source: orxonox.OLD/trunk/src/lib/script_engine/lunar.h

#ifndef _LUNAR_H
#define _LUNAR_H

#include <string>
#include <cassert>
#include "script.h"

#include "luaincl.h"
#include "script_method.h"



template <typename T> class Lunar
{
  typedef struct { T *pT; }
  userdataType;
public:
  typedef Executor<lua_State*>* mfp;
  typedef struct { const char *name; mfp mfunc; }
  RegType;


  static void Register(Script* script, const std::string& className, const ScriptMethod* scriptMethods)
  {
    if(script != NULL)
      Register(script->getLuaState(), className, scriptMethods);
  }

  static void Register(lua_State *L, const std::string& className, const ScriptMethod* scriptMethods)
  {
    Lunar<T>::className = className;
    Lunar<T>::scriptMethods = scriptMethods;
    lua_newtable(L);
    int methods = lua_gettop(L);

    luaL_newmetatable(L, Lunar<T>::className.c_str());
    int metatable = lua_gettop(L);

    // store method table in globals so that
    // scripts can add functions written in Lua.
    lua_pushvalue(L, methods);
    set(L, LUA_GLOBALSINDEX, Lunar<T>::className.c_str());

    // hide metatable from Lua getmetatable()
    lua_pushvalue(L, methods);
    set(L, metatable, "__metatable");

    lua_pushvalue(L, methods);
    set(L, metatable, "__index");

    lua_pushcfunction(L, tostring_T);
    set(L, metatable, "__tostring");

    lua_pushcfunction(L, gc_T);
    set(L, metatable, "__gc");

    lua_newtable(L);                // mt for method table
    lua_pushcfunction(L, new_T);
    lua_pushvalue(L, -1);           // dup new_T function
    set(L, methods, "new");         // add new_T to method table
    set(L, -3, "__call");           // mt.__call = new_T
    lua_setmetatable(L, methods);

    // fill method table with methods from class T
    /* as it was originally
    for (RegType *l = T::methods; l->name; l++)
    {
      lua_pushstring(L, l->name);
      lua_pushlightuserdata(L, (void*)l);
      lua_pushcclosure(L, thunk, 1);
      lua_settable(L, methods);
  }*/
    for (unsigned int i = 0; i < Lunar<T>::scriptMethods->size(); i++)
    {
      lua_pushstring(L, Lunar<T>::scriptMethods->name(i).c_str());
      lua_pushlightuserdata(L, (void*)Lunar<T>::scriptMethods->executor(i));
      lua_pushcclosure(L, thunk, 1);
      lua_settable(L, methods);
    }
    lua_pop(L, 2);  // drop metatable and method table
  }

  // call named lua method from userdata method table
  static int call(lua_State *L, const char *method,
                  int nargs=0, int nresults=LUA_MULTRET, int errfunc=0)
  {
    int base = lua_gettop(L) - nargs;  // userdata index
    if (!luaL_checkudata(L, base, Lunar<T>::className.c_str()))
    {
      lua_settop(L, base-1);           // drop userdata and args
      lua_pushfstring(L, "not a valid %s userdata", Lunar<T>::className.c_str());
      return -1;
    }

    lua_pushstring(L, method);         // method name
    lua_gettable(L, base);             // get method from userdata
    if (lua_isnil(L, -1))
    {            // no method?
      lua_settop(L, base-1);           // drop userdata and args
      lua_pushfstring(L, "%s missing method '%s'", Lunar<T>::className.c_str(), method);
      return -1;
    }
    lua_insert(L, base);               // put method under userdata, args

    int status = lua_pcall(L, 1+nargs, nresults, errfunc);  // call method
    if (status)
    {
      const char *msg = lua_tostring(L, -1);
      if (msg == NULL) msg = "(error with no message)";
      lua_pushfstring(L, "%s:%s status = %d\n%s",
                      Lunar<T>::className.c_str(), method, status, msg);
      lua_remove(L, base);             // remove old message
      return -1;
    }
    return lua_gettop(L) - base + 1;   // number of results
  }

  // push onto the Lua stack a userdata containing a pointer to T object
  static int push(lua_State *L, T *obj, bool gc=false)
  {
    if (!obj) { lua_pushnil(L); return 0; }
    luaL_getmetatable(L, Lunar<T>::className.c_str());  // lookup metatable in Lua registry
    if (lua_isnil(L, -1)) luaL_error(L, "%s missing metatable", Lunar<T>::className.c_str());
    int mt = lua_gettop(L);
    subtable(L, mt, "userdata", "v");
    userdataType *ud =
      static_cast<userdataType*>(pushuserdata(L, obj, sizeof(userdataType)));
    if (ud)
    {
      ud->pT = obj;  // store pointer to object in userdata
      lua_pushvalue(L, mt);
      lua_setmetatable(L, -2);
      if (gc == false)
      {
        lua_checkstack(L, 3);
        subtable(L, mt, "do not trash", "k");
        lua_pushvalue(L, -2);
        lua_pushboolean(L, 1);
        lua_settable(L, -3);
        lua_pop(L, 1);
      }
    }
    lua_replace(L, mt);
    lua_settop(L, mt);
    return mt;  // index of userdata containing pointer to T object
  }


