liblua/lstrlib.c

   1 /*
   2 ** $Id: lstrlib.c,v 1.178 2012/08/14 18:12:34 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 /*
  24 ** maximum number of captures that a pattern can do during
  25 ** pattern-matching. This limit is arbitrary.
  26 */
  27 #if !defined(LUA_MAXCAPTURES)
  28 #define LUA_MAXCAPTURES         32
  29 #endif
  30
  31
  32 /* macro to `unsign' a character */
  33 #define uchar(c)        ((unsigned char)(c))
  34
  35
  36
  37 static int str_len (lua_State *L) {
  38   size_t l;
  39   luaL_checklstring(L, 1, &l);
  40   lua_pushinteger(L, (lua_Integer)l);
  41   return 1;
  42 }
  43
  44
  45 /* translate a relative string position: negative means back from end */
  46 static size_t posrelat (ptrdiff_t pos, size_t len) {
  47   if (pos >= 0) return (size_t)pos;
  48   else if (0u - (size_t)pos > len) return 0;
  49   else return len - ((size_t)-pos) + 1;
  50 }
  51
  52
  53 static int str_sub (lua_State *L) {
  54   size_t l;
  55   const char *s = luaL_checklstring(L, 1, &l);
  56   size_t start = posrelat(luaL_checkinteger(L, 2), l);
  57   size_t end = posrelat(luaL_optinteger(L, 3, -1), l);
  58   if (start < 1) start = 1;
  59   if (end > l) end = l;
  60   if (start <= end)
  61     lua_pushlstring(L, s + start - 1, end - start + 1);
  62   else lua_pushliteral(L, "");
  63   return 1;
  64 }
  65
  66
  67 static int str_reverse (lua_State *L) {
  68   size_t l, i;
  69   luaL_Buffer b;
  70   const char *s = luaL_checklstring(L, 1, &l);
  71   char *p = luaL_buffinitsize(L, &b, l);
  72   for (i = 0; i < l; i++)
  73     p[i] = s[l - i - 1];
  74   luaL_pushresultsize(&b, l);
  75   return 1;
  76 }
  77
  78
  79 static int str_lower (lua_State *L) {
  80   size_t l;
  81   size_t i;
  82   luaL_Buffer b;
  83   const char *s = luaL_checklstring(L, 1, &l);
  84   char *p = luaL_buffinitsize(L, &b, l);
  85   for (i=0; i<l; i++)
  86     p[i] = tolower(uchar(s[i]));
  87   luaL_pushresultsize(&b, l);
  88   return 1;
  89 }
  90
  91
  92 static int str_upper (lua_State *L) {
  93   size_t l;
  94   size_t i;
  95   luaL_Buffer b;
  96   const char *s = luaL_checklstring(L, 1, &l);
  97   char *p = luaL_buffinitsize(L, &b, l);
  98   for (i=0; i<l; i++)
  99     p[i] = toupper(uchar(s[i]));
 100   luaL_pushresultsize(&b, l);
 101   return 1;
 102 }
 103
 104
 105 /* reasonable limit to avoid arithmetic overflow */
 106 #define MAXSIZE         ((~(size_t)0) >> 1)
 107
 108 static int str_rep (lua_State *L) {
 109   size_t l, lsep;
 110   const char *s = luaL_checklstring(L, 1, &l);
 111   int n = luaL_checkint(L, 2);
 112   const char *sep = luaL_optlstring(L, 3, "", &lsep);
 113   if (n <= 0) lua_pushliteral(L, "");
 114   else if (l + lsep < l || l + lsep >= MAXSIZE / n)  /* may overflow? */
 115     return luaL_error(L, "resulting string too large");
 116   else {
 117     size_t totallen = n * l + (n - 1) * lsep;
 118     luaL_Buffer b;
 119     char *p = luaL_buffinitsize(L, &b, totallen);
 120     while (n-- > 1) {  /* first n-1 copies (followed by separator) */
 121       memcpy(p, s, l * sizeof(char)); p += l;
 122       if (lsep > 0) {  /* avoid empty 'memcpy' (may be expensive) */
 123         memcpy(p, sep, lsep * sizeof(char)); p += lsep;
 124       }
 125     }
 126     memcpy(p, s, l * sizeof(char));  /* last copy (not followed by separator) */
 127     luaL_pushresultsize(&b, totallen);
 128   }
 129   return 1;
 130 }
 131
 132
 133 static int str_byte (lua_State *L) {
 134   size_t l;
 135   const char *s = luaL_checklstring(L, 1, &l);
 136   size_t posi = posrelat(luaL_optinteger(L, 2, 1), l);
 137   size_t pose = posrelat(luaL_optinteger(L, 3, posi), l);
 138   int n, i;
 139   if (posi < 1) posi = 1;
 140   if (pose > l) pose = l;
 141   if (posi > pose) return 0;  /* empty interval; return no values */
 142   n = (int)(pose -  posi + 1);
 143   if (posi + n <= pose)  /* (size_t -> int) overflow? */
 144     return luaL_error(L, "string slice too long");
 145   luaL_checkstack(L, n, "string slice too long");
 146   for (i=0; i<n; i++)
 147     lua_pushinteger(L, uchar(s[posi+i-1]));
 148   return n;
