lua_util.c

/* 
 * Copyright (c) 2016 Milovann Yanatchkov 
 *
 * This file is part of Mud, a free software
 * licensed under the GNU General Public License v2
 * see /LICENSE for more information
 *
 */

#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"

#ifdef HAVE_LUA_5_1
#include "compat-5.3.h"
#endif

#include "lua_util.h"

#ifdef HAVE_NO_COMPAT
void luaL_setmetatable (lua_State *L, const char *tname) {
  luaL_checkstack(L, 1, "not enough stack slots");
  luaL_getmetatable(L, tname);
  lua_setmetatable(L, -2);
}

void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {
  luaL_checkstack(L, nup+1, "too many upvalues");
  for (; l->name != NULL; l++) {  /* fill the table with given functions */
    int i;
    lua_pushstring(L, l->name);
    for (i = 0; i < nup; i++)  /* copy upvalues to the top */
      lua_pushvalue(L, -(nup + 1));
    lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
    lua_settable(L, -(nup + 3)); /* table must be below the upvalues, the name and the closure */
  }
  lua_pop(L, nup);  /* remove upvalues */
}
#endif


void Xet_add (lua_State *L, Xet_reg l)
{
	for (; l->name; l++) {
		lua_pushstring(L, l->name);
		lua_pushlightuserdata(L, (void*)l);
		lua_settable(L, -3);
	}
}

int Xet_call (lua_State *L)
{
	/* for get: stack has userdata, index, lightuserdata */
	/* for set: stack has userdata, index, value, lightuserdata */
	Xet_reg m = (Xet_reg)lua_touserdata(L, -1);  /* member info */
	lua_pop(L, 1);                               /* drop lightuserdata */
	luaL_checktype(L, 1, LUA_TUSERDATA);
	return m->func(L, (void *)((char *)lua_touserdata(L, 1) + m->offset));
}

int index_handler (lua_State *L)
{
	/* stack has userdata, index */
	lua_pushvalue(L, 2);                     /* dup index */
	lua_rawget(L, lua_upvalueindex(1));      /* lookup member by name */
	if (!lua_islightuserdata(L, -1)) {
		lua_pop(L, 1);                         /* drop value */
		lua_pushvalue(L, 2);                   /* dup index */
		lua_gettable(L, lua_upvalueindex(2));  /* else try methods */
		if (lua_isnil(L, -1))                  /* invalid member */
			luaL_error(L, "cannot get member '%s'", lua_tostring(L, 2));
		return 1;
	}
	return Xet_call(L);                      /* call get function */
}

int newindex_handler (lua_State *L)
{
	/* stack has userdata, index, value */
	lua_pushvalue(L, 2);                     /* dup index */
	lua_rawget(L, lua_upvalueindex(1));      /* lookup member by name */
	if (!lua_islightuserdata(L, -1))         /* invalid member */
		luaL_error(L, "cannot set member '%s'", lua_tostring(L, 2));
	return Xet_call(L);                      /* call set function */
}

void lua_set_getters_setters( lua_State *L, int methods, int metatable, Xet_reg getters , Xet_reg setters)
{
	lua_pushliteral(L, "__metatable");
	lua_pushvalue(L, methods);    /* dup methods table*/
	lua_rawset(L, metatable);     /* hide metatable:
					 metatable.__metatable = methods */
	lua_pushliteral(L, "__index");
	lua_pushvalue(L, metatable);  /* upvalue index 1 */
	Xet_add(L, getters);     /* fill metatable with getters */
	lua_pushvalue(L, methods);    /* upvalue index 2 */
	lua_pushcclosure(L, index_handler, 2);
	lua_rawset(L, metatable);     /* metatable.__index = index_handler */

	lua_pushliteral(L, "__newindex");
	lua_newtable(L);              /* table for members you can set */
	Xet_add(L, setters);     /* fill with setters */
	lua_pushcclosure(L, newindex_handler, 1);
	lua_rawset(L, metatable);     /* metatable.__newindex = newindex_handler */

	lua_pop(L, 1);                /* drop metatable */
	//return 1;                     /* return methods on the stack */
}