/*
** $Id: ltm.c,v 2.14.1.1 2013/04/12 18:48:47 roberto Exp $
** Tag methods
** See Copyright Notice in lua.h
*/

#include <string.h>

#define ltm_c
#define LUA_CORE

#include "lua.h"

#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"

static const char udatatypename[] = "userdata";

LUAI_DDEF const char *const luaT_typenames_[LUA_TOTALTAGS] = {
	"no value",
	"nil", "boolean", udatatypename, "number",
	"string", "table", "function", udatatypename, "thread",
	"proto", "upval" /* these last two cases are used for tests only */
};

void luaT_init(lua_State *L)
{
	static const char *const luaT_eventname[] = {/* ORDER TM */
												 "__index", "__newindex",
												 "__gc", "__mode", "__len", "__eq",
												 "__add", "__sub", "__mul", "__div", "__mod",
												 "__pow", "__unm", "__lt", "__le",
												 "__concat", "__call"};
	int i;
	for (i = 0; i < TM_N; i++)
	{
		G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
		luaS_fix(G(L)->tmname[i]); /* never collect these names */
	}
}

/*
** function to be used with macro "fasttm": optimized for absence of
** tag methods
*/
const TValue *luaT_gettm(Table *events, TMS event, TString *ename)
{
	const TValue *tm = luaH_getstr(events, ename);
	lua_assert(event <= TM_EQ);
	if (ttisnil(tm))
	{                                            /* no tag method? */
		events->flags |= cast_byte(1u << event); /* cache this fact */
		return NULL;
	}
	else
		return tm;
}

const TValue *luaT_gettmbyobj(lua_State *L, const TValue *o, TMS event)
{
	Table *mt;
	switch (ttypenv(o))
	{
		case LUA_TTABLE:
			mt = hvalue(o)->metatable;
			break;
		case LUA_TUSERDATA:
			mt = uvalue(o)->metatable;
			break;
		default:
			mt = G(L)->mt[ttypenv(o)];
	}
	return (mt ? luaH_getstr(mt, G(L)->tmname[event]) : luaO_nilobject);
}
