lua/src/lstrlib.c

   1 /*
   2 ** $Id: lstrlib.c,v 1.132a 2006/04/26 20:41:19 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   return (pos>=0) ? pos : (ptrdiff_t)len+pos+1;
  39 }
  40
  41
  42 static int str_sub (lua_State *L) {
  43   size_t l;
  44   const char *s = luaL_checklstring(L, 1, &l);
  45   ptrdiff_t start = posrelat(luaL_checkinteger(L, 2), l);
  46   ptrdiff_t end = posrelat(luaL_optinteger(L, 3, -1), l);
  47   if (start < 1) start = 1;
  48   if (end > (ptrdiff_t)l) end = (ptrdiff_t)l;
  49   if (start <= end)
  50     lua_pushlstring(L, s+start-1, end-start+1);
  51   else lua_pushliteral(L, "");
  52   return 1;
  53 }
  54
  55
  56 static int str_reverse (lua_State *L) {
  57   size_t l;
  58   luaL_Buffer b;
  59   const char *s = luaL_checklstring(L, 1, &l);
  60   luaL_buffinit(L, &b);
  61   while (l--) luaL_addchar(&b, s[l]);
  62   luaL_pushresult(&b);
  63   return 1;
  64 }
  65
  66
  67 static int str_lower (lua_State *L) {
  68   size_t l;
  69   size_t i;
  70   luaL_Buffer b;
  71   const char *s = luaL_checklstring(L, 1, &l);
  72   luaL_buffinit(L, &b);
  73   for (i=0; i<l; i++)
  74     luaL_addchar(&b, tolower(uchar(s[i])));
  75   luaL_pushresult(&b);
  76   return 1;
  77 }
  78
  79
  80 static int str_upper (lua_State *L) {
  81   size_t l;
  82   size_t i;
  83   luaL_Buffer b;
  84   const char *s = luaL_checklstring(L, 1, &l);
  85   luaL_buffinit(L, &b);
  86   for (i=0; i<l; i++)
  87     luaL_addchar(&b, toupper(uchar(s[i])));
  88   luaL_pushresult(&b);
  89   return 1;
  90 }
  91
  92 static int str_rep (lua_State *L) {
  93   size_t l;
  94   luaL_Buffer b;
  95   const char *s = luaL_checklstring(L, 1, &l);
  96   int n = luaL_checkint(L, 2);
  97   luaL_buffinit(L, &b);
  98   while (n-- > 0)
  99     luaL_addlstring(&b, s, l);
 100   luaL_pushresult(&b);
 101   return 1;
 102 }
 103
 104
 105 static int str_byte (lua_State *L) {
 106   size_t l;
 107   const char *s = luaL_checklstring(L, 1, &l);
 108   ptrdiff_t posi = posrelat(luaL_optinteger(L, 2, 1), l);
 109   ptrdiff_t pose = posrelat(luaL_optinteger(L, 3, posi), l);
 110   int n, i;
 111   if (posi <= 0) posi = 1;
 112   if ((size_t)pose > l) pose = l;
 113   if (posi > pose) return 0;  /* empty interval; return no values */
 114   n = (int)(pose -  posi + 1);
 115   if (posi + n <= pose)  /* overflow? */
 116     luaL_error(L, "string slice too long");
 117   luaL_checkstack(L, n, "string slice too long");
 118   for (i=0; i<n; i++)
 119     lua_pushinteger(L, uchar(s[posi+i-1]));
 120   return n;
 121 }
 122
 123
 124 static int str_char (lua_State *L) {
 125   int n = lua_gettop(L);  /* number of arguments */
 126   int i;
 127   luaL_Buffer b;
 128   luaL_buffinit(L, &b);
 129   for (i=1; i<=n; i++) {
 130     int c = luaL_checkint(L, i);
 131     luaL_argcheck(L, uchar(c) == c, i, "invalid value");
 132     luaL_addchar(&b, uchar(c));
 133   }
 134   luaL_pushresult(&b);
 135   return 1;
 136 }
 137
 138
 139 static int writer (lua_State *L, const void* b, size_t size, void* B) {
 140   (void)L;
 141   luaL_addlstring((luaL_Buffer*) B, (const char *)b, size);
 142   return 0;
 143 }
 144
 145
 146 static int str_dump (lua_State *L) {
 147   luaL_Buffer b;
 148   luaL_checktype(L, 1, LUA_TFUNCTION);
 149   lua_settop(L, 1);
 150   luaL_buffinit(L,&b);
