glib/gpattern.c

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997, 1999  Peter Mattis, Red Hat, Inc.
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include "config.h"
  19
  20 #include <string.h>
  21
  22 #include "gpattern.h"
  23
  24 #include "gmacros.h"
  25 #include "gmessages.h"
  26 #include "gmem.h"
  27 #include "gunicode.h"
  28 #include "gutils.h"
  29
  30 /**
  31  * SECTION:patterns
  32  * @title: Glob-style pattern matching
  33  * @short_description: matches strings against patterns containing '*'
  34  *                     (wildcard) and '?' (joker)
  35  *
  36  * The g_pattern_match* functions match a string
  37  * against a pattern containing '*' and '?' wildcards with similar
  38  * semantics as the standard glob() function: '*' matches an arbitrary,
  39  * possibly empty, string, '?' matches an arbitrary character.
  40  *
  41  * Note that in contrast to glob(), the '/' character can be matched by
  42  * the wildcards, there are no '[...]' character ranges and '*' and '?'
  43  * can not be escaped to include them literally in a pattern.
  44  *
  45  * When multiple strings must be matched against the same pattern, it
  46  * is better to compile the pattern to a #GPatternSpec using
  47  * g_pattern_spec_new() and use g_pattern_match_string() instead of
  48  * g_pattern_match_simple(). This avoids the overhead of repeated
  49  * pattern compilation.
  50  **/
  51
  52 /**
  53  * GPatternSpec:
  54  *
  55  * A GPatternSpec struct is the 'compiled' form of a pattern. This
  56  * structure is opaque and its fields cannot be accessed directly.
  57  */
  58
  59 /* keep enum and structure of gpattern.c and patterntest.c in sync */
  60 typedef enum
  61 {
  62   G_MATCH_ALL,       /* "*A?A*" */
  63   G_MATCH_ALL_TAIL,  /* "*A?AA" */
  64   G_MATCH_HEAD,      /* "AAAA*" */
  65   G_MATCH_TAIL,      /* "*AAAA" */
  66   G_MATCH_EXACT,     /* "AAAAA" */
  67   G_MATCH_LAST
  68 } GMatchType;
  69
  70 struct _GPatternSpec
  71 {
  72   GMatchType match_type;
  73   guint      pattern_length;
  74   guint      min_length;
  75   guint      max_length;
  76   gchar     *pattern;
  77 };
  78
  79
  80 /* --- functions --- */
  81 static inline gboolean
  82 g_pattern_ph_match (const gchar *match_pattern,
  83                     const gchar *match_string,
  84                     gboolean    *wildcard_reached_p)
  85 {
  86   const gchar *pattern, *string;
  87   gchar ch;
  88
  89   pattern = match_pattern;
  90   string = match_string;
  91
  92   ch = *pattern;
  93   pattern++;
  94   while (ch)
  95     {
  96       switch (ch)
  97         {
  98         case '?':
  99           if (!*string)
 100             return FALSE;
 101           string = g_utf8_next_char (string);
 102           break;
 103
 104         case '*':
 105           *wildcard_reached_p = TRUE;
 106           do
 107             {
 108               ch = *pattern;
 109               pattern++;
 110               if (ch == '?')
 111                 {
 112                   if (!*string)
 113                     return FALSE;
 114                   string = g_utf8_next_char (string);
 115                 }
 116             }
 117           while (ch == '*' || ch == '?');
 118           if (!ch)
 119             return TRUE;
 120           do
 121             {
 122               gboolean next_wildcard_reached = FALSE;
 123               while (ch != *string)
 124                 {
 125                   if (!*string)
 126                     return FALSE;
 127                   string = g_utf8_next_char (string);
 128                 }
 129               string++;
 130               if (g_pattern_ph_match (pattern, string, &next_wildcard_reached))
 131                 return TRUE;
 132               if (next_wildcard_reached)
 133                 /* the forthcoming pattern substring up to the next wildcard has
 134                  * been matched, but a mismatch occoured for the rest of the
 135                  * pattern, following the next wildcard.
