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