 151   if (lua_dump(L, writer, &b) != 0)
 152     luaL_error(L, "unable to dump given function");
 153   luaL_pushresult(&b);
 154   return 1;
 155 }
 156
 157
 158
 159 /*
 160 ** {======================================================
 161 ** PATTERN MATCHING
 162 ** =======================================================
 163 */
 164
 165
 166 #define CAP_UNFINISHED  (-1)
 167 #define CAP_POSITION    (-2)
 168
 169 typedef struct MatchState {
 170   const char *src_init;  /* init of source string */
 171   const char *src_end;  /* end (`\0') of source string */
 172   lua_State *L;
 173   int level;  /* total number of captures (finished or unfinished) */
 174   struct {
 175     const char *init;
 176     ptrdiff_t len;
 177   } capture[LUA_MAXCAPTURES];
 178 } MatchState;
 179
 180
 181 #define L_ESC           '%'
 182 #define SPECIALS        "^$*+?.([%-"
 183
 184
 185 static int check_capture (MatchState *ms, int l) {
 186   l -= '1';
 187   if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
 188     return luaL_error(ms->L, "invalid capture index");
 189   return l;
 190 }
 191
 192
 193 static int capture_to_close (MatchState *ms) {
 194   int level = ms->level;
 195   for (level--; level>=0; level--)
 196     if (ms->capture[level].len == CAP_UNFINISHED) return level;
 197   return luaL_error(ms->L, "invalid pattern capture");
 198 }
 199
 200
 201 static const char *classend (MatchState *ms, const char *p) {
 202   switch (*p++) {
 203     case L_ESC: {
 204       if (*p == '\0')
 205         luaL_error(ms->L, "malformed pattern (ends with " LUA_QL("%%") ")");
 206       return p+1;
 207     }
 208     case '[': {
 209       if (*p == '^') p++;
 210       do {  /* look for a `]' */
 211         if (*p == '\0')
 212           luaL_error(ms->L, "malformed pattern (missing " LUA_QL("]") ")");
 213         if (*(p++) == L_ESC && *p != '\0')
 214           p++;  /* skip escapes (e.g. `%]') */
 215       } while (*p != ']');
 216       return p+1;
 217     }
 218     default: {
 219       return p;
 220     }
 221   }
 222 }
 223
 224
 225 static int match_class (int c, int cl) {
 226   int res;
 227   switch (tolower(cl)) {
 228     case 'a' : res = isalpha(c); break;
 229     case 'c' : res = iscntrl(c); break;
 230     case 'd' : res = isdigit(c); break;
 231     case 'l' : res = islower(c); break;
 232     case 'p' : res = ispunct(c); break;
 233     case 's' : res = isspace(c); break;
 234     case 'u' : res = isupper(c); break;
 235     case 'w' : res = isalnum(c); break;
 236     case 'x' : res = isxdigit(c); break;
 237     case 'z' : res = (c == 0); break;
 238     default: return (cl == c);
 239   }
 240   return (islower(cl) ? res : !res);
 241 }
 242
 243
 244 static int matchbracketclass (int c, const char *p, const char *ec) {
 245   int sig = 1;
 246   if (*(p+1) == '^') {
 247     sig = 0;
 248     p++;  /* skip the `^' */
 249   }
 250   while (++p < ec) {
 251     if (*p == L_ESC) {
 252       p++;
 253       if (match_class(c, uchar(*p)))
 254         return sig;
 255     }
 256     else if ((*(p+1) == '-') && (p+2 < ec)) {
 257       p+=2;
 258       if (uchar(*(p-2)) <= c && c <= uchar(*p))
 259         return sig;
 260     }
 261     else if (uchar(*p) == c) return sig;
 262   }
 263   return !sig;
 264 }
 265
 266
 267 static int singlematch (int c, const char *p, const char *ep) {