 149 }
 150
 151
 152 static int str_char (lua_State *L) {
 153   int n = lua_gettop(L);  /* number of arguments */
 154   int i;
 155   luaL_Buffer b;
 156   char *p = luaL_buffinitsize(L, &b, n);
 157   for (i=1; i<=n; i++) {
 158     int c = luaL_checkint(L, i);
 159     luaL_argcheck(L, uchar(c) == c, i, "value out of range");
 160     p[i - 1] = uchar(c);
 161   }
 162   luaL_pushresultsize(&b, n);
 163   return 1;
 164 }
 165
 166
 167 static int writer (lua_State *L, const void* b, size_t size, void* B) {
 168   (void)L;
 169   luaL_addlstring((luaL_Buffer*) B, (const char *)b, size);
 170   return 0;
 171 }
 172
 173
 174 static int str_dump (lua_State *L) {
 175   luaL_Buffer b;
 176   luaL_checktype(L, 1, LUA_TFUNCTION);
 177   lua_settop(L, 1);
 178   luaL_buffinit(L,&b);
 179   if (lua_dump(L, writer, &b) != 0)
 180     return luaL_error(L, "unable to dump given function");
 181   luaL_pushresult(&b);
 182   return 1;
 183 }
 184
 185
 186
 187 /*
 188 ** {======================================================
 189 ** PATTERN MATCHING
 190 ** =======================================================
 191 */
 192
 193
 194 #define CAP_UNFINISHED  (-1)
 195 #define CAP_POSITION    (-2)
 196
 197
 198 typedef struct MatchState {
 199   int matchdepth;  /* control for recursive depth (to avoid C stack overflow) */
 200   const char *src_init;  /* init of source string */
 201   const char *src_end;  /* end ('\0') of source string */
 202   const char *p_end;  /* end ('\0') of pattern */
 203   lua_State *L;
 204   int level;  /* total number of captures (finished or unfinished) */
 205   struct {
 206     const char *init;
 207     ptrdiff_t len;
 208   } capture[LUA_MAXCAPTURES];
 209 } MatchState;
 210
 211
 212 /* recursive function */
 213 static const char *match (MatchState *ms, const char *s, const char *p);
 214
 215
 216 /* maximum recursion depth for 'match' */
 217 #if !defined(MAXCCALLS)
 218 #define MAXCCALLS       200
 219 #endif
 220
 221
 222 #define L_ESC           '%'
 223 #define SPECIALS        "^$*+?.([%-"
 224
 225
 226 static int check_capture (MatchState *ms, int l) {
 227   l -= '1';
 228   if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
 229     return luaL_error(ms->L, "invalid capture index %%%d", l + 1);
 230   return l;
 231 }
 232
 233
 234 static int capture_to_close (MatchState *ms) {
 235   int level = ms->level;
 236   for (level--; level>=0; level--)
 237     if (ms->capture[level].len == CAP_UNFINISHED) return level;
 238   return luaL_error(ms->L, "invalid pattern capture");
 239 }
 240
 241
 242 static const char *classend (MatchState *ms, const char *p) {
 243   switch (*p++) {
 244     case L_ESC: {
 245       if (p == ms->p_end)
 246         luaL_error(ms->L, "malformed pattern (ends with " LUA_QL("%%") ")");
 247       return p+1;
 248     }
 249     case '[': {
 250       if (*p == '^') p++;
 251       do {  /* look for a `]' */
 252         if (p == ms->p_end)
 253           luaL_error(ms->L, "malformed pattern (missing " LUA_QL("]") ")");
 254         if (*(p++) == L_ESC && p < ms->p_end)
 255           p++;  /* skip escapes (e.g. `%]') */
 256       } while (*p != ']');
 257       return p+1;
 258     }
 259     default: {
 260       return p;
 261     }
 262   }
 263 }
 264
 265
 266 static int match_class (int c, int cl) {
 267   int res;
 268   switch (tolower(cl)) {
 269     case 'a' : res = isalpha(c); break;
 270     case 'c' : res = iscntrl(c); break;
 271     case 'd' : res = isdigit(c); break;
 272     case 'g' : res = isgraph(c); break;
 273     case 'l' : res = islower(c); break;
 274     case 'p' : res = ispunct(c); break;
 275     case 's' : res = isspace(c); break;
 276     case 'u' : res = isupper(c); break;
 277     case 'w' : res = isalnum(c); break;
 278     case 'x' : res = isxdigit(c); break;
 279     case 'z' : res = (c == 0); break;  /* deprecated option */
 280     default: return (cl == c);
 281   }
 282   return (islower(cl) ? res : !res);
 283 }
 284
 285
 286 static int matchbracketclass (int c, const char *p, const char *ec) {
 287   int sig = 1;
 288   if (*(p+1) == '^') {
