drop scoped enum, for pre-C++11 compatibility

Author: cdunn2001

include/json/writer.h

@@ -41,11 +41,14 @@ class JSON_API StreamWriter {
 protected:
   std::ostream& sout_;  // not owned; will not delete
 public:
-  /// Decide whether to write comments.
-  enum class CommentStyle {
-    None,  ///< Drop all comments.
-    Most,  ///< Recover odd behavior of previous versions (not implemented yet).
-    All  ///< Keep all comments.
+  /// Scoped enums are not available until C++11.
+  struct CommentStyle {
+    /// Decide whether to write comments.
+    enum Enum {
+      None,  ///< Drop all comments.
+      Most,  ///< Recover odd behavior of previous versions (not implemented yet).
+      All  ///< Keep all comments.
+    };
   };
 
   /// Keep a reference, but do not take ownership of `sout`.
@@ -92,7 +95,7 @@ class JSON_API StreamWriterBuilder : public StreamWriter::Factory {
   /** \brief How to write comments.
    * Default: All
    */
-  StreamWriter::CommentStyle cs_;
+  StreamWriter::CommentStyle::Enum cs_;
   /** \brief Write in human-friendly style.
 
       If "", then skip all indentation and newlines.

src/lib_json/json_writer.cpp

@@ -673,7 +673,7 @@ struct BuiltStyledStreamWriter : public StreamWriter
   BuiltStyledStreamWriter(
       std::ostream* sout,
       std::string const& indentation,
-      StreamWriter::CommentStyle cs,
+      StreamWriter::CommentStyle::Enum cs,
       std::string const& colonSymbol,
       std::string const& nullSymbol,
       std::string const& endingLineFeedSymbol);
@@ -697,7 +697,7 @@ struct BuiltStyledStreamWriter : public StreamWriter
   std::string indentString_;
   int rightMargin_;
   std::string indentation_;
-  CommentStyle cs_;
+  CommentStyle::Enum cs_;
   std::string colonSymbol_;
   std::string nullSymbol_;
   std::string endingLineFeedSymbol_;
@@ -707,7 +707,7 @@ struct BuiltStyledStreamWriter : public StreamWriter
 BuiltStyledStreamWriter::BuiltStyledStreamWriter(
       std::ostream* sout,
       std::string const& indentation,
-      StreamWriter::CommentStyle cs,
+      StreamWriter::CommentStyle::Enum cs,
       std::string const& colonSymbol,
       std::string const& nullSymbol,
       std::string const& endingLineFeedSymbol)