1 /*
2 ** $Id: ltm.c $
3 ** Tag methods
4 ** See Copyright Notice in lua.h
5 */
6 
7 #define ltm_c
8 #define LUA_CORE
9 
10 #include "lprefix.h"
11 
12 
13 #include <string.h>
14 
15 #include "lua.h"
16 
17 #include "ldebug.h"
18 #include "ldo.h"
19 #include "lgc.h"
20 #include "lobject.h"
21 #include "lstate.h"
22 #include "lstring.h"
23 #include "ltable.h"
24 #include "ltm.h"
25 #include "lvm.h"
26 
27 
28 static const char udatatypename[] = "userdata";
29 
30 LUAI_DDEF const char *const luaT_typenames_[LUA_TOTALTYPES] = {
31   "no value",
32   "nil", "boolean", udatatypename, "number",
33   "string", "table", "function", udatatypename, "thread",
34   "upvalue", "proto" /* these last cases are used for tests only */
35 };
36 
37 
luaT_init(lua_State * L)38 void luaT_init (lua_State *L) {
39   static const char *const luaT_eventname[] = {  /* ORDER TM */
40     "__index", "__newindex",
41     "__gc", "__mode", "__len", "__eq",
42     "__add", "__sub", "__mul", "__mod", "__pow",
43     "__div", "__idiv",
44     "__band", "__bor", "__bxor", "__shl", "__shr",
45     "__unm", "__bnot", "__lt", "__le",
46     "__concat", "__call", "__close"
47   };
48   int i;
49   for (i=0; i<TM_N; i++) {
50     G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
51     luaC_fix(L, obj2gco(G(L)->tmname[i]));  /* never collect these names */
52   }
53 }
54 
55 
56 /*
57 ** function to be used with macro "fasttm": optimized for absence of
58 ** tag methods
59 */
luaT_gettm(Table * events,TMS event,TString * ename)60 const TValue *luaT_gettm (Table *events, TMS event, TString *ename) {
61   const TValue *tm = luaH_getshortstr(events, ename);
62   lua_assert(event <= TM_EQ);
63   if (notm(tm)) {  /* no tag method? */
64     events->flags |= cast_byte(1u<<event);  /* cache this fact */
65     return NULL;
66   }
67   else return tm;
68 }
69 
70 
luaT_gettmbyobj(lua_State * L,const TValue * o,TMS event)71 const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o, TMS event) {
72   Table *mt;
73   switch (ttype(o)) {
74     case LUA_TTABLE:
75       mt = hvalue(o)->metatable;
76       break;
77     case LUA_TUSERDATA:
78       mt = uvalue(o)->metatable;
79       break;
80     default:
81       mt = G(L)->mt[ttype(o)];
82   }
83   return (mt ? luaH_getshortstr(mt, G(L)->tmname[event]) : &G(L)->nilvalue);
84 }
85 
86 
87 /*
88 ** Return the name of the type of an object. For tables and userdata
89 ** with metatable, use their '__name' metafield, if present.
