libguile/regex-posix.c

   1 /*      Copyright (C) 1997, 1998, 1999 Free Software Foundation, Inc.
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2, or (at your option)
   6  * any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this software; see the file COPYING.  If not, write to
  15  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  16  * Boston, MA 02111-1307 USA
  17  *
  18  * As a special exception, the Free Software Foundation gives permission
  19  * for additional uses of the text contained in its release of GUILE.
  20  *
  21  * The exception is that, if you link the GUILE library with other files
  22  * to produce an executable, this does not by itself cause the
  23  * resulting executable to be covered by the GNU General Public License.
  24  * Your use of that executable is in no way restricted on account of
  25  * linking the GUILE library code into it.
  26  *
  27  * This exception does not however invalidate any other reasons why
  28  * the executable file might be covered by the GNU General Public License.
  29  *
  30  * This exception applies only to the code released by the
  31  * Free Software Foundation under the name GUILE.  If you copy
  32  * code from other Free Software Foundation releases into a copy of
  33  * GUILE, as the General Public License permits, the exception does
  34  * not apply to the code that you add in this way.  To avoid misleading
  35  * anyone as to the status of such modified files, you must delete
  36  * this exception notice from them.
  37  *
  38  * If you write modifications of your own for GUILE, it is your choice
  39  * whether to permit this exception to apply to your modifications.
  40  * If you do not wish that, delete this exception notice.
  41  */
  42
  43 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
  44    gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
  45
  46 \f
  47
  48 /* regex-posix.c -- POSIX regular expression support.
  49
  50    This code was written against Henry Spencer's famous regex package.
  51    The principal reference for POSIX behavior was the man page for this
  52    library, not the 1003.2 document itself.  Ergo, other `POSIX'
  53    libraries which do not agree with the Spencer implementation may
  54    produce varying behavior.  Sigh. */
  55
  56 #include <stdio.h>
  57 #include <sys/types.h>
  58
  59 #include "_scm.h"
  60
  61 /* Supposedly, this file is never compiled unless we know we have
  62    POSIX regular expressions.  But we still put this in an #ifdef so
  63    the file is CPP'able (for dependency scanning) even on systems that
  64    don't have a <regex.h> header.  */
  65 #ifdef HAVE_REGCOMP
  66 #ifdef HAVE_REGEX_H
  67 #include <regex.h>
  68 #else
  69 #ifdef HAVE_RXPOSIX_H
  70 #include <rxposix.h>            /* GNU Rx library */
  71 #else
  72 #ifdef HAVE_RX_RXPOSIX_H
  73 #include <rx/rxposix.h>         /* GNU Rx library on Linux */
  74 #endif
  75 #endif
  76 #endif
  77 #endif
  78
  79 #include "smob.h"
  80 #include "symbols.h"
  81 #include "vectors.h"
  82 #include "strports.h"
  83 #include "ports.h"
  84 #include "feature.h"
  85
  86 #include "scm_validate.h"
  87 #include "regex-posix.h"
  88
  89 /* This is defined by some regex libraries and omitted by others. */
  90 #ifndef REG_BASIC
  91 #define REG_BASIC 0
  92 #endif
  93
  94 long scm_tc16_regex;
  95
  96 static scm_sizet
  97 free_regex (SCM obj)
  98 {
  99   regfree (SCM_RGX (obj));
 100   free (SCM_RGX (obj));
 101   return sizeof(regex_t);
 102 }
 103
 104 \f
 105
 106 SCM_SYMBOL (scm_regexp_error_key, "regular-expression-syntax");
 107
 108 static char *
 109 scm_regexp_error_msg (int regerrno, regex_t *rx)
 110 {
 111   SCM errmsg;
 112   int l;
 113
 114   /* FIXME: must we wrap any external calls in SCM_DEFER_INTS...SCM_ALLOW_INTS?