 289     sig = 0;
 290     p++;  /* skip the `^' */
 291   }
 292   while (++p < ec) {
 293     if (*p == L_ESC) {
 294       p++;
 295       if (match_class(c, uchar(*p)))
 296         return sig;
 297     }
 298     else if ((*(p+1) == '-') && (p+2 < ec)) {
 299       p+=2;
 300       if (uchar(*(p-2)) <= c && c <= uchar(*p))
 301         return sig;
 302     }
 303     else if (uchar(*p) == c) return sig;
 304   }
 305   return !sig;
 306 }
 307
 308
 309 static int singlematch (MatchState *ms, const char *s, const char *p,
 310                         const char *ep) {
 311   if (s >= ms->src_end)
 312     return 0;
 313   else {
 314     int c = uchar(*s);
 315     switch (*p) {
 316       case '.': return 1;  /* matches any char */
 317       case L_ESC: return match_class(c, uchar(*(p+1)));
 318       case '[': return matchbracketclass(c, p, ep-1);
 319       default:  return (uchar(*p) == c);
 320     }
 321   }
 322 }
 323
 324
 325 static const char *matchbalance (MatchState *ms, const char *s,
 326                                    const char *p) {
 327   if (p >= ms->p_end - 1)
 328     luaL_error(ms->L, "malformed pattern "
 329                       "(missing arguments to " LUA_QL("%%b") ")");
 330   if (*s != *p) return NULL;
 331   else {
 332     int b = *p;
 333     int e = *(p+1);
 334     int cont = 1;
 335     while (++s < ms->src_end) {
 336       if (*s == e) {
 337         if (--cont == 0) return s+1;
 338       }
 339       else if (*s == b) cont++;
 340     }
 341   }
 342   return NULL;  /* string ends out of balance */
 343 }
 344
 345
 346 static const char *max_expand (MatchState *ms, const char *s,
 347                                  const char *p, const char *ep) {
 348   ptrdiff_t i = 0;  /* counts maximum expand for item */
 349   while (singlematch(ms, s + i, p, ep))
 350     i++;
 351   /* keeps trying to match with the maximum repetitions */
 352   while (i>=0) {
 353     const char *res = match(ms, (s+i), ep+1);
 354     if (res) return res;
 355     i--;  /* else didn't match; reduce 1 repetition to try again */
 356   }
 357   return NULL;
 358 }
 359
 360
 361 static const char *min_expand (MatchState *ms, const char *s,
 362                                  const char *p, const char *ep) {
 363   for (;;) {
 364     const char *res = match(ms, s, ep+1);
 365     if (res != NULL)
 366       return res;
 367     else if (singlematch(ms, s, p, ep))
 368       s++;  /* try with one more repetition */
 369     else return NULL;
 370   }
 371 }
 372
 373
 374 static const char *start_capture (MatchState *ms, const char *s,
 375                                     const char *p, int what) {
 376   const char *res;
 377   int level = ms->level;
 378   if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
 379   ms->capture[level].init = s;
 380   ms->capture[level].len = what;
 381   ms->level = level+1;
 382   if ((res=match(ms, s, p)) == NULL)  /* match failed? */
 383     ms->level--;  /* undo capture */
 384   return res;
 385 }
 386
 387
 388 static const char *end_capture (MatchState *ms, const char *s,
 389                                   const char *p) {
 390   int l = capture_to_close(ms);
 391   const char *res;
 392   ms->capture[l].len = s - ms->capture[l].init;  /* close capture */
 393   if ((res = match(ms, s, p)) == NULL)  /* match failed? */
 394     ms->capture[l].len = CAP_UNFINISHED;  /* undo capture */
 395   return res;
 396 }
 397
 398
 399 static const char *match_capture (MatchState *ms, const char *s, int l) {
 400   size_t len;
 401   l = check_capture(ms, l);
 402   len = ms->capture[l].len;
 403   if ((size_t)(ms->src_end-s) >= len &&
 404       memcmp(ms->capture[l].init, s, len) == 0)
 405     return s+len;
 406   else return NULL;
 407 }
 408
 409
 410 static const char *match (MatchState *ms, const char *s, const char *p) {
 411   if (ms->matchdepth-- == 0)
 412     luaL_error(ms->L, "pattern too complex");
 413   init: /* using goto's to optimize tail recursion */
 414   if (p != ms->p_end) {  /* end of pattern? */
 415     switch (*p) {
 416       case '(': {  /* start capture */
