git.r.bdr.sh - rbdr/pico-engine/blob - LuaThis.h

   1 // ---------------------------------------------------------------------------
   2 // FILE NAME            : LuaThis.h
   3 // ---------------------------------------------------------------------------
   4 // DESCRIPTION :
   5 //
   6 // Controls the "this" table
   7 //
   8 // ---------------------------------------------------------------------------
   9 // VERSION              : 1.01
  10 // DATE                 : 1-Sep-2005
  11 // AUTHOR               : Richard Shephard
  12 // ---------------------------------------------------------------------------
  13 // LIBRARY INCLUDE FILES
  14 #ifndef __LUA_THIS_H__
  15 #define __LUA_THIS_H__
  16
  17 #include "luainc.h"
  18 #include "luavirtualmachine.h"
  19
  20 // Sets the "this" global table that scripts use
  21
  22 class CLuaThis
  23 {
  24 public:
  25    CLuaThis (CLuaVirtualMachine& vm, int iRef) : m_iOldRef (0), m_vm (vm)
  26    {
  27       lua_State *state = (lua_State *) vm;
  28       if (vm.Ok ())
  29       {
  30          // Save the old "this" table
  31          lua_getglobal (state, "this");
  32          m_iOldRef = luaL_ref (state, LUA_REGISTRYINDEX);
  33
  34          // replace it with our new one
  35          lua_rawgeti(state, LUA_REGISTRYINDEX, iRef);
  36          lua_setglobal (state, "this");
  37       }
  38    }
  39
  40    virtual ~CLuaThis (void)
  41    {
  42       lua_State *state = (lua_State *) m_vm;
  43       if (m_iOldRef > 0 && m_vm.Ok ())
  44       {
  45          // Replace the old "this" table
  46          lua_rawgeti(state, LUA_REGISTRYINDEX, m_iOldRef);
  47          lua_setglobal (state, "this");
  48          luaL_unref (state, LUA_REGISTRYINDEX, m_iOldRef);
  49       }
  50    }
  51
  52
  53 protected:
  54    int m_iOldRef;
  55    CLuaVirtualMachine& m_vm;
  56 };
  57
  58 #endif // __LUA_THIS_H__