libguile/rdelim.c

   1 /* Copyright (C) 1995,1996,1997,1998,1999,2000,2001, 2006 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public License
   5  * as published by the Free Software Foundation; either version 3 of
   6  * the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301 USA
  17  */
  18
  19 #ifdef HAVE_CONFIG_H
  20 #  include <config.h>
  21 #endif
  22
  23 #include "libguile/_scm.h"
  24
  25 #include <stdio.h>
  26
  27 #ifdef HAVE_STRING_H
  28 #include <string.h>
  29 #endif
  30
  31 #include "libguile/chars.h"
  32 #include "libguile/modules.h"
  33 #include "libguile/ports.h"
  34 #include "libguile/rdelim.h"
  35 #include "libguile/root.h"
  36 #include "libguile/strings.h"
  37 #include "libguile/strports.h"
  38 #include "libguile/validate.h"
  39
  40 SCM_DEFINE (scm_read_delimited_x, "%read-delimited!", 3, 3, 0,
  41             (SCM delims, SCM str, SCM gobble, SCM port, SCM start, SCM end),
  42             "Read characters from @var{port} into @var{str} until one of the\n"
  43             "characters in the @var{delims} string is encountered.  If\n"
  44             "@var{gobble} is true, discard the delimiter character;\n"
  45             "otherwise, leave it in the input stream for the next read.  If\n"
  46             "@var{port} is not specified, use the value of\n"
  47             "@code{(current-input-port)}.  If @var{start} or @var{end} are\n"
  48             "specified, store data only into the substring of @var{str}\n"
  49             "bounded by @var{start} and @var{end} (which default to the\n"
  50             "beginning and end of the string, respectively).\n"
  51             "\n"
  52             " Return a pair consisting of the delimiter that terminated the\n"
  53             "string and the number of characters read.  If reading stopped\n"
  54             "at the end of file, the delimiter returned is the\n"
  55             "@var{eof-object}; if the string was filled without encountering\n"
  56             "a delimiter, this value is @code{#f}.")
  57 #define FUNC_NAME s_scm_read_delimited_x
  58 {
  59   size_t j;
  60   size_t cstart;
  61   size_t cend;
  62   scm_t_wchar c;
  63   size_t num_delims;
  64
  65   SCM_VALIDATE_STRING (1, delims);
  66   num_delims = scm_i_string_length (delims);
  67
  68   SCM_VALIDATE_STRING (2, str);
  69   scm_i_get_substring_spec (scm_i_string_length (str),
  70                             start, &cstart, end, &cend);
  71
  72   if (SCM_UNBNDP (port))
  73     port = scm_current_input_port ();
  74   else
  75     SCM_VALIDATE_OPINPORT (4, port);
  76
  77   for (j = cstart; j < cend; j++)
  78     {
  79       size_t k;
  80
  81       c = scm_getc (port);
  82       for (k = 0; k < num_delims; k++)
  83         {
  84           if (scm_i_string_ref (delims, k) == c)
  85             {
  86               if (scm_is_false (gobble))
  87                 scm_ungetc (c, port);
  88
  89               return scm_cons (SCM_MAKE_CHAR (c),
  90                                scm_from_size_t (j - cstart));
  91             }
  92         }
  93       if (c == EOF)
  94         return scm_cons (SCM_EOF_VAL,
  95                          scm_from_size_t (j - cstart));
  96
  97       scm_c_string_set_x (str, j, SCM_MAKE_CHAR (c));
  98     }
  99   return scm_cons (SCM_BOOL_F, scm_from_size_t (j - cstart));
 100 }
 101 #undef FUNC_NAME
 102
 103 static unsigned char *
 104 scm_do_read_line (SCM port, size_t *len_p)
 105 {
 106   scm_t_port *pt = SCM_PTAB_ENTRY (port);
 107   unsigned char *end;
 108
 109   /* I thought reading lines was simple.  Mercy me.  */
 110
 111   /* The common case: the buffer contains a complete line.
