Modules/regexmodule.c

   1 /*
   2 XXX support range parameter on search
   3 XXX support mstop parameter on search
   4 */
   5
   6
   7 /* Regular expression objects */
   8 /* This uses Tatu Ylonen's copyleft-free reimplementation of
   9    GNU regular expressions */
  10
  11 #include "Python.h"
  12
  13 #include <ctype.h>
  14
  15 #include "regexpr.h"
  16
  17 static PyObject *RegexError;    /* Exception */
  18
  19 typedef struct {
  20         PyObject_HEAD
  21         struct re_pattern_buffer re_patbuf; /* The compiled expression */
  22         struct re_registers re_regs; /* The registers from the last match */
  23         char re_fastmap[256];   /* Storage for fastmap */
  24         PyObject *re_translate; /* String object for translate table */
  25         PyObject *re_lastok;    /* String object last matched/searched */
  26         PyObject *re_groupindex;        /* Group name to index dictionary */
  27         PyObject *re_givenpat;  /* Pattern with symbolic groups */
  28         PyObject *re_realpat;   /* Pattern without symbolic groups */
  29 } regexobject;
  30
  31 /* Regex object methods */
  32
  33 static void
  34 reg_dealloc(regexobject *re)
  35 {
  36         if (re->re_patbuf.buffer)
  37                 free(re->re_patbuf.buffer);
  38         Py_XDECREF(re->re_translate);
  39         Py_XDECREF(re->re_lastok);
  40         Py_XDECREF(re->re_groupindex);
  41         Py_XDECREF(re->re_givenpat);
  42         Py_XDECREF(re->re_realpat);
  43         PyObject_Del(re);
  44 }
  45
  46 static PyObject *
  47 makeresult(struct re_registers *regs)
  48 {
  49         PyObject *v;
  50         int i;
  51         static PyObject *filler = NULL;
  52
  53         if (filler == NULL) {
  54                 filler = Py_BuildValue("(ii)", -1, -1);
  55                 if (filler == NULL)
  56                         return NULL;
  57         }
  58         v = PyTuple_New(RE_NREGS);
  59         if (v == NULL)
  60                 return NULL;
  61
  62         for (i = 0; i < RE_NREGS; i++) {
  63                 int lo = regs->start[i];
  64                 int hi = regs->end[i];
  65                 PyObject *w;
  66                 if (lo == -1 && hi == -1) {
  67                         w = filler;
  68                         Py_INCREF(w);
  69                 }
  70                 else
  71                         w = Py_BuildValue("(ii)", lo, hi);
  72                 if (w == NULL || PyTuple_SetItem(v, i, w) < 0) {
  73                         Py_DECREF(v);
  74                         return NULL;
  75                 }
  76         }
  77         return v;
  78 }
  79
  80 static PyObject *
  81 regobj_match(regexobject *re, PyObject *args)
  82 {
  83         PyObject *argstring;
  84         char *buffer;
  85         int size;
  86         int offset = 0;
  87         int result;
  88
  89         if (!PyArg_ParseTuple(args, "O|i:match", &argstring, &offset))
  90                 return NULL;
  91         if (!PyArg_Parse(argstring, "t#", &buffer, &size))
  92                 return NULL;
  93
  94         if (offset < 0 || offset > size) {
  95                 PyErr_SetString(RegexError, "match offset out of range");
  96                 return NULL;
  97         }
  98         Py_XDECREF(re->re_lastok);
  99         re->re_lastok = NULL;
 100         result = _Py_re_match(&re->re_patbuf, (unsigned char *)buffer, size, offset,
 101                               &re->re_regs);
 102         if (result < -1) {
 103                 /* Serious failure of some sort; if re_match didn't
 104                    set an exception, raise a generic error */
 105                 if (!PyErr_Occurred())
 106                         PyErr_SetString(RegexError, "match failure");
 107                 return NULL;
 108         }
 109         if (result >= 0) {
