libguile/vports.c

   1 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2002, 2003, 2006, 2009, 2010, 2011 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/fports.h"
  32 #include "libguile/root.h"
  33 #include "libguile/strings.h"
  34 #include "libguile/vectors.h"
  35
  36 #include "libguile/validate.h"
  37 #include "libguile/vports.h"
  38
  39 #ifdef HAVE_STRING_H
  40 #include <string.h>
  41 #endif
  42
  43 \f
  44
  45 /* {Ports - soft ports}
  46  *
  47  */
  48
  49
  50 static scm_t_bits scm_tc16_sfport;
  51
  52
  53 static void
  54 sf_flush (SCM port)
  55 {
  56   scm_t_port *pt = SCM_PTAB_ENTRY (port);
  57   SCM stream = SCM_PACK (pt->stream);
  58
  59   SCM f = SCM_SIMPLE_VECTOR_REF (stream, 2);
  60
  61   if (scm_is_true (f))
  62     scm_call_0 (f);
  63
  64 }
  65
  66 static void
  67 sf_write (SCM port, const void *data, size_t size)
  68 {
  69   SCM p = SCM_PACK (SCM_STREAM (port));
  70
  71   /* DATA is assumed to be a locale-encoded C string, which makes it
  72      hard to reliably pass binary data to a soft port.  It can be
  73      achieved by choosing a Latin-1 locale, though, but the recommended
  74      approach is to use an R6RS "custom binary output port" instead.  */
  75   scm_call_1 (SCM_SIMPLE_VECTOR_REF (p, 1),
  76               scm_from_locale_stringn ((char *) data, size));
  77 }
  78
  79 /* calling the flush proc (element 2) is in case old code needs it,
  80    but perhaps softports could the use port buffer in the same way as
  81    fports.  */
  82
  83 /* places a single char in the input buffer.  */
  84 static int
  85 sf_fill_input (SCM port)
  86 {
  87   SCM p = SCM_PACK (SCM_STREAM (port));
  88   SCM ans;
  89   scm_t_port *pt;
  90
  91   ans = scm_call_0 (SCM_SIMPLE_VECTOR_REF (p, 3)); /* get char.  */
  92   if (scm_is_false (ans) || SCM_EOF_OBJECT_P (ans))
  93     return EOF;
  94   SCM_ASSERT (SCM_CHARP (ans), ans, SCM_ARG1, "sf_fill_input");
  95   pt = SCM_PTAB_ENTRY (port);
  96
  97   if (pt->encoding == NULL)
  98     {
  99       scm_t_port *pt = SCM_PTAB_ENTRY (port);
 100
 101       *pt->read_buf = SCM_CHAR (ans);
 102       pt->read_pos = pt->read_buf;
 103       pt->read_end = pt->read_buf + 1;
 104       return *pt->read_buf;
 105     }
 106   else
 107     scm_ungetc_unlocked (SCM_CHAR (ans), port);
 108   return SCM_CHAR (ans);
 109 }
 110
 111
 112 static int
 113 sf_close (SCM port)
 114 {
 115   SCM p = SCM_PACK (SCM_STREAM (port));
 116   SCM f = SCM_SIMPLE_VECTOR_REF (p, 4);
 117   if (scm_is_false (f))
 118     return 0;
 119   f = scm_call_0 (f);
 120   errno = 0;
 121   return scm_is_false (f) ? EOF : 0;
 122 }
 123
 124
 125 static int
 126 sf_input_waiting (SCM port)
 127 {
 128   SCM p = SCM_PACK (SCM_STREAM (port));
 129   if (SCM_SIMPLE_VECTOR_LENGTH (p) >= 6)
 130     {
 131       SCM f = SCM_SIMPLE_VECTOR_REF (p, 5);
 132       if (scm_is_true (f))
 133         return scm_to_int (scm_call_0 (f));
 134     }
 135   /* Default is such that char-ready? for soft ports returns #t, as it
 136      did before this extension was implemented. */
 137   return 1;
 138 }
 139
 140
 141
 142 SCM_DEFINE (scm_make_soft_port, "make-soft-port", 2, 0, 0,
 143            (SCM pv, SCM modes),
 144             "Return a port capable of receiving or delivering characters as\n"
