src/lib/lstrlib.c

   1 /*
   2 ** $Id: lstrlib.c,v 1.56 2000/10/27 16:15:53 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 #include "lua.h"
  15
  16 #include "lauxlib.h"
  17 #include "lualib.h"
  18
  19
  20
  21 static int str_len (lua_State *L) {
  22   size_t l;
  23   luaL_check_lstr(L, 1, &l);
  24   lua_pushnumber(L, l);
  25   return 1;
  26 }
  27
  28
  29 static long posrelat (long pos, size_t len) {
  30   /* relative string position: negative means back from end */
  31   return (pos>=0) ? pos : (long)len+pos+1;
  32 }
  33
  34
  35 static int str_sub (lua_State *L) {
  36   size_t l;
  37   const char *s = luaL_check_lstr(L, 1, &l);
  38   long start = posrelat(luaL_check_long(L, 2), l);
  39   long end = posrelat(luaL_opt_long(L, 3, -1), l);
  40   if (start < 1) start = 1;
  41   if (end > (long)l) end = l;
  42   if (start <= end)
  43     lua_pushlstring(L, s+start-1, end-start+1);
  44   else lua_pushstring(L, "");
  45   return 1;
  46 }
  47
  48
  49 static int str_lower (lua_State *L) {
  50   size_t l;
  51   size_t i;
  52   luaL_Buffer b;
  53   const char *s = luaL_check_lstr(L, 1, &l);
  54   luaL_buffinit(L, &b);
  55   for (i=0; i<l; i++)
  56     luaL_putchar(&b, tolower((unsigned char)(s[i])));
  57   luaL_pushresult(&b);
  58   return 1;
  59 }
  60
  61
  62 static int str_upper (lua_State *L) {
  63   size_t l;
  64   size_t i;
  65   luaL_Buffer b;
  66   const char *s = luaL_check_lstr(L, 1, &l);
  67   luaL_buffinit(L, &b);
  68   for (i=0; i<l; i++)
  69     luaL_putchar(&b, toupper((unsigned char)(s[i])));
  70   luaL_pushresult(&b);
  71   return 1;
  72 }
  73
  74 static int str_rep (lua_State *L) {
  75   size_t l;
  76   luaL_Buffer b;
  77   const char *s = luaL_check_lstr(L, 1, &l);
  78   int n = luaL_check_int(L, 2);
  79   luaL_buffinit(L, &b);
  80   while (n-- > 0)
  81     luaL_addlstring(&b, s, l);
  82   luaL_pushresult(&b);
  83   return 1;
  84 }
  85
  86
  87 static int str_byte (lua_State *L) {
  88   size_t l;
  89   const char *s = luaL_check_lstr(L, 1, &l);
  90   long pos = posrelat(luaL_opt_long(L, 2, 1), l);
  91   luaL_arg_check(L, 0<pos && (size_t)pos<=l, 2,  "out of range");
  92   lua_pushnumber(L, (unsigned char)s[pos-1]);
  93   return 1;
  94 }
  95
  96
  97 static int str_char (lua_State *L) {
  98   int n = lua_gettop(L);  /* number of arguments */
  99   int i;
 100   luaL_Buffer b;
 101   luaL_buffinit(L, &b);
 102   for (i=1; i<=n; i++) {
 103     int c = luaL_check_int(L, i);
 104     luaL_arg_check(L, (unsigned char)c == c, i, "invalid value");
 105     luaL_putchar(&b, (unsigned char)c);
 106   }
 107   luaL_pushresult(&b);
 108   return 1;
 109 }
 110
 111
 112
 113 /*
 114 ** {======================================================
 115 ** PATTERN MATCHING
 116 ** =======================================================
 117 */
 118
 119 #ifndef MAX_CAPTURES
 120 #define MAX_CAPTURES 32  /* arbitrary limit */
 121 #endif
 122
 123
 124 struct Capture {
 125   const char *src_end;  /* end ('\0') of source string */
 126   int level;  /* total number of captures (finished or unfinished) */
 127   struct {
 128     const char *init;
 129     long len;  /* -1 signals unfinished capture */
 130   } capture[MAX_CAPTURES];
 131 };
 132
 133
 134 #define ESC             '%'
 135 #define SPECIALS        "^$*+?.([%-"
 136
 137
