Convert converion to c locale to use C++ locale or C global

Author: mborland

include/boost/decimal/detail/io.hpp

@@ -79,7 +79,7 @@ auto operator>>(std::basic_istream<charT, traits>& is, DecimalType& d)
         std::memcpy(buffer, t_buffer.c_str(), t_buffer.size());
     }
 
-    detail::convert_string_to_c_locale(buffer);
+    detail::convert_string_to_c_locale(buffer, is.getloc());
 
     auto fmt {chars_format::general};
     const auto flags {is.flags()};

include/boost/decimal/detail/locale_conversion.hpp

@@ -15,17 +15,18 @@ namespace boost {
 namespace decimal {
 namespace detail {
 
-inline void convert_string_to_c_locale(char* buffer) noexcept
+inline void convert_string_to_c_locale(char* buffer, const std::locale& loc) noexcept
 {
-    const auto* lconv {std::localeconv()};
-    const auto locale_decimal_point {*lconv->decimal_point};
-    auto locale_thousands_sep {*lconv->thousands_sep};
+    const std::numpunct<char>& np = std::use_facet<std::numpunct<char>>(loc);
+
+    const auto locale_decimal_point {np.decimal_point()};
+    auto locale_thousands_sep {np.thousands_sep()};
     if (locale_thousands_sep == -30)
     {
-        // Locales like french use a space, but thousands_sep does not give a space character
         locale_thousands_sep = ' ';
     }
-    const bool has_grouping {lconv->grouping && lconv->grouping[0] > 0};
+    const bool has_grouping {!np.grouping().empty() && np.grouping()[0] > 0};
+    const int grouping_size {has_grouping ? np.grouping()[0] : 0};
 
     // Remove thousands separator if it exists and grouping is enabled
     if (has_grouping && locale_thousands_sep != '\0')
@@ -73,6 +74,11 @@ inline void convert_string_to_c_locale(char* buffer) noexcept
     }
 }
 
+inline void convert_string_to_c_locale(char* buffer) noexcept
+{
+    convert_string_to_c_locale(buffer, std::locale());
+}
+
 inline int convert_pointer_pair_to_local_locale(char* first, char* last, const std::locale& loc) noexcept
 {
     const std::numpunct<char>& np = std::use_facet<std::numpunct<char>>(loc);