/*
** $Id: ltm.c,v 2.8.1.1 2007/12/27 13:02:25 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"

const char *const luaT_typenames[] = {
    "nil",      "boolean",  "userdata", "number", "string", "table",
    "function", "userdata", "thread",   "proto",  "upval"};

void luaT_init(lua_State *L)
{
    static const char *const luaT_eventname[] = {
        /* ORDER TM */
        "__index", "__newindex", "__gc",  "__mode",   "__eq",  "__add",
        "__sub",   "__mul",      "__div", "__mod",    "__pow", "__unm",
        "__len",   "__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 (ttype(o)) {
    case LUA_TTABLE:
        mt = hvalue(o)->metatable;
        break;
    case LUA_TUSERDATA:
        mt = uvalue(o)->metatable;
        break;
    default:
        mt = G(L)->mt[ttype(o)];
    }
    return (mt ? luaH_getstr(mt, G(L)->tmname[event]) : luaO_nilobject);
}
