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
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library 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 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 02110-1301 USA
  16  */
  17
  18 #ifdef HAVE_CONFIG_H
  19 #  include <config.h>
  20 #endif
  21
  22 #include "libguile/_scm.h"
  23
  24 #include <stdio.h>
  25
  26 #ifdef HAVE_STRING_H
  27 #include <string.h>
  28 #endif
  29
  30 #include "libguile/chars.h"
  31 #include "libguile/modules.h"
  32 #include "libguile/ports.h"
  33 #include "libguile/rdelim.h"
  34 #include "libguile/root.h"
  35 #include "libguile/strings.h"
  36 #include "libguile/strports.h"
  37 #include "libguile/validate.h"
  38
  39 SCM_DEFINE (scm_read_delimited_x, "%read-delimited!", 3, 3, 0,
  40             (SCM delims, SCM str, SCM gobble, SCM port, SCM start, SCM end),
  41             "Read characters from @var{port} into @var{str} until one of the\n"
  42             "characters in the @var{delims} string is encountered.  If\n"
  43             "@var{gobble} is true, discard the delimiter character;\n"
  44             "otherwise, leave it in the input stream for the next read.  If\n"
  45             "@var{port} is not specified, use the value of\n"
  46             "@code{(current-input-port)}.  If @var{start} or @var{end} are\n"
  47             "specified, store data only into the substring of @var{str}\n"
  48             "bounded by @var{start} and @var{end} (which default to the\n"
  49             "beginning and end of the string, respectively).\n"
  50             "\n"
  51             " Return a pair consisting of the delimiter that terminated the\n"
  52             "string and the number of characters read.  If reading stopped\n"
  53             "at the end of file, the delimiter returned is the\n"
  54             "@var{eof-object}; if the string was filled without encountering\n"
  55             "a delimiter, this value is @code{#f}.")
  56 #define FUNC_NAME s_scm_read_delimited_x
  57 {
  58   size_t j;
  59   size_t cstart;
  60   size_t cend;
  61   int c;
  62   const char *cdelims;
  63   size_t num_delims;
  64
  65   SCM_VALIDATE_STRING (1, delims);
  66   cdelims = scm_i_string_chars (delims);
  67   num_delims = scm_i_string_length (delims);
  68
  69   SCM_VALIDATE_STRING (2, str);
  70   scm_i_get_substring_spec (scm_i_string_length (str),
  71                             start, &cstart, end, &cend);
  72
  73   if (SCM_UNBNDP (port))
  74     port = scm_current_input_port ();
  75   else
  76     SCM_VALIDATE_OPINPORT (4, port);
  77
  78   for (j = cstart; j < cend; j++)
  79     {
  80       size_t k;
  81
  82       c = scm_getc (port);
  83       for (k = 0; k < num_delims; k++)
  84         {
  85           if (cdelims[k] == c)
  86             {
  87               if (scm_is_false (gobble))
  88                 scm_ungetc (c, port);
  89
  90               return scm_cons (SCM_MAKE_CHAR (c),
  91                                scm_from_size_t (j - cstart));
  92             }
  93         }
  94       if (c == EOF)
  95         return scm_cons (SCM_EOF_VAL,
  96                          scm_from_size_t (j - cstart));
  97
  98       scm_c_string_set_x (str, j, SCM_MAKE_CHAR (c));
  99     }
 100   return scm_cons (SCM_BOOL_F, scm_from_size_t (j - cstart));
 101 }
 102 #undef FUNC_NAME
 103
 104 static unsigned char *
 105 scm_do_read_line (SCM port, size_t *len_p)
 106 {
 107   scm_t_port *pt = SCM_PTAB_ENTRY (port);
 108   unsigned char *end;
 109
 110   /* I thought reading lines was simple.  Mercy me.  */
 111
 112   /* The common case: the buffer contains a complete line.
