LuaRef.h

Go to the documentation of this file.

//------------------------------------------------------------------------------
/*
  https://github.com/vinniefalco/LuaBridge
 
  Copyright 2012, Vinnie Falco <vinnie.falco@gmail.com>
  Copyright 2008, Nigel Atkinson <suprapilot+LuaCode@gmail.com>
 
  License: The MIT License (http://www.opensource.org/licenses/mit-license.php)
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
 
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
 
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
//==============================================================================
 
//------------------------------------------------------------------------------
struct Nil
{
};
 
//------------------------------------------------------------------------------
class LuaRef
{
private:
  class Proxy;
  friend struct Stack <Proxy>;
 
  //----------------------------------------------------------------------------
  class StackPop
  {
  public:
    StackPop (lua_State* L, int count)
      : m_L (L)
      , m_count (count)
    {
    }
 
    ~StackPop ()
    {
      lua_pop (m_L, m_count);
    }
 
  private:
    lua_State* m_L;
    int m_count;
  };
 
  //----------------------------------------------------------------------------
  class Proxy
  {
  private:
    lua_State* m_L;
    int m_tableRef;
    int m_keyRef;
 
  public:
    //--------------------------------------------------------------------------
    Proxy (lua_State* L, int tableRef)
      : m_L (L)
      , m_tableRef (tableRef)
      , m_keyRef (luaL_ref (L, LUA_REGISTRYINDEX))
    {
    }
 
    //--------------------------------------------------------------------------
    Proxy (Proxy const& other)
      : m_L (other.m_L)
      , m_tableRef (other.m_tableRef)
    {
      // If this assert goes off it means code is taking this path,
      // which is better avoided.
      //
      assert (0);
 
      lua_rawgeti (m_L, LUA_REGISTRYINDEX, other.m_keyRef);
      m_keyRef = luaL_ref (m_L, LUA_REGISTRYINDEX);
    }
 
    //--------------------------------------------------------------------------
    ~Proxy ()
    {
      luaL_unref (m_L, LUA_REGISTRYINDEX, m_keyRef);
    }
 
    //--------------------------------------------------------------------------
    int createRef () const
    {
      push (m_L);
      return luaL_ref (m_L, LUA_REGISTRYINDEX);
    }
 
    //--------------------------------------------------------------------------
    template <class T>
    Proxy& operator= (T v)
    {
      StackPop p (m_L, 1);
      lua_rawgeti (m_L, LUA_REGISTRYINDEX, m_tableRef);
      lua_rawgeti (m_L, LUA_REGISTRYINDEX, m_keyRef);
      Stack <T>::push (m_L, v);
      lua_rawset (m_L, -3);
      return *this;
    }
 
    // the implementation needs UserdataPtr, which
    // is not yet defined here.
    // -> libs/ardour/lua_api.cc
    Proxy& clone_instance (const void* key, void* p);
 
    //--------------------------------------------------------------------------
    template <class T>
    Proxy& rawset (T v)
    {
      StackPop p (m_L, 1);
      lua_rawgeti (m_L, LUA_REGISTRYINDEX, m_tableRef);
      lua_rawgeti (m_L, LUA_REGISTRYINDEX, m_keyRef);
      Stack <T>::push (m_L, v);
      lua_settable (m_L, -3);
      return *this;
    }
 
    //==========================================================================
    //
    // This group of member functions mirrors the member functions in LuaRef.
 
    lua_State* state () const
    {
      return m_L;
    }
 
    //--------------------------------------------------------------------------
    void push (lua_State* L) const
    {
      assert (equalstates (L, m_L));
      lua_rawgeti (L, LUA_REGISTRYINDEX, m_tableRef);
      lua_rawgeti (L, LUA_REGISTRYINDEX, m_keyRef);
      lua_gettable (L, -2);
      lua_remove (L, -2); // remove the table
    }
 
    //--------------------------------------------------------------------------
    int type () const
    {
      int result;
      push (m_L);
      result = lua_type (m_L, -1);
      lua_pop (m_L, 1);
      return result;
    }
 
    inline bool isNil () const { return type () == LUA_TNIL; }
    inline bool isBoolean () const { return type () == LUA_TBOOLEAN; }
    inline bool isNumber () const { return type () == LUA_TNUMBER; }
    inline bool isString () const { return type () == LUA_TSTRING; }
    inline bool isTable () const { return type () == LUA_TTABLE; }
    inline bool isFunction () const { return type () == LUA_TFUNCTION; }
    inline bool isUserdata () const { return type () == LUA_TUSERDATA; }
    inline bool isThread () const { return type () == LUA_TTHREAD; }
    inline bool isLightUserdata () const { return type () == LUA_TLIGHTUSERDATA; }
 