 268   switch (*p) {
 269     case '.': return 1;  /* matches any char */
 270     case L_ESC: return match_class(c, uchar(*(p+1)));
 271     case '[': return matchbracketclass(c, p, ep-1);
 272     default:  return (uchar(*p) == c);
 273   }
 274 }
 275
 276
 277 static const char *match (MatchState *ms, const char *s, const char *p);
 278
 279
 280 static const char *matchbalance (MatchState *ms, const char *s,
 281                                    const char *p) {
 282   if (*p == 0 || *(p+1) == 0)
 283     luaL_error(ms->L, "unbalanced pattern");
 284   if (*s != *p) return NULL;
 285   else {
 286     int b = *p;
 287     int e = *(p+1);
 288     int cont = 1;
 289     while (++s < ms->src_end) {
 290       if (*s == e) {
 291         if (--cont == 0) return s+1;
 292       }
 293       else if (*s == b) cont++;
 294     }
 295   }
 296   return NULL;  /* string ends out of balance */
 297 }
 298
 299
 300 static const char *max_expand (MatchState *ms, const char *s,
 301                                  const char *p, const char *ep) {
 302   ptrdiff_t i = 0;  /* counts maximum expand for item */
 303   while ((s+i)<ms->src_end && singlematch(uchar(*(s+i)), p, ep))
 304     i++;
 305   /* keeps trying to match with the maximum repetitions */
 306   while (i>=0) {
 307     const char *res = match(ms, (s+i), ep+1);
 308     if (res) return res;
 309     i--;  /* else didn't match; reduce 1 repetition to try again */
 310   }
 311   return NULL;
 312 }
 313
 314
 315 static const char *min_expand (MatchState *ms, const char *s,
 316                                  const char *p, const char *ep) {
 317   for (;;) {
 318     const char *res = match(ms, s, ep+1);
 319     if (res != NULL)
 320       return res;
 321     else if (s<ms->src_end && singlematch(uchar(*s), p, ep))
 322       s++;  /* try with one more repetition */
 323     else return NULL;
 324   }
 325 }
 326
 327
 328 static const char *start_capture (MatchState *ms, const char *s,
 329                                     const char *p, int what) {
 330   const char *res;
 331   int level = ms->level;
 332   if (level >= LUA_MAXCAPTURES) luaL_error(ms->L, "too many captures");
 333   ms->capture[level].init = s;
 334   ms->capture[level].len = what;
 335   ms->level = level+1;
 336   if ((res=match(ms, s, p)) == NULL)  /* match failed? */
 337     ms->level--;  /* undo capture */
 338   return res;
 339 }
 340
 341
 342 static const char *end_capture (MatchState *ms, const char *s,
 343                                   const char *p) {
 344   int l = capture_to_close(ms);
 345   const char *res;
 346   ms->capture[l].len = s - ms->capture[l].init;  /* close capture */
 347   if ((res = match(ms, s, p)) == NULL)  /* match failed? */
 348     ms->capture[l].len = CAP_UNFINISHED;  /* undo capture */
 349   return res;
 350 }
 351
 352
 353 static const char *match_capture (MatchState *ms, const char *s, int l) {
 354   size_t len;
 355   l = check_capture(ms, l);
 356   len = ms->capture[l].len;
 357   if ((size_t)(ms->src_end-s) >= len &&
 358       memcmp(ms->capture[l].init, s, len) == 0)
 359     return s+len;
 360   else return NULL;
 361 }
 362
 363
 364 static const char *match (MatchState *ms, const char *s, const char *p) {
 365   init: /* using goto's to optimize tail recursion */
 366   switch (*p) {
