libguile/vports.c

   1 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2002 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
  43 \f
  44 #if HAVE_CONFIG_H
  45 #  include <config.h>
  46 #endif
  47
  48 #include <stdio.h>
  49 #include <errno.h>
  50
  51 #include "libguile/_scm.h"
  52 #include "libguile/eval.h"
  53 #include "libguile/chars.h"
  54 #include "libguile/fports.h"
  55 #include "libguile/root.h"
  56 #include "libguile/strings.h"
  57 #include "libguile/vectors.h"
  58
  59 #include "libguile/validate.h"
  60 #include "libguile/vports.h"
  61
  62 #ifdef HAVE_STRING_H
  63 #include <string.h>
  64 #endif
  65
  66 \f
  67
  68 /* {Ports - soft ports}
  69  *
  70  */
  71
  72
  73 static scm_t_bits scm_tc16_sfport;
  74
  75
  76 static void
  77 sf_flush (SCM port)
  78 {
  79   scm_t_port *pt = SCM_PTAB_ENTRY (port);
  80   SCM stream = SCM_PACK (pt->stream);
  81
  82   if (pt->write_pos > pt->write_buf)
  83     {
  84       /* write the byte. */
  85       scm_call_1 (SCM_VELTS (stream)[0], SCM_MAKE_CHAR (*pt->write_buf));
  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_call_0 (f);
  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_call_1 (SCM_VELTS (p)[1], scm_mem2string ((char *) data, size));
 104 }
 105
 106 /* calling the flush proc (element 2) is in case old code needs it,
 107    but perhaps softports could the use port buffer in the same way as
 108    fports.  */
 109
 110 /* places a single char in the input buffer.  */
 111 static int
 112 sf_fill_input (SCM port)
 113 {
 114   SCM p = SCM_PACK (SCM_STREAM (port));
 115   SCM ans;
 116
 117   ans = scm_call_0 (SCM_VELTS (p)[3]); /* get char.  */
 118   if (SCM_FALSEP (ans) || SCM_EOF_OBJECT_P (ans))
 119     return EOF;
 120   SCM_ASSERT (SCM_CHARP (ans), ans, SCM_ARG1, "sf_fill_input");
 121   {
 122     scm_t_port *pt = SCM_PTAB_ENTRY (port);
 123
 124     *pt->read_buf = SCM_CHAR (ans);
 125     pt->read_pos = pt->read_buf;
 126     pt->read_end = pt->read_buf + 1;
 127     return *pt->read_buf;
 128   }
 129 }
 130
 131
 132 static int
 133 sf_close (SCM port)
 134 {
 135   SCM p = SCM_PACK (SCM_STREAM (port));
 136   SCM f = SCM_VELTS (p)[4];
 137   if (SCM_FALSEP (f))
 138     return 0;
 139   f = scm_call_0 (f);
 140   errno = 0;
 141   return SCM_FALSEP (f) ? EOF : 0;
 142 }
 143
 144
 145 static int
 146 sf_input_waiting (SCM port)
 147 {
 148   SCM p = SCM_PACK (SCM_STREAM (port));
 149   if (SCM_VECTOR_LENGTH (p) >= 6)
 150     {
 151       SCM f = SCM_VELTS (p)[5];
 152       if (SCM_NFALSEP (f))
 153         return scm_num2int (scm_call_0 (f), SCM_ARGn, NULL);
 154     }
 155   /* Default is such that char-ready? for soft ports returns #t, as it
 156      did before this extension was implemented. */
 157   return 1;
 158 }
 159
 160
 161
 162 SCM_DEFINE (scm_make_soft_port, "make-soft-port", 2, 0, 0,
 163            (SCM pv, SCM modes),
 164             "Return a port capable of receiving or delivering characters as\n"
 165             "specified by the @var{modes} string (@pxref{File Ports,\n"
 166             "open-file}).  @var{pv} must be a vector of length 5 or 6.  Its\n"
 167             "components are as follows:\n"
 168             "\n"
 169             "@enumerate 0\n"
 170             "@item\n"
 171             "procedure accepting one character for output\n"
 172             "@item\n"
 173             "procedure accepting a string for output\n"
 174             "@item\n"
 175             "thunk for flushing output\n"
 176             "@item\n"
 177             "thunk for getting one character\n"
 178             "@item\n"
 179             "thunk for closing port (not by garbage collection)\n"
 180             "@item\n"
 181             "(if present and not @code{#f}) thunk for computing the number of\n"
 182             "characters that can be read from the port without blocking.\n"
 183             "@end enumerate\n"
 184             "\n"
 185             "For an output-only port only elements 0, 1, 2, and 4 need be\n"
 186             "procedures.  For an input-only port only elements 3 and 4 need\n"
 187             "be procedures.  Thunks 2 and 4 can instead be @code{#f} if\n"
 188             "there is no useful operation for them to perform.\n"
 189             "\n"
 190             "If thunk 3 returns @code{#f} or an @code{eof-object}\n"
 191             "(@pxref{Input, eof-object?, ,r5rs, The Revised^5 Report on\n"
 192             "Scheme}) it indicates that the port has reached end-of-file.\n"
 193             "For example:\n"
 194             "\n"
 195             "@lisp\n"
 196             "(define stdout (current-output-port))\n"
 197             "(define p (make-soft-port\n"
 198             "           (vector\n"
 199             "            (lambda (c) (write c stdout))\n"
 200             "            (lambda (s) (display s stdout))\n"
 201             "            (lambda () (display \".\" stdout))\n"
 202             "            (lambda () (char-upcase (read-char)))\n"
 203             "            (lambda () (display \"@@\" stdout)))\n"
 204             "           \"rw\"))\n"
 205             "\n"
 206             "(write p p) @result{} #<input-output: soft 8081e20>\n"
 207             "@end lisp")
 208 #define FUNC_NAME s_scm_make_soft_port
 209 {
 210   int vlen;
 211   scm_t_port *pt;
 212   SCM z;
 213
 214   SCM_VALIDATE_VECTOR (1, pv);
 215   vlen = SCM_VECTOR_LENGTH (pv);
 216   SCM_ASSERT ((vlen == 5) || (vlen == 6), pv, 1, FUNC_NAME);
 217   SCM_VALIDATE_STRING (2, modes);
 218
 219   SCM_DEFER_INTS;
 220   z = scm_new_port_table_entry (scm_tc16_sfport);
 221   pt = SCM_PTAB_ENTRY (z);
 222   scm_port_non_buffer (pt);
 223   SCM_SET_CELL_TYPE (z, scm_tc16_sfport | scm_mode_bits (SCM_STRING_CHARS (modes)));
 224
 225   SCM_SETSTREAM (z, SCM_UNPACK (pv));
 226   SCM_ALLOW_INTS;
 227   return z;
 228 }
 229 #undef FUNC_NAME
 230
 231
 232 static scm_t_bits
 233 scm_make_sfptob ()
 234 {
 235   scm_t_bits tc = scm_make_port_type ("soft", sf_fill_input, sf_write);
 236
 237   scm_set_port_mark (tc, scm_markstream);
 238   scm_set_port_flush (tc, sf_flush);
 239   scm_set_port_close (tc, sf_close);
 240   scm_set_port_input_waiting (tc, sf_input_waiting);
 241
 242   return tc;
 243 }
 244
 245 void
 246 scm_init_vports ()
 247 {
 248   scm_tc16_sfport = scm_make_sfptob ();
 249
 250 #include "libguile/vports.x"
 251 }
 252
 253 /*
 254   Local Variables:
 255   c-file-style: "gnu"
 256   End:
 257 */