src/lua/lstrlib.c

   1 /*
   2 ** $Id: lstrlib.c,v 1.132.1.4 2008/07/11 17:27:21 roberto Exp $
   3 ** Standard library for string operations and pattern-matching
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <ctype.h>
   9 #include <stddef.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13
  14 #define lstrlib_c
  15 #define LUA_LIB
  16
  17 #include "lua.h"
  18
  19 #include "lauxlib.h"
  20 #include "lualib.h"
  21
  22
  23 /* macro to `unsign' a character */
  24 #define uchar(c)        ((unsigned char)(c))
  25
  26
  27
  28 static int str_len (lua_State *L) {
  29   size_t l;
  30   luaL_checklstring(L, 1, &l);
  31   lua_pushinteger(L, l);
  32   return 1;
  33 }
  34
  35
  36 static ptrdiff_t posrelat (ptrdiff_t pos, size_t len) {
  37   /* relative string position: negative means back from end */
  38   if (pos < 0) pos += (ptrdiff_t)len + 1;
  39   return (pos >= 0) ? pos : 0;
  40 }
  41
  42
  43 static int str_sub (lua_State *L) {
  44   size_t l;
  45   const char *s = luaL_checklstring(L, 1, &l);
  46   ptrdiff_t start = posrelat(luaL_checkinteger(L, 2), l);
  47   ptrdiff_t end = posrelat(luaL_optinteger(L, 3, -1), l);
  48   if (start < 1) start = 1;
  49   if (end > (ptrdiff_t)l) end = (ptrdiff_t)l;
  50   if (start <= end)
  51     lua_pushlstring(L, s+start-1, end-start+1);
  52   else lua_pushliteral(L, "");
  53   return 1;
  54 }
  55
  56
  57 static int str_reverse (lua_State *L) {
  58   size_t l;
  59   luaL_Buffer b;
  60   const char *s = luaL_checklstring(L, 1, &l);
  61   luaL_buffinit(L, &b);
  62   while (l--) luaL_addchar(&b, s[l]);
  63   luaL_pushresult(&b);
  64   return 1;
  65 }
  66
  67
  68 static int str_lower (lua_State *L) {
  69   size_t l;
  70   size_t i;
  71   luaL_Buffer b;
  72   const char *s = luaL_checklstring(L, 1, &l);
  73   luaL_buffinit(L, &b);
  74   for (i=0; i<l; i++)
  75     luaL_addchar(&b, tolower(uchar(s[i])));
  76   luaL_pushresult(&b);
  77   return 1;
  78 }
  79
  80
  81 static int str_upper (lua_State *L) {
  82   size_t l;
  83   size_t i;
  84   luaL_Buffer b;
  85   const char *s = luaL_checklstring(L, 1, &l);
  86   luaL_buffinit(L, &b);
  87   for (i=0; i<l; i++)
  88     luaL_addchar(&b, toupper(uchar(s[i])));
  89   luaL_pushresult(&b);
  90   return 1;
  91 }
  92
  93 static int str_rep (lua_State *L) {
  94   size_t l;
  95   luaL_Buffer b;
  96   const char *s = luaL_checklstring(L, 1, &l);
  97   int n = luaL_checkint(L, 2);
  98   luaL_buffinit(L, &b);
  99   while (n-- > 0)
 100     luaL_addlstring(&b, s, l);
 101   luaL_pushresult(&b);
 102   return 1;
 103 }
 104
 105
 106 static int str_byte (lua_State *L) {
 107   size_t l;
 108   const char *s = luaL_checklstring(L, 1, &l);
 109   ptrdiff_t posi = posrelat(luaL_optinteger(L, 2, 1), l);
 110   ptrdiff_t pose = posrelat(luaL_optinteger(L, 3, posi), l);
 111   int n, i;
 112   if (posi <= 0) posi = 1;
 113   if ((size_t)pose > l) pose = l;
 114   if (posi > pose) return 0;  /* empty interval; return no values */
 115   n = (int)(pose -  posi + 1);
 116   if (posi + n <= pose)  /* overflow? */
 117     luaL_error(L, "string slice too long");
 118   luaL_checkstack(L, n, "string slice too long");
 119   for (i=0; i<n; i++)
 120     lua_pushinteger(L, uchar(s[posi+i-1]));
 121   return n;
 122 }
 123
 124
 125 static int str_char (lua_State *L) {
 126   int n = lua_gettop(L);  /* number of arguments */
 127   int i;
 128   luaL_Buffer b;
