chore: respect previously set game when including additional zone files

src/ZoneCommon/Zone/Definition/ZoneDefinitionStream.h

@@ -1,33 +1,34 @@
 #pragma once
+
+#include "Game/IGame.h"
 #include "Parsing/IParserLineStream.h"
 #include "ZoneDefinition.h"
 
 #include <iostream>
 #include <memory>
+#include <optional>
 
 class ZoneDefinitionInputStream
 {
-    static constexpr const char* ZONE_CODE_GENERATOR_DEFINE_NAME = "__zonecodegenerator";
-    static constexpr const char* ZONE_CODE_GENERATOR_DEFINE_VALUE = "1";
+public:
+    ZoneDefinitionInputStream(std::istream& stream, std::string fileName, bool verbose);
+
+    void SetPreviouslySetGame(GameId game);
+    std::unique_ptr<ZoneDefinition> ReadDefinition();
+
+private:
+    bool OpenBaseStream(std::istream& stream);
+    void SetupStreamProxies();
 
     std::string m_file_name;
     bool m_verbose;
     IParserLineStream* m_stream;
     std::vector<std::unique_ptr<IParserLineStream>> m_open_streams;
-
-    bool OpenBaseStream(std::istream& stream);
-    void SetupStreamProxies();
-
-public:
-    ZoneDefinitionInputStream(std::istream& stream, std::string fileName, bool verbose);
-
-    std::unique_ptr<ZoneDefinition> ReadDefinition();
+    std::optional<GameId> m_previously_set_game;
 };
 
 class ZoneDefinitionOutputStream
 {
-    std::ostream& m_stream;
-
 public:
     explicit ZoneDefinitionOutputStream(std::ostream& stream);
 
@@ -35,4 +36,7 @@ public:
     void WriteComment(const std::string& comment) const;
     void WriteMetaData(const std::string& metaDataKey, const std::string& metaDataValue) const;
     void WriteEntry(const std::string& entryKey, const std::string& entryValue) const;
+
+private:
+    std::ostream& m_stream;
 };