 138 static int check_capture (lua_State *L, int l, struct Capture *cap) {
 139   l -= '1';
 140   if (!(0 <= l && l < cap->level && cap->capture[l].len != -1))
 141     lua_error(L, "invalid capture index");
 142   return l;
 143 }
 144
 145
 146 static int capture_to_close (lua_State *L, struct Capture *cap) {
 147   int level = cap->level;
 148   for (level--; level>=0; level--)
 149     if (cap->capture[level].len == -1) return level;
 150   lua_error(L, "invalid pattern capture");
 151   return 0;  /* to avoid warnings */
 152 }
 153
 154
 155 const char *luaI_classend (lua_State *L, const char *p) {
 156   switch (*p++) {
 157     case ESC:
 158       if (*p == '\0') lua_error(L, "malformed pattern (ends with `%')");
 159       return p+1;
 160     case '[':
 161       if (*p == '^') p++;
 162       do {  /* look for a ']' */
 163         if (*p == '\0') lua_error(L, "malformed pattern (missing `]')");
 164         if (*(p++) == ESC && *p != '\0') p++;  /* skip escapes (e.g. '%]') */
 165       } while (*p != ']');
 166       return p+1;
 167     default:
 168       return p;
 169   }
 170 }
 171
 172
 173 static int match_class (int c, int cl) {
 174   int res;
 175   switch (tolower(cl)) {
 176     case 'a' : res = isalpha(c); break;
 177     case 'c' : res = iscntrl(c); break;
 178     case 'd' : res = isdigit(c); break;
 179     case 'l' : res = islower(c); break;
 180     case 'p' : res = ispunct(c); break;
 181     case 's' : res = isspace(c); break;
 182     case 'u' : res = isupper(c); break;
 183     case 'w' : res = isalnum(c); break;
 184     case 'x' : res = isxdigit(c); break;
 185     case 'z' : res = (c == '\0'); break;
 186     default: return (cl == c);
 187   }
 188   return (islower(cl) ? res : !res);
 189 }
 190
 191
 192
 193 static int matchbracketclass (int c, const char *p, const char *endclass) {
 194   int sig = 1;
 195   if (*(p+1) == '^') {
 196     sig = 0;
 197     p++;  /* skip the '^' */
 198   }
 199   while (++p < endclass) {
 200     if (*p == ESC) {
 201       p++;
 202       if (match_class(c, (unsigned char)*p))
 203         return sig;
 204     }
 205     else if ((*(p+1) == '-') && (p+2 < endclass)) {
 206       p+=2;
 207       if ((int)(unsigned char)*(p-2) <= c && c <= (int)(unsigned char)*p)
 208         return sig;
 209     }
 210     else if ((int)(unsigned char)*p == c) return sig;
 211   }
 212   return !sig;
 213 }
 214
 215
 216
 217 int luaI_singlematch (int c, const char *p, const char *ep) {
 218   switch (*p) {
 219     case '.':  /* matches any char */
 220       return 1;
 221     case ESC:
 222       return match_class(c, (unsigned char)*(p+1));
 223     case '[':
 224       return matchbracketclass(c, p, ep-1);
 225     default:
 226       return ((unsigned char)*p == c);
 227   }
 228 }
 229
 230
 231 static const char *match (lua_State *L, const char *s, const char *p,
 232                           struct Capture *cap);
 233
 234
 235 static const char *matchbalance (lua_State *L, const char *s, const char *p,
 236                                  struct Capture *cap) {
 237   if (*p == 0 || *(p+1) == 0)
 238     lua_error(L, "unbalanced pattern");
 239   if (*s != *p) return NULL;
 240   else {
 241     int b = *p;
 242     int e = *(p+1);
 243     int cont = 1;
 244     while (++s < cap->src_end) {
 245       if (*s == e) {
 246         if (--cont == 0) return s+1;
