libguile/vports.c

   1 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2002, 2003, 2006, 2009, 2010, 2011, 2013 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 License
   5  * as published by the Free Software Foundation; either version 3 of
   6  * the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * 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
  16  * 02110-1301 USA
  17  */
  18
  19
  20 \f
  21 #ifdef HAVE_CONFIG_H
  22 #  include <config.h>
  23 #endif
  24
  25 #include <stdio.h>
  26 #include <errno.h>
  27
  28 #include "libguile/_scm.h"
  29 #include "libguile/eval.h"
  30 #include "libguile/chars.h"
  31 #include "libguile/ports.h"
  32 #include "libguile/ports-internal.h"
  33 #include "libguile/fports.h"
  34 #include "libguile/root.h"
  35 #include "libguile/strings.h"
  36 #include "libguile/vectors.h"
  37
  38 #include "libguile/validate.h"
  39 #include "libguile/vports.h"
  40
  41 #ifdef HAVE_STRING_H
  42 #include <string.h>
  43 #endif
  44
  45 \f
  46
  47 /* {Ports - soft ports}
  48  *
  49  */
  50
  51
  52 static scm_t_bits scm_tc16_sfport;
  53
  54
  55 static void
  56 sf_flush (SCM port)
  57 {
  58   scm_t_port *pt = SCM_PTAB_ENTRY (port);
  59   SCM stream = SCM_PACK (pt->stream);
  60
  61   SCM f = SCM_SIMPLE_VECTOR_REF (stream, 2);
  62
  63   if (scm_is_true (f))
  64     scm_call_0 (f);
  65
  66 }
  67
  68 static void
  69 sf_write (SCM port, const void *data, size_t size)
  70 {
  71   SCM p = SCM_PACK (SCM_STREAM (port));
  72
  73   /* DATA is assumed to be a locale-encoded C string, which makes it
  74      hard to reliably pass binary data to a soft port.  It can be
  75      achieved by choosing a Latin-1 locale, though, but the recommended
  76      approach is to use an R6RS "custom binary output port" instead.  */
  77   scm_call_1 (SCM_SIMPLE_VECTOR_REF (p, 1),
  78               scm_from_locale_stringn ((char *) data, size));
  79 }
  80
  81 /* calling the flush proc (element 2) is in case old code needs it,
  82    but perhaps softports could the use port buffer in the same way as
  83    fports.  */
  84
  85 /* places a single char in the input buffer.  */
  86 static int
  87 sf_fill_input (SCM port)
  88 {
  89   SCM p = SCM_PACK (SCM_STREAM (port));
  90   SCM ans;
  91   scm_t_port_internal *pti;
  92
  93   ans = scm_call_0 (SCM_SIMPLE_VECTOR_REF (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   pti = SCM_PORT_GET_INTERNAL (port);
  98
  99   if (pti->encoding_mode == SCM_PORT_ENCODING_MODE_LATIN1)
 100     {
 101       scm_t_port *pt = SCM_PTAB_ENTRY (port);
 102
 103       *pt->read_buf = SCM_CHAR (ans);
 104       pt->read_pos = pt->read_buf;
 105       pt->read_end = pt->read_buf + 1;
 106       return *pt->read_buf;
 107     }
 108   else
 109     scm_ungetc_unlocked (SCM_CHAR (ans), port);
 110   return SCM_CHAR (ans);
 111 }
 112
 113
 114 static int
 115 sf_close (SCM port)
 116 {
 117   SCM p = SCM_PACK (SCM_STREAM (port));
 118   SCM f = SCM_SIMPLE_VECTOR_REF (p, 4);
 119   if (scm_is_false (f))
 120     return 0;
 121   f = scm_call_0 (f);
 122   errno = 0;
 123   return scm_is_false (f) ? EOF : 0;
 124 }
 125
 126
 127 static int
 128 sf_input_waiting (SCM port)
 129 {
 130   SCM p = SCM_PACK (SCM_STREAM (port));
 131   if (SCM_SIMPLE_VECTOR_LENGTH (p) >= 6)
 132     {
 133       SCM f = SCM_SIMPLE_VECTOR_REF (p, 5);
 134       if (scm_is_true (f))
 135         return scm_to_int (scm_call_0 (f));
 136     }
 137   /* Default is such that char-ready? for soft ports returns #t, as it
 138      did before this extension was implemented. */
 139   return 1;
 140 }
 141
 142
 143
 144 SCM_DEFINE (scm_make_soft_port, "make-soft-port", 2, 0, 0,
 145            (SCM pv, SCM modes),
 146             "Return a port capable of receiving or delivering characters as\n"
 147             "specified by the @var{modes} string (@pxref{File Ports,\n"
 148             "open-file}).  @var{pv} must be a vector of length 5 or 6.  Its\n"
 149             "components are as follows:\n"
 150             "\n"
 151             "@enumerate 0\n"
 152             "@item\n"
 153             "procedure accepting one character for output\n"
 154             "@item\n"
 155             "procedure accepting a string for output\n"
 156             "@item\n"
 157             "thunk for flushing output\n"
 158             "@item\n"
 159             "thunk for getting one character\n"
 160             "@item\n"
 161             "thunk for closing port (not by garbage collection)\n"
 162             "@item\n"
 163             "(if present and not @code{#f}) thunk for computing the number of\n"
 164             "characters that can be read from the port without blocking.\n"
 165             "@end enumerate\n"
 166             "\n"
 167             "For an output-only port only elements 0, 1, 2, and 4 need be\n"
 168             "procedures.  For an input-only port only elements 3 and 4 need\n"
 169             "be procedures.  Thunks 2 and 4 can instead be @code{#f} if\n"
 170             "there is no useful operation for them to perform.\n"
 171             "\n"
 172             "If thunk 3 returns @code{#f} or an @code{eof-object}\n"
 173             "(@pxref{Input, eof-object?, ,r5rs, The Revised^5 Report on\n"
 174             "Scheme}) it indicates that the port has reached end-of-file.\n"
 175             "For example:\n"
 176             "\n"
 177             "@lisp\n"
 178             "(define stdout (current-output-port))\n"
 179             "(define p (make-soft-port\n"
 180             "           (vector\n"
 181             "            (lambda (c) (write c stdout))\n"
 182             "            (lambda (s) (display s stdout))\n"
 183             "            (lambda () (display \".\" stdout))\n"
 184             "            (lambda () (char-upcase (read-char)))\n"
 185             "            (lambda () (display \"@@\" stdout)))\n"
 186             "           \"rw\"))\n"
 187             "\n"
 188             "(write p p) @result{} #<input-output: soft 8081e20>\n"
 189             "@end lisp")
 190 #define FUNC_NAME s_scm_make_soft_port
 191 {
 192   int vlen;
 193   SCM z;
 194
 195   SCM_VALIDATE_VECTOR (1, pv);
 196   vlen = SCM_SIMPLE_VECTOR_LENGTH (pv);
 197   SCM_ASSERT ((vlen == 5) || (vlen == 6), pv, 1, FUNC_NAME);
 198   SCM_VALIDATE_STRING (2, modes);
 199
 200   z = scm_c_make_port (scm_tc16_sfport, scm_i_mode_bits (modes),
 201                        SCM_UNPACK (pv));
 202   scm_port_non_buffer (SCM_PTAB_ENTRY (z));
 203
 204   return z;
 205 }
 206 #undef FUNC_NAME
 207
 208
 209 static scm_t_bits
 210 scm_make_sfptob ()
 211 {
 212   scm_t_bits tc = scm_make_port_type ("soft", sf_fill_input, sf_write);
 213
 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 */