 367     case '(': {  /* start capture */
 368       if (*(p+1) == ')')  /* position capture? */
 369         return start_capture(ms, s, p+2, CAP_POSITION);
 370       else
 371         return start_capture(ms, s, p+1, CAP_UNFINISHED);
 372     }
 373     case ')': {  /* end capture */
 374       return end_capture(ms, s, p+1);
 375     }
 376     case L_ESC: {
 377       switch (*(p+1)) {
 378         case 'b': {  /* balanced string? */
 379           s = matchbalance(ms, s, p+2);
 380           if (s == NULL) return NULL;
 381           p+=4; goto init;  /* else return match(ms, s, p+4); */
 382         }
 383         case 'f': {  /* frontier? */
 384           const char *ep; char previous;
 385           p += 2;
 386           if (*p != '[')
 387             luaL_error(ms->L, "missing " LUA_QL("[") " after "
 388                                LUA_QL("%%f") " in pattern");
 389           ep = classend(ms, p);  /* points to what is next */
 390           previous = (s == ms->src_init) ? '\0' : *(s-1);
 391           if (matchbracketclass(uchar(previous), p, ep-1) ||
 392              !matchbracketclass(uchar(*s), p, ep-1)) return NULL;
 393           p=ep; goto init;  /* else return match(ms, s, ep); */
 394         }
 395         default: {
 396           if (isdigit(uchar(*(p+1)))) {  /* capture results (%0-%9)? */
 397             s = match_capture(ms, s, uchar(*(p+1)));
 398             if (s == NULL) return NULL;
 399             p+=2; goto init;  /* else return match(ms, s, p+2) */
 400           }
 401           goto dflt;  /* case default */
 402         }
 403       }
 404     }
 405     case '\0': {  /* end of pattern */
 406       return s;  /* match succeeded */
 407     }
 408     case '$': {
 409       if (*(p+1) == '\0')  /* is the `$' the last char in pattern? */
 410         return (s == ms->src_end) ? s : NULL;  /* check end of string */
 411       else goto dflt;
 412     }
 413     default: dflt: {  /* it is a pattern item */
 414       const char *ep = classend(ms, p);  /* points to what is next */
 415       int m = s<ms->src_end && singlematch(uchar(*s), p, ep);
 416       switch (*ep) {
 417         case '?': {  /* optional */
 418           const char *res;
 419           if (m && ((res=match(ms, s+1, ep+1)) != NULL))
 420             return res;
 421           p=ep+1; goto init;  /* else return match(ms, s, ep+1); */
 422         }
 423         case '*': {  /* 0 or more repetitions */
 424           return max_expand(ms, s, p, ep);
 425         }
 426         case '+': {  /* 1 or more repetitions */
 427           return (m ? max_expand(ms, s+1, p, ep) : NULL);
 428         }
 429         case '-': {  /* 0 or more repetitions (minimum) */
 430           return min_expand(ms, s, p, ep);
 431         }
 432         default: {
 433           if (!m) return NULL;
 434           s++; p=ep; goto init;  /* else return match(ms, s+1, ep); */
 435         }
 436       }
 437     }
 438   }
 439 }
 440
 441
 442
 443 static const char *lmemfind (const char *s1, size_t l1,
 444                                const char *s2, size_t l2) {
 445   if (l2 == 0) return s1;  /* empty strings are everywhere */
 446   else if (l2 > l1) return NULL;  /* avoids a negative `l1' */
 447   else {
 448     const char *init;  /* to search for a `*s2' inside `s1' */
 449     l2--;  /* 1st char will be checked by `memchr' */
