libguile/vports.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
  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 "_scm.h"
  49 #include "eval.h"
  50 #include "chars.h"
  51 #include "fports.h"
  52 #include "strings.h"
  53 #include "vectors.h"
  54
  55 #include "validate.h"
  56 #include "vports.h"
  57
  58 #ifdef HAVE_STRING_H
  59 #include <string.h>
  60 #endif
  61
  62 \f
  63
  64 /* {Ports - soft ports}
  65  *
  66  */
  67
  68
  69 static void
  70 sf_flush (SCM port)
  71 {
  72   scm_port *pt = SCM_PTAB_ENTRY (port);
  73   SCM stream = pt->stream;
  74
  75   if (pt->write_pos > pt->write_buf)
  76     {
  77       /* write the byte. */
  78       scm_apply (SCM_VELTS (stream)[0], SCM_MAKE_CHAR (*pt->write_buf),
  79                  scm_listofnull);
  80       pt->write_pos = pt->write_buf;
  81
  82       /* flush the output.  */
  83       {
  84         SCM f = SCM_VELTS (stream)[2];
  85
  86         if (f != SCM_BOOL_F)
  87           scm_apply (f, SCM_EOL, SCM_EOL);
  88       }
  89     }
  90 }
  91
  92 static void
  93 sf_write (SCM port, const void *data, size_t size)
  94 {
  95   SCM p = SCM_STREAM (port);
  96
  97   scm_apply (SCM_VELTS (p)[1],
  98              scm_cons (scm_makfromstr ((char *) data, size, 0), SCM_EOL),
  99              SCM_EOL);
 100 }
 101
 102 /* calling the flush proc (element 2) is in case old code needs it,
 103    but perhaps softports could the use port buffer in the same way as
 104    fports.  */
 105
 106 /* places a single char in the input buffer.  */
 107 static int
 108 sf_fill_input (SCM port)
 109 {
 110   SCM p = SCM_STREAM (port);
 111   SCM ans;
 112
 113   ans = scm_apply (SCM_VELTS (p)[3], SCM_EOL, SCM_EOL); /* get char.  */
 114   if (SCM_FALSEP (ans) || SCM_EOF_OBJECT_P (ans))
 115     return EOF;
 116   SCM_ASSERT (SCM_CHARP (ans), ans, SCM_ARG1, "sf_fill_input");
 117   {
 118     scm_port *pt = SCM_PTAB_ENTRY (port);
 119
 120     *pt->read_buf = SCM_CHAR (ans);
 121     pt->read_pos = pt->read_buf;
 122     pt->read_end = pt->read_buf + 1;
 123     return *pt->read_buf;
 124   }
 125 }
 126
 127
 128 static int
 129 sf_close (SCM port)
 130 {
 131   SCM p = SCM_STREAM (port);
 132   SCM f = SCM_VELTS (p)[4];
 133   if (SCM_BOOL_F == f)
 134     return 0;
 135   f = scm_apply (f, SCM_EOL, SCM_EOL);
 136   errno = 0;
 137   return SCM_BOOL_F == f ? EOF : 0;
 138 }
 139
 140
 141
 142 SCM_DEFINE (scm_make_soft_port, "make-soft-port", 2, 0, 0,
 143            (SCM pv, SCM modes),
 144             "Returns a port capable of receiving or delivering characters as\n"
 145             "specified by the @var{modes} string (@pxref{File Ports,\n"
 146             "open-file}).  @var{vector} must be a vector of length 6.  Its components\n"
 147             "are as follows:\n\n"
 148             "@enumerate 0\n"
 149             "@item\n"
 150             "procedure accepting one character for output\n"
 151             "@item\n"
 152             "procedure accepting a string for output\n"
 153             "@item\n"
 154             "thunk for flushing output\n"
 155             "@item\n"
 156             "thunk for getting one character\n"
 157             "@item\n"
 158             "thunk for closing port (not by garbage collection)\n"
 159             "@end enumerate\n\n"
 160             "For an output-only port only elements 0, 1, 2, and 4 need be\n"
 161             "procedures.  For an input-only port only elements 3 and 4 need be\n"
 162             "procedures.  Thunks 2 and 4 can instead be @code{#f} if there is no useful\n"
 163             "operation for them to perform.\n\n"
 164             "If thunk 3 returns @code{#f} or an @code{eof-object} (@pxref{Input,\n"
 165             "eof-object?, ,r4rs, The Revised^4 Report on Scheme}) it indicates that\n"
 166             "the port has reached end-of-file.  For example:\n\n"
 167             "@example\n"
 168             "(define stdout (current-output-port))\n"
 169             "(define p (make-soft-port\n"
 170             "           (vector\n"
 171             "            (lambda (c) (write c stdout))\n"
 172             "            (lambda (s) (display s stdout))\n"
 173             "            (lambda () (display \".\" stdout))\n"
 174             "            (lambda () (char-upcase (read-char)))\n"
 175             "            (lambda () (display \"@@\" stdout)))\n"
 176             "           \"rw\"))\n\n"
 177             "(write p p) @result{} #<input-output-soft#\space45d10#\>\n"
 178             "@end example")
 179 #define FUNC_NAME s_scm_make_soft_port
 180 {
 181   scm_port *pt;
 182   SCM z;
 183   SCM_VALIDATE_VECTOR_LEN (1,pv,5);
 184   SCM_VALIDATE_ROSTRING (2,modes);
 185   SCM_COERCE_SUBSTR (modes);
 186   SCM_NEWCELL (z);
 187   SCM_DEFER_INTS;
 188   pt = scm_add_to_port_table (z);
 189   scm_port_non_buffer (pt);
 190   SCM_SETCAR (z, scm_tc16_sfport | scm_mode_bits (SCM_ROCHARS (modes)));
 191   SCM_SETPTAB_ENTRY (z, pt);
 192   SCM_SETSTREAM (z, pv);
 193   SCM_ALLOW_INTS;
 194   return z;
 195 }
 196 #undef FUNC_NAME
 197
 198
 199 void scm_make_sfptob (void); /* Called from ports.c */
 200
 201 void
 202 scm_make_sfptob ()
 203 {
 204   long tc = scm_make_port_type ("soft", sf_fill_input, sf_write);
 205   scm_set_port_mark (tc, scm_markstream);
 206   scm_set_port_flush (tc, sf_flush);
 207   scm_set_port_close (tc, sf_close);
 208 }
 209
 210 void
 211 scm_init_vports ()
 212 {
 213 #include "vports.x"
 214 }