1 /* 2 ** $Id: ltm.c,v 2.14 2011/06/02 19:31:40 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
