libguile/vports.c

   1 /*      Copyright (C) 1995,1996,1998,1999, 2000, 2001 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 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
  43    gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
  44
  45 \f
  46
  47 #include <stdio.h>
  48 #include <errno.h>
  49
  50 #include "libguile/_scm.h"
  51 #include "libguile/eval.h"
  52 #include "libguile/chars.h"
  53 #include "libguile/fports.h"
  54 #include "libguile/root.h"
  55 #include "libguile/strings.h"
  56 #include "libguile/vectors.h"
  57
  58 #include "libguile/validate.h"
  59 #include "libguile/vports.h"
  60
  61 #ifdef HAVE_STRING_H
  62 #include <string.h>
  63 #endif
  64
  65 \f
  66
  67 /* {Ports - soft ports}
  68  *
  69  */
  70
  71
  72 static scm_bits_t scm_tc16_sfport;
  73
  74
  75 static void
  76 sf_flush (SCM port)
  77 {
  78   scm_port *pt = SCM_PTAB_ENTRY (port);
  79   SCM stream = SCM_PACK (pt->stream);
  80
  81   if (pt->write_pos > pt->write_buf)
  82     {
  83       /* write the byte. */
  84       scm_apply (SCM_VELTS (stream)[0], SCM_MAKE_CHAR (*pt->write_buf),
  85                  scm_listofnull);
  86       pt->write_pos = pt->write_buf;
  87
  88       /* flush the output.  */
  89       {
  90         SCM f = SCM_VELTS (stream)[2];
  91
  92         if (!SCM_FALSEP (f))
  93           scm_apply (f, SCM_EOL, SCM_EOL);
  94       }
  95     }
  96 }
  97
  98 static void
  99 sf_write (SCM port, const void *data, size_t size)
 100 {
 101   SCM p = SCM_PACK (SCM_STREAM (port));
 102
 103   scm_apply (SCM_VELTS (p)[1],
 104              scm_cons (scm_makfromstr ((char *) data, size, 0), SCM_EOL),
 105              SCM_EOL);
 106 }
 107
 108 /* calling the flush proc (element 2) is in case old code needs it,
 109    but perhaps softports could the use port buffer in the same way as
 110    fports.  */
 111
 112 /* places a single char in the input buffer.  */
 113 static int
 114 sf_fill_input (SCM port)
 115 {
 116   SCM p = SCM_PACK (SCM_STREAM (port));
 117   SCM ans;
 118
 119   ans = scm_apply (SCM_VELTS (p)[3], SCM_EOL, SCM_EOL); /* get char.  */
 120   if (SCM_FALSEP (ans) || SCM_EOF_OBJECT_P (ans))
 121     return EOF;
 122   SCM_ASSERT (SCM_CHARP (ans), ans, SCM_ARG1, "sf_fill_input");
 123   {
 124     scm_port *pt = SCM_PTAB_ENTRY (port);
 125
 126     *pt->read_buf = SCM_CHAR (ans);
 127     pt->read_pos = pt->read_buf;
 128     pt->read_end = pt->read_buf + 1;
 129     return *pt->read_buf;
 130   }
 131 }
 132
 133
 134 static int
 135 sf_close (SCM port)
 136 {
 137   SCM p = SCM_PACK (SCM_STREAM (port));
 138   SCM f = SCM_VELTS (p)[4];
 139   if (SCM_FALSEP (f))
 140     return 0;
 141   f = scm_apply (f, SCM_EOL, SCM_EOL);
 142   errno = 0;
 143   return SCM_FALSEP (f) ? EOF : 0;
 144 }
 145
 146
 147
 148 SCM_DEFINE (scm_make_soft_port, "make-soft-port", 2, 0, 0,
 149            (SCM pv, SCM modes),
 150             "Returns a port capable of receiving or delivering characters as\n"
 151             "specified by the @var{modes} string (@pxref{File Ports,\n"
 152             "open-file}).  @var{vector} must be a vector of length 6.  Its components\n"
 153             "are as follows:\n\n"
 154             "@enumerate 0\n"
 155             "@item\n"
 156             "procedure accepting one character for output\n"
 157             "@item\n"
 158             "procedure accepting a string for output\n"
 159             "@item\n"
 160             "thunk for flushing output\n"
 161             "@item\n"
 162             "thunk for getting one character\n"
 163             "@item\n"
 164             "thunk for closing port (not by garbage collection)\n"
 165             "@end enumerate\n\n"
 166             "For an output-only port only elements 0, 1, 2, and 4 need be\n"
 167             "procedures.  For an input-only port only elements 3 and 4 need be\n"
 168             "procedures.  Thunks 2 and 4 can instead be @code{#f} if there is no useful\n"
 169             "operation for them to perform.\n\n"
 170             "If thunk 3 returns @code{#f} or an @code{eof-object} (@pxref{Input,\n"
 171             "eof-object?, ,r4rs, The Revised^4 Report on Scheme}) it indicates that\n"
 172             "the port has reached end-of-file.  For example:\n\n"
 173             "@example\n"
 174             "(define stdout (current-output-port))\n"
 175             "(define p (make-soft-port\n"
 176             "           (vector\n"
 177             "            (lambda (c) (write c stdout))\n"
 178             "            (lambda (s) (display s stdout))\n"
 179             "            (lambda () (display \".\" stdout))\n"
 180             "            (lambda () (char-upcase (read-char)))\n"
 181             "            (lambda () (display \"@@\" stdout)))\n"
 182             "           \"rw\"))\n\n"
 183             "(write p p) @result{} #<input-output: soft 8081e20>\n"
 184             "@end example")
 185 #define FUNC_NAME s_scm_make_soft_port
 186 {
 187   scm_port *pt;
 188   SCM z;
 189   SCM_VALIDATE_VECTOR_LEN (1,pv,5);
 190   SCM_VALIDATE_STRING (2, modes);
 191   SCM_STRING_COERCE_0TERMINATION_X (modes);
 192   SCM_NEWCELL (z);
 193   SCM_DEFER_INTS;
 194   pt = scm_add_to_port_table (z);
 195   scm_port_non_buffer (pt);
 196   SCM_SET_CELL_TYPE (z, scm_tc16_sfport | scm_mode_bits (SCM_STRING_CHARS (modes)));
 197   SCM_SETPTAB_ENTRY (z, pt);
 198   SCM_SETSTREAM (z, SCM_UNPACK (pv));
 199   SCM_ALLOW_INTS;
 200   return z;
 201 }
 202 #undef FUNC_NAME
 203
 204
 205 static scm_bits_t
 206 scm_make_sfptob ()
 207 {
 208   scm_bits_t tc = scm_make_port_type ("soft", sf_fill_input, sf_write);
 209
 210   scm_set_port_mark (tc, scm_markstream);
 211   scm_set_port_flush (tc, sf_flush);
 212   scm_set_port_close (tc, sf_close);
 213
 214   return tc;
 215 }
 216
 217 void
 218 scm_init_vports ()
 219 {
 220   scm_tc16_sfport = scm_make_sfptob ();
 221
 222 #ifndef SCM_MAGIC_SNARFER
 223 #include "libguile/vports.x"
 224 #endif
 225 }
 226
 227 /*
 228   Local Variables:
 229   c-file-style: "gnu"
 230   End:
 231 */