 129   luaL_buffinit(L, &b);
 130   for (i=1; i<=n; i++) {
 131     int c = luaL_checkint(L, i);
 132     luaL_argcheck(L, uchar(c) == c, i, "invalid value");
 133     luaL_addchar(&b, uchar(c));
 134   }
 135   luaL_pushresult(&b);
 136   return 1;
 137 }
 138
 139
 140 static int writer (lua_State *L, const void* b, size_t size, void* B) {
 141   (void)L;
 142   luaL_addlstring((luaL_Buffer*) B, (const char *)b, size);
 143   return 0;
 144 }
 145
 146
 147 static int str_dump (lua_State *L) {
 148   luaL_Buffer b;
 149   luaL_checktype(L, 1, LUA_TFUNCTION);
 150   lua_settop(L, 1);
 151   luaL_buffinit(L,&b);
 152   if (lua_dump(L, writer, &b) != 0)
 153     luaL_error(L, "unable to dump given function");
 154   luaL_pushresult(&b);
 155   return 1;
 156 }
 157
 158
 159
 160 /*
 161 ** {======================================================
 162 ** PATTERN MATCHING
 163 ** =======================================================
 164 */
 165
 166
 167 #define CAP_UNFINISHED  (-1)
 168 #define CAP_POSITION    (-2)
 169
 170 typedef struct MatchState {
 171   const char *src_init;  /* init of source string */
 172   const char *src_end;  /* end (`\0') of source string */
 173   lua_State *L;
 174   int level;  /* total number of captures (finished or unfinished) */
 175   struct {
 176     const char *init;
 177     ptrdiff_t len;
 178   } capture[LUA_MAXCAPTURES];
 179 } MatchState;
 180
 181
 182 #define L_ESC           '%'
 183 #define SPECIALS        "^$*+?.([%-"
 184
 185
 186 static int check_capture (MatchState *ms, int l) {
 187   l -= '1';
 188   if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
 189     return luaL_error(ms->L, "invalid capture index");
 190   return l;
 191 }
 192
 193
 194 static int capture_to_close (MatchState *ms) {
 195   int level = ms->level;
 196   for (level--; level>=0; level--)
 197     if (ms->capture[level].len == CAP_UNFINISHED) return level;
 198   return luaL_error(ms->L, "invalid pattern capture");
 199 }
 200
 201
 202 static const char *classend (MatchState *ms, const char *p) {
 203   switch (*p++) {
 204     case L_ESC: {
 205       if (*p == '\0')
 206         luaL_error(ms->L, "malformed pattern (ends with " LUA_QL("%%") ")");
 207       return p+1;
 208     }
 209     case '[': {
 210       if (*p == '^') p++;
 211       do {  /* look for a `]' */
 212         if (*p == '\0')
 213           luaL_error(ms->L, "malformed pattern (missing " LUA_QL("]") ")");
 214         if (*(p++) == L_ESC && *p != '\0')
 215           p++;  /* skip escapes (e.g. `%]') */
 216       } while (*p != ']');
 217       return p+1;
 218     }
 219     default: {
 220       return p;
 221     }
 222   }
 223 }
 224
 225
 226 static int match_class (int c, int cl) {
 227   int res;
 228   switch (tolower(cl)) {
 229     case 'a' : res = isalpha(c); break;
 230     case 'c' : res = iscntrl(c); break;
 231     case 'd' : res = isdigit(c); break;
 232     case 'l' : res = islower(c); break;
 233     case 'p' : res = ispunct(c); break;
 234     case 's' : res = isspace(c); break;
 235     case 'u' : res = isupper(c); break;
 236     case 'w' : res = isalnum(c); break;
 237     case 'x' : res = isxdigit(c); break;
 238     case 'z' : res = (c == 0); break;
 239     default: return (cl == c);
 240   }
 241   return (islower(cl) ? res : !res);
 242 }
 243
 244
 245 static int matchbracketclass (int c, const char *p, const char *ec) {
 246   int sig = 1;
 247   if (*(p+1) == '^') {