 417         if (*(p + 1) == ')')  /* position capture? */
 418           s = start_capture(ms, s, p + 2, CAP_POSITION);
 419         else
 420           s = start_capture(ms, s, p + 1, CAP_UNFINISHED);
 421         break;
 422       }
 423       case ')': {  /* end capture */
 424         s = end_capture(ms, s, p + 1);
 425         break;
 426       }
 427       case '$': {
 428         if ((p + 1) != ms->p_end)  /* is the `$' the last char in pattern? */
 429           goto dflt;  /* no; go to default */
 430         s = (s == ms->src_end) ? s : NULL;  /* check end of string */
 431         break;
 432       }
 433       case L_ESC: {  /* escaped sequences not in the format class[*+?-]? */
 434         switch (*(p + 1)) {
 435           case 'b': {  /* balanced string? */
 436             s = matchbalance(ms, s, p + 2);
 437             if (s != NULL) {
 438               p += 4; goto init;  /* return match(ms, s, p + 4); */
 439             }  /* else fail (s == NULL) */
 440             break;
 441           }
 442           case 'f': {  /* frontier? */
 443             const char *ep; char previous;
 444             p += 2;
 445             if (*p != '[')
 446               luaL_error(ms->L, "missing " LUA_QL("[") " after "
 447                                  LUA_QL("%%f") " in pattern");
 448             ep = classend(ms, p);  /* points to what is next */
 449             previous = (s == ms->src_init) ? '\0' : *(s - 1);
 450             if (!matchbracketclass(uchar(previous), p, ep - 1) &&
 451                matchbracketclass(uchar(*s), p, ep - 1)) {
 452               p = ep; goto init;  /* return match(ms, s, ep); */
 453             }
 454             s = NULL;  /* match failed */
 455             break;
 456           }
 457           case '0': case '1': case '2': case '3':
 458           case '4': case '5': case '6': case '7':
 459           case '8': case '9': {  /* capture results (%0-%9)? */
 460             s = match_capture(ms, s, uchar(*(p + 1)));
 461             if (s != NULL) {
 462               p += 2; goto init;  /* return match(ms, s, p + 2) */
 463             }
 464             break;
 465           }
 466           default: goto dflt;
 467         }
 468         break;
 469       }
 470       default: dflt: {  /* pattern class plus optional suffix */
 471         const char *ep = classend(ms, p);  /* points to optional suffix */
 472         /* does not match at least once? */
 473         if (!singlematch(ms, s, p, ep)) {
 474           if (*ep == '*' || *ep == '?' || *ep == '-') {  /* accept empty? */
 475             p = ep + 1; goto init;  /* return match(ms, s, ep + 1); */
 476           }
 477           else  /* '+' or no suffix */
 478             s = NULL;  /* fail */
 479         }
 480         else {  /* matched once */
 481           switch (*ep) {  /* handle optional suffix */
 482             case '?': {  /* optional */
 483               const char *res;
 484               if ((res = match(ms, s + 1, ep + 1)) != NULL)
 485                 s = res;
 486               else {
 487                 p = ep + 1; goto init;  /* else return match(ms, s, ep + 1); */
 488               }
 489               break;
 490             }
 491             case '+':  /* 1 or more repetitions */
 492               s++;  /* 1 match already done */
 493               /* go through */
 494             case '*':  /* 0 or more repetitions */
 495               s = max_expand(ms, s, p, ep);
 496               break;
 497             case '-':  /* 0 or more repetitions (minimum) */
 498               s = min_expand(ms, s, p, ep);
 499               break;
 500             default:  /* no suffix */
 501               s++; p = ep; goto init;  /* return match(ms, s + 1, ep); */
 502           }
 503         }
 504         break;
 505       }
 506     }
 507   }
 508   ms->matchdepth++;
 509   return s;
 510 }
 511
 512
 513
 514 static const char *lmemfind (const char *s1, size_t l1,
 515                                const char *s2, size_t l2) {
 516   if (l2 == 0) return s1;  /* empty strings are everywhere */
