text: #ifndef __LANES_DEEP_H__
  #define __LANES_DEEP_H__ 1
  
  /*
   * public 'deep' API to be used by external modules if they want to implement Lanes-aware userdata
   * said modules will have to link against lanes (it is not really possible to separate the 'deep userdata' implementation from the rest of Lanes)
   */
  
  #include "lua.h"
  #include "platform.h"
  #include "uniquekey.h"
  
  // forwards
  struct s_Universe;
  typedef struct s_Universe Universe;
  
  #if !defined LANES_API // when deep is compiled standalone outside Lanes
  #if (defined PLATFORM_WIN32) || (defined PLATFORM_POCKETPC)
  #define LANES_API __declspec(dllexport)
  #else
  #define LANES_API
  #endif // (defined PLATFORM_WIN32) || (defined PLATFORM_POCKETPC)
  #endif // LANES_API
  
  enum eLookupMode
  {
  	eLM_LaneBody, // send the lane body directly from the source to the destination lane
  	eLM_ToKeeper, // send a function from a lane to a keeper state
  	eLM_FromKeeper // send a function from a keeper state to a lane
  };
  typedef enum eLookupMode LookupMode;
  
  enum eDeepOp
  {
  	eDO_new,
  	eDO_delete,
  	eDO_metatable,
  	eDO_module,
  };
  typedef enum eDeepOp DeepOp;
  
  typedef void* (*luaG_IdFunction)( lua_State* L, DeepOp op_);
  
  // ################################################################################################
  
  // fnv164 of string "DEEP_VERSION_2" generated at https://www.pelock.com/products/hash-calculator
  static DECLARE_CONST_UNIQUE_KEY( DEEP_VERSION, 0xB4B0119C10642B29);
  
  // should be used as header for full userdata
  struct s_DeepPrelude
  {
  	DECLARE_UNIQUE_KEY( magic); // must be filled by the Deep userdata idfunc that allocates it on eDO_new operation
  	// when stored in a keeper state, the full userdata doesn't have a metatable, so we need direct access to the idfunc
  	luaG_IdFunction idfunc;
  	// data is destroyed when refcount is 0
  	volatile int refcount;
  };
  typedef struct s_DeepPrelude DeepPrelude;
  
  char const* push_deep_proxy( Universe* U, lua_State* L, DeepPrelude* prelude, int nuv_, LookupMode mode_);
  void free_deep_prelude( lua_State* L, DeepPrelude* prelude_);
  
  extern LANES_API int luaG_newdeepuserdata( lua_State* L, luaG_IdFunction idfunc, int nuv_);
  extern LANES_API void* luaG_todeep( lua_State* L, luaG_IdFunction idfunc, int index);
  
  #endif // __LANES_DEEP_H__
  