 110                 Py_INCREF(argstring);
 111                 re->re_lastok = argstring;
 112         }
 113         return PyInt_FromLong((long)result); /* Length of the match or -1 */
 114 }
 115
 116 static PyObject *
 117 regobj_search(regexobject *re, PyObject *args)
 118 {
 119         PyObject *argstring;
 120         char *buffer;
 121         int size;
 122         int offset = 0;
 123         int range;
 124         int result;
 125
 126         if (!PyArg_ParseTuple(args, "O|i:search", &argstring, &offset))
 127                 return NULL;
 128         if (!PyArg_Parse(argstring, "t#:search", &buffer, &size))
 129                 return NULL;
 130
 131         if (offset < 0 || offset > size) {
 132                 PyErr_SetString(RegexError, "search offset out of range");
 133                 return NULL;
 134         }
 135         /* NB: In Emacs 18.57, the documentation for re_search[_2] and
 136            the implementation don't match: the documentation states that
 137            |range| positions are tried, while the code tries |range|+1
 138            positions.  It seems more productive to believe the code! */
 139         range = size - offset;
 140         Py_XDECREF(re->re_lastok);
 141         re->re_lastok = NULL;
 142         result = _Py_re_search(&re->re_patbuf, (unsigned char *)buffer, size, offset, range,
 143                            &re->re_regs);
 144         if (result < -1) {
 145                 /* Serious failure of some sort; if re_match didn't
 146                    set an exception, raise a generic error */
 147                 if (!PyErr_Occurred())
 148                         PyErr_SetString(RegexError, "match failure");
 149                 return NULL;
 150         }
 151         if (result >= 0) {
 152                 Py_INCREF(argstring);
 153                 re->re_lastok = argstring;
 154         }
 155         return PyInt_FromLong((long)result); /* Position of the match or -1 */
 156 }
 157
 158 /* get the group from the regex where index can be a string (group name) or
 159    an integer index [0 .. 99]
 160  */
 161 static PyObject*
 162 group_from_index(regexobject *re, PyObject *index)
 163 {
 164         int i, a, b;
 165         char *v;
 166
 167         if (PyString_Check(index))
 168                 if (re->re_groupindex == NULL ||
 169                     !(index = PyDict_GetItem(re->re_groupindex, index)))
 170                 {
 171                         PyErr_SetString(RegexError,
 172                                         "group() group name doesn't exist");
 173                         return NULL;
 174                 }
 175
 176         i = PyInt_AsLong(index);
 177         if (i == -1 && PyErr_Occurred())
 178                 return NULL;
 179
 180         if (i < 0 || i >= RE_NREGS) {
 181                 PyErr_SetString(RegexError, "group() index out of range");
 182                 return NULL;
 183         }
 184         if (re->re_lastok == NULL) {
 185                 PyErr_SetString(RegexError,
 186                            "group() only valid after successful match/search");
 187                 return NULL;
 188         }
 189         a = re->re_regs.start[i];
 190         b = re->re_regs.end[i];
 191         if (a < 0 || b < 0) {
 192                 Py_INCREF(Py_None);
 193                 return Py_None;
 194         }
 195
 196         if (!(v = PyString_AsString(re->re_lastok)))
 197                 return NULL;
 198
 199         return PyString_FromStringAndSize(v+a, b-a);
 200 }
 201
 202
 203 static PyObject *
 204 regobj_group(regexobject *re, PyObject *args)
 205 {
 206         int n = PyTuple_Size(args);
 207         int i;
 208         PyObject *res = NULL;
 209
 210         if (n < 0)
 211                 return NULL;
 212         if (n == 0) {
 213                 PyErr_SetString(PyExc_TypeError, "not enough arguments");