 517   else if (l2 > l1) return NULL;  /* avoids a negative `l1' */
 518   else {
 519     const char *init;  /* to search for a `*s2' inside `s1' */
 520     l2--;  /* 1st char will be checked by `memchr' */
 521     l1 = l1-l2;  /* `s2' cannot be found after that */
 522     while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL) {
 523       init++;   /* 1st char is already checked */
 524       if (memcmp(init, s2+1, l2) == 0)
 525         return init-1;
 526       else {  /* correct `l1' and `s1' to try again */
 527         l1 -= init-s1;
 528         s1 = init;
 529       }
 530     }
 531     return NULL;  /* not found */
 532   }
 533 }
 534
 535
 536 static void push_onecapture (MatchState *ms, int i, const char *s,
 537                                                     const char *e) {
 538   if (i >= ms->level) {
 539     if (i == 0)  /* ms->level == 0, too */
 540       lua_pushlstring(ms->L, s, e - s);  /* add whole match */
 541     else
 542       luaL_error(ms->L, "invalid capture index");
 543   }
 544   else {
 545     ptrdiff_t l = ms->capture[i].len;
 546     if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");
 547     if (l == CAP_POSITION)
 548       lua_pushinteger(ms->L, ms->capture[i].init - ms->src_init + 1);
 549     else
 550       lua_pushlstring(ms->L, ms->capture[i].init, l);
 551   }
 552 }
 553
 554
 555 static int push_captures (MatchState *ms, const char *s, const char *e) {
 556   int i;
 557   int nlevels = (ms->level == 0 && s) ? 1 : ms->level;
 558   luaL_checkstack(ms->L, nlevels, "too many captures");
 559   for (i = 0; i < nlevels; i++)
 560     push_onecapture(ms, i, s, e);
 561   return nlevels;  /* number of strings pushed */
 562 }
 563
 564
 565 /* check whether pattern has no special characters */
 566 static int nospecials (const char *p, size_t l) {
 567   size_t upto = 0;
 568   do {
 569     if (strpbrk(p + upto, SPECIALS))
 570       return 0;  /* pattern has a special character */
 571     upto += strlen(p + upto) + 1;  /* may have more after \0 */
 572   } while (upto <= l);
 573   return 1;  /* no special chars found */
 574 }
 575
 576
 577 static int str_find_aux (lua_State *L, int find) {
 578   size_t ls, lp;
 579   const char *s = luaL_checklstring(L, 1, &ls);
 580   const char *p = luaL_checklstring(L, 2, &lp);
 581   size_t init = posrelat(luaL_optinteger(L, 3, 1), ls);
 582   if (init < 1) init = 1;
 583   else if (init > ls + 1) {  /* start after string's end? */
 584     lua_pushnil(L);  /* cannot find anything */
 585     return 1;
 586   }
 587   /* explicit request or no special characters? */
 588   if (find && (lua_toboolean(L, 4) || nospecials(p, lp))) {
 589     /* do a plain search */
 590     const char *s2 = lmemfind(s + init - 1, ls - init + 1, p, lp);
 591     if (s2) {
 592       lua_pushinteger(L, s2 - s + 1);
 593       lua_pushinteger(L, s2 - s + lp);
 594       return 2;
 595     }
 596   }
 597   else {
 598     MatchState ms;
 599     const char *s1 = s + init - 1;
 600     int anchor = (*p == '^');
 601     if (anchor) {
 602       p++; lp--;  /* skip anchor character */
 603     }
 604     ms.L = L;
 605     ms.matchdepth = MAXCCALLS;
 606     ms.src_init = s;
 607     ms.src_end = s + ls;
 608     ms.p_end = p + lp;
 609     do {
 610       const char *res;
 611       ms.level = 0;
 612       lua_assert(ms.matchdepth == MAXCCALLS);
 613       if ((res=match(&ms, s1, p)) != NULL) {
 614         if (find) {
 615           lua_pushinteger(L, s1 - s + 1);  /* start */
 616           lua_pushinteger(L, res - s);   /* end */
 617           return push_captures(&ms, NULL, 0) + 2;
 618         }
 619         else
 620           return push_captures(&ms, s1, res);
 621       }
 622     } while (s1++ < ms.src_end && !anchor);
 623   }
 624   lua_pushnil(L);  /* not found */
 625   return 1;
 626 }
 627
 628
 629 static int str_find (lua_State *L) {
 630   return str_find_aux(L, 1);
 631 }
 632
 633
 634 static int str_match (lua_State *L) {
 635   return str_find_aux(L, 0);
 636 }
 637
 638
 639 static int gmatch_aux (lua_State *L) {
 640   MatchState ms;
 641   size_t ls, lp;