 248     sig = 0;
 249     p++;  /* skip the `^' */
 250   }
 251   while (++p < ec) {
 252     if (*p == L_ESC) {
 253       p++;
 254       if (match_class(c, uchar(*p)))
 255         return sig;
 256     }
 257     else if ((*(p+1) == '-') && (p+2 < ec)) {
 258       p+=2;
 259       if (uchar(*(p-2)) <= c && c <= uchar(*p))
 260         return sig;
 261     }
 262     else if (uchar(*p) == c) return sig;
 263   }
 264   return !sig;
 265 }
 266
 267
 268 static int singlematch (int c, const char *p, const char *ep) {
 269   switch (*p) {
 270     case '.': return 1;  /* matches any char */
 271     case L_ESC: return match_class(c, uchar(*(p+1)));
 272     case '[': return matchbracketclass(c, p, ep-1);
 273     default:  return (uchar(*p) == c);
 274   }
 275 }
 276
 277
 278 static const char *match (MatchState *ms, const char *s, const char *p);
 279
 280
 281 static const char *matchbalance (MatchState *ms, const char *s,
 282                                    const char *p) {
 283   if (*p == 0 || *(p+1) == 0)
 284     luaL_error(ms->L, "unbalanced pattern");
 285   if (*s != *p) return NULL;
 286   else {
 287     int b = *p;
 288     int e = *(p+1);
 289     int cont = 1;
 290     while (++s < ms->src_end) {
 291       if (*s == e) {
 292         if (--cont == 0) return s+1;
 293       }
 294       else if (*s == b) cont++;
 295     }
 296   }
 297   return NULL;  /* string ends out of balance */
 298 }
 299
 300
 301 static const char *max_expand (MatchState *ms, const char *s,
 302                                  const char *p, const char *ep) {
 303   ptrdiff_t i = 0;  /* counts maximum expand for item */
 304   while ((s+i)<ms->src_end && singlematch(uchar(*(s+i)), p, ep))
 305     i++;
 306   /* keeps trying to match with the maximum repetitions */
 307   while (i>=0) {
 308     const char *res = match(ms, (s+i), ep+1);
 309     if (res) return res;
 310     i--;  /* else didn't match; reduce 1 repetition to try again */
 311   }
 312   return NULL;
 313 }
 314
 315
 316 static const char *min_expand (MatchState *ms, const char *s,
 317                                  const char *p, const char *ep) {
 318   for (;;) {
 319     const char *res = match(ms, s, ep+1);
 320     if (res != NULL)
 321       return res;
 322     else if (s<ms->src_end && singlematch(uchar(*s), p, ep))
 323       s++;  /* try with one more repetition */
 324     else return NULL;
 325   }
 326 }
 327
 328
 329 static const char *start_capture (MatchState *ms, const char *s,
 330                                     const char *p, int what) {
 331   const char *res;
 332   int level = ms->level;
 333   if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
 334   ms->capture[level].init = s;
 335   ms->capture[level].len = what;
 336   ms->level = level+1;
 337   if ((res=match(ms, s, p)) == NULL)  /* match failed? */
 338     ms->level--;  /* undo capture */
 339   return res;
 340 }
 341
 342
 343 static const char *end_capture (MatchState *ms, const char *s,
 344                                   const char *p) {
 345   int l = capture_to_close(ms);
 346   const char *res;
 347   ms->capture[l].len = s - ms->capture[l].init;  /* close capture */
 348   if ((res = match(ms, s, p)) == NULL)  /* match failed? */
 349     ms->capture[l].len = CAP_UNFINISHED;  /* undo capture */
 350   return res;
 351 }
 352
 353
 354 static const char *match_capture (MatchState *ms, const char *s, int l) {
 355   size_t len;
