Click here to Skip to main content
15,895,799 members
Articles / Containers / Virtual Machine

Integrating Lua into C++

Rate me:
Please Sign up or sign in to vote.
4.82/5 (42 votes)
2 Sep 2005CPOL8 min read 333.9K   8.6K   127  
An article about embedding the Lua scripting language with C++ objects.
#include "luavirtualmachine.h"
#include "luascript.h"
#include "luadebugger.h"
#include "lualib/luainc.h"
#include <assert.h>
#include <stdio.h>
#include <string.h>


class CMyScript : public CLuaScript
{
public:
   CMyScript (CLuaVirtualMachine& vm) : CLuaScript (vm)
   {
      m_iMethodBase = RegisterFunction ("hello1");
      RegisterFunction ("hello2");
      RegisterFunction ("hello3");
   }

   int ScriptCalling (CLuaVirtualMachine& vm, int iFunctionNumber)
   {
      switch (iFunctionNumber - m_iMethodBase)
      {
      case 0:
         return Hello1 (vm);
      case 1:
         return Hello2 (vm);
      case 2:
         return Hello3 (vm);
      }

      return 0;
   }

   int Hello1 (CLuaVirtualMachine& vm)
   {
      printf ("Hellow (1)\n");
      return 0;
   }

   int Hello2 (CLuaVirtualMachine& vm)
   {
      lua_State *state = (lua_State *) vm;

      int iNumber = (int) lua_tonumber (state, -1);
      printf ("Hellow (2) -> %d\n", iNumber);
      return 0;
   }

   int Hello3 (CLuaVirtualMachine& vm)
   {
      lua_State *state = (lua_State *) vm;

      int iNumber = (int) lua_tonumber (state, -1);
      printf ("Hello (3) -> %d\n", iNumber);
      lua_pushnumber (state, iNumber + 2);
      return 1;
   }

   void HandleReturns (CLuaVirtualMachine& vm, const char *strFunc)
   {
      if (strcmp (strFunc, "divideMe") == 0)
      {
         // frames returns an answer of the stack
         lua_State *state = (lua_State *) vm;
         int itop = lua_gettop (state);
         int iType = lua_type (state, -1);
         const char *s = lua_typename (state, iType);
         double fFrameCount = lua_tonumber (state, -1);
         
         printf ("frame count = %f\n", fFrameCount);
      }
   }

protected:
   int m_iMethodBase;
};

class CMyScript2 : public CLuaScript
{
public:
   CMyScript2 (CLuaVirtualMachine& vm) : CLuaScript (vm)
   {
      m_iMethodBase = RegisterFunction ("hello1");
      RegisterFunction ("hello2");
      RegisterFunction ("hello3");
   }

   int Hello1 (CLuaVirtualMachine& vm)
   {
      printf ("Hello2 (1)\n");
      return 0;
   }

   int Hello2 (CLuaVirtualMachine& vm)
   {
      printf ("Hello2 (2)\n");
      return 0;
   }

   int Hello3 (CLuaVirtualMachine& vm)
   {
      printf ("Hello2 (3)\n");
      return 0;
   }

   int ScriptCalling (CLuaVirtualMachine& vm, int iFunctionNumber)
   {
      switch (iFunctionNumber - m_iMethodBase)
      {
      case 0:
         return Hello1 (vm);
      case 1:
         return Hello2 (vm);
      case 2:
         return Hello3 (vm);
      }

      return 0;
   }

   void HandleReturns (CLuaVirtualMachine& vm, const char *strFunc)
   {
      if (strcmp (strFunc, "addme") == 0)
      {
         // frames returns an answer of the stack
         lua_State *state = (lua_State *) vm;
         
         double addres = lua_tonumber (state, -1);
         
         printf ("add res = %f\n", addres);
      }
      else if (strcmp (strFunc, "subme") == 0)
      {
         lua_State *state = (lua_State *) vm;
         
         double addres = lua_tonumber (state, -1);
         
         printf ("sub res = %f\n", addres);
      }
   }

protected:
   int m_iMethodBase;

};


void main (void)
{
   CLuaVirtualMachine vm;
   vm.InitialiseVM ();

   CLuaDebugger dbg (vm);
   dbg.SetCount (10);
   //dbg.SetHooksFlag (DBG_MASK_LINE);
   
   CMyScript ms (vm);
   ms.CompileFile ("test.lua");

   CMyScript2 ms2 (vm);
   ms2.CompileFile ("test2.lua");

   int iTopS = lua_gettop ((lua_State *) vm);

   assert (ms.ScriptHasFunction ("CountAndCall"));
   assert (!ms.ScriptHasFunction ("countAndCall"));
   assert (!ms.ScriptHasFunction ("test"));

   ms.SelectScriptFunction ("CountAndCall");
   ms.AddParam (2);
   ms.Go ();

   ms.SelectScriptFunction ("divideMe");
   ms.AddParam (33);
   ms.Go (1);

   ms.SelectScriptFunction ("returnToMe");
   ms.AddParam (10);
   ms.Go (0);

   int iTopE = lua_gettop ((lua_State *) vm);

   if (iTopS != iTopE)
   {
      printf ("ERROR: Stack Not Balanced!");
   }

   ms2.SelectScriptFunction ("test");
   ms2.Go ();

   ms2.SelectScriptFunction ("addme");
   ms2.AddParam (2);
   ms2.AddParam (3);
   ms2.Go (1);

   ms2.SelectScriptFunction ("subme");
   ms2.AddParam (4);
   ms2.AddParam (2);
   ms2.Go (1);
}

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Technical Lead
South Africa South Africa
This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

Comments and Discussions