 642   const char *s = lua_tolstring(L, lua_upvalueindex(1), &ls);
 643   const char *p = lua_tolstring(L, lua_upvalueindex(2), &lp);
 644   const char *src;
 645   ms.L = L;
 646   ms.matchdepth = MAXCCALLS;
 647   ms.src_init = s;
 648   ms.src_end = s+ls;
 649   ms.p_end = p + lp;
 650   for (src = s + (size_t)lua_tointeger(L, lua_upvalueindex(3));
 651        src <= ms.src_end;
 652        src++) {
 653     const char *e;
 654     ms.level = 0;
 655     lua_assert(ms.matchdepth == MAXCCALLS);
 656     if ((e = match(&ms, src, p)) != NULL) {
 657       lua_Integer newstart = e-s;
 658       if (e == src) newstart++;  /* empty match? go at least one position */
 659       lua_pushinteger(L, newstart);
 660       lua_replace(L, lua_upvalueindex(3));
 661       return push_captures(&ms, src, e);
 662     }
 663   }
 664   return 0;  /* not found */
 665 }
 666
 667
 668 static int gmatch (lua_State *L) {
 669   luaL_checkstring(L, 1);
 670   luaL_checkstring(L, 2);
 671   lua_settop(L, 2);
 672   lua_pushinteger(L, 0);
 673   lua_pushcclosure(L, gmatch_aux, 3);
 674   return 1;
 675 }
 676
 677
 678 static void add_s (MatchState *ms, luaL_Buffer *b, const char *s,
 679                                                    const char *e) {
 680   size_t l, i;
 681   const char *news = lua_tolstring(ms->L, 3, &l);
 682   for (i = 0; i < l; i++) {
 683     if (news[i] != L_ESC)
 684       luaL_addchar(b, news[i]);
 685     else {
 686       i++;  /* skip ESC */
 687       if (!isdigit(uchar(news[i]))) {
 688         if (news[i] != L_ESC)
 689           luaL_error(ms->L, "invalid use of " LUA_QL("%c")
 690                            " in replacement string", L_ESC);
 691         luaL_addchar(b, news[i]);
 692       }
 693       else if (news[i] == '0')
 694           luaL_addlstring(b, s, e - s);
 695       else {
 696         push_onecapture(ms, news[i] - '1', s, e);
 697         luaL_addvalue(b);  /* add capture to accumulated result */
 698       }
 699     }
 700   }
 701 }
 702
 703
 704 static void add_value (MatchState *ms, luaL_Buffer *b, const char *s,
 705                                        const char *e, int tr) {
 706   lua_State *L = ms->L;
 707   switch (tr) {
 708     case LUA_TFUNCTION: {
 709       int n;
 710       lua_pushvalue(L, 3);
 711       n = push_captures(ms, s, e);
 712       lua_call(L, n, 1);
 713       break;
 714     }
 715     case LUA_TTABLE: {
 716       push_onecapture(ms, 0, s, e);
 717       lua_gettable(L, 3);
 718       break;
 719     }
 720     default: {  /* LUA_TNUMBER or LUA_TSTRING */
 721       add_s(ms, b, s, e);
 722       return;
 723     }
 724   }
 725   if (!lua_toboolean(L, -1)) {  /* nil or false? */
 726     lua_pop(L, 1);
 727     lua_pushlstring(L, s, e - s);  /* keep original text */
 728   }
 729   else if (!lua_isstring(L, -1))
 730     luaL_error(L, "invalid replacement value (a %s)", luaL_typename(L, -1));
 731   luaL_addvalue(b);  /* add result to accumulator */
 732 }
 733
 734
 735 static int str_gsub (lua_State *L) {
 736   size_t srcl, lp;
 737   const char *src = luaL_checklstring(L, 1, &srcl);
 738   const char *p = luaL_checklstring(L, 2, &lp);
 739   int tr = lua_type(L, 3);
 740   size_t max_s = luaL_optinteger(L, 4, srcl+1);
 741   int anchor = (*p == '^');
 742   size_t n = 0;
 743   MatchState ms;
 744   luaL_Buffer b;
 745   luaL_argcheck(L, tr == LUA_TNUMBER || tr == LUA_TSTRING ||
 746                    tr == LUA_TFUNCTION || tr == LUA_TTABLE, 3,
 747                       "string/function/table expected");
 748   luaL_buffinit(L, &b);
 749   if (anchor) {
 750     p++; lp--;  /* skip anchor character */
 751   }
 752   ms.L = L;
 753   ms.matchdepth = MAXCCALLS;
 754   ms.src_init = src;
 755   ms.src_end = src+srcl;
 756   ms.p_end = p + lp;
 757   while (n < max_s) {
 758     const char *e;
 759     ms.level = 0;
 760     lua_assert(ms.matchdepth == MAXCCALLS);
 761     e = match(&ms, src, p);
 762     if (e) {
 763       n++;
 764       add_value(&ms, &b, src, e, tr);
 765     }
 766     if (e && e>src) /* non empty match? */
 767       src = e;  /* skip it */
 768     else if (src < ms.src_end)