 136                  * there's no need to advance the current match position any
 137                  * further if the rest pattern will not match.
 138                  */
 139                 return FALSE;
 140             }
 141           while (*string);
 142           break;
 143
 144         default:
 145           if (ch == *string)
 146             string++;
 147           else
 148             return FALSE;
 149           break;
 150         }
 151
 152       ch = *pattern;
 153       pattern++;
 154     }
 155
 156   return *string == 0;
 157 }
 158
 159 /**
 160  * g_pattern_match:
 161  * @pspec: a #GPatternSpec
 162  * @string_length: the length of @string (in bytes, i.e. strlen(),
 163  *     not g_utf8_strlen())
 164  * @string: the UTF-8 encoded string to match
 165  * @string_reversed: (allow-none): the reverse of @string or %NULL
 166  *
 167  * Matches a string against a compiled pattern. Passing the correct
 168  * length of the string given is mandatory. The reversed string can be
 169  * omitted by passing %NULL, this is more efficient if the reversed
 170  * version of the string to be matched is not at hand, as
 171  * g_pattern_match() will only construct it if the compiled pattern
 172  * requires reverse matches.
 173  *
 174  * Note that, if the user code will (possibly) match a string against a
 175  * multitude of patterns containing wildcards, chances are high that
 176  * some patterns will require a reversed string. In this case, it's
 177  * more efficient to provide the reversed string to avoid multiple
 178  * constructions thereof in the various calls to g_pattern_match().
 179  *
 180  * Note also that the reverse of a UTF-8 encoded string can in general
 181  * not be obtained by g_strreverse(). This works only if the string
 182  * does not contain any multibyte characters. GLib offers the
 183  * g_utf8_strreverse() function to reverse UTF-8 encoded strings.
 184  *
 185  * Returns: %TRUE if @string matches @pspec
 186  **/
 187 gboolean
 188 g_pattern_match (GPatternSpec *pspec,
 189                  guint         string_length,
 190                  const gchar  *string,
 191                  const gchar  *string_reversed)
 192 {
 193   g_return_val_if_fail (pspec != NULL, FALSE);
 194   g_return_val_if_fail (string != NULL, FALSE);
 195
 196   if (string_length < pspec->min_length ||
 197       string_length > pspec->max_length)
 198     return FALSE;
 199
 200   switch (pspec->match_type)
 201     {
 202       gboolean dummy;
 203     case G_MATCH_ALL:
 204       return g_pattern_ph_match (pspec->pattern, string, &dummy);
 205     case G_MATCH_ALL_TAIL:
 206       if (string_reversed)
 207         return g_pattern_ph_match (pspec->pattern, string_reversed, &dummy);
 208       else
 209         {
 210           gboolean result;
 211           gchar *tmp;
 212           tmp = g_utf8_strreverse (string, string_length);
 213           result = g_pattern_ph_match (pspec->pattern, tmp, &dummy);
 214           g_free (tmp);
 215           return result;
 216         }
 217     case G_MATCH_HEAD:
 218       if (pspec->pattern_length == string_length)
 219         return strcmp (pspec->pattern, string) == 0;
 220       else if (pspec->pattern_length)
 221         return strncmp (pspec->pattern, string, pspec->pattern_length) == 0;
 222       else
 223         return TRUE;
 224     case G_MATCH_TAIL:
 225       if (pspec->pattern_length)
 226         return strcmp (pspec->pattern, string + (string_length - pspec->pattern_length)) == 0;
 227       else
 228         return TRUE;
 229     case G_MATCH_EXACT:
 230       if (pspec->pattern_length != string_length)
 231         return FALSE;
 232       else
 233         return strcmp (pspec->pattern, string) == 0;
 234     default:
 235       g_return_val_if_fail (pspec->match_type < G_MATCH_LAST, FALSE);
 236       return FALSE;
 237     }
 238 }
 239
 240 /**
 241  * g_pattern_spec_new:
 242  * @pattern: a zero-terminated UTF-8 encoded string
 243  *
 244  * Compiles a pattern to a #GPatternSpec.