 356   l = check_capture(ms, l);
 357   len = ms->capture[l].len;
 358   if ((size_t)(ms->src_end-s) >= len &&
 359       memcmp(ms->capture[l].init, s, len) == 0)
 360     return s+len;
 361   else return NULL;
 362 }
 363
 364
 365 static const char *match (MatchState *ms, const char *s, const char *p) {
 366   init: /* using goto's to optimize tail recursion */
 367   switch (*p) {
 368     case '(': {  /* start capture */
 369       if (*(p+1) == ')')  /* position capture? */
 370         return start_capture(ms, s, p+2, CAP_POSITION);
 371       else
 372         return start_capture(ms, s, p+1, CAP_UNFINISHED);
 373     }
 374     case ')': {  /* end capture */
 375       return end_capture(ms, s, p+1);
 376     }
 377     case L_ESC: {
 378       switch (*(p+1)) {
 379         case 'b': {  /* balanced string? */
 380           s = matchbalance(ms, s, p+2);
 381           if (s == NULL) return NULL;
 382           p+=4; goto init;  /* else return match(ms, s, p+4); */
 383         }
 384         case 'f': {  /* frontier? */
 385           const char *ep; char previous;
 386           p += 2;
 387           if (*p != '[')
 388             luaL_error(ms->L, "missing " LUA_QL("[") " after "
 389                                LUA_QL("%%f") " in pattern");
 390           ep = classend(ms, p);  /* points to what is next */
 391           previous = (s == ms->src_init) ? '\0' : *(s-1);
 392           if (matchbracketclass(uchar(previous), p, ep-1) ||
 393              !matchbracketclass(uchar(*s), p, ep-1)) return NULL;
 394           p=ep; goto init;  /* else return match(ms, s, ep); */
 395         }
 396         default: {
 397           if (isdigit(uchar(*(p+1)))) {  /* capture results (%0-%9)? */
 398             s = match_capture(ms, s, uchar(*(p+1)));
 399             if (s == NULL) return NULL;
 400             p+=2; goto init;  /* else return match(ms, s, p+2) */
 401           }
 402           goto dflt;  /* case default */
 403         }
 404       }
 405     }
 406     case '\0': {  /* end of pattern */
 407       return s;  /* match succeeded */
 408     }
 409     case '$': {
 410       if (*(p+1) == '\0')  /* is the `$' the last char in pattern? */
 411         return (s == ms->src_end) ? s : NULL;  /* check end of string */
 412       else goto dflt;
 413     }
 414     default: dflt: {  /* it is a pattern item */
 415       const char *ep = classend(ms, p);  /* points to what is next */
 416       int m = s<ms->src_end && singlematch(uchar(*s), p, ep);
 417       switch (*ep) {
 418         case '?': {  /* optional */
 419           const char *res;
 420           if (m && ((res=match(ms, s+1, ep+1)) != NULL))
 421             return res;
 422           p=ep+1; goto init;  /* else return match(ms, s, ep+1); */
 423         }
 424         case '*': {  /* 0 or more repetitions */
 425           return max_expand(ms, s, p, ep);
 426         }
 427         case '+': {  /* 1 or more repetitions */
 428           return (m ? max_expand(ms, s+1, p, ep) : NULL);
 429         }
 430         case '-': {  /* 0 or more repetitions (minimum) */
 431           return min_expand(ms, s, p, ep);
 432         }
 433         default: {
 434           if (!m) return NULL;
 435           s++; p=ep; goto init;  /* else return match(ms, s+1, ep); */
 436         }
 437       }
 438     }
 439   }
 440 }
 441
 442
 443
 444 static const char *lmemfind (const char *s1, size_t l1,