90 */
luaT_objtypename(lua_State * L,const TValue * o)91 const char *luaT_objtypename (lua_State *L, const TValue *o) {
92   Table *mt;
93   if ((ttistable(o) && (mt = hvalue(o)->metatable) != NULL) ||
94       (ttisfulluserdata(o) && (mt = uvalue(o)->metatable) != NULL)) {
95     const TValue *name = luaH_getshortstr(mt, luaS_new(L, "__name"));
96     if (ttisstring(name))  /* is '__name' a string? */
97       return getstr(tsvalue(name));  /* use it as type name */
98   }
99   return ttypename(ttype(o));  /* else use standard type name */
100 }
101 
102 
luaT_callTM(lua_State * L,const TValue * f,const TValue * p1,const TValue * p2,const TValue * p3)103 void luaT_callTM (lua_State *L, const TValue *f, const TValue *p1,
104                   const TValue *p2, const TValue *p3) {
105   StkId func = L->top;
106   setobj2s(L, func, f);  /* push function (assume EXTRA_STACK) */
107   setobj2s(L, func + 1, p1);  /* 1st argument */
108   setobj2s(L, func + 2, p2);  /* 2nd argument */
109   setobj2s(L, func + 3, p3);  /* 3rd argument */
110   L->top = func + 4;
111   /* metamethod may yield only when called from Lua code */
112   if (isLuacode(L->ci))
113     luaD_call(L, func, 0);
114   else
115     luaD_callnoyield(L, func, 0);
116 }
117 
118 
luaT_callTMres(lua_State * L,const TValue * f,const TValue * p1,const TValue * p2,StkId res)119 void luaT_callTMres (lua_State *L, const TValue *f, const TValue *p1,
120                      const TValue *p2, StkId res) {
121   ptrdiff_t result = savestack(L, res);
122   StkId func = L->top;
123   setobj2s(L, func, f);  /* push function (assume EXTRA_STACK) */
124   setobj2s(L, func + 1, p1);  /* 1st argument */
125   setobj2s(L, func + 2, p2);  /* 2nd argument */
126   L->top += 3;
127   /* metamethod may yield only when called from Lua code */
128   if (isLuacode(L->ci))
129     luaD_call(L, func, 1);
130   else
131     luaD_callnoyield(L, func, 1);
132   res = restorestack(L, result);
133   setobjs2s(L, res, --L->top);  /* move result to its place */
134 }
135 
136 
callbinTM(lua_State * L,const TValue * p1,const TValue * p2,StkId res,TMS event)137 static int callbinTM (lua_State *L, const TValue *p1, const TValue *p2,
138                       StkId res, TMS event) {
139   const TValue *tm = luaT_gettmbyobj(L, p1, event);  /* try first operand */
140   if (notm(tm))
141     tm = luaT_gettmbyobj(L, p2, event);  /* try second operand */
142   if (notm(tm)) return 0;
143   luaT_callTMres(L, tm, p1, p2, res);
144   return 1;
145 }
146 
147 
luaT_trybinTM(lua_State * L,const TValue * p1,const TValue * p2,StkId res,TMS event)148 void luaT_trybinTM (lua_State *L, const TValue *p1, const TValue *p2,
149                     StkId res, TMS event) {
150   if (l_unlikely(!callbinTM(L, p1, p2, res, event))) {
151     switch (event) {
152       case TM_BAND: case TM_BOR: case TM_BXOR:
153       case TM_SHL: case TM_SHR: case TM_BNOT: {
154         if (ttisnumber(p1) && ttisnumber(p2))
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 
luaT_tryconcatTM(lua_State * L)167 void luaT_tryconcatTM (lua_State *L) {
168   StkId top = L->top;
169   if (l_unlikely(!callbinTM(L, s2v(top - 2), s2v(top - 1), top - 2,
170                                TM_CONCAT)))
171     luaG_concaterror(L, s2v(top - 2), s2v(top - 1));
172 }
173 
174 
luaT_trybinassocTM(lua_State * L,const TValue * p1,const TValue * p2,int flip,StkId res,TMS event)175 void luaT_trybinassocTM (lua_State *L, const TValue *p1, const TValue *p2,
176                                        int flip, StkId res, TMS event) {
177   if (flip)
178     luaT_trybinTM(L, p2, p1, res, event);
179   else
180     luaT_trybinTM(L, p1, p2, res, event);
181 }
182 
183 
luaT_trybiniTM(lua_State * L,const TValue * p1,lua_Integer i2,int flip,StkId res,TMS event)184 void luaT_trybiniTM (lua_State *L, const TValue *p1, lua_Integer i2,
185                                    int flip, StkId res, TMS event) {
186   TValue aux;
187   setivalue(&aux, i2);
188   luaT_trybinassocTM(L, p1, &aux, flip, res, event);
189 }
190 
191 
192 /*
193 ** Calls an order tag method.
