Userdata.h

Go to the documentation of this file.

//------------------------------------------------------------------------------
/*
  https://github.com/vinniefalco/LuaBridge
 
  Copyright 2016, Robin Gareus <robin@gareus.org>
  Copyright 2012, Vinnie Falco <vinnie.falco@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.
*/
//==============================================================================
 
//==============================================================================
#ifdef  PLATFORM_WINDOWS
# ifdef COMPILER_MSVC
#include "LuaBridge/LuaBridge.h" /* Needed for LuaBridge_API */
LuaBridge_API void* getIdentityKey ();
# else
extern void* getIdentityKey ();
# endif
#else
inline void* getIdentityKey ()
{
  static char value;
  return &value;
}
#endif
 
class Userdata
{
protected:
  void* m_p; // subclasses must set this
 
  //--------------------------------------------------------------------------
  inline void* getPointer () const
  {
    return m_p;
  }
 
private:
  //--------------------------------------------------------------------------
  static Userdata* getExactClass (lua_State* L,
                                  int narg,
                                  void const* classKey)
  {
    Userdata* ud = 0;
    int const index = lua_absindex (L, narg);
 
    bool mismatch = false;
    char const* got = 0;
 
    lua_rawgetp (L, LUA_REGISTRYINDEX, classKey);
    assert (lua_istable (L, -1));
 
    // Make sure we have a userdata.
    if (!lua_isuserdata (L, index))
      mismatch = true;
 
    // Make sure it's metatable is ours.
    if (!mismatch)
    {
      lua_getmetatable (L, index);
      lua_rawgetp (L, -1, getIdentityKey ());
      if (lua_isboolean (L, -1))
      {
        lua_pop (L, 1);
      }
      else
      {
        lua_pop (L, 2);
        mismatch = true;
      }
    }
 
    if (!mismatch)
    {
      if (lua_rawequal (L, -1, -2))
      {
        // Matches class table.
        lua_pop (L, 2);
        ud = static_cast <Userdata*> (lua_touserdata (L, index));
      }
      else
      {
        rawgetfield (L, -2, "__const");
        if (lua_rawequal (L, -1, -2))
        {
          // Matches const table
          lua_pop (L, 3);
          ud = static_cast <Userdata*> (lua_touserdata (L, index));
        }
        else
        {
          // Mismatch, but its one of ours so get a type name.
          rawgetfield (L, -2, "__type");
          lua_insert (L, -4);
          lua_pop (L, 2);
          got = lua_tostring (L, -2);
          mismatch = true;
        }
      }
    }
 
    if (mismatch)
    {
      rawgetfield (L, -1, "__type");
      assert (lua_type (L, -1) == LUA_TSTRING);
      char const* const expected = lua_tostring (L, -1);
 
      if (got == 0)
        got = lua_typename (L, lua_type (L, index));
 
      char const* const msg = lua_pushfstring (
        L, "%s expected, got %s", expected, got);
 
      if (narg > 0)
        luaL_argerror (L, narg, msg);
      else
        lua_error (L);
    }
 
    return ud;
  }
 
  //--------------------------------------------------------------------------
  static Userdata* getClass (lua_State* L,
                             int index,
                             void const* baseClassKey,
                             bool canBeConst,
                             bool errorOnMismatch = true)
  {
    assert (index > 0);
    Userdata* ud = 0;
 
    bool mismatch = false;
    char const* got = 0;
 
    lua_rawgetp (L, LUA_REGISTRYINDEX, baseClassKey);
    assert (lua_istable (L, -1));
 
    // Make sure we have a userdata.
    if (lua_isuserdata (L, index))
    {
      // Make sure it's metatable is ours.
      lua_getmetatable (L, index);
      lua_rawgetp (L, -1, getIdentityKey ());
      if (lua_isboolean (L, -1))
      {
        lua_pop (L, 1);
 
        // If __const is present, object is NOT const.
        rawgetfield (L, -1, "__const");
        assert (lua_istable (L, -1) || lua_isnil (L, -1));
        bool const isConst = lua_isnil (L, -1);
        lua_pop (L, 1);
 
        // Replace the class table with the const table if needed.
        if (isConst)
        {
          rawgetfield (L, -2, "__const");
          assert (lua_istable (L, -1));
          lua_replace (L, -3);
        }
 
        for (;;)
        {
          if (lua_rawequal (L, -1, -2))
          {
            lua_pop (L, 2);
 