 445                                const char *s2, size_t l2) {
 446   if (l2 == 0) return s1;  /* empty strings are everywhere */
 447   else if (l2 > l1) return NULL;  /* avoids a negative `l1' */
 448   else {
 449     const char *init;  /* to search for a `*s2' inside `s1' */
 450     l2--;  /* 1st char will be checked by `memchr' */
 451     l1 = l1-l2;  /* `s2' cannot be found after that */
 452     while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL) {
 453       init++;   /* 1st char is already checked */
 454       if (memcmp(init, s2+1, l2) == 0)
 455         return init-1;
 456       else {  /* correct `l1' and `s1' to try again */
 457         l1 -= init-s1;
 458         s1 = init;
 459       }
 460     }
 461     return NULL;  /* not found */
 462   }
 463 }
 464
 465
 466 static void push_onecapture (MatchState *ms, int i, const char *s,
 467                                                     const char *e) {
 468   if (i >= ms->level) {
 469     if (i == 0)  /* ms->level == 0, too */
 470       lua_pushlstring(ms->L, s, e - s);  /* add whole match */
 471     else
 472       luaL_error(ms->L, "invalid capture index");
 473   }
 474   else {
 475     ptrdiff_t l = ms->capture[i].len;
 476     if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");
 477     if (l == CAP_POSITION)
 478       lua_pushinteger(ms->L, ms->capture[i].init - ms->src_init + 1);
 479     else
 480       lua_pushlstring(ms->L, ms->capture[i].init, l);
 481   }
 482 }
 483
 484
 485 static int push_captures (MatchState *ms, const char *s, const char *e) {
 486   int i;
 487   int nlevels = (ms->level == 0 && s) ? 1 : ms->level;
 488   luaL_checkstack(ms->L, nlevels, "too many captures");
 489   for (i = 0; i < nlevels; i++)
 490     push_onecapture(ms, i, s, e);
 491   return nlevels;  /* number of strings pushed */
 492 }
 493
 494
 495 static int str_find_aux (lua_State *L, int find) {
 496   size_t l1, l2;
 497   const char *s = luaL_checklstring(L, 1, &l1);
 498   const char *p = luaL_checklstring(L, 2, &l2);
 499   ptrdiff_t init = posrelat(luaL_optinteger(L, 3, 1), l1) - 1;
 500   if (init < 0) init = 0;
 501   else if ((size_t)(init) > l1) init = (ptrdiff_t)l1;
 502   if (find && (lua_toboolean(L, 4) ||  /* explicit request? */
 503       strpbrk(p, SPECIALS) == NULL)) {  /* or no special characters? */
 504     /* do a plain search */
 505     const char *s2 = lmemfind(s+init, l1-init, p, l2);
 506     if (s2) {
 507       lua_pushinteger(L, s2-s+1);
 508       lua_pushinteger(L, s2-s+l2);
 509       return 2;
 510     }
 511   }
 512   else {
 513     MatchState ms;
 514     int anchor = (*p == '^') ? (p++, 1) : 0;
 515     const char *s1=s+init;
 516     ms.L = L;
 517     ms.src_init = s;
 518     ms.src_end = s+l1;
 519     do {
 520       const char *res;
 521       ms.level = 0;
 522       if ((res=match(&ms, s1, p)) != NULL) {
 523         if (find) {
 524           lua_pushinteger(L, s1-s+1);  /* start */
 525           lua_pushinteger(L, res-s);   /* end */
 526           return push_captures(&ms, NULL, 0) + 2;
 527         }
 528         else
 529           return push_captures(&ms, s1, res);
 530       }
 531     } while (s1++ < ms.src_end && !anchor);
 532   }
 533   lua_pushnil(L);  /* not found */
 534   return 1;
 535 }
 536
 537
 538 static int str_find (lua_State *L) {
 539   return str_find_aux(L, 1);
 540 }
 541
 542
 543 static int str_match (lua_State *L) {
 544   return str_find_aux(L, 0);
