libguile/strports.c

   1 /*      Copyright (C) 1995,1996,1998,1999 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 \f
  42
  43 #include "_scm.h"
  44
  45 #include <stdio.h>
  46 #ifdef HAVE_UNISTD_H
  47 #include <unistd.h>
  48 #endif
  49
  50 #include "unif.h"
  51 #include "eval.h"
  52 #include "read.h"
  53
  54 #include "strports.h"
  55
  56 #ifdef HAVE_STRING_H
  57 #include <string.h>
  58 #endif
  59
  60 \f
  61
  62 /* {Ports - string ports}
  63  *
  64  */
  65
  66 /* NOTES:
  67    write_buf/write_end point to the ends of the allocated string.
  68    read_buf/read_end in principle point to the part of the string which
  69    has been written to, but this is only updated after a flush.
  70    read_pos and write_pos in principle should be equal, but this is only true
  71    when rw_active is SCM_PORT_NEITHER.
  72 */
  73
  74 static int
  75 stfill_buffer (SCM port)
  76 {
  77   scm_port *pt = SCM_PTAB_ENTRY (port);
  78
  79   if (pt->read_pos >= pt->read_end)
  80     return EOF;
  81   else
  82     return scm_return_first (*pt->read_pos, port);
  83 }
  84
  85 /* change the size of a port's string to new_size.  this doesn't
  86    change read_buf_size.  */
  87 static void
  88 st_resize_port (scm_port *pt, off_t new_size)
  89 {
  90   off_t index = pt->write_pos - pt->write_buf;
  91
  92   pt->write_buf_size = new_size;
  93
  94   scm_vector_set_length_x (pt->stream, SCM_MAKINUM (new_size));
  95
  96   /* reset buffer in case reallocation moved the string. */
  97   {
  98     pt->read_buf = pt->write_buf = SCM_CHARS (pt->stream);
  99     pt->read_pos = pt->write_pos = pt->write_buf + index;
 100     pt->write_end = pt->write_buf + pt->write_buf_size;
 101     pt->read_end = pt->read_buf + pt->read_buf_size;
 102   }
 103 }
 104
 105 /* amount by which write_buf is expanded.  */
 106 #define SCM_WRITE_BLOCK 80
 107
 108 /* ensure that write_pos < write_end by enlarging the buffer when
 109    necessary.  update read_buf to account for written chars.  */
 110 static void
 111 st_flush (SCM port)
 112 {
 113   scm_port *pt = SCM_PTAB_ENTRY (port);
 114
 115   if (pt->write_pos == pt->write_end)
 116     {
 117       st_resize_port (pt, pt->write_buf_size + SCM_WRITE_BLOCK);
 118     }
 119   pt->read_pos = pt->write_pos;
 120   if (pt->read_pos > pt->read_end)
 121     {
 122       pt->read_end = (unsigned char *) pt->read_pos;
 123       pt->read_buf_size = pt->read_end - pt->read_buf;
 124     }
 125   pt->rw_active = SCM_PORT_NEITHER;
 126 }
 127
 128 static void
 129 st_write (SCM port, void *data, size_t size)
 130 {
 131   scm_port *pt = SCM_PTAB_ENTRY (port);
 132   const char *input = (char *) data;
 133
 134   while (size > 0)
 135     {
 136       int space = pt->write_end - pt->write_pos;
 137       int write_len = (size > space) ? space : size;
 138
 139       strncpy (pt->write_pos, input, write_len);
 140       pt->write_pos += write_len;
 141       size -= write_len;
 142       input += write_len;
 143       if (write_len == space)
 144         st_flush (port);
 145     }
 146 }
 147
 148 static void
 149 st_end_input (SCM port, int offset)
 150 {
 151   scm_port *pt = SCM_PTAB_ENTRY (port);
 152   const unsigned char *pos = pt->read_pos - offset;
 153
 154   if (pos < pt->read_buf)
 155     scm_misc_error ("st_end_input", "negative position", SCM_EOL);
 156
 157   pt->write_pos = (unsigned char *) pt->read_pos = pos;
 158   pt->rw_active = SCM_PORT_NEITHER;
 159 }
 160
 161 static off_t
 162 st_seek (SCM port, off_t offset, int whence)
 163 {
 164   scm_port *pt = SCM_PTAB_ENTRY (port);
 165   off_t target;
 166
 167   if (pt->rw_active == SCM_PORT_READ && offset == 0 && whence == SEEK_CUR)
 168     /* special case to avoid disturbing the unread-char buffer.  */
 169     {
 170       if (pt->read_buf == pt->putback_buf)
 171         {
 172           target = pt->saved_read_pos - pt->saved_read_buf
 173             - (pt->read_end - pt->read_pos);
 174         }
 175       else
 176         {
 177           target = pt->read_pos - pt->read_buf;
 178         }
 179     }
 180   else
 181     /* all other cases.  */
 182     {
 183       if (pt->rw_active == SCM_PORT_WRITE)
 184         st_flush (port);