 769       luaL_addchar(&b, *src++);
 770     else break;
 771     if (anchor) break;
 772   }
 773   luaL_addlstring(&b, src, ms.src_end-src);
 774   luaL_pushresult(&b);
 775   lua_pushinteger(L, n);  /* number of substitutions */
 776   return 2;
 777 }
 778
 779 /* }====================================================== */
 780
 781
 782
 783 /*
 784 ** {======================================================
 785 ** STRING FORMAT
 786 ** =======================================================
 787 */
 788
 789 /*
 790 ** LUA_INTFRMLEN is the length modifier for integer conversions in
 791 ** 'string.format'; LUA_INTFRM_T is the integer type corresponding to
 792 ** the previous length
 793 */
 794 #if !defined(LUA_INTFRMLEN)     /* { */
 795 #if defined(LUA_USE_LONGLONG)
 796
 797 #define LUA_INTFRMLEN           "ll"
 798 #define LUA_INTFRM_T            long long
 799
 800 #else
 801
 802 #define LUA_INTFRMLEN           "l"
 803 #define LUA_INTFRM_T            long
 804
 805 #endif
 806 #endif                          /* } */
 807
 808
 809 /*
 810 ** LUA_FLTFRMLEN is the length modifier for float conversions in
 811 ** 'string.format'; LUA_FLTFRM_T is the float type corresponding to
 812 ** the previous length
 813 */
 814 #if !defined(LUA_FLTFRMLEN)
 815
 816 #define LUA_FLTFRMLEN           ""
 817 #define LUA_FLTFRM_T            double
 818
 819 #endif
 820
 821
 822 /* maximum size of each formatted item (> len(format('%99.99f', -1e308))) */
 823 #define MAX_ITEM        512
 824 /* valid flags in a format specification */
 825 #define FLAGS   "-+ #0"
 826 /*
 827 ** maximum size of each format specification (such as '%-099.99d')
 828 ** (+10 accounts for %99.99x plus margin of error)
 829 */
 830 #define MAX_FORMAT      (sizeof(FLAGS) + sizeof(LUA_INTFRMLEN) + 10)
 831
 832
 833 static void addquoted (lua_State *L, luaL_Buffer *b, int arg) {
 834   size_t l;
 835   const char *s = luaL_checklstring(L, arg, &l);
 836   luaL_addchar(b, '"');
 837   while (l--) {
 838     if (*s == '"' || *s == '\\' || *s == '\n') {
 839       luaL_addchar(b, '\\');
 840       luaL_addchar(b, *s);
 841     }
 842     else if (*s == '\0' || iscntrl(uchar(*s))) {
 843       char buff[10];
 844       if (!isdigit(uchar(*(s+1))))
 845         sprintf(buff, "\\%d", (int)uchar(*s));
 846       else
 847         sprintf(buff, "\\%03d", (int)uchar(*s));
 848       luaL_addstring(b, buff);
 849     }
 850     else
 851       luaL_addchar(b, *s);
 852     s++;
 853   }
 854   luaL_addchar(b, '"');
 855 }
 856
 857 static const char *scanformat (lua_State *L, const char *strfrmt, char *form) {
 858   const char *p = strfrmt;
 859   while (*p != '\0' && strchr(FLAGS, *p) != NULL) p++;  /* skip flags */
 860   if ((size_t)(p - strfrmt) >= sizeof(FLAGS)/sizeof(char))
 861     luaL_error(L, "invalid format (repeated flags)");
 862   if (isdigit(uchar(*p))) p++;  /* skip width */
 863   if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
 864   if (*p == '.') {
 865     p++;
 866     if (isdigit(uchar(*p))) p++;  /* skip precision */
 867     if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
 868   }
 869   if (isdigit(uchar(*p)))
 870     luaL_error(L, "invalid format (width or precision too long)");
 871   *(form++) = '%';
 872   memcpy(form, strfrmt, (p - strfrmt + 1) * sizeof(char));
 873   form += p - strfrmt + 1;
 874   *form = '\0';
 875   return p;
 876 }
 877
 878
 879 /*
 880 ** add length modifier into formats
 881 */
 882 static void addlenmod (char *form, const char *lenmod) {
 883   size_t l = strlen(form);
 884   size_t lm = strlen(lenmod);
 885   char spec = form[l - 1];
 886   strcpy(form + l - 1, lenmod);
 887   form[l + lm - 1] = spec;
 888   form[l + lm] = '\0';
 889 }
 890
 891
 892 static int str_format (lua_State *L) {
 893   int top = lua_gettop(L);
 894   int arg = 1;
 895   size_t sfl;
 896   const char *strfrmt = luaL_checklstring(L, arg, &sfl);
 897   const char *strfrmt_end = strfrmt+sfl;
 898   luaL_Buffer b;
 899   luaL_buffinit(L, &b);
 900   while (strfrmt < strfrmt_end) {
 901     if (*strfrmt != L_ESC)
 902       luaL_addchar(&b, *strfrmt++);