  static int insertObject(lua_State* L, T* obj, const std::string& name, bool gc=false)
  {
    int objectRef = push(L, obj, gc);

    lua_pushlstring(L, name.c_str(), name.size());
    lua_pushvalue(L, objectRef );
    lua_settable(L, LUA_GLOBALSINDEX );

    return objectRef;
  }


  static int insertObject(Script* script, T* obj, const std::string& name, bool gc=false)
  {
    assert (script != NULL);
    return insertObject(script->getLuaState(), obj, name, gc);
  }

  // get userdata from Lua stack and return pointer to T object
  static T *check(lua_State *L, int narg)
  {
    userdataType *ud =
      static_cast<userdataType*>(luaL_checkudata(L, narg, Lunar<T>::className.c_str()));
    if(!ud) luaL_typerror(L, narg, Lunar<T>::className.c_str());
    return ud->pT;  // pointer to T object
  }

private:
  Lunar();  // hide default constructor

  // member function dispatcher
  static int thunk(lua_State *L)
  {
    // stack has userdata, followed by method args
    T *obj = check(L, 1);  // get 'self', or if you prefer, 'this'
    lua_remove(L, 1);  // remove self so member function args start at index 1
    // get member function from upvalue
    mfp l = static_cast<mfp>(lua_touserdata(L, lua_upvalueindex(1)));
    (*l)(obj, L);  // call member function
    return l->hasRetVal()? 1 : 0;
  }

  // create a new T object and
  // push onto the Lua stack a userdata containing a pointer to T object
  static int new_T(lua_State *L)
  {
    lua_remove(L, 1);   // use classname:new(), instead of classname.new()
    T *obj = new T();  // call constructor for T objects
    push(L, obj, true); // gc_T will delete this object
    return 1;           // userdata containing pointer to T object
  }

  // garbage collection metamethod
  static int gc_T(lua_State *L)
  {
    if (luaL_getmetafield(L, 1, "do not trash"))
    {
      lua_pushvalue(L, 1);  // dup userdata
      lua_gettable(L, -2);
      if (!lua_isnil(L, -1)) return 0;  // do not delete object
    }
    userdataType *ud = static_cast<userdataType*>(lua_touserdata(L, 1));
    T *obj = ud->pT;
    if (obj) delete obj;  // call destructor for T objects
    return 0;
  }

  static int tostring_T (lua_State *L)
  {
    char buff[32];
    userdataType *ud = static_cast<userdataType*>(lua_touserdata(L, 1));
    T *obj = ud->pT;
    sprintf(buff, "%p", obj);
    lua_pushfstring(L, "%s (%s)", Lunar<T>::className.c_str(), buff);
    return 1;
  }

  static void set(lua_State *L, int table_index, const char *key)
  {
    lua_pushstring(L, key);
    lua_insert(L, -2);  // swap value and key
    lua_settable(L, table_index);
  }

  static void weaktable(lua_State *L, const char *mode)
  {
    lua_newtable(L);
    lua_pushvalue(L, -1);  // table is its own metatable
    lua_setmetatable(L, -2);
    lua_pushliteral(L, "__mode");
    lua_pushstring(L, mode);
    lua_settable(L, -3);   // metatable.__mode = mode
  }

  static void subtable(lua_State *L, int tindex, const char *name, const char *mode)
  {
    lua_pushstring(L, name);
    lua_gettable(L, tindex);
    if (lua_isnil(L, -1))
    {
      lua_pop(L, 1);
      lua_checkstack(L, 3);
      weaktable(L, mode);
      lua_pushstring(L, name);
      lua_pushvalue(L, -2);
      lua_settable(L, tindex);
    }
  }

  static void *pushuserdata(lua_State *L, void *key, size_t sz)
  {
    void *ud = 0;
    lua_pushlightuserdata(L, key);
    lua_gettable(L, -2);     // lookup[key]
    if (lua_isnil(L, -1))
    {
      lua_pop(L, 1);         // drop nil
      lua_checkstack(L, 3);
      ud = lua_newuserdata(L, sz);  // create new userdata
      lua_pushlightuserdata(L, key);
      lua_pushvalue(L, -2);  // dup userdata
      lua_settable(L, -4);   // lookup[key] = userdata
    }
    return ud;
  }

  private:
    static std::string className;
    static const ScriptMethod* scriptMethods;
};

template <typename T>
    std::string Lunar<T>::className = "";
template <typename T>
    const ScriptMethod* Lunar<T>::scriptMethods = NULL;

#endif /* _LUNAR_H */