 245  *
 246  * Returns: a newly-allocated #GPatternSpec
 247  **/
 248 GPatternSpec*
 249 g_pattern_spec_new (const gchar *pattern)
 250 {
 251   GPatternSpec *pspec;
 252   gboolean seen_joker = FALSE, seen_wildcard = FALSE, more_wildcards = FALSE;
 253   gint hw_pos = -1, tw_pos = -1, hj_pos = -1, tj_pos = -1;
 254   gboolean follows_wildcard = FALSE;
 255   guint pending_jokers = 0;
 256   const gchar *s;
 257   gchar *d;
 258   guint i;
 259
 260   g_return_val_if_fail (pattern != NULL, NULL);
 261
 262   /* canonicalize pattern and collect necessary stats */
 263   pspec = g_new (GPatternSpec, 1);
 264   pspec->pattern_length = strlen (pattern);
 265   pspec->min_length = 0;
 266   pspec->max_length = 0;
 267   pspec->pattern = g_new (gchar, pspec->pattern_length + 1);
 268   d = pspec->pattern;
 269   for (i = 0, s = pattern; *s != 0; s++)
 270     {
 271       switch (*s)
 272         {
 273         case '*':
 274           if (follows_wildcard) /* compress multiple wildcards */
 275             {
 276               pspec->pattern_length--;
 277               continue;
 278             }
 279           follows_wildcard = TRUE;
 280           if (hw_pos < 0)
 281             hw_pos = i;
 282           tw_pos = i;
 283           break;
 284         case '?':
 285           pending_jokers++;
 286           pspec->min_length++;
 287           pspec->max_length += 4; /* maximum UTF-8 character length */
 288           continue;
 289         default:
 290           for (; pending_jokers; pending_jokers--, i++) {
 291             *d++ = '?';
 292             if (hj_pos < 0)
 293              hj_pos = i;
 294             tj_pos = i;
 295           }
 296           follows_wildcard = FALSE;
 297           pspec->min_length++;
 298           pspec->max_length++;
 299           break;
 300         }
 301       *d++ = *s;
 302       i++;
 303     }
 304   for (; pending_jokers; pending_jokers--) {
 305     *d++ = '?';
 306     if (hj_pos < 0)
 307       hj_pos = i;
 308     tj_pos = i;
 309   }
 310   *d++ = 0;
 311   seen_joker = hj_pos >= 0;
 312   seen_wildcard = hw_pos >= 0;
 313   more_wildcards = seen_wildcard && hw_pos != tw_pos;
 314   if (seen_wildcard)
 315     pspec->max_length = G_MAXUINT;
 316
 317   /* special case sole head/tail wildcard or exact matches */
 318   if (!seen_joker && !more_wildcards)
 319     {
 320       if (pspec->pattern[0] == '*')
 321         {
 322           pspec->match_type = G_MATCH_TAIL;
 323           memmove (pspec->pattern, pspec->pattern + 1, --pspec->pattern_length);
 324           pspec->pattern[pspec->pattern_length] = 0;
 325           return pspec;
 326         }
 327       if (pspec->pattern_length > 0 &&
 328           pspec->pattern[pspec->pattern_length - 1] == '*')
 329         {
 330           pspec->match_type = G_MATCH_HEAD;
 331           pspec->pattern[--pspec->pattern_length] = 0;
 332           return pspec;
 333         }
 334       if (!seen_wildcard)
 335         {
 336           pspec->match_type = G_MATCH_EXACT;
 337           return pspec;
 338         }
 339     }
 340
 341   /* now just need to distinguish between head or tail match start */
 342   tw_pos = pspec->pattern_length - 1 - tw_pos;  /* last pos to tail distance */
 343   tj_pos = pspec->pattern_length - 1 - tj_pos;  /* last pos to tail distance */
 344   if (seen_wildcard)
 345     pspec->match_type = tw_pos > hw_pos ? G_MATCH_ALL_TAIL : G_MATCH_ALL;
 346   else /* seen_joker */
 347     pspec->match_type = tj_pos > hj_pos ? G_MATCH_ALL_TAIL : G_MATCH_ALL;
 348   if (pspec->match_type == G_MATCH_ALL_TAIL) {
 349     gchar *tmp = pspec->pattern;
 350     pspec->pattern = g_utf8_strreverse (pspec->pattern, pspec->pattern_length);
 351     g_free (tmp);
 352   }
 353   return pspec;
 354 }
 355
 356 /**
 357  * g_pattern_spec_free:
 358  * @pspec: a #GPatternSpec
 359  *
 360  * Frees the memory allocated for the #GPatternSpec.