 545 }
 546
 547
 548 static int gmatch_aux (lua_State *L) {
 549   MatchState ms;
 550   size_t ls;
 551   const char *s = lua_tolstring(L, lua_upvalueindex(1), &ls);
 552   const char *p = lua_tostring(L, lua_upvalueindex(2));
 553   const char *src;
 554   ms.L = L;
 555   ms.src_init = s;
 556   ms.src_end = s+ls;
 557   for (src = s + (size_t)lua_tointeger(L, lua_upvalueindex(3));
 558        src <= ms.src_end;
 559        src++) {
 560     const char *e;
 561     ms.level = 0;
 562     if ((e = match(&ms, src, p)) != NULL) {
 563       lua_Integer newstart = e-s;
 564       if (e == src) newstart++;  /* empty match? go at least one position */
 565       lua_pushinteger(L, newstart);
 566       lua_replace(L, lua_upvalueindex(3));
 567       return push_captures(&ms, src, e);
 568     }
 569   }
 570   return 0;  /* not found */
 571 }
 572
 573
 574 static int gmatch (lua_State *L) {
 575   luaL_checkstring(L, 1);
 576   luaL_checkstring(L, 2);
 577   lua_settop(L, 2);
 578   lua_pushinteger(L, 0);
 579   lua_pushcclosure(L, gmatch_aux, 3);
 580   return 1;
 581 }
 582
 583
 584 static int gfind_nodef (lua_State *L) {
 585   return luaL_error(L, LUA_QL("string.gfind") " was renamed to "
 586                        LUA_QL("string.gmatch"));
 587 }
 588
 589
 590 static void add_s (MatchState *ms, luaL_Buffer *b, const char *s,
 591                                                    const char *e) {
 592   size_t l, i;
 593   const char *news = lua_tolstring(ms->L, 3, &l);
 594   for (i = 0; i < l; i++) {
 595     if (news[i] != L_ESC)
 596       luaL_addchar(b, news[i]);
 597     else {
 598       i++;  /* skip ESC */
 599       if (!isdigit(uchar(news[i])))
 600         luaL_addchar(b, news[i]);
 601       else if (news[i] == '0')
 602           luaL_addlstring(b, s, e - s);
 603       else {
 604         push_onecapture(ms, news[i] - '1', s, e);
 605         luaL_addvalue(b);  /* add capture to accumulated result */
 606       }
 607     }
 608   }
 609 }
 610
 611
 612 static void add_value (MatchState *ms, luaL_Buffer *b, const char *s,
 613                                                        const char *e) {
 614   lua_State *L = ms->L;
 615   switch (lua_type(L, 3)) {
 616     case LUA_TNUMBER:
 617     case LUA_TSTRING: {
 618       add_s(ms, b, s, e);
 619       return;
 620     }
 621     case LUA_TFUNCTION: {
 622       int n;
 623       lua_pushvalue(L, 3);
 624       n = push_captures(ms, s, e);
 625       lua_call(L, n, 1);
 626       break;
 627     }
 628     case LUA_TTABLE: {
 629       push_onecapture(ms, 0, s, e);
 630       lua_gettable(L, 3);
 631       break;
 632     }
 633   }
 634   if (!lua_toboolean(L, -1)) {  /* nil or false? */
 635     lua_pop(L, 1);
 636     lua_pushlstring(L, s, e - s);  /* keep original text */
 637   }
 638   else if (!lua_isstring(L, -1))
 639     luaL_error(L, "invalid replacement value (a %s)", luaL_typename(L, -1));
 640   luaL_addvalue(b);  /* add result to accumulator */
 641 }
 642
 643
 644 static int str_gsub (lua_State *L) {
 645   size_t srcl;
 646   const char *src = luaL_checklstring(L, 1, &srcl);
 647   const char *p = luaL_checkstring(L, 2);
 648   int  tr = lua_type(L, 3);
 649   int max_s = luaL_optint(L, 4, srcl+1);
 650   int anchor = (*p == '^') ? (p++, 1) : 0;
 651   int n = 0;
 652   MatchState ms;
 653   luaL_Buffer b;
 654   luaL_argcheck(L, tr == LUA_TNUMBER || tr == LUA_TSTRING ||
