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
  53 #include "scm_validate.h"
  54 #include "vports.h"
  55
  56 #ifdef HAVE_STRING_H
  57 #include <string.h>
  58 #endif
  59
  60 \f
  61
  62 /* {Ports - soft ports}
  63  *
  64  */
  65
  66
  67 static void
  68 sf_flush (SCM port)
  69 {
  70   scm_port *pt = SCM_PTAB_ENTRY (port);
  71   SCM stream = pt->stream;
  72
  73   if (pt->write_pos > pt->write_buf)
  74     {
  75       /* write the byte. */
  76       scm_apply (SCM_VELTS (stream)[0], SCM_MAKICHR (*pt->write_buf),
  77                  scm_listofnull);
  78       pt->write_pos = pt->write_buf;
  79
  80       /* flush the output.  */
  81       {
  82         SCM f = SCM_VELTS (stream)[2];
  83
  84         if (f != SCM_BOOL_F)
  85           scm_apply (f, SCM_EOL, SCM_EOL);
  86       }
  87     }
  88 }
  89
  90 static void
  91 sf_write (SCM port, void *data, size_t size)
  92 {
  93   SCM p = SCM_STREAM (port);
  94
  95   scm_apply (SCM_VELTS (p)[1],
  96              scm_cons (scm_makfromstr ((char *) data, size, 0), SCM_EOL),
  97              SCM_EOL);
  98 }
  99
 100 /* calling the flush proc (element 2) is in case old code needs it,
 101    but perhaps softports could the use port buffer in the same way as
 102    fports.  */
 103
 104 /* places a single char in the input buffer.  */
 105 static int
 106 sf_fill_input (SCM port)
 107 {
 108   SCM p = SCM_STREAM (port);
 109   SCM ans;
 110
 111   ans = scm_apply (SCM_VELTS (p)[3], SCM_EOL, SCM_EOL); /* get char.  */
 112   if (SCM_FALSEP (ans) || SCM_EOF_OBJECT_P (ans))
 113     return EOF;
 114   SCM_ASSERT (SCM_ICHRP (ans), ans, SCM_ARG1, "sf_fill_input");
 115   {
 116     scm_port *pt = SCM_PTAB_ENTRY (port);
 117
 118     *pt->read_buf = SCM_ICHR (ans);
 119     pt->read_pos = pt->read_buf;
 120     pt->read_end = pt->read_buf + 1;
 121     return *pt->read_buf;
 122   }
 123 }
 124
 125
 126 static int
 127 sf_close (SCM port)
 128 {
 129   SCM p = SCM_STREAM (port);
 130   SCM f = SCM_VELTS (p)[4];
 131   if (SCM_BOOL_F == f)
 132     return 0;
 133   f = scm_apply (f, SCM_EOL, SCM_EOL);
 134   errno = 0;
 135   return SCM_BOOL_F == f ? EOF : 0;
 136 }
 137
 138
 139
 140 SCM_DEFINE(scm_make_soft_port, "make-soft-port", 2, 0, 0,
 141            (SCM pv, SCM modes),
 142 "Returns a port capable of receiving or delivering characters as
 143 specified by the @var{modes} string (@pxref{File Ports,
 144 open-file}).  @var{vector} must be a vector of length 6.  Its components
 145 are as follows:
 146
 147 @enumerate 0
 148 @item
 149 procedure accepting one character for output
 150 @item
 151 procedure accepting a string for output
 152 @item
 153 thunk for flushing output
 154 @item
 155 thunk for getting one character
 156 @item
 157 thunk for closing port (not by garbage collection)
 158 @end enumerate
 159
 160 For an output-only port only elements 0, 1, 2, and 4 need be
 161 procedures.  For an input-only port only elements 3 and 4 need be
 162 procedures.  Thunks 2 and 4 can instead be @code{#f} if there is no useful
 163 operation for them to perform.
 164
 165 If thunk 3 returns @code{#f} or an @code{eof-object} (@pxref{Input,
 166 eof-object?, ,r4rs, The Revised^4 Report on Scheme}) it indicates that
 167 the port has reached end-of-file.  For example:
 168
 169 @example
 170 (define stdout (current-output-port))
 171 (define p (make-soft-port
 172            (vector
 173             (lambda (c) (write c stdout))
 174             (lambda (s) (display s stdout))
 175             (lambda () (display "." stdout))
 176             (lambda () (char-upcase (read-char)))
 177             (lambda () (display "@@" stdout)))
 178            "rw"))
 179
 180 (write p p) @result{} #<input-output-soft#\space45d10#\>
 181 @end example")
 182 #define FUNC_NAME s_scm_make_soft_port
 183 {
 184   scm_port *pt;
 185   SCM z;
 186   SCM_VALIDATE_VECTOR_LEN(1,pv,5);
 187   SCM_VALIDATE_ROSTRING(2,modes);
 188   SCM_COERCE_SUBSTR (modes);
 189   SCM_NEWCELL (z);
 190   SCM_DEFER_INTS;
 191   pt = scm_add_to_port_table (z);
 192   SCM_SETCAR (z, scm_tc16_sfport | scm_mode_bits (SCM_ROCHARS (modes)));
 193   SCM_SETPTAB_ENTRY (z, pt);
 194   SCM_SETSTREAM (z, pv);
 195   pt->read_pos = pt->read_buf = pt->read_end = &pt->shortbuf;
 196   pt->write_buf = pt->write_pos = &pt->shortbuf;
 197   pt->read_buf_size = pt->write_buf_size = 1;
 198   pt->write_end = pt->write_buf + pt->write_buf_size;
 199   pt->rw_random = 0;
 200   SCM_ALLOW_INTS;
 201   return z;
 202 }
 203 #undef FUNC_NAME
 204
 205
 206 void scm_make_sfptob (void); /* Called from ports.c */
 207
 208 void
 209 scm_make_sfptob ()
 210 {
 211   long tc = scm_make_port_type ("soft", sf_fill_input, sf_write);
 212   scm_set_port_mark (tc, scm_markstream);
 213   scm_set_port_flush (tc, sf_flush);
 214   scm_set_port_close (tc, sf_close);
 215 }
 216
 217 void
 218 scm_init_vports ()
 219 {
 220 #include "vports.x"
 221 }