 361  **/
 362 void
 363 g_pattern_spec_free (GPatternSpec *pspec)
 364 {
 365   g_return_if_fail (pspec != NULL);
 366
 367   g_free (pspec->pattern);
 368   g_free (pspec);
 369 }
 370
 371 /**
 372  * g_pattern_spec_equal:
 373  * @pspec1: a #GPatternSpec
 374  * @pspec2: another #GPatternSpec
 375  *
 376  * Compares two compiled pattern specs and returns whether they will
 377  * match the same set of strings.
 378  *
 379  * Returns: Whether the compiled patterns are equal
 380  **/
 381 gboolean
 382 g_pattern_spec_equal (GPatternSpec *pspec1,
 383                       GPatternSpec *pspec2)
 384 {
 385   g_return_val_if_fail (pspec1 != NULL, FALSE);
 386   g_return_val_if_fail (pspec2 != NULL, FALSE);
 387
 388   return (pspec1->pattern_length == pspec2->pattern_length &&
 389           pspec1->match_type == pspec2->match_type &&
 390           strcmp (pspec1->pattern, pspec2->pattern) == 0);
 391 }
 392
 393 /**
 394  * g_pattern_match_string:
 395  * @pspec: a #GPatternSpec
 396  * @string: the UTF-8 encoded string to match
 397  *
 398  * Matches a string against a compiled pattern. If the string is to be
 399  * matched against more than one pattern, consider using
 400  * g_pattern_match() instead while supplying the reversed string.
 401  *
 402  * Returns: %TRUE if @string matches @pspec
 403  **/
 404 gboolean
 405 g_pattern_match_string (GPatternSpec *pspec,
 406                         const gchar  *string)
 407 {
 408   g_return_val_if_fail (pspec != NULL, FALSE);
 409   g_return_val_if_fail (string != NULL, FALSE);
 410
 411   return g_pattern_match (pspec, strlen (string), string, NULL);
 412 }
 413
 414 /**
 415  * g_pattern_match_simple:
 416  * @pattern: the UTF-8 encoded pattern
 417  * @string: the UTF-8 encoded string to match
 418  *
 419  * Matches a string against a pattern given as a string. If this
 420  * function is to be called in a loop, it's more efficient to compile
 421  * the pattern once with g_pattern_spec_new() and call
 422  * g_pattern_match_string() repeatedly.
 423  *
 424  * Returns: %TRUE if @string matches @pspec
 425  **/
 426 gboolean
 427 g_pattern_match_simple (const gchar *pattern,
 428                         const gchar *string)
 429 {
 430   GPatternSpec *pspec;
 431   gboolean ergo;
 432
 433   g_return_val_if_fail (pattern != NULL, FALSE);
 434   g_return_val_if_fail (string != NULL, FALSE);
 435
 436   pspec = g_pattern_spec_new (pattern);
 437   ergo = g_pattern_match (pspec, strlen (string), string, NULL);
 438   g_pattern_spec_free (pspec);
 439
 440   return ergo;
 441 }