reset locale (for #272)

src/json.hpp

@@ -5658,10 +5658,13 @@ class basic_json
         // reset width to 0 for subsequent calls to this stream
         o.width(0);
         // fix locale problems
-        o.imbue(std::locale(std::locale(), new DecimalSeparator));
+        auto old_locale = o.imbue(std::locale(std::locale(), new DecimalSeparator));
 
         // do the actual serialization
         j.dump(o, pretty_print, static_cast<unsigned int>(indentation));
+
+        // reset locale
+        o.imbue(old_locale);
         return o;
     }
 

src/json.hpp.re2c

@@ -5658,10 +5658,13 @@ class basic_json
         // reset width to 0 for subsequent calls to this stream
         o.width(0);
         // fix locale problems
-        o.imbue(std::locale(std::locale(), new DecimalSeparator));
+        auto old_locale = o.imbue(std::locale(std::locale(), new DecimalSeparator));
 
         // do the actual serialization
         j.dump(o, pretty_print, static_cast<unsigned int>(indentation));
+
+        // reset locale
+        o.imbue(old_locale);
         return o;
     }
 

test/src/unit.cpp

@@ -14079,9 +14079,15 @@ TEST_CASE("regression tests")
         CHECK(j1a.dump() == "23.42");
         CHECK(j1b.dump() == "23.42");
 
+        // check if locale is properly reset
         std::stringstream ss;
+        ss.imbue(std::locale(std::locale(), new CommaDecimalSeparator));
+        ss << 47.11;
+        CHECK(ss.str() == "47,11");
         ss << j1a;
-        CHECK(ss.str() == "23.42");
+        CHECK(ss.str() == "47,1123.42");
+        ss << 47.11;
+        CHECK(ss.str() == "47,1123.4247,11");
 
         CHECK(j2a.dump() == "23.42");
         //issue #230