 214                 return NULL;
 215         }
 216         if (n == 1) {
 217                 /* return value is a single string */
 218                 PyObject *index = PyTuple_GetItem(args, 0);
 219                 if (!index)
 220                         return NULL;
 221
 222                 return group_from_index(re, index);
 223         }
 224
 225         /* return value is a tuple */
 226         if (!(res = PyTuple_New(n)))
 227                 return NULL;
 228
 229         for (i = 0; i < n; i++) {
 230                 PyObject *index = PyTuple_GetItem(args, i);
 231                 PyObject *group = NULL;
 232
 233                 if (!index)
 234                         goto finally;
 235                 if (!(group = group_from_index(re, index)))
 236                         goto finally;
 237                 if (PyTuple_SetItem(res, i, group) < 0)
 238                         goto finally;
 239         }
 240         return res;
 241
 242   finally:
 243         Py_DECREF(res);
 244         return NULL;
 245 }
 246
 247
 248 static struct PyMethodDef reg_methods[] = {
 249         {"match",       (PyCFunction)regobj_match, METH_VARARGS},
 250         {"search",      (PyCFunction)regobj_search, METH_VARARGS},
 251         {"group",       (PyCFunction)regobj_group, METH_VARARGS},
 252         {NULL,          NULL}           /* sentinel */
 253 };
 254
 255
 256 \f
 257 static char* members[] = {
 258         "last", "regs", "translate",
 259         "groupindex", "realpat", "givenpat",
 260         NULL
 261 };
 262
 263
 264 static PyObject *
 265 regobj_getattr(regexobject *re, char *name)
 266 {
 267         if (strcmp(name, "regs") == 0) {
 268                 if (re->re_lastok == NULL) {
 269                         Py_INCREF(Py_None);
 270                         return Py_None;
 271                 }
 272                 return makeresult(&re->re_regs);
 273         }
 274         if (strcmp(name, "last") == 0) {
 275                 if (re->re_lastok == NULL) {
 276                         Py_INCREF(Py_None);
 277                         return Py_None;
 278                 }
 279                 Py_INCREF(re->re_lastok);
 280                 return re->re_lastok;
 281         }
 282         if (strcmp(name, "translate") == 0) {
 283                 if (re->re_translate == NULL) {
 284                         Py_INCREF(Py_None);
 285                         return Py_None;
 286                 }
 287                 Py_INCREF(re->re_translate);
 288                 return re->re_translate;
 289         }
 290         if (strcmp(name, "groupindex") == 0) {
 291                 if (re->re_groupindex == NULL) {
 292                         Py_INCREF(Py_None);
 293                         return Py_None;
 294                 }
 295                 Py_INCREF(re->re_groupindex);
 296                 return re->re_groupindex;
 297         }
 298         if (strcmp(name, "realpat") == 0) {
 299                 if (re->re_realpat == NULL) {
 300                         Py_INCREF(Py_None);
 301                         return Py_None;
 302                 }
 303                 Py_INCREF(re->re_realpat);
 304                 return re->re_realpat;
 305         }
 306         if (strcmp(name, "givenpat") == 0) {
 307                 if (re->re_givenpat == NULL) {
 308                         Py_INCREF(Py_None);
 309                         return Py_None;
 310                 }
 311                 Py_INCREF(re->re_givenpat);
 312                 return re->re_givenpat;
 313         }
 314         if (strcmp(name, "__members__") == 0) {
 315                 int i = 0;
 316                 PyObject *list = NULL;
 317
 318                 /* okay, so it's unlikely this list will change that often.
 319                    still, it's easier to change it in just one place.
