libguile/vports.c

   1 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2002, 2003 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library 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 GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  16  */
  17
  18
  19 \f
  20 #if HAVE_CONFIG_H
  21 #  include <config.h>
  22 #endif
  23
  24 #include <stdio.h>
  25 #include <errno.h>
  26
  27 #include "libguile/_scm.h"
  28 #include "libguile/eval.h"
  29 #include "libguile/chars.h"
  30 #include "libguile/fports.h"
  31 #include "libguile/root.h"
  32 #include "libguile/strings.h"
  33 #include "libguile/vectors.h"
  34
  35 #include "libguile/validate.h"
  36 #include "libguile/vports.h"
  37
  38 #ifdef HAVE_STRING_H
  39 #include <string.h>
  40 #endif
  41
  42 \f
  43
  44 /* {Ports - soft ports}
  45  *
  46  */
  47
  48
  49 static scm_t_bits scm_tc16_sfport;
  50
  51
  52 static void
  53 sf_flush (SCM port)
  54 {
  55   scm_t_port *pt = SCM_PTAB_ENTRY (port);
  56   SCM stream = SCM_PACK (pt->stream);
  57
  58   if (pt->write_pos > pt->write_buf)
  59     {
  60       /* write the byte. */
  61       scm_call_1 (SCM_VELTS (stream)[0], SCM_MAKE_CHAR (*pt->write_buf));
  62       pt->write_pos = pt->write_buf;
  63
  64       /* flush the output.  */
  65       {
  66         SCM f = SCM_VELTS (stream)[2];
  67
  68         if (scm_is_true (f))
  69           scm_call_0 (f);
  70       }
  71     }
  72 }
  73
  74 static void
  75 sf_write (SCM port, const void *data, size_t size)
  76 {
  77   SCM p = SCM_PACK (SCM_STREAM (port));
  78
  79   scm_call_1 (SCM_VELTS (p)[1], scm_mem2string ((char *) data, size));
  80 }
  81
  82 /* calling the flush proc (element 2) is in case old code needs it,
  83    but perhaps softports could the use port buffer in the same way as
  84    fports.  */
  85
  86 /* places a single char in the input buffer.  */
  87 static int
  88 sf_fill_input (SCM port)
  89 {
  90   SCM p = SCM_PACK (SCM_STREAM (port));
  91   SCM ans;
  92
  93   ans = scm_call_0 (SCM_VELTS (p)[3]); /* get char.  */
  94   if (scm_is_false (ans) || SCM_EOF_OBJECT_P (ans))
  95     return EOF;
  96   SCM_ASSERT (SCM_CHARP (ans), ans, SCM_ARG1, "sf_fill_input");
  97   {
  98     scm_t_port *pt = SCM_PTAB_ENTRY (port);
  99
 100     *pt->read_buf = SCM_CHAR (ans);
 101     pt->read_pos = pt->read_buf;
 102     pt->read_end = pt->read_buf + 1;
 103     return *pt->read_buf;
 104   }
 105 }
 106
 107
 108 static int
 109 sf_close (SCM port)
 110 {
 111   SCM p = SCM_PACK (SCM_STREAM (port));
 112   SCM f = SCM_VELTS (p)[4];
 113   if (scm_is_false (f))
 114     return 0;
 115   f = scm_call_0 (f);
 116   errno = 0;
 117   return scm_is_false (f) ? EOF : 0;
 118 }
 119
 120
 121 static int
 122 sf_input_waiting (SCM port)
 123 {
 124   SCM p = SCM_PACK (SCM_STREAM (port));
 125   if (SCM_VECTOR_LENGTH (p) >= 6)
 126     {
 127       SCM f = SCM_VELTS (p)[5];
 128       if (scm_is_true (f))
 129         return scm_num2int (scm_call_0 (f), SCM_ARGn, NULL);
 130     }
 131   /* Default is such that char-ready? for soft ports returns #t, as it
 132      did before this extension was implemented. */
 133   return 1;
 134 }
 135
 136
 137
 138 SCM_DEFINE (scm_make_soft_port, "make-soft-port", 2, 0, 0,
 139            (SCM pv, SCM modes),
 140             "Return a port capable of receiving or delivering characters as\n"
 141             "specified by the @var{modes} string (@pxref{File Ports,\n"
