libguile/vports.c

   1 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2002, 2003, 2006, 2009, 2010 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   if (pt->write_pos > pt->write_buf)
  60     {
  61       /* write the byte. */
  62       scm_call_1 (SCM_SIMPLE_VECTOR_REF (stream, 0),
  63                   SCM_MAKE_CHAR (*pt->write_buf));
  64       pt->write_pos = pt->write_buf;
  65
  66       /* flush the output.  */
  67       {
  68         SCM f = SCM_SIMPLE_VECTOR_REF (stream, 2);
  69
  70         if (scm_is_true (f))
  71           scm_call_0 (f);
  72       }
  73     }
  74 }
  75
  76 static void
  77 sf_write (SCM port, const void *data, size_t size)
  78 {
  79   SCM p = SCM_PACK (SCM_STREAM (port));
  80
  81   /* DATA is assumed to be a locale-encoded C string, which makes it
  82      hard to reliably pass binary data to a soft port.  It can be
  83      achieved by choosing a Latin-1 locale, though, but the recommended
  84      approach is to use an R6RS "custom binary output port" instead.  */
  85   scm_call_1 (SCM_SIMPLE_VECTOR_REF (p, 1),
  86               scm_from_locale_stringn ((char *) data, size));
  87 }
  88
  89 /* calling the flush proc (element 2) is in case old code needs it,
  90    but perhaps softports could the use port buffer in the same way as
  91    fports.  */
  92
  93 /* places a single char in the input buffer.  */
  94 static int
  95 sf_fill_input (SCM port)
  96 {
  97   SCM p = SCM_PACK (SCM_STREAM (port));
  98   SCM ans;
  99   scm_t_port *pt;
 100
 101   ans = scm_call_0 (SCM_SIMPLE_VECTOR_REF (p, 3)); /* get char.  */
 102   if (scm_is_false (ans) || SCM_EOF_OBJECT_P (ans))
 103     return EOF;
 104   SCM_ASSERT (SCM_CHARP (ans), ans, SCM_ARG1, "sf_fill_input");
 105   pt = SCM_PTAB_ENTRY (port);
 106
 107   if (pt->encoding == NULL)
 108     {
 109       scm_t_port *pt = SCM_PTAB_ENTRY (port);
 110
 111       *pt->read_buf = SCM_CHAR (ans);
 112       pt->read_pos = pt->read_buf;
 113       pt->read_end = pt->read_buf + 1;
 114       return *pt->read_buf;
 115     }
 116   else
 117     scm_ungetc (SCM_CHAR (ans), port);
 118   return SCM_CHAR (ans);
 119 }
 120
 121
 122 static int
 123 sf_close (SCM port)
 124 {
 125   SCM p = SCM_PACK (SCM_STREAM (port));
 126   SCM f = SCM_SIMPLE_VECTOR_REF (p, 4);
 127   if (scm_is_false (f))
 128     return 0;
 129   f = scm_call_0 (f);
 130   errno = 0;
 131   return scm_is_false (f) ? EOF : 0;
 132 }
 133
 134
 135 static int
 136 sf_input_waiting (SCM port)
 137 {
 138   SCM p = SCM_PACK (SCM_STREAM (port));
 139   if (SCM_SIMPLE_VECTOR_LENGTH (p) >= 6)
 140     {
 141       SCM f = SCM_SIMPLE_VECTOR_REF (p, 5);
 142       if (scm_is_true (f))
 143         return scm_to_int (scm_call_0 (f));
 144     }
 145   /* Default is such that char-ready? for soft ports returns #t, as it
 146      did before this extension was implemented. */
 147   return 1;
 148 }
 149
 150
 151
 152 SCM_DEFINE (scm_make_soft_port, "make-soft-port", 2, 0, 0,
 153            (SCM pv, SCM modes),
 154             "Return a port capable of receiving or delivering characters as\n"
 155             "specified by the @var{modes} string (@pxref{File Ports,\n"
 156             "open-file}).  @var{pv} must be a vector of length 5 or 6.  Its\n"
 157             "components are as follows:\n"