 247       }
 248       else if (*s == b) cont++;
 249     }
 250   }
 251   return NULL;  /* string ends out of balance */
 252 }
 253
 254
 255 static const char *max_expand (lua_State *L, const char *s, const char *p,
 256                                const char *ep, struct Capture *cap) {
 257   long i = 0;  /* counts maximum expand for item */
 258   while ((s+i)<cap->src_end && luaI_singlematch((unsigned char)*(s+i), p, ep))
 259     i++;
 260   /* keeps trying to match with the maximum repetitions */
 261   while (i>=0) {
 262     const char *res = match(L, (s+i), ep+1, cap);
 263     if (res) return res;
 264     i--;  /* else didn't match; reduce 1 repetition to try again */
 265   }
 266   return NULL;
 267 }
 268
 269
 270 static const char *min_expand (lua_State *L, const char *s, const char *p,
 271                                const char *ep, struct Capture *cap) {
 272   for (;;) {
 273     const char *res = match(L, s, ep+1, cap);
 274     if (res != NULL)
 275       return res;
 276     else if (s<cap->src_end && luaI_singlematch((unsigned char)*s, p, ep))
 277       s++;  /* try with one more repetition */
 278     else return NULL;
 279   }
 280 }
 281
 282
 283 static const char *start_capture (lua_State *L, const char *s, const char *p,
 284                                   struct Capture *cap) {
 285   const char *res;
 286   int level = cap->level;
 287   if (level >= MAX_CAPTURES) lua_error(L, "too many captures");
 288   cap->capture[level].init = s;
 289   cap->capture[level].len = -1;
 290   cap->level = level+1;
 291   if ((res=match(L, s, p+1, cap)) == NULL)  /* match failed? */
 292     cap->level--;  /* undo capture */
 293   return res;
 294 }
 295
 296
 297 static const char *end_capture (lua_State *L, const char *s, const char *p,
 298                                 struct Capture *cap) {
 299   int l = capture_to_close(L, cap);
 300   const char *res;
 301   cap->capture[l].len = s - cap->capture[l].init;  /* close capture */
 302   if ((res = match(L, s, p+1, cap)) == NULL)  /* match failed? */
 303     cap->capture[l].len = -1;  /* undo capture */
 304   return res;
 305 }
 306
 307
 308 static const char *match_capture (lua_State *L, const char *s, int level,
 309                                   struct Capture *cap) {
 310   int l = check_capture(L, level, cap);
 311   size_t len = cap->capture[l].len;
 312   if ((size_t)(cap->src_end-s) >= len &&
 313       memcmp(cap->capture[l].init, s, len) == 0)
 314     return s+len;
 315   else return NULL;
 316 }
 317
 318
 319 static const char *match (lua_State *L, const char *s, const char *p,
 320                           struct Capture *cap) {
 321   init: /* using goto's to optimize tail recursion */
 322   switch (*p) {
 323     case '(':  /* start capture */
 324       return start_capture(L, s, p, cap);
 325     case ')':  /* end capture */
 326       return end_capture(L, s, p, cap);
 327     case ESC:  /* may be %[0-9] or %b */
 328       if (isdigit((unsigned char)(*(p+1)))) {  /* capture? */
 329         s = match_capture(L, s, *(p+1), cap);
 330         if (s == NULL) return NULL;
 331         p+=2; goto init;  /* else return match(L, s, p+2, cap) */
 332       }
 333       else if (*(p+1) == 'b') {  /* balanced string? */
 334         s = matchbalance(L, s, p+2, cap);
 335         if (s == NULL) return NULL;