 655                    tr == LUA_TFUNCTION || tr == LUA_TTABLE, 3,
 656                       "string/function/table expected");
 657   luaL_buffinit(L, &b);
 658   ms.L = L;
 659   ms.src_init = src;
 660   ms.src_end = src+srcl;
 661   while (n < max_s) {
 662     const char *e;
 663     ms.level = 0;
 664     e = match(&ms, src, p);
 665     if (e) {
 666       n++;
 667       add_value(&ms, &b, src, e);
 668     }
 669     if (e && e>src) /* non empty match? */
 670       src = e;  /* skip it */
 671     else if (src < ms.src_end)
 672       luaL_addchar(&b, *src++);
 673     else break;
 674     if (anchor) break;
 675   }
 676   luaL_addlstring(&b, src, ms.src_end-src);
 677   luaL_pushresult(&b);
 678   lua_pushinteger(L, n);  /* number of substitutions */
 679   return 2;
 680 }
 681
 682 /* }====================================================== */
 683
 684
 685 /* maximum size of each formatted item (> len(format('%99.99f', -1e308))) */
 686 #define MAX_ITEM        512
 687 /* valid flags in a format specification */
 688 #define FLAGS   "-+ #0"
 689 /*
 690 ** maximum size of each format specification (such as '%-099.99d')
 691 ** (+10 accounts for %99.99x plus margin of error)
 692 */
 693 #define MAX_FORMAT      (sizeof(FLAGS) + sizeof(LUA_INTFRMLEN) + 10)
 694
 695
 696 static void addquoted (lua_State *L, luaL_Buffer *b, int arg) {
 697   size_t l;
 698   const char *s = luaL_checklstring(L, arg, &l);
 699   luaL_addchar(b, '"');
 700   while (l--) {
 701     switch (*s) {
 702       case '"': case '\\': case '\n': {
 703         luaL_addchar(b, '\\');
 704         luaL_addchar(b, *s);
 705         break;
 706       }
 707       case '\r': {
 708         luaL_addlstring(b, "\\r", 2);
 709         break;
 710       }
 711       case '\0': {
 712         luaL_addlstring(b, "\\000", 4);
 713         break;
 714       }
 715       default: {
 716         luaL_addchar(b, *s);
 717         break;
 718       }
 719     }
 720     s++;
 721   }
 722   luaL_addchar(b, '"');
 723 }
 724
 725 static const char *scanformat (lua_State *L, const char *strfrmt, char *form) {
 726   const char *p = strfrmt;
 727   while (*p != '\0' && strchr(FLAGS, *p) != NULL) p++;  /* skip flags */
 728   if ((size_t)(p - strfrmt) >= sizeof(FLAGS))
 729     luaL_error(L, "invalid format (repeated flags)");
 730   if (isdigit(uchar(*p))) p++;  /* skip width */
 731   if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
 732   if (*p == '.') {
 733     p++;
 734     if (isdigit(uchar(*p))) p++;  /* skip precision */
 735     if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
 736   }
 737   if (isdigit(uchar(*p)))
 738     luaL_error(L, "invalid format (width or precision too long)");
 739   *(form++) = '%';
 740   strncpy(form, strfrmt, p - strfrmt + 1);
 741   form += p - strfrmt + 1;
 742   *form = '\0';
 743   return p;
 744 }
 745
 746
 747 static void addintlen (char *form) {
 748   size_t l = strlen(form);
 749   char spec = form[l - 1];
 750   strcpy(form + l - 1, LUA_INTFRMLEN);
 751   form[l + sizeof(LUA_INTFRMLEN) - 2] = spec;
 752   form[l + sizeof(LUA_INTFRMLEN) - 1] = '\0';
 753 }
 754
 755
 756 static int str_format (lua_State *L) {
 757   int arg = 1;
 758   size_t sfl;
 759   const char *strfrmt = luaL_checklstring(L, arg, &sfl);
 760   const char *strfrmt_end = strfrmt+sfl;
 761   luaL_Buffer b;
 762   luaL_buffinit(L, &b);
 763   while (strfrmt < strfrmt_end) {
 764     if (*strfrmt != L_ESC)
 765       luaL_addchar(&b, *strfrmt++);
