src/ltm.c

   1 /*
   2 ** $Id: ltm.c,v 2.8 2006/01/10 12:50:00 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 const char *const luaT_typenames[] = {
  23     "nil", "boolean", "userdata", "number",
  24     "string", "table", "function", "userdata", "thread",
  25     "proto", "upval"
  26 };
  27
  28
  29 void luaT_init (lua_State *L) {
  30   static const char *const luaT_eventname[] = {  /* ORDER TM */
  31     "__index", "__newindex",
  32     "__gc", "__mode", "__eq",
  33     "__add", "__sub", "__mul", "__div", "__mod",
  34     "__pow", "__unm", "__len", "__lt", "__le",
  35     "__concat", "__call"
  36   };
  37   int i;
  38   for (i=0; i<TM_N; i++) {
  39     G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
  40     luaS_fix(G(L)->tmname[i]);  /* never collect these names */
  41   }
  42 }
  43
  44
  45 /*
  46 ** function to be used with macro "fasttm": optimized for absence of
  47 ** tag methods
  48 */
  49 const TValue *luaT_gettm (Table *events, TMS event, TString *ename) {
  50   const TValue *tm = luaH_getstr(events, ename);
  51   lua_assert(event <= TM_EQ);
  52   if (ttisnil(tm)) {  /* no tag method? */
  53     events->flags |= cast_byte(1u<<event);  /* cache this fact */
  54     return NULL;
  55   }
  56   else return tm;
  57 }
  58
  59
  60 const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o, TMS event) {
  61   Table *mt;
  62   switch (ttype(o)) {
  63     case LUA_TTABLE:
  64       mt = hvalue(o)->metatable;
  65       break;
  66     case LUA_TUSERDATA:
  67       mt = uvalue(o)->metatable;
  68       break;
  69     default:
  70       mt = G(L)->mt[ttype(o)];
  71   }
  72   return (mt ? luaH_getstr(mt, G(L)->tmname[event]) : luaO_nilobject);
  73 }
  74