 450     l1 = l1-l2;  /* `s2' cannot be found after that */
 451     while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL) {
 452       init++;   /* 1st char is already checked */
 453       if (memcmp(init, s2+1, l2) == 0)
 454         return init-1;
 455       else {  /* correct `l1' and `s1' to try again */
 456         l1 -= init-s1;
 457         s1 = init;
 458       }
 459     }
 460     return NULL;  /* not found */
 461   }
 462 }
 463
 464
 465 static void push_onecapture (MatchState *ms, int i, const char *s,
 466                                                     const char *e) {
 467   if (i >= ms->level) {
 468     if (i == 0)  /* ms->level == 0, too */
 469       lua_pushlstring(ms->L, s, e - s);  /* add whole match */
 470     else
 471       luaL_error(ms->L, "invalid capture index");
 472   }
 473   else {
 474     ptrdiff_t l = ms->capture[i].len;
 475     if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");
 476     if (l == CAP_POSITION)
 477       lua_pushinteger(ms->L, ms->capture[i].init - ms->src_init + 1);
 478     else
 479       lua_pushlstring(ms->L, ms->capture[i].init, l);
 480   }
 481 }
 482
 483
 484 static int push_captures (MatchState *ms, const char *s, const char *e) {
 485   int i;
 486   int nlevels = (ms->level == 0 && s) ? 1 : ms->level;
 487   luaL_checkstack(ms->L, nlevels, "too many captures");
 488   for (i = 0; i < nlevels; i++)
 489     push_onecapture(ms, i, s, e);
 490   return nlevels;  /* number of strings pushed */
 491 }
 492
 493
 494 static int str_find_aux (lua_State *L, int find) {
 495   size_t l1, l2;
 496   const char *s = luaL_checklstring(L, 1, &l1);
 497   const char *p = luaL_checklstring(L, 2, &l2);
 498   ptrdiff_t init = posrelat(luaL_optinteger(L, 3, 1), l1) - 1;
 499   if (init < 0) init = 0;
 500   else if ((size_t)(init) > l1) init = (ptrdiff_t)l1;
 501   if (find && (lua_toboolean(L, 4) ||  /* explicit request? */
 502       strpbrk(p, SPECIALS) == NULL)) {  /* or no special characters? */
 503     /* do a plain search */
 504     const char *s2 = lmemfind(s+init, l1-init, p, l2);
 505     if (s2) {
 506       lua_pushinteger(L, s2-s+1);
 507       lua_pushinteger(L, s2-s+l2);
 508       return 2;
 509     }
 510   }
 511   else {
 512     MatchState ms;
 513     int anchor = (*p == '^') ? (p++, 1) : 0;
 514     const char *s1=s+init;
 515     ms.L = L;
 516     ms.src_init = s;
 517     ms.src_end = s+l1;
 518     do {
 519       const char *res;
 520       ms.level = 0;
 521       if ((res=match(&ms, s1, p)) != NULL) {
 522         if (find) {
 523           lua_pushinteger(L, s1-s+1);  /* start */
 524           lua_pushinteger(L, res-s);   /* end */
 525           return push_captures(&ms, NULL, 0) + 2;
 526         }
 527         else
 528           return push_captures(&ms, s1, res);
 529       }
 530     } while (s1++ < ms.src_end && !anchor);
 531   }
 532   lua_pushnil(L);  /* not found */
 533   return 1;
 534 }
 535
 536
 537 static int str_find (lua_State *L) {
 538   return str_find_aux(L, 1);
 539 }
 540
 541
 542 static int str_match (lua_State *L) {
 543   return str_find_aux(L, 0);
 544 }
 545
 546
 547 static int gmatch_aux (lua_State *L) {
 548   MatchState ms;
 549   size_t ls;
 550   const char *s = lua_tolstring(L, lua_upvalueindex(1), &ls);
 551   const char *p = lua_tostring(L, lua_upvalueindex(2));