 336         p+=4; goto init;  /* else return match(L, s, p+4, cap); */
 337       }
 338       else goto dflt;  /* case default */
 339     case '\0':  /* end of pattern */
 340       return s;  /* match succeeded */
 341     case '$':
 342       if (*(p+1) == '\0')  /* is the '$' the last char in pattern? */
 343         return (s == cap->src_end) ? s : NULL;  /* check end of string */
 344       else goto dflt;
 345     default: dflt: {  /* it is a pattern item */
 346       const char *ep = luaI_classend(L, p);  /* points to what is next */
 347       int m = s<cap->src_end && luaI_singlematch((unsigned char)*s, p, ep);
 348       switch (*ep) {
 349         case '?': {  /* optional */
 350           const char *res;
 351           if (m && ((res=match(L, s+1, ep+1, cap)) != NULL))
 352             return res;
 353           p=ep+1; goto init;  /* else return match(L, s, ep+1, cap); */
 354         }
 355         case '*':  /* 0 or more repetitions */
 356           return max_expand(L, s, p, ep, cap);
 357         case '+':  /* 1 or more repetitions */
 358           return (m ? max_expand(L, s+1, p, ep, cap) : NULL);
 359         case '-':  /* 0 or more repetitions (minimum) */
 360           return min_expand(L, s, p, ep, cap);
 361         default:
 362           if (!m) return NULL;
 363           s++; p=ep; goto init;  /* else return match(L, s+1, ep, cap); */
 364       }
 365     }
 366   }
 367 }
 368
 369
 370
 371 static const char *lmemfind (const char *s1, size_t l1,
 372                              const char *s2, size_t l2) {
 373   if (l2 == 0) return s1;  /* empty strings are everywhere */
 374   else if (l2 > l1) return NULL;  /* avoids a negative `l1' */
 375   else {
 376     const char *init;  /* to search for a `*s2' inside `s1' */
 377     l2--;  /* 1st char will be checked by `memchr' */
 378     l1 = l1-l2;  /* `s2' cannot be found after that */
 379     while (l1 > 0 && (init = (const char *)memchr(s1, *s2, l1)) != NULL) {
 380       init++;   /* 1st char is already checked */
 381       if (memcmp(init, s2+1, l2) == 0)
 382         return init-1;
 383       else {  /* correct `l1' and `s1' to try again */
 384         l1 -= init-s1;
 385         s1 = init;
 386       }
 387     }
 388     return NULL;  /* not found */
 389   }
 390 }
 391
 392
 393 static int push_captures (lua_State *L, struct Capture *cap) {
 394   int i;
 395   luaL_checkstack(L, cap->level, "too many captures");
 396   for (i=0; i<cap->level; i++) {
 397     int l = cap->capture[i].len;
 398     if (l == -1) lua_error(L, "unfinished capture");
 399     lua_pushlstring(L, cap->capture[i].init, l);
 400   }
 401   return cap->level;  /* number of strings pushed */
 402 }
 403
 404
 405 static int str_find (lua_State *L) {
 406   size_t l1, l2;
 407   const char *s = luaL_check_lstr(L, 1, &l1);
 408   const char *p = luaL_check_lstr(L, 2, &l2);
 409   long init = posrelat(luaL_opt_long(L, 3, 1), l1) - 1;
 410   struct Capture cap;
 411   luaL_arg_check(L, 0 <= init && (size_t)init <= l1, 3, "out of range");
 412   if (lua_gettop(L) > 3 ||  /* extra argument? */
 413       strpbrk(p, SPECIALS) == NULL) {  /* or no special characters? */
 414     const char *s2 = lmemfind(s+init, l1-init, p, l2);
 415     if (s2) {
 416       lua_pushnumber(L, s2-s+1);
 417       lua_pushnumber(L, s2-s+l2);
 418       return 2;
 419     }