 113      This needs to be fast.  */
 114   if ((end = memchr (pt->read_pos, '\n', (pt->read_end - pt->read_pos)))
 115            != 0)
 116     {
 117       size_t buf_len = (end + 1) - pt->read_pos;
 118       /* Allocate a buffer of the perfect size.  */
 119       unsigned char *buf = scm_malloc (buf_len + 1);
 120
 121       memcpy (buf, pt->read_pos, buf_len);
 122       pt->read_pos += buf_len;
 123
 124       buf[buf_len] = '\0';
 125
 126       *len_p = buf_len;
 127       return buf;
 128     }
 129
 130   /* The buffer contains no newlines.  */
 131   {
 132     /* When live, len is always the number of characters in the
 133        current buffer that are part of the current line.  */
 134     size_t len = (pt->read_end - pt->read_pos);
 135     size_t buf_size = (len < 50) ? 60 : len * 2;
 136     /* Invariant: buf always has buf_size + 1 characters allocated;
 137        the `+ 1' is for the final '\0'.  */
 138     unsigned char *buf = scm_malloc (buf_size + 1);
 139     size_t buf_len = 0;
 140
 141     for (;;)
 142       {
 143         if (buf_len + len > buf_size)
 144           {
 145             size_t new_size = (buf_len + len) * 2;
 146             buf = scm_realloc (buf, new_size + 1);
 147             buf_size = new_size;
 148           }
 149
 150         /* Copy what we've got out of the port, into our buffer.  */
 151         memcpy (buf + buf_len, pt->read_pos, len);
 152         buf_len += len;
 153         pt->read_pos += len;
 154
 155         /* If we had seen a newline, we're done now.  */
 156         if (end)
 157           break;
 158
 159         /* Get more characters.  */
 160         if (scm_fill_input (port) == EOF)
 161           {
 162             /* If we're missing a final newline in the file, return
 163                what we did get, sans newline.  */
 164             if (buf_len > 0)
 165               break;
 166
 167             free (buf);
 168             return 0;
 169           }
 170
 171         /* Search the buffer for newlines.  */
 172         if ((end = memchr (pt->read_pos, '\n',
 173                            (len = (pt->read_end - pt->read_pos))))
 174             != 0)
 175           len = (end - pt->read_pos) + 1;
 176       }
 177
 178     /* I wonder how expensive this realloc is.  */
 179     buf = scm_realloc (buf, buf_len + 1);
 180     buf[buf_len] = '\0';
 181     *len_p = buf_len;
 182     return buf;
 183   }
 184 }
 185
 186
 187 /*
 188  * %read-line
 189  * truncates any terminating newline from its input, and returns
 190  * a cons of the string read and its terminating character.  Doing
 191  * so makes it easy to implement the hairy `read-line' options
 192  * efficiently in Scheme.
 193  */
 194
 195 SCM_DEFINE (scm_read_line, "%read-line", 0, 1, 0,
 196             (SCM port),
 197             "Read a newline-terminated line from @var{port}, allocating storage as\n"
 198             "necessary.  The newline terminator (if any) is removed from the string,\n"
 199             "and a pair consisting of the line and its delimiter is returned.  The\n"
 200             "delimiter may be either a newline or the @var{eof-object}; if\n"
 201             "@code{%read-line} is called at the end of file, it returns the pair\n"
 202             "@code{(#<eof> . #<eof>)}.")
 203 #define FUNC_NAME s_scm_read_line
 204 {
 205   scm_t_port *pt;
 206   char *s;
 207   size_t slen = 0;
 208   SCM line, term;
 209
 210   if (SCM_UNBNDP (port))
 211     port = scm_current_input_port ();
 212   SCM_VALIDATE_OPINPORT (1,port);
 213
 214   pt = SCM_PTAB_ENTRY (port);
 215   if (pt->rw_active == SCM_PORT_WRITE)
 216     scm_ptobs[SCM_PTOBNUM (port)].flush (port);
 217
 218   s = (char *) scm_do_read_line (port, &slen);
 219
 220   if (s == NULL)
 221     term = line = SCM_EOF_VAL;
 222   else
 223     {
 224       if (s[slen-1] == '\n')
 225         {
 226           term = SCM_MAKE_CHAR ('\n');
 227           s[slen-1] = '\0';
 228           line = scm_take_locale_stringn (s, slen-1);
 229           SCM_INCLINE (port);
 230         }
 231       else
 232         {
 233           /* Fix: we should check for eof on the port before assuming this. */
 234           term = SCM_EOF_VAL;
 235           line = scm_take_locale_stringn (s, slen);
 236           SCM_COL (port) += slen;
 237         }
 238     }
 239
 240   if (pt->rw_random)
 241     pt->rw_active = SCM_PORT_READ;
 242
 243   return scm_cons (line, term);
 244 }
 245 #undef FUNC_NAME
 246
 247 SCM_DEFINE (scm_write_line, "write-line", 1, 1, 0,
 248             (SCM obj, SCM port),
 249             "Display @var{obj} and a newline character to @var{port}.  If\n"
 250             "@var{port} is not specified, @code{(current-output-port)} is\n"
 251             "used.  This function is equivalent to:\n"
 252             "@lisp\n"
 253             "(display obj [port])\n"
 254             "(newline [port])\n"
 255             "@end lisp")
 256 #define FUNC_NAME s_scm_write_line
 257 {
 258   scm_display (obj, port);
 259   return scm_newline (port);
 260 }
 261 #undef FUNC_NAME
 262
 263 SCM
 264 scm_init_rdelim_builtins (void)
 265 {
 266 #include "libguile/rdelim.x"
 267
 268   return SCM_UNSPECIFIED;
 269 }
 270
 271 void
 272 scm_init_rdelim (void)
 273 {
 274   scm_c_define_gsubr ("%init-rdelim-builtins", 0, 0, 0,
 275                       scm_init_rdelim_builtins);
 276 }
 277
 278 /*
 279   Local Variables:
 280   c-file-style: "gnu"
 281   End:
 282 */