 903     else if (*++strfrmt == L_ESC)
 904       luaL_addchar(&b, *strfrmt++);  /* %% */
 905     else { /* format item */
 906       char form[MAX_FORMAT];  /* to store the format (`%...') */
 907       char *buff = luaL_prepbuffsize(&b, MAX_ITEM);  /* to put formatted item */
 908       int nb = 0;  /* number of bytes in added item */
 909       if (++arg > top)
 910         luaL_argerror(L, arg, "no value");
 911       strfrmt = scanformat(L, strfrmt, form);
 912       switch (*strfrmt++) {
 913         case 'c': {
 914           nb = sprintf(buff, form, luaL_checkint(L, arg));
 915           break;
 916         }
 917         case 'd': case 'i': {
 918           lua_Number n = luaL_checknumber(L, arg);
 919           LUA_INTFRM_T ni = (LUA_INTFRM_T)n;
 920           lua_Number diff = n - (lua_Number)ni;
 921           luaL_argcheck(L, -1 < diff && diff < 1, arg,
 922                         "not a number in proper range");
 923           addlenmod(form, LUA_INTFRMLEN);
 924           nb = sprintf(buff, form, ni);
 925           break;
 926         }
 927         case 'o': case 'u': case 'x': case 'X': {
 928           lua_Number n = luaL_checknumber(L, arg);
 929           unsigned LUA_INTFRM_T ni = (unsigned LUA_INTFRM_T)n;
 930           lua_Number diff = n - (lua_Number)ni;
 931           luaL_argcheck(L, -1 < diff && diff < 1, arg,
 932                         "not a non-negative number in proper range");
 933           addlenmod(form, LUA_INTFRMLEN);
 934           nb = sprintf(buff, form, ni);
 935           break;
 936         }
 937         case 'e': case 'E': case 'f':
 938 #if defined(LUA_USE_AFORMAT)
 939         case 'a': case 'A':
 940 #endif
 941         case 'g': case 'G': {
 942           addlenmod(form, LUA_FLTFRMLEN);
 943           nb = sprintf(buff, form, (LUA_FLTFRM_T)luaL_checknumber(L, arg));
 944           break;
 945         }
 946         case 'q': {
 947           addquoted(L, &b, arg);
 948           break;
 949         }
 950         case 's': {
 951           size_t l;
 952           const char *s = luaL_tolstring(L, arg, &l);
 953           if (!strchr(form, '.') && l >= 100) {
 954             /* no precision and string is too long to be formatted;
 955                keep original string */
 956             luaL_addvalue(&b);
 957             break;
 958           }
 959           else {
 960             nb = sprintf(buff, form, s);
 961             lua_pop(L, 1);  /* remove result from 'luaL_tolstring' */
 962             break;
 963           }
 964         }
 965         default: {  /* also treat cases `pnLlh' */
 966           return luaL_error(L, "invalid option " LUA_QL("%%%c") " to "
 967                                LUA_QL("format"), *(strfrmt - 1));
 968         }
 969       }
 970       luaL_addsize(&b, nb);
 971     }
 972   }
 973   luaL_pushresult(&b);
 974   return 1;
 975 }
 976
 977 /* }====================================================== */
 978
 979
 980 static const luaL_Reg strlib[] = {
 981   {"byte", str_byte},
 982   {"char", str_char},
 983   {"dump", str_dump},
 984   {"find", str_find},
 985   {"format", str_format},
 986   {"gmatch", gmatch},
 987   {"gsub", str_gsub},
 988   {"len", str_len},
 989   {"lower", str_lower},
 990   {"match", str_match},
 991   {"rep", str_rep},
 992   {"reverse", str_reverse},
 993   {"sub", str_sub},
 994   {"upper", str_upper},
 995   {NULL, NULL}
 996 };
 997
 998
 999 static void createmetatable (lua_State *L) {
1000   lua_createtable(L, 0, 1);  /* table to be metatable for strings */
1001   lua_pushliteral(L, "");  /* dummy string */
1002   lua_pushvalue(L, -2);  /* copy table */
1003   lua_setmetatable(L, -2);  /* set table as metatable for strings */
1004   lua_pop(L, 1);  /* pop dummy string */
1005   lua_pushvalue(L, -2);  /* get string library */
1006   lua_setfield(L, -2, "__index");  /* metatable.__index = string */
1007   lua_pop(L, 1);  /* pop metatable */
1008 }
1009
1010
1011 /*
1012 ** Open string library
1013 */
1014 LUAMOD_API int luaopen_string (lua_State *L) {
1015   luaL_newlib(L, strlib);
1016   createmetatable(L);
1017   return 1;
1018 }
1019