    //--------------------------------------------------------------------------
    template <class T>
    T cast () const
    {
      StackPop p (m_L, 1);
      push (m_L);
 
      // lua_gettop is used because Userdata::getClass() doesn't handle
      // negative stack indexes.
      //
      return Stack <T>::get (m_L, lua_gettop (m_L));
    }
 
    //--------------------------------------------------------------------------
    template <class T>
    inline operator T () const
    {
      return cast <T> ();
    }
 
    //--------------------------------------------------------------------------
    template <class T>
    bool operator== (T rhs) const
    {
      StackPop p (m_L, 2);
      push (m_L);
      Stack <T>::push (m_L, rhs);
      return lua_compare (m_L, -2, -1, LUA_OPEQ) == 1;
    }
 
    template <class T>
    bool operator< (T rhs) const
    {
      StackPop p (m_L, 2);
      push (m_L);
      Stack <T>::push (m_L, rhs);
      return lua_compare (m_L, -2, -1, LUA_OPLT) == 1;
    }
 
    template <class T>
    bool operator<= (T rhs) const
    {
      StackPop p (m_L, 2);
      push (m_L);
      Stack <T>::push (m_L, rhs);
      return lua_compare (m_L, -2, -1, LUA_OPLE) == 1;
    }
 
    template <class T>
    bool operator> (T rhs) const
    {
      StackPop p (m_L, 2);
      push (m_L);
      Stack <T>::push (m_L, rhs);
      return lua_compare (m_L, -1, -2, LUA_OPLT) == 1;
    }
 
    template <class T>
    bool operator>= (T rhs) const
    {
      StackPop p (m_L, 2);
      push (m_L);
      Stack <T>::push (m_L, rhs);
      return lua_compare (m_L, -1, -2, LUA_OPLE) == 1;
    }
 
    template <class T>
    bool rawequal (T rhs) const
    {
      StackPop p (m_L, 2);
      push (m_L);
      Stack <T>::push (m_L, rhs);
      return lua_rawequal (m_L, -1, -2) == 1;
    }
    //--------------------------------------------------------------------------
    template <class T>
    Proxy operator[] (T key) const
    {
      return LuaRef (*this) [key];
    }
 
    //--------------------------------------------------------------------------
    template <class T>
    LuaRef rawget (T key) const
    {
      StackPop (m_L, 1);
      push (m_L);
      Stack <T>::push (m_L, key);
      lua_rawget (m_L, -2);
      return LuaRef (m_L, FromStack ());
    }
 
    //--------------------------------------------------------------------------
    template <class T>
    void append (T v) const
    {
      push (m_L);
      Stack <T>::push (m_L, v);
      luaL_ref (m_L, -2);
      lua_pop (m_L, 1);
    }
 
    //--------------------------------------------------------------------------
    int length () const
    {
      StackPop p (m_L, 1);
      push (m_L);
      return get_length (m_L, -1);
    }
 
    //--------------------------------------------------------------------------
    LuaRef const operator() () const
    {
      push (m_L);
      LuaException::pcall (m_L, 0, 1);
      return LuaRef (m_L, FromStack ());
    }
 
    template <class P1>
    LuaRef const operator() (P1 p1) const
    {
      push (m_L);
      Stack <P1>::push (m_L, p1);
      LuaException::pcall (m_L, 1, 1);
      return LuaRef (m_L, FromStack ());
    }
 
    template <class P1, class P2>
    LuaRef const operator() (P1 p1, P2 p2) const
    {
      push (m_L);
      Stack <P1>::push (m_L, p1);
      Stack <P2>::push (m_L, p2);
      LuaException::pcall (m_L, 2, 1);
      return LuaRef (m_L, FromStack ());
    }
 
    template <class P1, class P2, class P3>
    LuaRef const operator() (P1 p1, P2 p2, P3 p3) const
    {
      push (m_L);
      Stack <P1>::push (m_L, p1);
      Stack <P2>::push (m_L, p2);
      Stack <P3>::push (m_L, p3);
      LuaException::pcall (m_L, 3, 1);
      return LuaRef (m_L, FromStack ());
    }
 
