/*

** $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);

}