1.0
         {