    template <class P1, class P2, class P3, class P4>
    LuaRef const operator() (P1 p1, P2 p2, P3 p3, P4 p4) const
    {
      push (m_L);
      Stack <P1>::push (m_L, p1);
      Stack <P2>::push (m_L, p2);
      Stack <P3>::push (m_L, p3);
      Stack <P4>::push (m_L, p4);
      LuaException::pcall (m_L, 4, 1);
      return LuaRef (m_L, FromStack ());
    }
 
    template <class P1, class P2, class P3, class P4, class P5>
    LuaRef const operator() (P1 p1, P2 p2, P3 p3, P4 p4, P5 p5) const
    {
      push (m_L);
      Stack <P1>::push (m_L, p1);
      Stack <P2>::push (m_L, p2);
      Stack <P3>::push (m_L, p3);
      Stack <P4>::push (m_L, p4);
      Stack <P5>::push (m_L, p5);
      LuaException::pcall (m_L, 5, 1);
      return LuaRef (m_L, FromStack ());
    }
 
    template <class P1, class P2, class P3, class P4, class P5, class P6>
    LuaRef const operator() (P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6) const
    {
      push (m_L);
      Stack <P1>::push (m_L, p1);
      Stack <P2>::push (m_L, p2);
      Stack <P3>::push (m_L, p3);
      Stack <P4>::push (m_L, p4);
      Stack <P5>::push (m_L, p5);
      Stack <P6>::push (m_L, p6);
      LuaException::pcall (m_L, 6, 1);
      return LuaRef (m_L, FromStack ());
    }
 
    template <class P1, class P2, class P3, class P4, class P5, class P6, class P7>
    LuaRef const operator() (P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7) const
    {
      push (m_L);
      Stack <P1>::push (m_L, p1);
      Stack <P2>::push (m_L, p2);
      Stack <P3>::push (m_L, p3);
      Stack <P4>::push (m_L, p4);
      Stack <P5>::push (m_L, p5);
      Stack <P6>::push (m_L, p6);
      Stack <P7>::push (m_L, p7);
      LuaException::pcall (m_L, 7, 1);
      return LuaRef (m_L, FromStack ());
    }
 
    template <class P1, class P2, class P3, class P4, class P5, class P6, class P7, class P8>
    LuaRef const operator() (P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8) const
    {
      push (m_L);
      Stack <P1>::push (m_L, p1);
      Stack <P2>::push (m_L, p2);
      Stack <P3>::push (m_L, p3);
      Stack <P4>::push (m_L, p4);
      Stack <P5>::push (m_L, p5);
      Stack <P6>::push (m_L, p6);
      Stack <P7>::push (m_L, p7);
      Stack <P8>::push (m_L, p8);
      LuaException::pcall (m_L, 8, 1);
      return LuaRef (m_L, FromStack ());
    }
    //==========================================================================
  };
 
private:
  friend struct Stack <LuaRef>;
 
  //----------------------------------------------------------------------------
  struct FromStack { };
 
  //----------------------------------------------------------------------------
  LuaRef (lua_State* L, FromStack)
    : m_L (L)
  {
    m_ref = luaL_ref (m_L, LUA_REGISTRYINDEX);
  }
 
  //----------------------------------------------------------------------------
  LuaRef (lua_State* L, int index, FromStack)
    : m_L (L)
  {
    lua_pushvalue (m_L, index);
    m_ref = luaL_ref (m_L, LUA_REGISTRYINDEX);
  }
 
  //----------------------------------------------------------------------------
 
  // This type of construction is disallowed, since we don't have a `lua_State`.
  //
  template <class T>
  LuaRef (T)
  {
  }
 
  //----------------------------------------------------------------------------
  int createRef () const
  {
    if (m_ref != LUA_REFNIL)
    {
      push (m_L);
      return luaL_ref (m_L, LUA_REGISTRYINDEX);
    }
    else
    {
      return LUA_REFNIL;
    }
  }
 
public:
  //----------------------------------------------------------------------------
  LuaRef (lua_State* L)
    : m_L (L)
    , m_ref (LUA_REFNIL)
  {
  }
 
  //----------------------------------------------------------------------------
  template <class T>
  LuaRef (lua_State* L, T v)
    : m_L (L)
  {
    Stack <T>::push (m_L, v);
    m_ref = luaL_ref (m_L, LUA_REGISTRYINDEX);
  }
 