 112      This needs to be fast.  */
 113   if ((end = memchr (pt->read_pos, '\n', (pt->read_end - pt->read_pos)))
 114            != 0)
 115     {
 116       size_t buf_len = (end + 1) - pt->read_pos;
 117       /* Allocate a buffer of the perfect size.  */
 118       unsigned char *buf = scm_malloc (buf_len + 1);
 119
 120       memcpy (buf, pt->read_pos, buf_len);
 121       pt->read_pos += buf_len;
 122
 123       buf[buf_len] = '\0';
 124
 125       *len_p = buf_len;
 126       return buf;
 127     }
 128
 129   /* The buffer contains no newlines.  */
 130   {
 131     /* When live, len is always the number of characters in the
 132        current buffer that are part of the current line.  */
 133     size_t len = (pt->read_end - pt->read_pos);
 134     size_t buf_size = (len < 50) ? 60 : len * 2;
 135     /* Invariant: buf always has buf_size + 1 characters allocated;
 136        the `+ 1' is for the final '\0'.  */
 137     unsigned char *buf = scm_malloc (buf_size + 1);
 138     size_t buf_len = 0;
 139
 140     for (;;)
 141       {
 142         if (buf_len + len > buf_size)
 143           {
 144             size_t new_size = (buf_len + len) * 2;
 145             buf = scm_realloc (buf, new_size + 1);
 146             buf_size = new_size;
 147           }
 148
 149         /* Copy what we've got out of the port, into our buffer.  */
 150         memcpy (buf + buf_len, pt->read_pos, len);
 151         buf_len += len;
 152         pt->read_pos += len;
 153
 154         /* If we had seen a newline, we're done now.  */
 155         if (end)
 156           break;
 157
 158         /* Get more characters.  */
 159         if (scm_fill_input (port) == EOF)
 160           {
 161             /* If we're missing a final newline in the file, return
 162                what we did get, sans newline.  */
 163             if (buf_len > 0)
 164               break;
 165
 166             free (buf);
 167             return 0;
 168           }
 169
 170         /* Search the buffer for newlines.  */
 171         if ((end = memchr (pt->read_pos, '\n',
 172                            (len = (pt->read_end - pt->read_pos))))
 173             != 0)
 174           len = (end - pt->read_pos) + 1;
 175       }
 176
 177     /* I wonder how expensive this realloc is.  */
 178     buf = scm_realloc (buf, buf_len + 1);
 179     buf[buf_len] = '\0';
 180     *len_p = buf_len;
 181     return buf;
 182   }
 183 }
 184
 185
 186 /*
 187  * %read-line
 188  * truncates any terminating newline from its input, and returns
 189  * a cons of the string read and its terminating character.  Doing
 190  * so makes it easy to implement the hairy `read-line' options
 191  * efficiently in Scheme.
 192  */
 193
 194 SCM_DEFINE (scm_read_line, "%read-line", 0, 1, 0,
 195             (SCM port),
 196             "Read a newline-terminated line from @var{port}, allocating storage as\n"
 197             "necessary.  The newline terminator (if any) is removed from the string,\n"
 198             "and a pair consisting of the line and its delimiter is returned.  The\n"
 199             "delimiter may be either a newline or the @var{eof-object}; if\n"
 200             "@code{%read-line} is called at the end of file, it returns the pair\n"
 201             "@code{(#<eof> . #<eof>)}.")
 202 #define FUNC_NAME s_scm_read_line
 203 {
 204   scm_t_port *pt;
 205   char *s;
 206   size_t slen = 0;
 207   SCM line, term;
 208
 209   if (SCM_UNBNDP (port))
 210     port = scm_current_input_port ();
 211   SCM_VALIDATE_OPINPORT (1,port);
 212
 213   pt = SCM_PTAB_ENTRY (port);
 214   if (pt->rw_active == SCM_PORT_WRITE)
 215     scm_ptobs[SCM_PTOBNUM (port)].flush (port);
 216
 217   s = (char *) scm_do_read_line (port, &slen);
 218
 219   if (s == NULL)
 220     term = line = SCM_EOF_VAL;
 221   else
 222     {
 223       if (s[slen-1] == '\n')
 224         {
 225           term = SCM_MAKE_CHAR ('\n');
 226           s[slen-1] = '\0';
 227           line = scm_take_locale_stringn (s, slen-1);
 228           SCM_INCLINE (port);
 229         }
 230       else
 231         {
 232           /* Fix: we should check for eof on the port before assuming this. */
 233           term = SCM_EOF_VAL;
 234           line = scm_take_locale_stringn (s, slen);
 235           SCM_COL (port) += slen;
 236         }
 237     }
 238
 239   if (pt->rw_random)
 240     pt->rw_active = SCM_PORT_READ;
 241
 242   return scm_cons (line, term);
 243 }
 244 #undef FUNC_NAME
 245
 246 SCM_DEFINE (scm_write_line, "write-line", 1, 1, 0,
 247             (SCM obj, SCM port),
 248             "Display @var{obj} and a newline character to @var{port}.  If\n"
 249             "@var{port} is not specified, @code{(current-output-port)} is\n"
 250             "used.  This function is equivalent to:\n"
 251             "@lisp\n"
 252             "(display obj [port])\n"
 253             "(newline [port])\n"
 254             "@end lisp")
 255 #define FUNC_NAME s_scm_write_line
 256 {
 257   scm_display (obj, port);
 258   return scm_newline (port);
 259 }
 260 #undef FUNC_NAME
 261
 262 SCM
 263 scm_init_rdelim_builtins (void)
 264 {
 265 #include "libguile/rdelim.x"
 266
 267   return SCM_UNSPECIFIED;
 268 }
 269
 270 void
 271 scm_init_rdelim (void)
 272 {
 273   scm_c_define_gsubr ("%init-rdelim-builtins", 0, 0, 0,
 274                       scm_init_rdelim_builtins);
 275 }
 276
 277 /*
 278   Local Variables:
 279   c-file-style: "gnu"
 280   End:
 281 */