 142             "open-file}).  @var{pv} must be a vector of length 5 or 6.  Its\n"
 143             "components are as follows:\n"
 144             "\n"
 145             "@enumerate 0\n"
 146             "@item\n"
 147             "procedure accepting one character for output\n"
 148             "@item\n"
 149             "procedure accepting a string for output\n"
 150             "@item\n"
 151             "thunk for flushing output\n"
 152             "@item\n"
 153             "thunk for getting one character\n"
 154             "@item\n"
 155             "thunk for closing port (not by garbage collection)\n"
 156             "@item\n"
 157             "(if present and not @code{#f}) thunk for computing the number of\n"
 158             "characters that can be read from the port without blocking.\n"
 159             "@end enumerate\n"
 160             "\n"
 161             "For an output-only port only elements 0, 1, 2, and 4 need be\n"
 162             "procedures.  For an input-only port only elements 3 and 4 need\n"
 163             "be procedures.  Thunks 2 and 4 can instead be @code{#f} if\n"
 164             "there is no useful operation for them to perform.\n"
 165             "\n"
 166             "If thunk 3 returns @code{#f} or an @code{eof-object}\n"
 167             "(@pxref{Input, eof-object?, ,r5rs, The Revised^5 Report on\n"
 168             "Scheme}) it indicates that the port has reached end-of-file.\n"
 169             "For example:\n"
 170             "\n"
 171             "@lisp\n"
 172             "(define stdout (current-output-port))\n"
 173             "(define p (make-soft-port\n"
 174             "           (vector\n"
 175             "            (lambda (c) (write c stdout))\n"
 176             "            (lambda (s) (display s stdout))\n"
 177             "            (lambda () (display \".\" stdout))\n"
 178             "            (lambda () (char-upcase (read-char)))\n"
 179             "            (lambda () (display \"@@\" stdout)))\n"
 180             "           \"rw\"))\n"
 181             "\n"
 182             "(write p p) @result{} #<input-output: soft 8081e20>\n"
 183             "@end lisp")
 184 #define FUNC_NAME s_scm_make_soft_port
 185 {
 186   int vlen;
 187   scm_t_port *pt;
 188   SCM z;
 189
 190   SCM_VALIDATE_VECTOR (1, pv);
 191   vlen = SCM_VECTOR_LENGTH (pv);
 192   SCM_ASSERT ((vlen == 5) || (vlen == 6), pv, 1, FUNC_NAME);
 193   SCM_VALIDATE_STRING (2, modes);
 194
 195   scm_mutex_lock (&scm_i_port_table_mutex);
 196   z = scm_new_port_table_entry (scm_tc16_sfport);
 197   pt = SCM_PTAB_ENTRY (z);
 198   scm_port_non_buffer (pt);
 199   SCM_SET_CELL_TYPE (z, scm_tc16_sfport | scm_mode_bits (SCM_STRING_CHARS (modes)));
 200
 201   SCM_SETSTREAM (z, SCM_UNPACK (pv));
 202   scm_mutex_unlock (&scm_i_port_table_mutex);
 203   return z;
 204 }
 205 #undef FUNC_NAME
 206
 207
 208 static scm_t_bits
 209 scm_make_sfptob ()
 210 {
 211   scm_t_bits tc = scm_make_port_type ("soft", sf_fill_input, sf_write);
 212
 213   scm_set_port_mark (tc, scm_markstream);
 214   scm_set_port_flush (tc, sf_flush);
 215   scm_set_port_close (tc, sf_close);
 216   scm_set_port_input_waiting (tc, sf_input_waiting);
 217
 218   return tc;
 219 }
 220
 221 void
 222 scm_init_vports ()
 223 {
 224   scm_tc16_sfport = scm_make_sfptob ();
 225
 226 #include "libguile/vports.x"
 227 }
 228
 229 /*
 230   Local Variables:
 231   c-file-style: "gnu"
 232   End:
 233 */