Show lunar.h syntax highlighted
#ifndef lunar_h
#define lunar_h
extern "C"
{
#include "lua.h"
#include "lauxlib.h"
}
template <typename T> class Lunar {
typedef struct { T *pT; } userdataType;
public:
typedef int (T::*mfp)(lua_State *L);
typedef struct { const char *name; mfp mfunc; } RegType;
static void Register(lua_State *L) {
lua_newtable(L);
int methods = lua_gettop(L);
luaL_newmetatable(L, T::className);
int metatable = lua_gettop(L);
// store method table in globals so that
// scripts can add functions written in Lua.
lua_pushvalue(L, methods);
set(L, LUA_GLOBALSINDEX, T::className);
// hide metatable from Lua getmetatable()
lua_pushvalue(L, methods);
set(L, metatable, "__metatable");
lua_pushvalue(L, methods);
set(L, metatable, "__index");
lua_pushcfunction(L, tostring_T);
set(L, metatable, "__tostring");
lua_pushcfunction(L, gc_T);
set(L, metatable, "__gc");
lua_newtable(L); // mt for method table
lua_pushcfunction(L, new_T);
lua_pushvalue(L, -1); // dup new_T function
set(L, methods, "new"); // add new_T to method table
set(L, -3, "__call"); // mt.__call = new_T
lua_setmetatable(L, methods);
// fill method table with methods from class T
for (RegType *l = T::methods; l->name; l++) {
lua_pushstring(L, l->name);
lua_pushlightuserdata(L, (void*)l);
lua_pushcclosure(L, thunk, 1);
lua_settable(L, methods);
}
lua_pop(L, 2); // drop metatable and method table
}
// call named lua method from userdata method table
static int call(lua_State *L, const char *method,
int nargs=0, int nresults=LUA_MULTRET, int errfunc=0)
{
int base = lua_gettop(L) - nargs; // userdata index
if (!luaL_checkudata(L, base, T::className)) {
lua_settop(L, base-1); // drop userdata and args
lua_pushfstring(L, "not a valid %s userdata", T::className);
return -1;
}
lua_pushstring(L, method); // method name
lua_gettable(L, base); // get method from userdata
if (lua_isnil(L, -1)) { // no method?
lua_settop(L, base-1); // drop userdata and args
lua_pushfstring(L, "%s missing method '%s'", T::className, method);
return -1;
}
lua_insert(L, base); // put method under userdata, args
int status = lua_pcall(L, 1+nargs, nresults, errfunc); // call method
if (status) {
const char *msg = lua_tostring(L, -1);
if (msg == NULL) msg = "(error with no message)";
lua_pushfstring(L, "%s:%s status = %d\n%s",
T::className, method, status, msg);
lua_remove(L, base); // remove old message
return -1;
}
return lua_gettop(L) - base + 1; // number of results
}
// push onto the Lua stack a userdata containing a pointer to T object
static int push(lua_State *L, T *obj, bool gc=false) {
if (!obj) { lua_pushnil(L); return 0; }
luaL_getmetatable(L, T::className); // lookup metatable in Lua registry
if (lua_isnil(L, -1)) luaL_error(L, "%s missing metatable", T::className);
int mt = lua_gettop(L);
subtable(L, mt, "userdata", "v");
userdataType *ud =
static_cast<userdataType*>(pushuserdata(L, obj, sizeof(userdataType)));
if (ud) {
ud->pT = obj; // store pointer to object in userdata
lua_pushvalue(L, mt);
lua_setmetatable(L, -2);
if (gc == false) {
lua_checkstack(L, 3);
subtable(L, mt, "do not trash", "k");
lua_pushvalue(L, -2);
lua_pushboolean(L, 1);
lua_settable(L, -3);
lua_pop(L, 1);
}
}
lua_replace(L, mt);
lua_settop(L, mt);
return mt; // index of userdata containing pointer to T object
}
// get userdata from Lua stack and return pointer to T object
static T *check(lua_State *L, int narg) {
userdataType *ud =
static_cast<userdataType*>(luaL_checkudata(L, narg, T::className));
if(!ud) luaL_typerror(L, narg, T::className);
return ud->pT; // pointer to T object
}
private:
Lunar(); // hide default constructor
// member function dispatcher
static int thunk(lua_State *L) {
// stack has userdata, followed by method args
T *obj = check(L, 1); // get 'self', or if you prefer, 'this'
lua_remove(L, 1); // remove self so member function args start at index 1
// get member function from upvalue
RegType *l = static_cast<RegType*>(lua_touserdata(L, lua_upvalueindex(1)));
return (obj->*(l->mfunc))(L); // call member function
}
// create a new T object and
// push onto the Lua stack a userdata containing a pointer to T object
static int new_T(lua_State *L) {
lua_remove(L, 1); // use classname:new(), instead of classname.new()
T *obj = new T(L); // call constructor for T objects
push(L, obj, true); // gc_T will delete this object
return 1; // userdata containing pointer to T object
}
// garbage collection metamethod
static int gc_T(lua_State *L) {
if (luaL_getmetafield(L, 1, "do not trash")) {
lua_pushvalue(L, 1); // dup userdata
lua_gettable(L, -2);
if (!lua_isnil(L, -1)) return 0; // do not delete object
}
userdataType *ud = static_cast<userdataType*>(lua_touserdata(L, 1));
T *obj = ud->pT;
if (obj) delete obj; // call destructor for T objects
return 0;
}
static int tostring_T (lua_State *L) {
char buff[32];
userdataType *ud = static_cast<userdataType*>(lua_touserdata(L, 1));
T *obj = ud->pT;
sprintf(buff, "%p", obj);
lua_pushfstring(L, "%s (%s)", T::className, buff);
return 1;
}
static void set(lua_State *L, int table_index, const char *key) {
lua_pushstring(L, key);
lua_insert(L, -2); // swap value and key
lua_settable(L, table_index);
}
static void weaktable(lua_State *L, const char *mode) {
lua_newtable(L);
lua_pushvalue(L, -1); // table is its own metatable
lua_setmetatable(L, -2);
lua_pushliteral(L, "__mode");
lua_pushstring(L, mode);
lua_settable(L, -3); // metatable.__mode = mode
}
static void subtable(lua_State *L, int tindex, const char *name, const char *mode) {
lua_pushstring(L, name);
lua_gettable(L, tindex);
if (lua_isnil(L, -1)) {
lua_pop(L, 1);
lua_checkstack(L, 3);
weaktable(L, mode);
lua_pushstring(L, name);
lua_pushvalue(L, -2);
lua_settable(L, tindex);
}
}
static void *pushuserdata(lua_State *L, void *key, size_t sz) {
void *ud = 0;
lua_pushlightuserdata(L, key);
lua_gettable(L, -2); // lookup[key]
if (lua_isnil(L, -1)) {
lua_pop(L, 1); // drop nil
lua_checkstack(L, 3);
ud = lua_newuserdata(L, sz); // create new userdata
lua_pushlightuserdata(L, key);
lua_pushvalue(L, -2); // dup userdata
lua_settable(L, -4); // lookup[key] = userdata
}
return ud;
}
};
#endif
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