 320                  */
 321                 while (members[i])
 322                         i++;
 323                 if (!(list = PyList_New(i)))
 324                         return NULL;
 325
 326                 i = 0;
 327                 while (members[i]) {
 328                         PyObject* v = PyString_FromString(members[i]);
 329                         if (!v || PyList_SetItem(list, i, v) < 0) {
 330                                 Py_DECREF(list);
 331                                 return NULL;
 332                         }
 333                         i++;
 334                 }
 335                 return list;
 336         }
 337         return Py_FindMethod(reg_methods, (PyObject *)re, name);
 338 }
 339
 340 static PyTypeObject Regextype = {
 341         PyObject_HEAD_INIT(NULL)
 342         0,                                   /*ob_size*/
 343         "regex.regex",                       /*tp_name*/
 344         sizeof(regexobject),                 /*tp_size*/
 345         0,                                   /*tp_itemsize*/
 346         /* methods */
 347         (destructor)reg_dealloc,             /*tp_dealloc*/
 348         0,                                   /*tp_print*/
 349         (getattrfunc)regobj_getattr,         /*tp_getattr*/
 350         0,                                   /*tp_setattr*/
 351         0,                                   /*tp_compare*/
 352         0,                                   /*tp_repr*/
 353 };
 354
 355 /* reference counting invariants:
 356    pattern: borrowed
 357    translate: borrowed
 358    givenpat: borrowed
 359    groupindex: transferred
 360 */
 361 static PyObject *
 362 newregexobject(PyObject *pattern, PyObject *translate, PyObject *givenpat, PyObject *groupindex)
 363 {
 364         regexobject *re;
 365         char *pat;
 366         int size;
 367
 368         if (!PyArg_Parse(pattern, "t#", &pat, &size))
 369                 return NULL;
 370
 371         if (translate != NULL && PyString_Size(translate) != 256) {
 372                 PyErr_SetString(RegexError,
 373                                 "translation table must be 256 bytes");
 374                 return NULL;
 375         }
 376         re = PyObject_New(regexobject, &Regextype);
 377         if (re != NULL) {
 378                 char *error;
 379                 re->re_patbuf.buffer = NULL;
 380                 re->re_patbuf.allocated = 0;
 381                 re->re_patbuf.fastmap = (unsigned char *)re->re_fastmap;
 382                 if (translate) {
 383                         re->re_patbuf.translate = (unsigned char *)PyString_AsString(translate);
 384                         if (!re->re_patbuf.translate)
 385                                 goto finally;
 386                         Py_INCREF(translate);
 387                 }
 388                 else
 389                         re->re_patbuf.translate = NULL;
 390                 re->re_translate = translate;
 391                 re->re_lastok = NULL;
 392                 re->re_groupindex = groupindex;
 393                 Py_INCREF(pattern);
 394                 re->re_realpat = pattern;
 395                 Py_INCREF(givenpat);
 396                 re->re_givenpat = givenpat;
 397                 error = _Py_re_compile_pattern((unsigned char *)pat, size, &re->re_patbuf);
 398                 if (error != NULL) {
 399                         PyErr_SetString(RegexError, error);
 400                         goto finally;
 401                 }
 402         }
 403         return (PyObject *)re;
 404   finally:
 405         Py_DECREF(re);
 406         return NULL;
 407 }
 408
 409 static PyObject *
 410 regex_compile(PyObject *self, PyObject *args)
 411 {
 412         PyObject *pat = NULL;
 413         PyObject *tran = NULL;
 414
 415         if (!PyArg_ParseTuple(args, "S|S:compile", &pat, &tran))
 416                 return NULL;
 417         return newregexobject(pat, tran, pat, NULL);
 418 }
 419
 420 static PyObject *
 421 symcomp(PyObject *pattern, PyObject *gdict)
 422 {
 423         char *opat, *oend, *o, *n, *g, *v;
 424         int group_count = 0;
 425         int sz;
 426         int escaped = 0;
 427         char name_buf[128];
 428         PyObject *npattern;
 429         int require_escape = re_syntax & RE_NO_BK_PARENS ? 0 : 1;
 430
 431         if (!(opat = PyString_AsString(pattern)))
 432                 return NULL;
 433
 434         if ((sz = PyString_Size(pattern)) < 0)
 435                 return NULL;
 436
 437         oend = opat + sz;
 438         o = opat;
 439
 440         if (oend == opat) {