  //----------------------------------------------------------------------------
  LuaRef (Proxy const& v)
    : m_L (v.state ())
    , m_ref (v.createRef ())
  {
  }
 
  //----------------------------------------------------------------------------
  LuaRef (LuaRef const& other)
    : m_L (other.m_L)
    , m_ref (other.createRef ())
  {
  }
 
  //----------------------------------------------------------------------------
  ~LuaRef ()
  {
    luaL_unref (m_L, LUA_REGISTRYINDEX, m_ref);
  }
 
  //----------------------------------------------------------------------------
  static LuaRef fromStack (lua_State* L, int index)
  {
    lua_pushvalue (L, index);
    return LuaRef (L, FromStack ());
  }
 
  //----------------------------------------------------------------------------
  static LuaRef newTable (lua_State* L)
  {
    lua_newtable (L);
    return LuaRef (L, FromStack ());
  }
 
  //----------------------------------------------------------------------------
  static LuaRef getGlobal (lua_State *L, char const* name)
  {
    lua_getglobal (L, name);
    return LuaRef (L, FromStack ());
  }
 
  //----------------------------------------------------------------------------
  template <class T>
  LuaRef& operator= (T rhs)
  {
    luaL_unref (m_L, LUA_REGISTRYINDEX, m_ref);
    Stack <T>::push (m_L, rhs);
    m_ref = luaL_ref (m_L, LUA_REGISTRYINDEX);
    return *this;
  }
 
  //----------------------------------------------------------------------------
  LuaRef& operator= (LuaRef const& rhs)
  {
    luaL_unref (m_L, LUA_REGISTRYINDEX, m_ref);
    rhs.push (m_L);
    m_L = rhs.state ();
    m_ref = luaL_ref (m_L, LUA_REGISTRYINDEX);
    return *this;
  }
 
  //----------------------------------------------------------------------------
  std::string tostring() const
  {
    lua_getglobal (m_L, "tostring");
    push (m_L);
    lua_call (m_L, 1, 1);
    const char* str = lua_tostring(m_L, 1);
    lua_pop(m_L, 1);
    return std::string(str);
  }
 
  //----------------------------------------------------------------------------
  void print (std::ostream& os) const
  {
    switch (type ())
    {
    case LUA_TNIL:
      os << "nil";
      break;
 
    case LUA_TNUMBER:
      os << cast <lua_Number> ();
      break;
 
    case LUA_TBOOLEAN:
      os << (cast <bool> () ? "true" : "false");
      break;
 
    case LUA_TSTRING:
      os << '"' << cast <std::string> () << '"';
      break;
 
    case LUA_TTABLE:
      os << "table: " << tostring();
      break;
 
    case LUA_TFUNCTION:
      os << "function: " << tostring();
      break;
 
    case LUA_TUSERDATA:
      os << "userdata: " << tostring();
      break;
 
    case LUA_TTHREAD:
      os << "thread: " << tostring();
      break;
 
    case LUA_TLIGHTUSERDATA:
      os << "lightuserdata: " << tostring();
      break;
 
    default:
      os << "unknown";
      break;
    }
  }
 
  //============================================================================
  //
  // This group of member functions is mirrored in Proxy
  //
 
  lua_State* state () const
  {
    return m_L;
  }
 
  //----------------------------------------------------------------------------
  void push (lua_State* L) const
  {
    assert (equalstates (L, m_L));
    lua_rawgeti (L, LUA_REGISTRYINDEX, m_ref);
  }
 
  //----------------------------------------------------------------------------
  void pop (lua_State* L)
  {
    assert (equalstates (L, m_L));
    luaL_unref (m_L, LUA_REGISTRYINDEX, m_ref);
    m_ref = luaL_ref (m_L, LUA_REGISTRYINDEX);
  }
 