194 ** For lessequal, LUA_COMPAT_LT_LE keeps compatibility with old
195 ** behavior: if there is no '__le', try '__lt', based on l <= r iff
196 ** !(r < l) (assuming a total order). If the metamethod yields during
197 ** this substitution, the continuation has to know about it (to negate
198 ** the result of r<l); bit CIST_LEQ in the call status keeps that
199 ** information.
200 */
luaT_callorderTM(lua_State * L,const TValue * p1,const TValue * p2,TMS event)201 int luaT_callorderTM (lua_State *L, const TValue *p1, const TValue *p2,
202                       TMS event) {
203   if (callbinTM(L, p1, p2, L->top, event))  /* try original event */
204     return !l_isfalse(s2v(L->top));
205 #if defined(LUA_COMPAT_LT_LE)
206   else if (event == TM_LE) {
207       /* try '!(p2 < p1)' for '(p1 <= p2)' */
208       L->ci->callstatus |= CIST_LEQ;  /* mark it is doing 'lt' for 'le' */
209       if (callbinTM(L, p2, p1, L->top, TM_LT)) {
210         L->ci->callstatus ^= CIST_LEQ;  /* clear mark */
211         return l_isfalse(s2v(L->top));
212       }
213       /* else error will remove this 'ci'; no need to clear mark */
214   }
215 #endif
216   luaG_ordererror(L, p1, p2);  /* no metamethod found */
217   return 0;  /* to avoid warnings */
218 }
219 
220 
luaT_callorderiTM(lua_State * L,const TValue * p1,int v2,int flip,int isfloat,TMS event)221 int luaT_callorderiTM (lua_State *L, const TValue *p1, int v2,
222                        int flip, int isfloat, TMS event) {
223   TValue aux; const TValue *p2;
224   if (isfloat) {
225     setfltvalue(&aux, cast_num(v2));
226   }
227   else
228     setivalue(&aux, v2);
229   if (flip) {  /* arguments were exchanged? */
230     p2 = p1; p1 = &aux;  /* correct them */
231   }
232   else
233     p2 = &aux;
234   return luaT_callorderTM(L, p1, p2, event);
235 }
236 
237 
luaT_adjustvarargs(lua_State * L,int nfixparams,CallInfo * ci,const Proto * p)238 void luaT_adjustvarargs (lua_State *L, int nfixparams, CallInfo *ci,
239                          const Proto *p) {
240   int i;
241   int actual = cast_int(L->top - ci->func) - 1;  /* number of arguments */
242   int nextra = actual - nfixparams;  /* number of extra arguments */
243   ci->u.l.nextraargs = nextra;
244   luaD_checkstack(L, p->maxstacksize + 1);
245   /* copy function to the top of the stack */
246   setobjs2s(L, L->top++, ci->func);
247   /* move fixed parameters to the top of the stack */
248   for (i = 1; i <= nfixparams; i++) {
249     setobjs2s(L, L->top++, ci->func + i);
250     setnilvalue(s2v(ci->func + i));  /* erase original parameter (for GC) */
251   }
252   ci->func += actual + 1;
253   ci->top += actual + 1;
254   lua_assert(L->top <= ci->top && ci->top <= L->stack_last);
255 }
256 
257 
luaT_getvarargs(lua_State * L,CallInfo * ci,StkId where,int wanted)258 void luaT_getvarargs (lua_State *L, CallInfo *ci, StkId where, int wanted) {
259   int i;
260   int nextra = ci->u.l.nextraargs;
261   if (wanted < 0) {
262     wanted = nextra;  /* get all extra arguments available */
263     checkstackGCp(L, nextra, where);  /* ensure stack space */
264     L->top = where + nextra;  /* next instruction will need top */
265   }
266   for (i = 0; i < wanted && i < nextra; i++)
267     setobjs2s(L, where + i, ci->func - nextra + i);
268   for (; i < wanted; i++)   /* complete required results with nil */
269     setnilvalue(s2v(where + i));
270 }
271 
272