 441                 Py_INCREF(pattern);
 442                 return pattern;
 443         }
 444
 445         if (!(npattern = PyString_FromStringAndSize((char*)NULL, sz)) ||
 446             !(n = PyString_AsString(npattern)))
 447                 return NULL;
 448
 449         while (o < oend) {
 450                 if (*o == '(' && escaped == require_escape) {
 451                         char *backtrack;
 452                         escaped = 0;
 453                         ++group_count;
 454                         *n++ = *o;
 455                         if (++o >= oend || *o != '<')
 456                                 continue;
 457                         /* *o == '<' */
 458                         if (o+1 < oend && *(o+1) == '>')
 459                                 continue;
 460                         backtrack = o;
 461                         g = name_buf;
 462                         for (++o; o < oend;) {
 463                                 if (*o == '>') {
 464                                     PyObject *group_name = NULL;
 465                                     PyObject *group_index = NULL;
 466                                     *g++ = '\0';
 467                                     group_name = PyString_FromString(name_buf);
 468                                     group_index = PyInt_FromLong(group_count);
 469                                     if (group_name == NULL ||
 470                                         group_index == NULL ||
 471                                         PyDict_SetItem(gdict, group_name,
 472                                                        group_index) != 0)
 473                                     {
 474                                             Py_XDECREF(group_name);
 475                                             Py_XDECREF(group_index);
 476                                             Py_XDECREF(npattern);
 477                                             return NULL;
 478                                     }
 479                                     Py_DECREF(group_name);
 480                                     Py_DECREF(group_index);
 481                                     ++o;     /* eat the '>' */
 482                                     break;
 483                                 }
 484                                 if (!isalnum(Py_CHARMASK(*o)) && *o != '_') {
 485                                         o = backtrack;
 486                                         break;
 487                                 }
 488                                 *g++ = *o++;
 489                         }
 490                 }
 491                 else if (*o == '[' && !escaped) {
 492                         *n++ = *o;
 493                         ++o;                 /* eat the char following '[' */
 494                         *n++ = *o;
 495                         while (o < oend && *o != ']') {
 496                                 ++o;
 497                                 *n++ = *o;
 498                         }
 499                         if (o < oend)
 500                                 ++o;
 501                 }
 502                 else if (*o == '\\') {
 503                         escaped = 1;
 504                         *n++ = *o;
 505                         ++o;
 506                 }
 507                 else {
 508                         escaped = 0;
 509                         *n++ = *o;
 510                         ++o;
 511                 }
 512         }
 513
 514         if (!(v = PyString_AsString(npattern))) {
 515                 Py_DECREF(npattern);
 516                 return NULL;
 517         }
 518         /* _PyString_Resize() decrements npattern on failure */
 519         _PyString_Resize(&npattern, n - v);
 520         return npattern;
 521
 522 }
 523
 524 static PyObject *
 525 regex_symcomp(PyObject *self, PyObject *args)
 526 {
 527         PyObject *pattern;
 528         PyObject *tran = NULL;
 529         PyObject *gdict = NULL;
 530         PyObject *npattern;
 531         PyObject *retval = NULL;
 532
 533         if (!PyArg_ParseTuple(args, "S|S:symcomp", &pattern, &tran))
 534                 return NULL;
 535
 536         gdict = PyDict_New();
 537         if (gdict == NULL || (npattern = symcomp(pattern, gdict)) == NULL) {
 538                 Py_DECREF(gdict);
 539                 Py_DECREF(pattern);
 540                 return NULL;
 541         }
 542         retval = newregexobject(npattern, tran, pattern, gdict);
 543         Py_DECREF(npattern);
 544         return retval;
 545 }
 546
 547
 548 static PyObject *cache_pat;