            // Match, now check const-ness.
            if (isConst && !canBeConst)
            {
              luaL_argerror (L, index, "cannot be const");
            }
            else
            {
              ud = static_cast <Userdata*> (lua_touserdata (L, index));
              break;
            }
          }
          else
          {
            // Replace current metatable with it's base class.
            rawgetfield (L, -1, "__parent");
/*
ud
class metatable
ud metatable
ud __parent (nil)
*/
 
            if (lua_isnil (L, -1))
            {
              lua_remove (L, -1);
              // Mismatch, but its one of ours so get a type name.
              rawgetfield (L, -1, "__type");
              lua_insert (L, -3);
              lua_pop (L, 1);
              got = lua_tostring (L, -2);
              mismatch = true;
              break;
            }
            else
            {
              lua_remove (L, -2);
            }
          }
        }
      }
      else
      {
        lua_pop (L, 2);
        mismatch = true;
      }
    }
    else
    {
      mismatch = true;
    }
 
    if (mismatch && errorOnMismatch)
    {
      assert (lua_type (L, -1) == LUA_TTABLE);
      rawgetfield (L, -1, "__type");
      assert (lua_type (L, -1) == LUA_TSTRING);
      char const* const expected = lua_tostring (L, -1);
 
      if (got == 0)
        got = lua_typename (L, lua_type (L, index));
 
      char const* const msg = lua_pushfstring (
        L, "%s expected, got %s", expected, got);
 
      luaL_argerror (L, index, msg);
    }
 
    return ud;
  }
 
public:
  virtual ~Userdata () { }
 
  static void* get_ptr (lua_State* L, int index) {
    Userdata* ud = static_cast <Userdata*> (lua_touserdata (L, index));
    return ud->m_p;
  }
 
  //--------------------------------------------------------------------------
  template <class T>
  static inline Userdata* getExact (lua_State* L, int index)
  {
    return getExactClass (L, index, ClassInfo <T>::getClassKey ());
  }
 
  //--------------------------------------------------------------------------
  template <class T>
  static inline T* get (lua_State* L, int index, bool canBeConst)
  {
    if (lua_isnil (L, index))
      return 0;
    else
      return static_cast <T*> (getClass (L, index,
        ClassInfo <T>::getClassKey (), canBeConst)->getPointer ());
  }
 
  template <class T>
  static inline T* try_get (lua_State* L, int index, bool canBeConst)
        {
                if (!lua_isnil (L, index)) {
                        Userdata* ud = getClass (L, index, ClassInfo <T>::getClassKey (), canBeConst, false);
                        if (ud) {
                                return static_cast <T*> (ud->getPointer ());
                        }
                }
                return 0;
        }
};
 
//----------------------------------------------------------------------------
template <class T>
class UserdataValue : public Userdata
{
private:
  UserdataValue (UserdataValue<T> const&);
  UserdataValue<T> operator= (UserdataValue<T> const&);
 
  char m_storage [sizeof (T)];
 
  inline T* getObject ()
  {
    // If this fails to compile it means you forgot to provide
    // a Container specialization for your container!
    //
    return reinterpret_cast <T*> (&m_storage [0]);
  }
 
private:
  UserdataValue ()
  {
    m_p = getObject ();
  }
 
  ~UserdataValue ()
  {
    getObject ()->~T ();
  }
 
public:
  static void* place (lua_State* const L)
  {
    UserdataValue <T>* const ud = new (
      lua_newuserdata (L, sizeof (UserdataValue <T>))) UserdataValue <T> ();
    lua_rawgetp (L, LUA_REGISTRYINDEX, ClassInfo <T>::getClassKey ());
    // If this goes off it means you forgot to register the class!
    assert (lua_istable (L, -1));
    lua_setmetatable (L, -2);
    return ud->getPointer ();
  }
 
  template <class U>
  static inline void push (lua_State* const L, U const& u)
  {
    new (place (L)) U (u);
  }
};
 