 552   const char *src;
 553   ms.L = L;
 554   ms.src_init = s;
 555   ms.src_end = s+ls;
 556   for (src = s + (size_t)lua_tointeger(L, lua_upvalueindex(3));
 557        src <= ms.src_end;
 558        src++) {
 559     const char *e;
 560     ms.level = 0;
 561     if ((e = match(&ms, src, p)) != NULL) {
 562       lua_Integer newstart = e-s;
 563       if (e == src) newstart++;  /* empty match? go at least one position */
 564       lua_pushinteger(L, newstart);
 565       lua_replace(L, lua_upvalueindex(3));
 566       return push_captures(&ms, src, e);
 567     }
 568   }
 569   return 0;  /* not found */
 570 }
 571
 572
 573 static int gmatch (lua_State *L) {
 574   luaL_checkstring(L, 1);
 575   luaL_checkstring(L, 2);
 576   lua_settop(L, 2);
 577   lua_pushinteger(L, 0);
 578   lua_pushcclosure(L, gmatch_aux, 3);
 579   return 1;
 580 }
 581
 582
 583 static int gfind_nodef (lua_State *L) {
 584   return luaL_error(L, LUA_QL("string.gfind") " was renamed to "
 585                        LUA_QL("string.gmatch"));
 586 }
 587
 588
 589 static void add_s (MatchState *ms, luaL_Buffer *b, const char *s,
 590                                                    const char *e) {
 591   size_t l, i;
 592   const char *news = lua_tolstring(ms->L, 3, &l);
 593   for (i = 0; i < l; i++) {
 594     if (news[i] != L_ESC)
 595       luaL_addchar(b, news[i]);
 596     else {
 597       i++;  /* skip ESC */
 598       if (!isdigit(uchar(news[i])))
 599         luaL_addchar(b, news[i]);
 600       else if (news[i] == '0')
 601           luaL_addlstring(b, s, e - s);
 602       else {
 603         push_onecapture(ms, news[i] - '1', s, e);
 604         luaL_addvalue(b);  /* add capture to accumulated result */
 605       }
 606     }
 607   }
 608 }
 609
 610
 611 static void add_value (MatchState *ms, luaL_Buffer *b, const char *s,
 612                                                        const char *e) {
 613   lua_State *L = ms->L;
 614   switch (lua_type(L, 3)) {
 615     case LUA_TNUMBER:
 616     case LUA_TSTRING: {
 617       add_s(ms, b, s, e);
 618       return;
 619     }
 620     case LUA_TFUNCTION: {
 621       int n;
 622       lua_pushvalue(L, 3);
 623       n = push_captures(ms, s, e);
 624       lua_call(L, n, 1);
 625       break;
 626     }
 627     case LUA_TTABLE: {
 628       push_onecapture(ms, 0, s, e);
 629       lua_gettable(L, 3);
 630       break;
 631     }
 632     default: {
 633       luaL_argerror(L, 3, "string/function/table expected");
 634       return;
 635     }
 636   }
 637   if (!lua_toboolean(L, -1)) {  /* nil or false? */
 638     lua_pop(L, 1);
 639     lua_pushlstring(L, s, e - s);  /* keep original text */
 640   }
 641   else if (!lua_isstring(L, -1))
 642     luaL_error(L, "invalid replacement value (a %s)", luaL_typename(L, -1));
 643   luaL_addvalue(b);  /* add result to accumulator */
 644 }
 645
 646
 647 static int str_gsub (lua_State *L) {
 648   size_t srcl;
 649   const char *src = luaL_checklstring(L, 1, &srcl);
 650   const char *p = luaL_checkstring(L, 2);
 651   int max_s = luaL_optint(L, 4, srcl+1);
 652   int anchor = (*p == '^') ? (p++, 1) : 0;
 653   int n = 0;
 654   MatchState ms;
 655   luaL_Buffer b;
 656   luaL_buffinit(L, &b);
 657   ms.L = L;
 658   ms.src_init = src;
 659   ms.src_end = src+srcl;
