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  1. /*
  2. ** $Id: ltm.c,v 2.14.1.1 2013/04/12 18:48:47 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. static const char udatatypename[] = "userdata";
  23.  
  24. LUAI_DDEF const char *const luaT_typenames_[LUA_TOTALTAGS] = {
  25.   "no value",
  26.   "nil", "boolean", udatatypename, "number",
  27.   "string", "table", "function", udatatypename, "thread",
  28.   "proto", "upval"  /* these last two cases are used for tests only */
  29. };
  30.  
  31.  
  32. void luaT_init (lua_State *L) {
  33.   static const char *const luaT_eventname[] = {  /* ORDER TM */
  34.     "__index", "__newindex",
  35.     "__gc", "__mode", "__len", "__eq",
  36.     "__add", "__sub", "__mul", "__div", "__mod",
  37.     "__pow", "__unm", "__lt", "__le",
  38.     "__concat", "__call"
  39.   };
  40.   int i;
  41.   for (i=0; i<TM_N; i++) {
  42.     G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
  43.     luaS_fix(G(L)->tmname[i]);  /* never collect these names */
  44.   }
  45. }
  46.  
  47.  
  48. /*
  49. ** function to be used with macro "fasttm": optimized for absence of
  50. ** tag methods
  51. */
  52. const TValue *luaT_gettm (Table *events, TMS event, TString *ename) {
  53.   const TValue *tm = luaH_getstr(events, ename);
  54.   lua_assert(event <= TM_EQ);
  55.   if (ttisnil(tm)) {  /* no tag method? */
  56.     events->flags |= cast_byte(1u<<event);  /* cache this fact */
  57.     return NULL;
  58.   }
  59.   else return tm;
  60. }
  61.  
  62.  
  63. const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o, TMS event) {
  64.   Table *mt;
  65.   switch (ttypenv(o)) {
  66.     case LUA_TTABLE:
  67.       mt = hvalue(o)->metatable;
  68.       break;
  69.     case LUA_TUSERDATA:
  70.       mt = uvalue(o)->metatable;
  71.       break;
  72.     default:
  73.       mt = G(L)->mt[ttypenv(o)];
  74.   }
  75.   return (mt ? luaH_getstr(mt, G(L)->tmname[event]) : luaO_nilobject);
  76. }
  77.  
  78.