 185
 186       if (pt->rw_active == SCM_PORT_READ)
 187         scm_end_input (port);
 188
 189       switch (whence)
 190         {
 191         case SEEK_CUR:
 192           target = pt->read_pos - pt->read_buf + offset;
 193           break;
 194         case SEEK_END:
 195           target = pt->read_end - pt->read_buf + offset;
 196           break;
 197         default: /* SEEK_SET */
 198           target = offset;
 199           break;
 200         }
 201
 202       if (target < 0)
 203         scm_misc_error ("st_seek", "negative offset", SCM_EOL);
 204
 205       if (target >= pt->write_buf_size)
 206         {
 207           if (!(SCM_CAR (port) & SCM_WRTNG))
 208             {
 209               if (target > pt->write_buf_size)
 210                 {
 211                   scm_misc_error ("st_seek",
 212                                   "seek past end of read-only strport",
 213                                   SCM_EOL);
 214                 }
 215             }
 216           else
 217             {
 218               st_resize_port (pt, target + (target == pt->write_buf_size
 219                                             ? SCM_WRITE_BLOCK
 220                                             : 0));
 221             }
 222         }
 223       pt->read_pos = pt->write_pos = pt->read_buf + target;
 224       if (pt->read_pos > pt->read_end)
 225         {
 226           pt->read_end = (unsigned char *) pt->read_pos;
 227           pt->read_buf_size = pt->read_end - pt->read_buf;
 228         }
 229     }
 230   return target;
 231 }
 232
 233 static void
 234 st_truncate (SCM port, off_t length)
 235 {
 236   scm_port *pt = SCM_PTAB_ENTRY (port);
 237
 238   if (length > pt->write_buf_size)
 239     st_resize_port (pt, length);
 240
 241   pt->read_buf_size = length;
 242   pt->read_end = pt->read_buf + length;
 243   if (pt->read_pos > pt->read_end)
 244     pt->read_pos = pt->read_end;
 245
 246   if (pt->write_pos > pt->read_end)
 247     pt->write_pos = pt->read_end;
 248 }
 249
 250 SCM
 251 scm_mkstrport (pos, str, modes, caller)
 252      SCM pos;
 253      SCM str;
 254      long modes;
 255      const char * caller;
 256 {
 257   SCM z;
 258   scm_port *pt;
 259   int str_len;
 260
 261   SCM_ASSERT (SCM_INUMP(pos) && SCM_INUM(pos) >= 0, pos, SCM_ARG1, caller);
 262   SCM_ASSERT (SCM_NIMP(str) && SCM_ROSTRINGP(str), str, SCM_ARG1, caller);
 263   str_len = SCM_ROLENGTH (str);
 264   if (SCM_INUM (pos) > str_len)
 265     scm_out_of_range (caller, pos);
 266   if (!((modes & SCM_WRTNG) || (modes & SCM_RDNG)))
 267     scm_misc_error ("scm_mkstrport", "port must read or write", SCM_EOL);
 268   SCM_NEWCELL (z);
 269   SCM_DEFER_INTS;
 270   pt = scm_add_to_port_table (z);
 271   SCM_SETCAR (z, scm_tc16_strport | modes);
 272   SCM_SETPTAB_ENTRY (z, pt);
 273   SCM_SETSTREAM (z, str);
 274   pt->write_buf = pt->read_buf = SCM_ROCHARS (str);
 275   pt->read_pos = pt->write_pos = pt->read_buf + SCM_INUM (pos);
 276   pt->write_buf_size = pt->read_buf_size = str_len;
 277   pt->write_end = pt->read_end = pt->read_buf + pt->read_buf_size;
 278
 279   pt->rw_random = 1;
 280
 281   SCM_ALLOW_INTS;
 282
 283   /* ensure write_pos is writable. */
 284   if ((modes & SCM_WRTNG) && pt->write_pos == pt->write_end)
 285     st_flush (z);
 286   return z;
 287 }
 288
 289 /* create a new string from a string port's buffer.  */
 290 SCM scm_strport_to_string (SCM port)
 291 {
 292   scm_port *pt = SCM_PTAB_ENTRY (port);
 293
 294   if (pt->rw_active == SCM_PORT_WRITE)
 295     st_flush (port);
 296   return scm_makfromstr (pt->read_buf, pt->read_buf_size, 0);
 297 }
 298
 299 SCM_PROC(s_call_with_output_string, "call-with-output-string", 1, 0, 0, scm_call_with_output_string);
 300
 301 SCM
 302 scm_call_with_output_string (proc)
 303      SCM proc;
 304 {
 305   SCM p;
 306
 307   p = scm_mkstrport (SCM_INUM0,
 308                      scm_make_string (SCM_INUM0, SCM_UNDEFINED),
 309                      SCM_OPN | SCM_WRTNG,
 310                      s_call_with_output_string);
 311   scm_apply (proc, p, scm_listofnull);
 312
 313   return scm_strport_to_string (p);
 314 }
 315
 316
 317
 318 /* Return a Scheme string obtained by printing a given object.