  //----------------------------------------------------------------------------
  int type () const
  {
    int result;
    if (m_ref != LUA_REFNIL)
    {
      push (m_L);
      result = lua_type (m_L, -1);
      lua_pop (m_L, 1);
    }
    else
    {
      result = LUA_TNIL;
    }
 
    return result;
  }
 
  // should never happen
  //inline bool isNone () const { return m_ref == LUA_NOREF; }
 
  inline bool isNil () const { return type () == LUA_TNIL; }
  inline bool isBoolean () const { return type () == LUA_TBOOLEAN; }
  inline bool isNumber () const { return type () == LUA_TNUMBER; }
  inline bool isString () const { return type () == LUA_TSTRING; }
  inline bool isTable () const { return type () == LUA_TTABLE; }
  inline bool isFunction () const { return type () == LUA_TFUNCTION; }
  inline bool isUserdata () const { return type () == LUA_TUSERDATA; }
  inline bool isThread () const { return type () == LUA_TTHREAD; }
  inline bool isLightUserdata () const { return type () == LUA_TLIGHTUSERDATA; }
  //----------------------------------------------------------------------------
  template <class T>
  T cast () const
  {
    StackPop p (m_L, 1);
    push (m_L);
 
    // lua_gettop is used because Userdata::getClass() doesn't handle
    // negative stack indexes.
    //
    return Stack <T>::get (m_L, lua_gettop (m_L));
  }
 
  //----------------------------------------------------------------------------
  template <class T>
  inline operator T () const
  {
    return cast <T> ();
  }
 
  //----------------------------------------------------------------------------
  template <class T>
  bool operator== (T rhs) const
  {
    StackPop p (m_L, 2);
    push (m_L);
    Stack <T>::push (m_L, rhs);
    return lua_compare (m_L, -2, -1, LUA_OPEQ) == 1;
  }
 
  template <class T>
  bool operator< (T rhs) const
  {
    StackPop p (m_L, 2);
    push (m_L);
    Stack <T>::push (m_L, rhs);
    return lua_compare (m_L, -2, -1, LUA_OPLT) == 1;
  }
 
  template <class T>
  bool operator<= (T rhs) const
  {
    StackPop p (m_L, 2);
    push (m_L);
    Stack <T>::push (m_L, rhs);
    return lua_compare (m_L, -2, -1, LUA_OPLE) == 1;
  }
 
  template <class T>
  bool operator> (T rhs) const
  {
    StackPop p (m_L, 2);
    push (m_L);
    Stack <T>::push (m_L, rhs);
    return lua_compare (m_L, -1, -2, LUA_OPLT) == 1;
  }
 
  template <class T>
  bool operator>= (T rhs) const
  {
    StackPop p (m_L, 2);
    push (m_L);
    Stack <T>::push (m_L, rhs);
    return lua_compare (m_L, -1, -2, LUA_OPLE) == 1;
  }
 
  template <class T>
  bool rawequal (T rhs) const
  {
    StackPop p (m_L, 2);
    push (m_L);
    Stack <T>::push (m_L, rhs);
    return lua_rawequal (m_L, -1, -2) == 1;
  }
  //----------------------------------------------------------------------------
  template <class T>
  void append (T v) const
  {
    push (m_L);
    Stack <T>::push (m_L, v);
    luaL_ref (m_L, -2);
    lua_pop (m_L, 1);
  }
 
  //----------------------------------------------------------------------------
  int length () const
  {
    StackPop p (m_L, 1);
    push (m_L);
    return get_length (m_L, -1);
  }
 
  //----------------------------------------------------------------------------
  template <class T>
  Proxy operator[] (T key) const
  {
    Stack <T>::push (m_L, key);
    return Proxy (m_L, m_ref);
  }
 
  //----------------------------------------------------------------------------
  LuaRef const operator() () const
  {
    push (m_L);
    LuaException::pcall (m_L, 0, 1);
    return LuaRef (m_L, FromStack ());
  }
 
  template <class P1>
  LuaRef const operator() (P1 p1) const
  {
    push (m_L);
    Stack <P1>::push (m_L, p1);
    LuaException::pcall (m_L, 1, 1);
    return LuaRef (m_L, FromStack ());
  }
 
  template <class P1, class P2>
  LuaRef const operator() (P1 p1, P2 p2) const
  {
    push (m_L);
    Stack <P1>::push (m_L, p1);
    Stack <P2>::push (m_L, p2);
    LuaException::pcall (m_L, 2, 1);
    return LuaRef (m_L, FromStack ());
  }
 
  template <class P1, class P2, class P3>
  LuaRef const operator() (P1 p1, P2 p2, P3 p3) const
  {
    push (m_L);
    Stack <P1>::push (m_L, p1);
    Stack <P2>::push (m_L, p2);
    Stack <P3>::push (m_L, p3);
    LuaException::pcall (m_L, 3, 1);
    return LuaRef (m_L, FromStack ());
  }
 