 420   }
 421   else {
 422     int anchor = (*p == '^') ? (p++, 1) : 0;
 423     const char *s1=s+init;
 424     cap.src_end = s+l1;
 425     do {
 426       const char *res;
 427       cap.level = 0;
 428       if ((res=match(L, s1, p, &cap)) != NULL) {
 429         lua_pushnumber(L, s1-s+1);  /* start */
 430         lua_pushnumber(L, res-s);   /* end */
 431         return push_captures(L, &cap) + 2;
 432       }
 433     } while (s1++<cap.src_end && !anchor);
 434   }
 435   lua_pushnil(L);  /* not found */
 436   return 1;
 437 }
 438
 439
 440 static void add_s (lua_State *L, luaL_Buffer *b, struct Capture *cap) {
 441   if (lua_isstring(L, 3)) {
 442     const char *news = lua_tostring(L, 3);
 443     size_t l = lua_strlen(L, 3);
 444     size_t i;
 445     for (i=0; i<l; i++) {
 446       if (news[i] != ESC)
 447         luaL_putchar(b, news[i]);
 448       else {
 449         i++;  /* skip ESC */
 450         if (!isdigit((unsigned char)news[i]))
 451           luaL_putchar(b, news[i]);
 452         else {
 453           int level = check_capture(L, news[i], cap);
 454           luaL_addlstring(b, cap->capture[level].init, cap->capture[level].len);
 455         }
 456       }
 457     }
 458   }
 459   else {  /* is a function */
 460     int n;
 461     lua_pushvalue(L, 3);
 462     n = push_captures(L, cap);
 463     lua_rawcall(L, n, 1);
 464     if (lua_isstring(L, -1))
 465       luaL_addvalue(b);  /* add return to accumulated result */
 466     else
 467       lua_pop(L, 1);  /* function result is not a string: pop it */
 468   }
 469 }
 470
 471
 472 static int str_gsub (lua_State *L) {
 473   size_t srcl;
 474   const char *src = luaL_check_lstr(L, 1, &srcl);
 475   const char *p = luaL_check_string(L, 2);
 476   int max_s = luaL_opt_int(L, 4, srcl+1);
 477   int anchor = (*p == '^') ? (p++, 1) : 0;
 478   int n = 0;
 479   struct Capture cap;
 480   luaL_Buffer b;
 481   luaL_arg_check(L,
 482     lua_gettop(L) >= 3 && (lua_isstring(L, 3) || lua_isfunction(L, 3)),
 483     3, "string or function expected");
 484   luaL_buffinit(L, &b);
 485   cap.src_end = src+srcl;
 486   while (n < max_s) {
 487     const char *e;
 488     cap.level = 0;
 489     e = match(L, src, p, &cap);
 490     if (e) {
 491       n++;
 492       add_s(L, &b, &cap);
 493     }
 494     if (e && e>src) /* non empty match? */
 495       src = e;  /* skip it */
 496     else if (src < cap.src_end)
 497       luaL_putchar(&b, *src++);
 498     else break;
 499     if (anchor) break;
 500   }
 501   luaL_addlstring(&b, src, cap.src_end-src);
 502   luaL_pushresult(&b);
 503   lua_pushnumber(L, n);  /* number of substitutions */
 504   return 2;
 505 }
 506
 507 /* }====================================================== */
 508
 509
 510 static void luaI_addquoted (lua_State *L, luaL_Buffer *b, int arg) {
 511   size_t l;
 512   const char *s = luaL_check_lstr(L, arg, &l);
 513   luaL_putchar(b, '"');
 514   while (l--) {
 515     switch (*s) {
 516       case '"':  case '\\':  case '\n':
 517         luaL_putchar(b, '\\');
 518         luaL_putchar(b, *s);
 519         break;
 520       case '\0': luaL_addlstring(b, "\\000", 4); break;
 521       default: luaL_putchar(b, *s);
 522     }
 523     s++;
 524   }
 525   luaL_putchar(b, '"');
 526 }
 527
 528 /* maximum size of each formatted item (> len(format('%99.99f', -1e308))) */
