lua/ltm.c

   1 /*
   2 ** $Id: ltm.c,v 2.8.1.1 2007/12/27 13:02:25 roberto Exp $
   3 ** Tag methods
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7 #if 0
   8 #include <string.h>
   9 #endif
  10
  11 #define ltm_c
  12 #define LUA_CORE
  13
  14 #include "lua.h"
  15
  16 #include "lobject.h"
  17 #include "lstate.h"
  18 #include "lstring.h"
  19 #include "ltable.h"
  20 #include "ltm.h"
  21
  22
  23
  24 const char *const luaT_typenames[] = {
  25   "nil", "boolean", "userdata", "number",
  26   "string", "table", "function", "userdata", "thread",
  27   "proto", "upval"
  28 };
  29
  30
  31 void luaT_init (lua_State *L) {
  32   static const char *const luaT_eventname[] = {  /* ORDER TM */
  33     "__index", "__newindex",
  34     "__gc", "__mode", "__eq",
  35     "__add", "__sub", "__mul", "__div", "__mod",
  36     "__pow", "__unm", "__len", "__lt", "__le",
  37     "__concat", "__call"
  38   };
  39   int i;
  40   for (i=0; i<TM_N; i++) {
  41     G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
  42     luaS_fix(G(L)->tmname[i]);  /* never collect these names */
  43   }
  44 }
  45
  46
  47 /*
  48 ** function to be used with macro "fasttm": optimized for absence of
  49 ** tag methods
  50 */
  51 const TValue *luaT_gettm (Table *events, TMS event, TString *ename) {
  52   const TValue *tm = luaH_getstr(events, ename);
  53   lua_assert(event <= TM_EQ);
  54   if (ttisnil(tm)) {  /* no tag method? */
  55     events->flags |= cast_byte(1u<<event);  /* cache this fact */
  56     return NULL;
  57   }
  58   else return tm;
  59 }
  60
  61
  62 const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o, TMS event) {
  63   Table *mt;
  64   switch (ttype(o)) {
  65     case LUA_TTABLE:
  66       mt = hvalue(o)->metatable;
  67       break;
  68     case LUA_TUSERDATA:
  69       mt = uvalue(o)->metatable;
  70       break;
  71     default:
  72       mt = G(L)->mt[ttype(o)];
  73   }
  74   return (mt ? luaH_getstr(mt, G(L)->tmname[event]) : luaO_nilobject);
  75 }
  76