lua loader

//自定义lua的loader

void CCLuaStack::addLuaLoader(lua_CFunction func)
{
    if (!func) return;

    // stack content after the invoking of the function
    // get loader table
    lua_getglobal(m_state, "package");                                  /* L: package */
    lua_getfield(m_state, -1, "loaders");                               /* L: package, loaders */

    // insert loader into index 2
    lua_pushcfunction(m_state, func);                                   /* L: package, loaders, func */
    for (int i = lua_objlen(m_state, -2) + 1; i > 2; --i)
    {
        lua_rawgeti(m_state, -2, i - 1);                                /* L: package, loaders, func, function */
        // we call lua_rawgeti, so the loader table now is at -3
        lua_rawseti(m_state, -3, i);                                    /* L: package, loaders, func */
    }
    lua_rawseti(m_state, -2, 2);                                        /* L: package, loaders */

    // set loaders into package
    lua_setfield(m_state, -2, "loaders");                               /* L: package */

    lua_pop(m_state, 1);
}