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
28static const char udatatypename[] = "userdata";
29
30LUAI_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
38void 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*/
60const 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
71const 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*/
91const 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
103void luaT_callTM (lua_State *L, const TValue *f, const TValue *p1,
104 const TValue *p2, const TValue *p3) {
105 StkId func = L->top.p;
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.p = 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
119void 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.p;
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.p += 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.p); /* move result to its place */
134}
135
136
137static 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
148void 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
167void luaT_tryconcatTM (lua_State *L) {
168 StkId top = L->top.p;
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
175void 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
184void 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*/
201int luaT_callorderTM (lua_State *L, const TValue *p1, const TValue *p2,
202 TMS event) {
203 if (callbinTM(L, p1, p2, L->top.p, event)) /* try original event */
204 return !l_isfalse(s2v(L->top.p));
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.p, TM_LT)) {
210 L->ci->callstatus ^= CIST_LEQ; /* clear mark */
211 return l_isfalse(s2v(L->top.p));
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
221int 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
238void luaT_adjustvarargs (lua_State *L, int nfixparams, CallInfo *ci,
239 const Proto *p) {
240 int i;
241 int actual = cast_int(L->top.p - ci->func.p) - 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.p++, ci->func.p);
247 /* move fixed parameters to the top of the stack */
248 for (i = 1; i <= nfixparams; i++) {
249 setobjs2s(L, L->top.p++, ci->func.p + i);
250 setnilvalue(s2v(ci->func.p + i)); /* erase original parameter (for GC) */
251 }
252 ci->func.p += actual + 1;
253 ci->top.p += actual + 1;
254 lua_assert(L->top.p <= ci->top.p && ci->top.p <= L->stack_last.p);
255}
256
257
258void 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.p = where + nextra; /* next instruction will need top */
265 }
266 for (i = 0; i < wanted && i < nextra; i++)
267 setobjs2s(L, where + i, ci->func.p - nextra + i);
268 for (; i < wanted; i++) /* complete required results with nil */
269 setnilvalue(s2v(where + i));
270}
271