 115      Or are these only necessary when a SCM object may be left in an
 116      undetermined state (half-formed)?  If the latter then I believe we
 117      may do without the critical section code. -twp */
 118
 119   /* We could simply make errmsg a char pointer, and allocate space with
 120      malloc.  But since we are about to pass the pointer to scm_error, which
 121      never returns, we would never have the opportunity to free it.  Creating
 122      it as a SCM object means that the system will GC it at some point. */
 123
 124   errmsg = scm_make_string (SCM_MAKINUM (80), SCM_UNDEFINED);
 125   SCM_DEFER_INTS;
 126   l = regerror (regerrno, rx, SCM_CHARS (errmsg), 80);
 127   if (l > 80)
 128     {
 129       errmsg = scm_make_string (SCM_MAKINUM (l), SCM_UNDEFINED);
 130       regerror (regerrno, rx, SCM_CHARS (errmsg), l);
 131     }
 132   SCM_ALLOW_INTS;
 133   return SCM_CHARS (errmsg);
 134 }
 135
 136 SCM_DEFINE (scm_regexp_p, "regexp?", 1, 0, 0,
 137             (SCM x),
 138             "Return @code{#t} if @var{obj} is a compiled regular expression, or\n"
 139             "@code{#f} otherwise.")
 140 #define FUNC_NAME s_scm_regexp_p
 141 {
 142   return SCM_BOOL(SCM_RGXP (x));
 143 }
 144 #undef FUNC_NAME
 145
 146 SCM_DEFINE (scm_make_regexp, "make-regexp", 1, 0, 1,
 147             (SCM pat, SCM flags),
 148             "Compile the regular expression described by @var{str}, and return the\n"
 149             "compiled regexp structure.  If @var{str} does not describe a legal\n"
 150             "regular expression, @code{make-regexp} throws a\n"
 151             "@code{regular-expression-syntax} error.\n\n"
 152             "The @var{flag} arguments change the behavior of the compiled regexp.\n"
 153             "The following flags may be supplied:\n\n"
 154             "@table @code\n"
 155             "@item regexp/icase\n"
 156             "Consider uppercase and lowercase letters to be the same when matching.\n\n"
 157             "@item regexp/newline\n"
 158             "If a newline appears in the target string, then permit the @samp{^} and\n"
 159             "@samp{$} operators to match immediately after or immediately before the\n"
 160             "newline, respectively.  Also, the @samp{.} and @samp{[^...]} operators\n"
 161             "will never match a newline character.  The intent of this flag is to\n"
 162             "treat the target string as a buffer containing many lines of text, and\n"
 163             "the regular expression as a pattern that may match a single one of those\n"
 164             "lines.\n\n"
 165             "@item regexp/basic\n"
 166             "Compile a basic (``obsolete'') regexp instead of the extended\n"
 167             "(``modern'') regexps that are the default.  Basic regexps do not\n"
 168             "consider @samp{|}, @samp{+} or @samp{?} to be special characters, and\n"
 169             "require the @samp{@{...@}} and @samp{(...)} metacharacters to be\n"
 170             "backslash-escaped (@pxref{Backslash Escapes}).  There are several other\n"
 171             "differences between basic and extended regular expressions, but these\n"
 172             "are the most significant.\n\n"
 173             "@item regexp/extended\n"
 174             "Compile an extended regular expression rather than a basic regexp.  This\n"
 175             "is the default behavior; this flag will not usually be needed.  If a\n"
 176             "call to @code{make-regexp} includes both @code{regexp/basic} and\n"
 177             "@code{regexp/extended} flags, the one which comes last will override\n"
 178             "the earlier one.\n"
 179             "@end table\n")
 180 #define FUNC_NAME s_scm_make_regexp
 181 {
 182   SCM flag;
 183   regex_t *rx;
 184   int status, cflags;
 185
 186   SCM_VALIDATE_ROSTRING (1,pat);
 187   SCM_COERCE_SUBSTR (pat);
 188
 189   /* Examine list of regexp flags.  If REG_BASIC is supplied, then
 190      turn off REG_EXTENDED flag (on by default). */
 191   cflags = REG_EXTENDED;
 192   flag = flags;
 193   while (SCM_NNULLP (flag))
 194     {
 195       if (SCM_INUM (SCM_CAR (flag)) == REG_BASIC)
 196         cflags &= ~REG_EXTENDED;
 197       else
 198         cflags |= SCM_INUM (SCM_CAR (flag));
 199       flag = SCM_CDR (flag);
 200     }
 201
 202   rx = SCM_MUST_MALLOC_TYPE(regex_t);
 203   status = regcomp (rx, SCM_ROCHARS (pat),
 204                     /* Make sure they're not passing REG_NOSUB;
 205                        regexp-exec assumes we're getting match data.  */
 206                     cflags & ~REG_NOSUB);
 207   if (status != 0)
 208     {
 209       scm_error (scm_regexp_error_key,
 210                  FUNC_NAME,
 211                  scm_regexp_error_msg (status, rx),
 212                  SCM_BOOL_F,
 213                  SCM_BOOL_F);
 214       /* never returns */
 215     }
 216   SCM_RETURN_NEWSMOB (scm_tc16_regex, rx);
 217 }
 218 #undef FUNC_NAME
 219
 220 SCM_DEFINE (scm_regexp_exec, "regexp-exec", 2, 2, 0,
 221             (SCM rx, SCM str, SCM start, SCM flags),
 222             "Match the compiled regular expression @var{regexp} against @code{str}.\n"
 223             "If the optional integer @var{start} argument is provided, begin matching\n"
 224             "from that position in the string.  Return a match structure describing\n"
 225             "the results of the match, or @code{#f} if no match could be found.")
