[1611376]writer now escapes special characters. When no special chars are present, old behavior is retained. New method might have a performance penalty b/c of operator new inside std::string. (This would not exist if the whole thing operated on ostream instead, I think.)

src/lib_json/json_reader.cpp

@@ -560,6 +560,7 @@ Reader::decodeString( Token &token, std::string &decoded )
                if ( !decodeUnicodeEscapeSequence( token, current, end, unicode ) )
                   return false;
                // @todo encode unicode as utf8.
+	       // @todo remember to alter the writer too.
             }
             break;
          default:

src/lib_json/json_writer.cpp

@@ -64,7 +64,45 @@ std::string valueToString( bool value )
 
 std::string valueToQuotedString( const char *value )
 {
-   return std::string("\"") + value + "\"";
+   // Not sure how to handle unicode...
+   if (std::strpbrk(value, "\"\\\b\f\n\r\t") == NULL)
+      return std::string("\"") + value + "\"";
+   // We have to walk value and escape any special characters.
+   // Appending to std::string is not efficient, but this should be rare.
+   // (Note: forward slashes are *not* rare, but I am not escaping them.)
+   std::string result("\"");
+   for (const char* c=value; *c != 0; ++c){
+      switch(*c){
+         case '\"':
+	 result += "\\\"";
+	 break;
+	 case '\\':
+	 result += "\\\\";
+	 break;
+	 case '\b':
+	 result += "\\b";
+	 break;
+	 case '\f':
+	 result += "\\f";
+	 break;
+	 case '\n':
+	 result += "\\n";
+	 break;
+	 case '\r':
+	 result += "\\r";
+	 break;
+	 case '\t':
+	 result += "\\t";
+	 break;
+	 case '/':
+	 // Even though \/ is considered a legal escape in JSON, a bare
+	 // slash is also legal, so I see no reason to escape it.
+	 // (I hope I am not misunderstanding something.)
+	 default:
+	    result += *c;
+      }
+   }
+   return result + "\"";
 }
 
 // Class Writer