ltm.c revision 1.7 
1/*	$NetBSD: ltm.c,v 1.7 2017/04/26 12:49:34 mbalmer Exp $	*/
2
3/*
4** Id: ltm.c,v 2.38 2016/12/22 13:08:50 roberto Exp
5** Tag methods
6** See Copyright Notice in lua.h
7*/
8
9#define ltm_c
10#define LUA_CORE
11
12#include "lprefix.h"
13
14
15#ifndef _KERNEL
16#include <string.h>
17#endif /* _KERNEL */
18
19#include "lua.h"
20
21#include "ldebug.h"
22#include "ldo.h"
23#include "lobject.h"
24#include "lstate.h"
25#include "lstring.h"
26#include "ltable.h"
27#include "ltm.h"
28#include "lvm.h"
29
30
31static const char udatatypename[] = "userdata";
32
33LUAI_DDEF const char *const luaT_typenames_[LUA_TOTALTAGS] = {
34  "no value",
35  "nil", "boolean", udatatypename, "number",
36  "string", "table", "function", udatatypename, "thread",
37  "proto" /* this last case is used for tests only */
38};
39
40
41void luaT_init (lua_State *L) {
42  static const char *const luaT_eventname[] = {  /* ORDER TM */
43    "__index", "__newindex",
44    "__gc", "__mode", "__len", "__eq",
45#ifndef _KERNEL
46    "__add", "__sub", "__mul", "__mod", "__pow",
47    "__div", "__idiv",
48#else /* _KERNEL */
49    "__add", "__sub", "__mul", "__mod",
50    "__idiv",
51#endif /* _KERNEL */
52    "__band", "__bor", "__bxor", "__shl", "__shr",
53    "__unm", "__bnot", "__lt", "__le",
54    "__concat", "__call"
55  };
56  int i;
57  for (i=0; i<TM_N; i++) {
58    G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
59    luaC_fix(L, obj2gco(G(L)->tmname[i]));  /* never collect these names */
60  }
61}
62
63
64/*
65** function to be used with macro "fasttm": optimized for absence of
66** tag methods
67*/
68const TValue *luaT_gettm (Table *events, TMS event, TString *ename) {
69  const TValue *tm = luaH_getshortstr(events, ename);
70  lua_assert(event <= TM_EQ);
71  if (ttisnil(tm)) {  /* no tag method? */
72    events->flags |= cast_byte(1u<<event);  /* cache this fact */
73    return NULL;
74  }
75  else return tm;
76}
77
78
79const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o, TMS event) {
80  Table *mt;
81  switch (ttnov(o)) {
82    case LUA_TTABLE:
83      mt = hvalue(o)->metatable;
84      break;
85    case LUA_TUSERDATA:
86      mt = uvalue(o)->metatable;
87      break;
88    default:
89      mt = G(L)->mt[ttnov(o)];
90  }
91  return (mt ? luaH_getshortstr(mt, G(L)->tmname[event]) : luaO_nilobject);
92}
93
94
95/*
96** Return the name of the type of an object. For tables and userdata
97** with metatable, use their '__name' metafield, if present.
98*/
99const char *luaT_objtypename (lua_State *L, const TValue *o) {
100  Table *mt;
101  if ((ttistable(o) && (mt = hvalue(o)->metatable) != NULL) ||
102      (ttisfulluserdata(o) && (mt = uvalue(o)->metatable) != NULL)) {
103    const TValue *name = luaH_getshortstr(mt, luaS_new(L, "__name"));
104    if (ttisstring(name))  /* is '__name' a string? */
105      return getstr(tsvalue(name));  /* use it as type name */
106  }
107  return ttypename(ttnov(o));  /* else use standard type name */
108}
109
110
111void luaT_callTM (lua_State *L, const TValue *f, const TValue *p1,
112                  const TValue *p2, TValue *p3, int hasres) {
113  ptrdiff_t result = savestack(L, p3);
114  StkId func = L->top;
115  setobj2s(L, func, f);  /* push function (assume EXTRA_STACK) */
116  setobj2s(L, func + 1, p1);  /* 1st argument */
117  setobj2s(L, func + 2, p2);  /* 2nd argument */
118  L->top += 3;
119  if (!hasres)  /* no result? 'p3' is third argument */
120    setobj2s(L, L->top++, p3);  /* 3rd argument */
121  /* metamethod may yield only when called from Lua code */
122  if (isLua(L->ci))
123    luaD_call(L, func, hasres);
124  else
125    luaD_callnoyield(L, func, hasres);
126  if (hasres) {  /* if has result, move it to its place */
127    p3 = restorestack(L, result);
128    setobjs2s(L, p3, --L->top);
129  }
130}
131
132
133int luaT_callbinTM (lua_State *L, const TValue *p1, const TValue *p2,
134                    StkId res, TMS event) {
135  const TValue *tm = luaT_gettmbyobj(L, p1, event);  /* try first operand */
136  if (ttisnil(tm))
137    tm = luaT_gettmbyobj(L, p2, event);  /* try second operand */
138  if (ttisnil(tm)) return 0;
139  luaT_callTM(L, tm, p1, p2, res, 1);
140  return 1;
141}
142
143
144void luaT_trybinTM (lua_State *L, const TValue *p1, const TValue *p2,
145                    StkId res, TMS event) {
146  if (!luaT_callbinTM(L, p1, p2, res, event)) {
147    switch (event) {
148      case TM_CONCAT:
149        luaG_concaterror(L, p1, p2);
150      /* call never returns, but to avoid warnings: *//* FALLTHROUGH */
151      case TM_BAND: case TM_BOR: case TM_BXOR:
152      case TM_SHL: case TM_SHR: case TM_BNOT: {
153        lua_Number dummy;
154        if (tonumber(p1, &dummy) && tonumber(p2, &dummy))
155          luaG_tointerror(L, p1, p2);
156        else
157          luaG_opinterror(L, p1, p2, "perform bitwise operation on");
158      }
159      /* calls never return, but to avoid warnings: *//* FALLTHROUGH */
160      default:
161        luaG_opinterror(L, p1, p2, "perform arithmetic on");
162    }
163  }
164}
165
166
167int luaT_callorderTM (lua_State *L, const TValue *p1, const TValue *p2,
168                      TMS event) {
169  if (!luaT_callbinTM(L, p1, p2, L->top, event))
170    return -1;  /* no metamethod */
171  else
172    return !l_isfalse(L->top);
173}
174
175