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
luaT_init(lua_State * L)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 */
luaT_gettm(Table * events,TMS event,TString * ename)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
luaT_gettmbyobj(lua_State * L,const TValue * o,TMS event)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