 529 #define MAX_ITEM        512
 530 /* maximum size of each format specification (such as '%-099.99d') */
 531 #define MAX_FORMAT      20
 532
 533 static int str_format (lua_State *L) {
 534   int arg = 1;
 535   const char *strfrmt = luaL_check_string(L, arg);
 536   luaL_Buffer b;
 537   luaL_buffinit(L, &b);
 538   while (*strfrmt) {
 539     if (*strfrmt != '%')
 540       luaL_putchar(&b, *strfrmt++);
 541     else if (*++strfrmt == '%')
 542       luaL_putchar(&b, *strfrmt++);  /* %% */
 543     else { /* format item */
 544       struct Capture cap;
 545       char form[MAX_FORMAT];  /* to store the format ('%...') */
 546       char buff[MAX_ITEM];  /* to store the formatted item */
 547       const char *initf = strfrmt;
 548       form[0] = '%';
 549       if (isdigit((unsigned char)*initf) && *(initf+1) == '$') {
 550         arg = *initf - '0';
 551         initf += 2;  /* skip the 'n$' */
 552       }
 553       arg++;
 554       cap.src_end = strfrmt+strlen(strfrmt)+1;
 555       cap.level = 0;
 556       strfrmt = match(L, initf, "[-+ #0]*(%d*)%.?(%d*)", &cap);
 557       if (cap.capture[0].len > 2 || cap.capture[1].len > 2 ||  /* < 100? */
 558           strfrmt-initf > MAX_FORMAT-2)
 559         lua_error(L, "invalid format (width or precision too long)");
 560       strncpy(form+1, initf, strfrmt-initf+1); /* +1 to include conversion */
 561       form[strfrmt-initf+2] = 0;
 562       switch (*strfrmt++) {
 563         case 'c':  case 'd':  case 'i':
 564           sprintf(buff, form, luaL_check_int(L, arg));
 565           break;
 566         case 'o':  case 'u':  case 'x':  case 'X':
 567           sprintf(buff, form, (unsigned int)luaL_check_number(L, arg));
 568           break;
 569         case 'e':  case 'E': case 'f': case 'g': case 'G':
 570           sprintf(buff, form, luaL_check_number(L, arg));
 571           break;
 572         case 'q':
 573           luaI_addquoted(L, &b, arg);
 574           continue;  /* skip the "addsize" at the end */
 575         case 's': {
 576           size_t l;
 577           const char *s = luaL_check_lstr(L, arg, &l);
 578           if (cap.capture[1].len == 0 && l >= 100) {
 579             /* no precision and string is too long to be formatted;
 580                keep original string */
 581             lua_pushvalue(L, arg);
 582             luaL_addvalue(&b);
 583             continue;  /* skip the "addsize" at the end */
 584           }
 585           else {
 586             sprintf(buff, form, s);
 587             break;
 588           }
 589         }
 590         default:  /* also treat cases 'pnLlh' */
 591           lua_error(L, "invalid option in `format'");
 592       }
 593       luaL_addlstring(&b, buff, strlen(buff));
 594     }
 595   }
 596   luaL_pushresult(&b);
 597   return 1;
 598 }
 599
 600
 601 static const struct luaL_reg strlib[] = {
 602 {"strlen", str_len},
 603 {"strsub", str_sub},
 604 {"strlower", str_lower},
 605 {"strupper", str_upper},
 606 {"strchar", str_char},
 607 {"strrep", str_rep},
 608 {"ascii", str_byte},  /* for compatibility with 3.0 and earlier */
 609 {"strbyte", str_byte},
 610 {"format", str_format},
 611 {"strfind", str_find},
 612 {"gsub", str_gsub}
 613 };
 614
 615
 616 /*
 617 ** Open string library
 618 */
 619 LUALIB_API void lua_strlibopen (lua_State *L) {
 620   luaL_openl(L, strlib);
 621 }