 766     else if (*++strfrmt == L_ESC)
 767       luaL_addchar(&b, *strfrmt++);  /* %% */
 768     else { /* format item */
 769       char form[MAX_FORMAT];  /* to store the format (`%...') */
 770       char buff[MAX_ITEM];  /* to store the formatted item */
 771       arg++;
 772       strfrmt = scanformat(L, strfrmt, form);
 773       switch (*strfrmt++) {
 774         case 'c': {
 775           sprintf(buff, form, (int)luaL_checknumber(L, arg));
 776           break;
 777         }
 778         case 'd':  case 'i': {
 779           addintlen(form);
 780           sprintf(buff, form, (LUA_INTFRM_T)luaL_checknumber(L, arg));
 781           break;
 782         }
 783         case 'o':  case 'u':  case 'x':  case 'X': {
 784           addintlen(form);
 785           sprintf(buff, form, (unsigned LUA_INTFRM_T)luaL_checknumber(L, arg));
 786           break;
 787         }
 788         case 'e':  case 'E': case 'f':
 789         case 'g': case 'G': {
 790           sprintf(buff, form, (double)luaL_checknumber(L, arg));
 791           break;
 792         }
 793         case 'q': {
 794           addquoted(L, &b, arg);
 795           continue;  /* skip the 'addsize' at the end */
 796         }
 797         case 's': {
 798           size_t l;
 799           const char *s = luaL_checklstring(L, arg, &l);
 800           if (!strchr(form, '.') && l >= 100) {
 801             /* no precision and string is too long to be formatted;
 802                keep original string */
 803             lua_pushvalue(L, arg);
 804             luaL_addvalue(&b);
 805             continue;  /* skip the `addsize' at the end */
 806           }
 807           else {
 808             sprintf(buff, form, s);
 809             break;
 810           }
 811         }
 812         default: {  /* also treat cases `pnLlh' */
 813           return luaL_error(L, "invalid option " LUA_QL("%%%c") " to "
 814                                LUA_QL("format"), *(strfrmt - 1));
 815         }
 816       }
 817       luaL_addlstring(&b, buff, strlen(buff));
 818     }
 819   }
 820   luaL_pushresult(&b);
 821   return 1;
 822 }
 823
 824
 825 static const luaL_Reg strlib[] = {
 826   {"byte", str_byte},
 827   {"char", str_char},
 828   {"dump", str_dump},
 829   {"find", str_find},
 830   {"format", str_format},
 831   {"gfind", gfind_nodef},
 832   {"gmatch", gmatch},
 833   {"gsub", str_gsub},
 834   {"len", str_len},
 835   {"lower", str_lower},
 836   {"match", str_match},
 837   {"rep", str_rep},
 838   {"reverse", str_reverse},
 839   {"sub", str_sub},
 840   {"upper", str_upper},
 841   {NULL, NULL}
 842 };
 843
 844
 845 static void createmetatable (lua_State *L) {
 846   lua_createtable(L, 0, 1);  /* create metatable for strings */
 847   lua_pushliteral(L, "");  /* dummy string */
 848   lua_pushvalue(L, -2);
 849   lua_setmetatable(L, -2);  /* set string metatable */
 850   lua_pop(L, 1);  /* pop dummy string */
 851   lua_pushvalue(L, -2);  /* string library... */
 852   lua_setfield(L, -2, "__index");  /* ...is the __index metamethod */
 853   lua_pop(L, 1);  /* pop metatable */
 854 }
 855
 856
 857 /*
 858 ** Open string library
 859 */
 860 LUALIB_API int luaopen_string (lua_State *L) {
 861   luaL_register(L, LUA_STRLIBNAME, strlib);
 862 #if defined(LUA_COMPAT_GFIND)
 863   lua_getfield(L, -1, "gmatch");
 864   lua_setfield(L, -2, "gfind");
 865 #endif
 866   createmetatable(L);
 867   return 1;
 868 }
 869