 549 static PyObject *cache_prog;
 550
 551 static int
 552 update_cache(PyObject *pat)
 553 {
 554         PyObject *tuple = PyTuple_Pack(1, pat);
 555         int status = 0;
 556
 557         if (!tuple)
 558                 return -1;
 559
 560         if (pat != cache_pat) {
 561                 Py_XDECREF(cache_pat);
 562                 cache_pat = NULL;
 563                 Py_XDECREF(cache_prog);
 564                 cache_prog = regex_compile((PyObject *)NULL, tuple);
 565                 if (cache_prog == NULL) {
 566                         status = -1;
 567                         goto finally;
 568                 }
 569                 cache_pat = pat;
 570                 Py_INCREF(cache_pat);
 571         }
 572   finally:
 573         Py_DECREF(tuple);
 574         return status;
 575 }
 576
 577 static PyObject *
 578 regex_match(PyObject *self, PyObject *args)
 579 {
 580         PyObject *pat, *string;
 581         PyObject *tuple, *v;
 582
 583         if (!PyArg_ParseTuple(args, "SS:match", &pat, &string))
 584                 return NULL;
 585         if (update_cache(pat) < 0)
 586                 return NULL;
 587
 588         if (!(tuple = Py_BuildValue("(S)", string)))
 589                 return NULL;
 590         v = regobj_match((regexobject *)cache_prog, tuple);
 591         Py_DECREF(tuple);
 592         return v;
 593 }
 594
 595 static PyObject *
 596 regex_search(PyObject *self, PyObject *args)
 597 {
 598         PyObject *pat, *string;
 599         PyObject *tuple, *v;
 600
 601         if (!PyArg_ParseTuple(args, "SS:search", &pat, &string))
 602                 return NULL;
 603         if (update_cache(pat) < 0)
 604                 return NULL;
 605
 606         if (!(tuple = Py_BuildValue("(S)", string)))
 607                 return NULL;
 608         v = regobj_search((regexobject *)cache_prog, tuple);
 609         Py_DECREF(tuple);
 610         return v;
 611 }
 612
 613 static PyObject *
 614 regex_set_syntax(PyObject *self, PyObject *args)
 615 {
 616         int syntax;
 617         if (!PyArg_ParseTuple(args, "i:set_syntax", &syntax))
 618                 return NULL;
 619         syntax = re_set_syntax(syntax);
 620         /* wipe the global pattern cache */
 621         Py_XDECREF(cache_pat);
 622         cache_pat = NULL;
 623         Py_XDECREF(cache_prog);
 624         cache_prog = NULL;
 625         return PyInt_FromLong((long)syntax);
 626 }
 627
 628 static PyObject *
 629 regex_get_syntax(PyObject *self)
 630 {
 631         return PyInt_FromLong((long)re_syntax);
 632 }
 633
 634
 635 static struct PyMethodDef regex_global_methods[] = {
 636         {"compile",     regex_compile, METH_VARARGS},
 637         {"symcomp",     regex_symcomp, METH_VARARGS},
 638         {"match",       regex_match, METH_VARARGS},
 639         {"search",      regex_search, METH_VARARGS},
 640         {"set_syntax",  regex_set_syntax, METH_VARARGS},
 641         {"get_syntax",  (PyCFunction)regex_get_syntax, METH_NOARGS},
 642         {NULL,          NULL}                /* sentinel */
 643 };
 644
 645 PyMODINIT_FUNC
 646 initregex(void)
 647 {
 648         PyObject *m, *d, *v;
 649         int i;
 650         char *s;
 651
 652         /* Initialize object type */
 653         Regextype.ob_type = &PyType_Type;
 654
 655         m = Py_InitModule("regex", regex_global_methods);
 656         if (m == NULL)
 657                 return;
 658         d = PyModule_GetDict(m);
 659
 660         if (PyErr_Warn(PyExc_DeprecationWarning,
 661                        "the regex module is deprecated; "
 662                        "please use the re module") < 0)
 663                 return;
 664
 665         /* Initialize regex.error exception */
 666         v = RegexError = PyErr_NewException("regex.error", NULL, NULL);
 667         if (v == NULL || PyDict_SetItemString(d, "error", v) != 0)
 668                 goto finally;
 669
 670         /* Initialize regex.casefold constant */
 671         if (!(v = PyString_FromStringAndSize((char *)NULL, 256)))
 672                 goto finally;
 673
 674         if (!(s = PyString_AsString(v)))
 675                 goto finally;
 676
 677         for (i = 0; i < 256; i++) {
 678                 if (isupper(i))
 679                         s[i] = tolower(i);
 680                 else
 681                         s[i] = i;
 682         }
 683         if (PyDict_SetItemString(d, "casefold", v) < 0)
 684                 goto finally;
 685         Py_DECREF(v);
 686
 687         if (!PyErr_Occurred())
 688                 return;
 689   finally:
 690         /* Nothing */ ;
 691 }