 660   while (n < max_s) {
 661     const char *e;
 662     ms.level = 0;
 663     e = match(&ms, src, p);
 664     if (e) {
 665       n++;
 666       add_value(&ms, &b, src, e);
 667     }
 668     if (e && e>src) /* non empty match? */
 669       src = e;  /* skip it */
 670     else if (src < ms.src_end)
 671       luaL_addchar(&b, *src++);
 672     else break;
 673     if (anchor) break;
 674   }
 675   luaL_addlstring(&b, src, ms.src_end-src);
 676   luaL_pushresult(&b);
 677   lua_pushinteger(L, n);  /* number of substitutions */
 678   return 2;
 679 }
 680
 681 /* }====================================================== */
 682
 683
 684 /* maximum size of each formatted item (> len(format('%99.99f', -1e308))) */
 685 #define MAX_ITEM        512
 686 /* valid flags in a format specification */
 687 #define FLAGS   "-+ #0"
 688 /*
 689 ** maximum size of each format specification (such as '%-099.99d')
 690 ** (+10 accounts for %99.99x plus margin of error)
 691 */
 692 #define MAX_FORMAT      (sizeof(FLAGS) + sizeof(LUA_INTFRMLEN) + 10)
 693
 694
 695 static void addquoted (lua_State *L, luaL_Buffer *b, int arg) {
 696   size_t l;
 697   const char *s = luaL_checklstring(L, arg, &l);
 698   luaL_addchar(b, '"');
 699   while (l--) {
 700     switch (*s) {
 701       case '"': case '\\': case '\n': {
 702         luaL_addchar(b, '\\');
 703         luaL_addchar(b, *s);
 704         break;
 705       }
 706       case '\r': {
 707         luaL_addlstring(b, "\\r", 2);
 708         break;
 709       }
 710       case '\0': {
 711         luaL_addlstring(b, "\\000", 4);
 712         break;
 713       }
 714       default: {
 715         luaL_addchar(b, *s);
 716         break;
 717       }
 718     }
 719     s++;
 720   }
 721   luaL_addchar(b, '"');
 722 }
 723
 724 static const char *scanformat (lua_State *L, const char *strfrmt, char *form) {
 725   const char *p = strfrmt;
 726   while (*p != '\0' && strchr(FLAGS, *p) != NULL) p++;  /* skip flags */
 727   if ((size_t)(p - strfrmt) >= sizeof(FLAGS))
 728     luaL_error(L, "invalid format (repeated flags)");
 729   if (isdigit(uchar(*p))) p++;  /* skip width */
 730   if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
 731   if (*p == '.') {
 732     p++;
 733     if (isdigit(uchar(*p))) p++;  /* skip precision */
 734     if (isdigit(uchar(*p))) p++;  /* (2 digits at most) */
 735   }
 736   if (isdigit(uchar(*p)))
 737     luaL_error(L, "invalid format (width or precision too long)");
 738   *(form++) = '%';
 739   strncpy(form, strfrmt, p - strfrmt + 1);
 740   form += p - strfrmt + 1;
 741   *form = '\0';
 742   return p;
 743 }
 744
 745
 746 static void addintlen (char *form) {
 747   size_t l = strlen(form);
 748   char spec = form[l - 1];
 749   strcpy(form + l - 1, LUA_INTFRMLEN);
 750   form[l + sizeof(LUA_INTFRMLEN) - 2] = spec;
 751   form[l + sizeof(LUA_INTFRMLEN) - 1] = '\0';
 752 }
 753
 754
 755 static int str_format (lua_State *L) {
 756   int arg = 1;
 757   size_t sfl;
 758   const char *strfrmt = luaL_checklstring(L, arg, &sfl);
 759   const char *strfrmt_end = strfrmt+sfl;
 760   luaL_Buffer b;
 761   luaL_buffinit(L, &b);
 762   while (strfrmt < strfrmt_end) {
 763     if (*strfrmt != L_ESC)
 764       luaL_addchar(&b, *strfrmt++);
 765     else if (*++strfrmt == L_ESC)
 766       luaL_addchar(&b, *strfrmt++);  /* %% */