 226 #define FUNC_NAME s_scm_regexp_exec
 227 {
 228   int status, nmatches, offset;
 229   regmatch_t *matches;
 230   SCM mvec = SCM_BOOL_F;
 231
 232   SCM_VALIDATE_RGXP (1,rx);
 233   SCM_VALIDATE_ROSTRING (2,str);
 234   SCM_VALIDATE_INUM_DEF_COPY (3,start,0,offset);
 235   SCM_ASSERT_RANGE (3,start,offset >= 0 && (unsigned) offset <= SCM_LENGTH (str));
 236   if (SCM_UNBNDP (flags))
 237     flags = SCM_INUM0;
 238   SCM_VALIDATE_INUM (4,flags);
 239   SCM_COERCE_SUBSTR (str);
 240
 241   /* re_nsub doesn't account for the `subexpression' representing the
 242      whole regexp, so add 1 to nmatches. */
 243
 244   nmatches = SCM_RGX(rx)->re_nsub + 1;
 245   SCM_DEFER_INTS;
 246   matches = SCM_MUST_MALLOC_TYPE_NUM (regmatch_t,nmatches);
 247   status = regexec (SCM_RGX (rx), SCM_ROCHARS (str) + offset,
 248                     nmatches, matches,
 249                     SCM_INUM (flags));
 250   if (!status)
 251     {
 252       int i;
 253       /* The match vector must include a cell for the string that was matched,
 254          so add 1. */
 255       mvec = scm_make_vector (SCM_MAKINUM (nmatches + 1), SCM_UNSPECIFIED);
 256       SCM_VELTS(mvec)[0] = str;
 257       for (i = 0; i < nmatches; ++i)
 258         if (matches[i].rm_so == -1)
 259           SCM_VELTS(mvec)[i+1] = scm_cons (SCM_MAKINUM (-1), SCM_MAKINUM (-1));
 260         else
 261           SCM_VELTS(mvec)[i+1]
 262             = scm_cons(SCM_MAKINUM(matches[i].rm_so + offset),
 263                        SCM_MAKINUM(matches[i].rm_eo + offset));
 264     }
 265   scm_must_free ((char *) matches);
 266   SCM_ALLOW_INTS;
 267
 268   if (status != 0 && status != REG_NOMATCH)
 269     scm_error (scm_regexp_error_key,
 270                FUNC_NAME,
 271                scm_regexp_error_msg (status, SCM_RGX (rx)),
 272                SCM_BOOL_F,
 273                SCM_BOOL_F);
 274   return mvec;
 275 }
 276 #undef FUNC_NAME
 277
 278 void
 279 scm_init_regex_posix ()
 280 {
 281   scm_tc16_regex = scm_make_smob_type_mfpe ("regexp", sizeof (regex_t),
 282                                             NULL, free_regex, NULL, NULL);
 283
 284   /* Compilation flags.  */
 285   scm_sysintern ("regexp/basic", scm_long2num (REG_BASIC));
 286   scm_sysintern ("regexp/extended", scm_long2num (REG_EXTENDED));
 287   scm_sysintern ("regexp/icase", scm_long2num (REG_ICASE));
 288   scm_sysintern ("regexp/newline", scm_long2num (REG_NEWLINE));
 289
 290   /* Execution flags.  */
 291   scm_sysintern ("regexp/notbol", scm_long2num (REG_NOTBOL));
 292   scm_sysintern ("regexp/noteol", scm_long2num (REG_NOTEOL));
 293
 294 #include "regex-posix.x"
 295
 296   scm_add_feature ("regex");
 297 }