  template <class P1, class P2, class P3, class P4>
  LuaRef const operator() (P1 p1, P2 p2, P3 p3, P4 p4) const
  {
    push (m_L);
    Stack <P1>::push (m_L, p1);
    Stack <P2>::push (m_L, p2);
    Stack <P3>::push (m_L, p3);
    Stack <P4>::push (m_L, p4);
    LuaException::pcall (m_L, 4, 1);
    return LuaRef (m_L, FromStack ());
  }
 
  template <class P1, class P2, class P3, class P4, class P5>
  LuaRef const operator() (P1 p1, P2 p2, P3 p3, P4 p4, P5 p5) const
  {
    push (m_L);
    Stack <P1>::push (m_L, p1);
    Stack <P2>::push (m_L, p2);
    Stack <P3>::push (m_L, p3);
    Stack <P4>::push (m_L, p4);
    Stack <P5>::push (m_L, p5);
    LuaException::pcall (m_L, 5, 1);
    return LuaRef (m_L, FromStack ());
  }
 
  template <class P1, class P2, class P3, class P4, class P5, class P6>
  LuaRef const operator() (P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6) const
  {
    push (m_L);
    Stack <P1>::push (m_L, p1);
    Stack <P2>::push (m_L, p2);
    Stack <P3>::push (m_L, p3);
    Stack <P4>::push (m_L, p4);
    Stack <P5>::push (m_L, p5);
    Stack <P6>::push (m_L, p6);
    LuaException::pcall (m_L, 6, 1);
    return LuaRef (m_L, FromStack ());
  }
 
  template <class P1, class P2, class P3, class P4, class P5, class P6, class P7>
  LuaRef const operator() (P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7) const
  {
    push (m_L);
    Stack <P1>::push (m_L, p1);
    Stack <P2>::push (m_L, p2);
    Stack <P3>::push (m_L, p3);
    Stack <P4>::push (m_L, p4);
    Stack <P5>::push (m_L, p5);
    Stack <P6>::push (m_L, p6);
    Stack <P7>::push (m_L, p7);
    LuaException::pcall (m_L, 7, 1);
    return LuaRef (m_L, FromStack ());
  }
 
  template <class P1, class P2, class P3, class P4, class P5, class P6, class P7, class P8>
  LuaRef const operator() (P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8) const
  {
    push (m_L);
    Stack <P1>::push (m_L, p1);
    Stack <P2>::push (m_L, p2);
    Stack <P3>::push (m_L, p3);
    Stack <P4>::push (m_L, p4);
    Stack <P5>::push (m_L, p5);
    Stack <P6>::push (m_L, p6);
    Stack <P7>::push (m_L, p7);
    Stack <P8>::push (m_L, p8);
    LuaException::pcall (m_L, 8, 1);
    return LuaRef (m_L, FromStack ());
  }
  //============================================================================
 
private:
  lua_State* m_L;
  int m_ref;
};
 
//------------------------------------------------------------------------------
template <>
struct Stack <Nil>
{
public:
  static inline void push (lua_State* L, Nil)
  {
    lua_pushnil (L);
  }
};
 
//------------------------------------------------------------------------------
template <>
struct Stack <LuaRef>
{
public:
  // The value is const& to prevent a copy construction.
  //
  static inline void push (lua_State* L, LuaRef const& v)
  {
    v.push (L);
  }
 
  static inline LuaRef get (lua_State* L, int index)
  {
    return LuaRef (L, index, LuaRef::FromStack ());
  }
};
 
//------------------------------------------------------------------------------
template <>
struct Stack <LuaRef::Proxy>
{
public:
  // The value is const& to prevent a copy construction.
  //
  static inline void push (lua_State* L, LuaRef::Proxy const& v)
  {
    v.push (L);
  }
};
 
//------------------------------------------------------------------------------
inline LuaRef newTable (lua_State* L)
{
  return LuaRef::newTable (L);
}
 
//------------------------------------------------------------------------------
inline LuaRef getGlobal (lua_State *L, char const* name)
{
  return LuaRef::getGlobal (L, name);
}
 
//------------------------------------------------------------------------------
inline std::ostream& operator<< (std::ostream& os, LuaRef const& ref)
{
  ref.print (os);
  return os;
}
 
//------------------------------------------------------------------------------
 
// more C++-like cast syntax
//
template<class T>
inline T LuaRef_cast(LuaRef const& lr)
{
  return lr.cast<T>();
}