 158             "\n"
 159             "@enumerate 0\n"
 160             "@item\n"
 161             "procedure accepting one character for output\n"
 162             "@item\n"
 163             "procedure accepting a string for output\n"
 164             "@item\n"
 165             "thunk for flushing output\n"
 166             "@item\n"
 167             "thunk for getting one character\n"
 168             "@item\n"
 169             "thunk for closing port (not by garbage collection)\n"
 170             "@item\n"
 171             "(if present and not @code{#f}) thunk for computing the number of\n"
 172             "characters that can be read from the port without blocking.\n"
 173             "@end enumerate\n"
 174             "\n"
 175             "For an output-only port only elements 0, 1, 2, and 4 need be\n"
 176             "procedures.  For an input-only port only elements 3 and 4 need\n"
 177             "be procedures.  Thunks 2 and 4 can instead be @code{#f} if\n"
 178             "there is no useful operation for them to perform.\n"
 179             "\n"
 180             "If thunk 3 returns @code{#f} or an @code{eof-object}\n"
 181             "(@pxref{Input, eof-object?, ,r5rs, The Revised^5 Report on\n"
 182             "Scheme}) it indicates that the port has reached end-of-file.\n"
 183             "For example:\n"
 184             "\n"
 185             "@lisp\n"
 186             "(define stdout (current-output-port))\n"
 187             "(define p (make-soft-port\n"
 188             "           (vector\n"
 189             "            (lambda (c) (write c stdout))\n"
 190             "            (lambda (s) (display s stdout))\n"
 191             "            (lambda () (display \".\" stdout))\n"
 192             "            (lambda () (char-upcase (read-char)))\n"
 193             "            (lambda () (display \"@@\" stdout)))\n"
 194             "           \"rw\"))\n"
 195             "\n"
 196             "(write p p) @result{} #<input-output: soft 8081e20>\n"
 197             "@end lisp")
 198 #define FUNC_NAME s_scm_make_soft_port
 199 {
 200   int vlen;
 201   scm_t_port *pt;
 202   SCM z;
 203
 204   SCM_VALIDATE_VECTOR (1, pv);
 205   vlen = SCM_SIMPLE_VECTOR_LENGTH (pv);
 206   SCM_ASSERT ((vlen == 5) || (vlen == 6), pv, 1, FUNC_NAME);
 207   SCM_VALIDATE_STRING (2, modes);
 208
 209   scm_i_scm_pthread_mutex_lock (&scm_i_port_table_mutex);
 210   z = scm_new_port_table_entry (scm_tc16_sfport);
 211   pt = SCM_PTAB_ENTRY (z);
 212   scm_port_non_buffer (pt);
 213   SCM_SET_CELL_TYPE (z, scm_tc16_sfport | scm_i_mode_bits (modes));
 214
 215   SCM_SETSTREAM (z, SCM_UNPACK (pv));
 216   scm_i_pthread_mutex_unlock (&scm_i_port_table_mutex);
 217   return z;
 218 }
 219 #undef FUNC_NAME
 220
 221
 222 static scm_t_bits
 223 scm_make_sfptob ()
 224 {
 225   scm_t_bits tc = scm_make_port_type ("soft", sf_fill_input, sf_write);
 226
 227   scm_set_port_flush (tc, sf_flush);
 228   scm_set_port_close (tc, sf_close);
 229   scm_set_port_input_waiting (tc, sf_input_waiting);
 230
 231   return tc;
 232 }
 233
 234 void
 235 scm_init_vports ()
 236 {
 237   scm_tc16_sfport = scm_make_sfptob ();
 238
 239 #include "libguile/vports.x"
 240 }
 241
 242 /*
 243   Local Variables:
 244   c-file-style: "gnu"
 245   End:
 246 */