//----------------------------------------------------------------------------
class UserdataPtr : public Userdata
{
private:
  UserdataPtr (UserdataPtr const&);
  UserdataPtr operator= (UserdataPtr const&);
 
private:
  static void push (lua_State* L, void* const p, void const* const key)
  {
    if (p)
    {
      new (lua_newuserdata (L, sizeof (UserdataPtr))) UserdataPtr (p);
      lua_rawgetp (L, LUA_REGISTRYINDEX, key);
      // If this goes off it means you forgot to register the class!
      assert (lua_istable (L, -1));
      lua_setmetatable (L, -2);
    }
    else
    {
      lua_pushnil (L);
    }
  }
 
  static void push (lua_State* L, void const* const p, void const* const key)
  {
    if (p)
    {
      new (lua_newuserdata (L, sizeof (UserdataPtr)))
        UserdataPtr (const_cast <void*> (p));
      lua_rawgetp (L, LUA_REGISTRYINDEX, key);
      // If this goes off it means you forgot to register the class!
      assert (lua_istable (L, -1));
      lua_setmetatable (L, -2);
    }
    else
    {
      lua_pushnil (L);
    }
  }
 
  explicit UserdataPtr (void* const p)
  {
    m_p = p;
 
    // Can't construct with a null pointer!
    //
    assert (m_p != 0);
  }
 
  friend class LuaRef;
  static inline void push_raw (lua_State* const L, void* p, const void* classkey)
  {
    new (lua_newuserdata (L, sizeof (UserdataPtr))) UserdataPtr (p);
    lua_rawgetp (L, LUA_REGISTRYINDEX, classkey);
    assert (lua_istable (L, -1));
    lua_setmetatable (L, -2);
  }
 
public:
  template <class T>
  static inline void push (lua_State* const L, T* const p)
  {
    if (p)
      push (L, p, ClassInfo <T>::getClassKey ());
    else
      lua_pushnil (L);
  }
 
  template <class T>
  static inline void push (lua_State* const L, T const* const p)
  {
    if (p)
      push (L, p, ClassInfo <T>::getConstKey ());
    else
      lua_pushnil (L);
  }
};
 
//============================================================================
template <class C>
class UserdataShared : public Userdata
{
private:
  UserdataShared (UserdataShared <C> const&);
  UserdataShared <C>& operator= (UserdataShared <C> const&);
 
  typedef typename TypeTraits::removeConst <
    typename ContainerTraits <C>::Type>::Type T;
 
  C m_c;
 
private:
  ~UserdataShared ()
  {
  }
 
public:
  template <class U>
  explicit UserdataShared (U const& u) : m_c (u)
  {
    m_p = const_cast <void*> (reinterpret_cast <void const*> (
        (ContainerTraits <C>::get (m_c))));
  }
 
  template <class U>
  explicit UserdataShared (U* u) : m_c (u)
  {
    m_p = const_cast <void*> (reinterpret_cast <void const*> (
        (ContainerTraits <C>::get (m_c))));
  }
};
 
//----------------------------------------------------------------------------
 
template <class C, bool makeObjectConst>
struct UserdataSharedHelper
{
private:
 
  typedef typename TypeTraits::removeConst <
    typename ContainerTraits <C>::Type>::Type T;
 
public:
 
  static void push (lua_State* L, C const& c)
  {
    if (ContainerTraits <C>::get (c) != 0)
    {
      new (lua_newuserdata (L, sizeof (UserdataShared <C>))) UserdataShared <C> (c);
      if constexpr (makeObjectConst) {
        lua_rawgetp (L, LUA_REGISTRYINDEX, ClassInfo <T>::getConstKey ());
      } else {
        lua_rawgetp (L, LUA_REGISTRYINDEX, ClassInfo <T>::getClassKey ());
      }
      // If this goes off it means the class T is unregistered!
      assert (lua_istable (L, -1));
      lua_setmetatable (L, -2);
    }
    else
    {
      lua_pushnil (L);
    }
  }
 
  static void push (lua_State* L, T* const t)
  {
    if (t)
    {
      new (lua_newuserdata (L, sizeof (UserdataShared <C>))) UserdataShared <C> (t);
      if constexpr (makeObjectConst) {
        lua_rawgetp (L, LUA_REGISTRYINDEX, ClassInfo <T>::getConstKey ());
      } else {
        lua_rawgetp (L, LUA_REGISTRYINDEX, ClassInfo <T>::getClassKey ());
      }
      // If this goes off it means the class T is unregistered!
      assert (lua_istable (L, -1));
      lua_setmetatable (L, -2);
    }
    else
    {
      lua_pushnil (L);
    }
  }
};
 