 767     else { /* format item */
 768       char form[MAX_FORMAT];  /* to store the format (`%...') */
 769       char buff[MAX_ITEM];  /* to store the formatted item */
 770       arg++;
 771       strfrmt = scanformat(L, strfrmt, form);
 772       switch (*strfrmt++) {
 773         case 'c': {
 774           sprintf(buff, form, (int)luaL_checknumber(L, arg));
 775           break;
 776         }
 777         case 'd':  case 'i': {
 778           addintlen(form);
 779           sprintf(buff, form, (LUA_INTFRM_T)luaL_checknumber(L, arg));
 780           break;
 781         }
 782         case 'o':  case 'u':  case 'x':  case 'X': {
 783           addintlen(form);
 784           sprintf(buff, form, (unsigned LUA_INTFRM_T)luaL_checknumber(L, arg));
 785           break;
 786         }
 787         case 'e':  case 'E': case 'f':
 788         case 'g': case 'G': {
 789           sprintf(buff, form, (double)luaL_checknumber(L, arg));
 790           break;
 791         }
 792         case 'q': {
 793           addquoted(L, &b, arg);
 794           continue;  /* skip the 'addsize' at the end */
 795         }
 796         case 's': {
 797           size_t l;
 798           const char *s = luaL_checklstring(L, arg, &l);
 799           if (!strchr(form, '.') && l >= 100) {
 800             /* no precision and string is too long to be formatted;
 801                keep original string */
 802             lua_pushvalue(L, arg);
 803             luaL_addvalue(&b);
 804             continue;  /* skip the `addsize' at the end */
 805           }
 806           else {
 807             sprintf(buff, form, s);
 808             break;
 809           }
 810         }
 811         default: {  /* also treat cases `pnLlh' */
 812           return luaL_error(L, "invalid option " LUA_QL("%%%c") " to "
 813                                LUA_QL("format"), *(strfrmt - 1));
 814         }
 815       }
 816       luaL_addlstring(&b, buff, strlen(buff));
 817     }
 818   }
 819   luaL_pushresult(&b);
 820   return 1;
 821 }
 822
 823
 824 static const luaL_Reg strlib[] = {
 825   {"byte", str_byte},
 826   {"char", str_char},
 827   {"dump", str_dump},
 828   {"find", str_find},
 829   {"format", str_format},
 830   {"gfind", gfind_nodef},
 831   {"gmatch", gmatch},
 832   {"gsub", str_gsub},
 833   {"len", str_len},
 834   {"lower", str_lower},
 835   {"match", str_match},
 836   {"rep", str_rep},
 837   {"reverse", str_reverse},
 838   {"sub", str_sub},
 839   {"upper", str_upper},
 840   {NULL, NULL}
 841 };
 842
 843
 844 static void createmetatable (lua_State *L) {
 845   lua_createtable(L, 0, 1);  /* create metatable for strings */
 846   lua_pushliteral(L, "");  /* dummy string */
 847   lua_pushvalue(L, -2);
 848   lua_setmetatable(L, -2);  /* set string metatable */
 849   lua_pop(L, 1);  /* pop dummy string */
 850   lua_pushvalue(L, -2);  /* string library... */
 851   lua_setfield(L, -2, "__index");  /* ...is the __index metamethod */
 852   lua_pop(L, 1);  /* pop metatable */
 853 }
 854
 855
 856 /*
 857 ** Open string library
 858 */
 859 LUALIB_API int luaopen_string (lua_State *L) {
 860   luaL_register(L, LUA_STRLIBNAME, strlib);
 861 #if defined(LUA_COMPAT_GFIND)
 862   lua_getfield(L, -1, "gmatch");
 863   lua_setfield(L, -2, "gfind");
 864 #endif
 865   createmetatable(L);
 866   return 1;
 867 }
 868