libguile/vports.c

   1 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2002, 2003, 2006 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18
  19 \f
  20 #ifdef 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_SIMPLE_VECTOR_REF (stream, 0),
  62                   SCM_MAKE_CHAR (*pt->write_buf));
  63       pt->write_pos = pt->write_buf;
  64
  65       /* flush the output.  */
  66       {
  67         SCM f = SCM_SIMPLE_VECTOR_REF (stream, 2);
  68
  69         if (scm_is_true (f))
  70           scm_call_0 (f);
  71       }
  72     }
  73 }
  74
  75 static void
  76 sf_write (SCM port, const void *data, size_t size)
  77 {
  78   SCM p = SCM_PACK (SCM_STREAM (port));
  79
  80   scm_call_1 (SCM_SIMPLE_VECTOR_REF (p, 1),
  81               scm_from_locale_stringn ((char *) data, size));
  82 }
  83
  84 /* calling the flush proc (element 2) is in case old code needs it,
  85    but perhaps softports could the use port buffer in the same way as
  86    fports.  */
  87
  88 /* places a single char in the input buffer.  */
  89 static int
  90 sf_fill_input (SCM port)
  91 {
  92   SCM p = SCM_PACK (SCM_STREAM (port));
  93   SCM ans;
  94
  95   ans = scm_call_0 (SCM_SIMPLE_VECTOR_REF (p, 3)); /* get char.  */
  96   if (scm_is_false (ans) || SCM_EOF_OBJECT_P (ans))
  97     return EOF;
  98   SCM_ASSERT (SCM_CHARP (ans), ans, SCM_ARG1, "sf_fill_input");
  99   {
 100     scm_t_port *pt = SCM_PTAB_ENTRY (port);
 101
 102     *pt->read_buf = SCM_CHAR (ans);
 103     pt->read_pos = pt->read_buf;
 104     pt->read_end = pt->read_buf + 1;
 105     return *pt->read_buf;
 106   }
 107 }
 108
 109
 110 static int
 111 sf_close (SCM port)
 112 {
 113   SCM p = SCM_PACK (SCM_STREAM (port));
 114   SCM f = SCM_SIMPLE_VECTOR_REF (p, 4);
 115   if (scm_is_false (f))
 116     return 0;
 117   f = scm_call_0 (f);
 118   errno = 0;
 119   return scm_is_false (f) ? EOF : 0;
 120 }
 121
 122
 123 static int
 124 sf_input_waiting (SCM port)
 125 {
 126   SCM p = SCM_PACK (SCM_STREAM (port));
 127   if (SCM_SIMPLE_VECTOR_LENGTH (p) >= 6)
 128     {
 129       SCM f = SCM_SIMPLE_VECTOR_REF (p, 5);
 130       if (scm_is_true (f))
 131         return scm_to_int (scm_call_0 (f));
 132     }
 133   /* Default is such that char-ready? for soft ports returns #t, as it
 134      did before this extension was implemented. */
 135   return 1;
 136 }
 137
 138
 139
 140 SCM_DEFINE (scm_make_soft_port, "make-soft-port", 2, 0, 0,
 141            (SCM pv, SCM modes),
 142             "Return a port capable of receiving or delivering characters as\n"
 143             "specified by the @var{modes} string (@pxref{File Ports,\n"
 144             "open-file}).  @var{pv} must be a vector of length 5 or 6.  Its\n"
 145             "components are as follows:\n"
 146             "\n"
 147             "@enumerate 0\n"
 148             "@item\n"
 149             "procedure accepting one character for output\n"
 150             "@item\n"
 151             "procedure accepting a string for output\n"
 152             "@item\n"
 153             "thunk for flushing output\n"
 154             "@item\n"
 155             "thunk for getting one character\n"
 156             "@item\n"
 157             "thunk for closing port (not by garbage collection)\n"
 158             "@item\n"
 159             "(if present and not @code{#f}) thunk for computing the number of\n"
 160             "characters that can be read from the port without blocking.\n"
 161             "@end enumerate\n"
 162             "\n"
 163             "For an output-only port only elements 0, 1, 2, and 4 need be\n"
 164             "procedures.  For an input-only port only elements 3 and 4 need\n"
 165             "be procedures.  Thunks 2 and 4 can instead be @code{#f} if\n"
 166             "there is no useful operation for them to perform.\n"
 167             "\n"
 168             "If thunk 3 returns @code{#f} or an @code{eof-object}\n"
 169             "(@pxref{Input, eof-object?, ,r5rs, The Revised^5 Report on\n"
 170             "Scheme}) it indicates that the port has reached end-of-file.\n"
 171             "For example:\n"
 172             "\n"
 173             "@lisp\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"
 183             "\n"
 184             "(write p p) @result{} #<input-output: soft 8081e20>\n"
 185             "@end lisp")
 186 #define FUNC_NAME s_scm_make_soft_port
 187 {
 188   int vlen;
 189   scm_t_port *pt;
 190   SCM z;
 191
 192   SCM_VALIDATE_VECTOR (1, pv);
 193   vlen = SCM_SIMPLE_VECTOR_LENGTH (pv);
 194   SCM_ASSERT ((vlen == 5) || (vlen == 6), pv, 1, FUNC_NAME);
 195   SCM_VALIDATE_STRING (2, modes);
 196
 197   scm_i_scm_pthread_mutex_lock (&scm_i_port_table_mutex);
 198   z = scm_new_port_table_entry (scm_tc16_sfport);
 199   pt = SCM_PTAB_ENTRY (z);
 200   scm_port_non_buffer (pt);
 201   SCM_SET_CELL_TYPE (z, scm_tc16_sfport | scm_i_mode_bits (modes));
 202
 203   SCM_SETSTREAM (z, SCM_UNPACK (pv));
 204   scm_i_pthread_mutex_unlock (&scm_i_port_table_mutex);
 205   return z;
 206 }
 207 #undef FUNC_NAME
 208
 209
 210 static scm_t_bits
 211 scm_make_sfptob ()
 212 {
 213   scm_t_bits tc = scm_make_port_type ("soft", sf_fill_input, sf_write);
 214
 215   scm_set_port_mark (tc, scm_markstream);
 216   scm_set_port_flush (tc, sf_flush);
 217   scm_set_port_close (tc, sf_close);
 218   scm_set_port_input_waiting (tc, sf_input_waiting);
 219
 220   return tc;
 221 }
 222
 223 void
 224 scm_init_vports ()
 225 {
 226   scm_tc16_sfport = scm_make_sfptob ();
 227
 228 #include "libguile/vports.x"
 229 }
 230
 231 /*
 232   Local Variables:
 233   c-file-style: "gnu"
 234   End:
 235 */