//==============================================================================
 
template <class T>
struct Stack
{
private:
 
  static constexpr bool passByContainer = TypeTraits::isContainer<T>::value;
 
  static constexpr bool passByValueNotEnum = !passByContainer && !std::is_enum_v<T>;
  static constexpr bool passByValueEnum = !passByContainer && std::is_enum_v<T>;
 
public:
 
  static inline void push (lua_State* L, T const& t)
  {
    if constexpr (passByValueNotEnum) {
 
      UserdataValue <T>::push (L, t);
 
    } else if constexpr (passByValueEnum) {
 
      int v = static_cast <int> (t);
      lua_pushinteger (L, static_cast <lua_Integer> (v));
 
    } else {
 
      UserdataSharedHelper <T,
        TypeTraits::isConst <typename ContainerTraits <T>::Type>::value>::push (L, t);
 
    }
  }
 
  static inline
  std::conditional_t<passByValueNotEnum, T const&, T>
  get (lua_State* L, int index)
  {
    if constexpr (passByValueNotEnum) {
 
      return *Userdata::get <T> (L, index, true);
 
    } else if constexpr (passByValueEnum) {
 
      int v = static_cast <int> (luaL_checkinteger (L, index));
      return T (v);
 
    } else {
 
      typedef typename TypeTraits::removeConst <
       typename ContainerTraits <T>::Type>::Type U;
 
      return Userdata::get <U> (L, index, true);
 
    }
  }
 
};
 
//------------------------------------------------------------------------------
// pointer
template <class T>
struct Stack <T*>
{
  static inline void push (lua_State* L, T* const p)
  {
    UserdataPtr::push (L, p);
  }
 
  static inline T* get (lua_State* L, int index)
  {
    return Userdata::get <T> (L, index, false);
  }
};
 
// Strips the const off the right side of *
template <class T>
struct Stack <T* const>
{
  static inline void push (lua_State* L, T* const p)
  {
    UserdataPtr::push (L, p);
  }
 
  static inline T* get (lua_State* L, int index)
  {
    return Userdata::get <T> (L, index, false);
  }
};
 
// pointer to const
template <class T>
struct Stack <T const*>
{
  static inline void push (lua_State* L, T const* const p)
  {
    UserdataPtr::push (L, p);
  }
 
  static inline T const* get (lua_State* L, int index)
  {
    return Userdata::get <T> (L, index, true);
  }
};
 
// Strips the const off the right side of *
template <class T>
struct Stack <T const* const>
{
  static inline void push (lua_State* L, T const* const p)
  {
    UserdataPtr::push (L, p);
  }
 
  static inline T const* get (lua_State* L, int index)
  {
    return Userdata::get <T> (L, index, true);
  }
};
 
// const references to class-instance pointers
// e.g.   std::list<T*>::push_back ( const T* & )
template <class T>
struct Stack <T* const&>
{
  static inline void push (lua_State* L, T* const& p)
  {
    UserdataPtr::push (L, p);
  }
 
  static inline T* get (lua_State* L, int index)
  {
    return Userdata::get <T> (L, index, true);
  }
};
 
// reference
template <class T>
struct Stack <T&>
{
  static inline void push (lua_State* L, T& t)
  {
    UserdataPtr::push (L, &t);
  }
 
  static T& get (lua_State* L, int index)
  {
    T* const t = Userdata::get <T> (L, index, false);
    if (!t)
      luaL_error (L, "nil passed to reference");
    return *t;
  }
};
 
// reference to const
template <class T>
struct Stack <T const&>
{
private:
 
  static constexpr bool passByContainer = TypeTraits::isContainer<T>::value;
 
public:
 
  static inline void push (lua_State* L, T const& t)
  {
    if constexpr (passByContainer) {
 
      UserdataSharedHelper <T,
      TypeTraits::isConst <typename ContainerTraits <T>::Type>::value>::push (L, t);
 
    } else {
 
      UserdataPtr::push (L, &t);
 
    }
  }
 
  static
  std::conditional_t<passByContainer, T, T const&>
  get (lua_State* L, int index)
  {
    if constexpr (passByContainer) {
 
      typedef typename TypeTraits::removeConst <
        typename ContainerTraits <T>::Type>::Type U;
 
      return Userdata::get <U> (L, index, true);
 
    } else {
 
      T const* const t = Userdata::get <T> (L, index, true);
 
      if (!t)
        luaL_error (L, "nil passed to reference");
      return *t;
 
    }
  }
 
};