 319  */
 320
 321
 322 SCM
 323 scm_strprint_obj (obj)
 324      SCM obj;
 325 {
 326   SCM str;
 327   SCM port;
 328
 329   str = scm_makstr (0, 0);
 330   port = scm_mkstrport (SCM_INUM0, str, SCM_OPN | SCM_WRTNG, "scm_strprint_obj");
 331   scm_prin1 (obj, port, 1);
 332   {
 333     return scm_strport_to_string (port);
 334   }
 335 }
 336
 337
 338
 339
 340 SCM_PROC(s_call_with_input_string, "call-with-input-string", 2, 0, 0, scm_call_with_input_string);
 341
 342 SCM
 343 scm_call_with_input_string (str, proc)
 344      SCM str;
 345      SCM proc;
 346 {
 347   SCM p = scm_mkstrport(SCM_INUM0, str, SCM_OPN | SCM_RDNG, s_call_with_input_string);
 348   return scm_apply (proc, p, scm_listofnull);
 349 }
 350
 351
 352
 353 /* Given a null-terminated string EXPR containing a Scheme expression
 354    read it, and return it as an SCM value. */
 355 SCM
 356 scm_read_0str (expr)
 357      char *expr;
 358 {
 359   SCM port = scm_mkstrport (SCM_INUM0,
 360                             scm_makfrom0str (expr),
 361                             SCM_OPN | SCM_RDNG,
 362                             "scm_eval_0str");
 363   SCM form;
 364
 365   /* Read expressions from that port; ignore the values.  */
 366   form = scm_read (port);
 367
 368   scm_close_port (port);
 369   return form;
 370 }
 371
 372 /* Given a null-terminated string EXPR containing Scheme program text,
 373    evaluate it, and return the result of the last expression evaluated.  */
 374 SCM
 375 scm_eval_0str (expr)
 376      char *expr;
 377 {
 378   return scm_eval_string (scm_makfrom0str (expr));
 379 }
 380
 381
 382 SCM_PROC (s_eval_string, "eval-string", 1, 0, 0, scm_eval_string);
 383
 384 SCM
 385 scm_eval_string (string)
 386      SCM string;
 387 {
 388   SCM port = scm_mkstrport (SCM_INUM0, string, SCM_OPN | SCM_RDNG,
 389                             "scm_eval_0str");
 390   SCM form;
 391   SCM ans = SCM_UNSPECIFIED;
 392
 393   /* Read expressions from that port; ignore the values.  */
 394   while (!SCM_EOF_OBJECT_P (form = scm_read (port)))
 395     ans = scm_eval_x (form);
 396
 397   /* Don't close the port here; if we re-enter this function via a
 398      continuation, then the next time we enter it, we'll get an error.
 399      It's a string port anyway, so there's no advantage to closing it
 400      early.  */
 401
 402   return ans;
 403 }
 404
 405 void scm_make_stptob (void); /* Called from ports.c */
 406
 407 void
 408 scm_make_stptob ()
 409 {
 410   long tc = scm_make_port_type ("string", stfill_buffer, st_write);
 411   scm_set_port_mark        (tc, scm_markstream);
 412   scm_set_port_end_input   (tc, st_end_input);
 413   scm_set_port_flush       (tc, st_flush);
 414   scm_set_port_seek        (tc, st_seek);
 415   scm_set_port_truncate    (tc, st_truncate);
 416 }
 417
 418 void
 419 scm_init_strports ()
 420 {
 421 #include "strports.x"
 422 }
 423