 145             "specified by the @var{modes} string (@pxref{File Ports,\n"
 146             "open-file}).  @var{pv} must be a vector of length 5 or 6.  Its\n"
 147             "components are as follows:\n"
 148             "\n"
 149             "@enumerate 0\n"
 150             "@item\n"
 151             "procedure accepting one character for output\n"
 152             "@item\n"
 153             "procedure accepting a string for output\n"
 154             "@item\n"
 155             "thunk for flushing output\n"
 156             "@item\n"
 157             "thunk for getting one character\n"
 158             "@item\n"
 159             "thunk for closing port (not by garbage collection)\n"
 160             "@item\n"
 161             "(if present and not @code{#f}) thunk for computing the number of\n"
 162             "characters that can be read from the port without blocking.\n"
 163             "@end enumerate\n"
 164             "\n"
 165             "For an output-only port only elements 0, 1, 2, and 4 need be\n"
 166             "procedures.  For an input-only port only elements 3 and 4 need\n"
 167             "be procedures.  Thunks 2 and 4 can instead be @code{#f} if\n"
 168             "there is no useful operation for them to perform.\n"
 169             "\n"
 170             "If thunk 3 returns @code{#f} or an @code{eof-object}\n"
 171             "(@pxref{Input, eof-object?, ,r5rs, The Revised^5 Report on\n"
 172             "Scheme}) it indicates that the port has reached end-of-file.\n"
 173             "For example:\n"
 174             "\n"
 175             "@lisp\n"
 176             "(define stdout (current-output-port))\n"
 177             "(define p (make-soft-port\n"
 178             "           (vector\n"
 179             "            (lambda (c) (write c stdout))\n"
 180             "            (lambda (s) (display s stdout))\n"
 181             "            (lambda () (display \".\" stdout))\n"
 182             "            (lambda () (char-upcase (read-char)))\n"
 183             "            (lambda () (display \"@@\" stdout)))\n"
 184             "           \"rw\"))\n"
 185             "\n"
 186             "(write p p) @result{} #<input-output: soft 8081e20>\n"
 187             "@end lisp")
 188 #define FUNC_NAME s_scm_make_soft_port
 189 {
 190   int vlen;
 191   SCM z;
 192
 193   SCM_VALIDATE_VECTOR (1, pv);
 194   vlen = SCM_SIMPLE_VECTOR_LENGTH (pv);
 195   SCM_ASSERT ((vlen == 5) || (vlen == 6), pv, 1, FUNC_NAME);
 196   SCM_VALIDATE_STRING (2, modes);
 197
 198   z = scm_c_make_port (scm_tc16_sfport, scm_i_mode_bits (modes),
 199                        SCM_UNPACK (pv));
 200   scm_port_non_buffer (SCM_PTAB_ENTRY (z));
 201
 202   return z;
 203 }
 204 #undef FUNC_NAME
 205
 206
 207 static scm_t_bits
 208 scm_make_sfptob ()
 209 {
 210   scm_t_bits tc = scm_make_port_type ("soft", sf_fill_input, sf_write);
 211
 212   scm_set_port_flush (tc, sf_flush);
 213   scm_set_port_close (tc, sf_close);
 214   scm_set_port_input_waiting (tc, sf_input_waiting);
 215
 216   return tc;
 217 }
 218
 219 void
 220 scm_init_vports ()
 221 {
 222   scm_tc16_sfport = scm_make_sfptob ();
 223
 224 #include "libguile/vports.x"
 225 }
 226
 227 /*
 228   Local Variables:
 229   c-file-style: "gnu"
 230   End:
 231 */