lib/trim.c

   1 /* Removes leading and/or trailing whitespaces
   2    Copyright (C) 2006-2024 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program 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
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Davide Angelocola <davide.angelocola@gmail.com> */
  18
  19 #include <config.h>
  20
  21 /* Specification.  */
  22 #include "trim.h"
  23
  24 #include <ctype.h>
  25 #include <string.h>
  26 #include <stddef.h>
  27 #include <stdlib.h>
  28
  29 #if GNULIB_MCEL_PREFER
  30 # include "mcel.h"
  31 #else
  32 # include "mbchar.h"
  33 # include "mbuiterf.h"
  34 #endif
  35 #include "xalloc.h"
  36
  37 char *
  38 trim2 (const char *s, int how)
  39 {
  40   const char *start = s;
  41   const char *end;
  42
  43   if (MB_CUR_MAX > 1)
  44     {
  45 #if GNULIB_MCEL_PREFER
  46       /* Skip leading whitespace. */
  47       if (how != TRIM_TRAILING)
  48         for (mcel_t g; *start; start += g.len)
  49           {
  50             g = mcel_scanz (start);
  51             if (!c32isspace (g.ch))
  52               break;
  53           }
  54
  55       /* Find start of any trailing whitespace.  */
  56       if (how != TRIM_LEADING)
  57         for (const char *p = end = start; *p; )
  58           {
  59             mcel_t g = mcel_scanz (p);
  60             p += g.len;
  61             if (!c32isspace (g.ch))
  62               end = p;
  63           }
  64 #else
  65       mbuif_state_t state;
  66       mbuif_init (state);
  67
  68       /* Skip leading whitespace. */
  69       if (how != TRIM_TRAILING)
  70         while (mbuif_avail (state, start))
  71           {
  72             mbchar_t cur = mbuif_next (state, start);
  73             if (!mb_isspace (cur))
  74               break;
  75             start += mb_len (cur);
  76           }
  77
  78       /* Find start of any trailing whitespace.  */
  79       if (how != TRIM_LEADING)
  80         for (const char *p = end = start; mbuif_avail (state, p); )
  81           {
  82             mbchar_t cur = mbuif_next (state, p);
  83             p += mb_len (cur);
  84             if (!mb_isspace (cur))
  85               end = p;
  86           }
  87 #endif
  88     }
  89   else
  90     {
  91       /* Skip leading whitespace. */
  92       if (how != TRIM_TRAILING)
  93         while (isspace ((unsigned char) *start))
  94           start++;
  95
  96       /* Find start of any trailing whitespace.  */
  97       if (how != TRIM_LEADING)
  98         for (const char *p = end = start; *p; )
  99           if (!isspace ((unsigned char) *p++))
 100             end = p;
 101     }
 102
 103   /* Create trimmed copy.  */
 104   size_t dlen = how == TRIM_LEADING ? strlen (start) : end - start;
 105   char *d = malloc (dlen + 1);
 106   if (!d)
 107     xalloc_die ();
 108   char *d_end = mempcpy (d, start, dlen);
 109   *d_end = '\0';
 110
 111   return d;
 112 }