libguile/values.c

   1 /* Copyright (C) 2000, 2001, 2006, 2008, 2009, 2011, 2012 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 #ifdef HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22
  23 #include "libguile/_scm.h"
  24 #include "libguile/eval.h"
  25 #include "libguile/feature.h"
  26 #include "libguile/gc.h"
  27 #include "libguile/numbers.h"
  28 #include "libguile/ports.h"
  29 #include "libguile/root.h"
  30 #include "libguile/strings.h"
  31 #include "libguile/struct.h"
  32 #include "libguile/validate.h"
  33
  34 #include "libguile/values.h"
  35
  36 SCM scm_values_vtable;
  37
  38 /* OBJ must be a values object containing exactly two values.
  39    scm_i_extract_values_2 puts those two values into *p1 and *p2.  */
  40 void
  41 scm_i_extract_values_2 (SCM obj, SCM *p1, SCM *p2)
  42 {
  43   SCM values;
  44
  45   SCM_ASSERT_TYPE (SCM_VALUESP (obj), obj, SCM_ARG1,
  46                    "scm_i_extract_values_2", "values");
  47   values = scm_struct_ref (obj, SCM_INUM0);
  48   if (scm_ilength (values) != 2)
  49     scm_wrong_type_arg_msg
  50       ("scm_i_extract_values_2", SCM_ARG1, obj,
  51        "a values object containing exactly two values");
  52   *p1 = SCM_CAR (values);
  53   *p2 = SCM_CADR (values);
  54 }
  55
  56 static SCM
  57 print_values (SCM obj, SCM pwps)
  58 {
  59   SCM values = scm_struct_ref (obj, SCM_INUM0);
  60   SCM port = SCM_PORT_WITH_PS_PORT (pwps);
  61   scm_print_state *ps = SCM_PRINT_STATE (SCM_PORT_WITH_PS_PS (pwps));
  62
  63   scm_puts_unlocked ("#<values ", port);
  64   scm_iprin1 (values, port, ps);
  65   scm_puts_unlocked (">", port);
  66
  67   return SCM_UNSPECIFIED;
  68 }
  69
  70 size_t
  71 scm_c_nvalues (SCM obj)
  72 {
  73   if (SCM_LIKELY (SCM_VALUESP (obj)))
  74     return scm_ilength (scm_struct_ref (obj, SCM_INUM0));
  75   else
  76     return 1;
  77 }
  78
  79 SCM
  80 scm_c_value_ref (SCM obj, size_t idx)
  81 {
  82   if (SCM_LIKELY (SCM_VALUESP (obj)))
  83     {
  84       SCM values = scm_struct_ref (obj, SCM_INUM0);
  85       size_t i = idx;
  86       while (SCM_LIKELY (scm_is_pair (values)))
  87         {
  88           if (i == 0)
  89             return SCM_CAR (values);
  90           values = SCM_CDR (values);
  91           i--;
  92         }
  93     }
  94   else if (idx == 0)
  95     return obj;
  96
  97   scm_error (scm_out_of_range_key,
  98              "scm_c_value_ref",
  99              "Too few values in ~S to access index ~S",
 100              scm_list_2 (obj, scm_from_size_t (idx)),
 101              scm_list_1 (scm_from_size_t (idx)));
 102 }
 103
 104 SCM_DEFINE (scm_values, "values", 0, 0, 1,
 105             (SCM args),
 106             "Delivers all of its arguments to its continuation.  Except for\n"
 107             "continuations created by the @code{call-with-values} procedure,\n"
 108             "all continuations take exactly one value.  The effect of\n"
 109             "passing no value or more than one value to continuations that\n"
 110             "were not created by @code{call-with-values} is unspecified.")
 111 #define FUNC_NAME s_scm_values
 112 {
 113   long n;
 114   SCM result;
 115
 116   SCM_VALIDATE_LIST_COPYLEN (1, args, n);
 117   if (n == 1)
 118     result = SCM_CAR (args);
 119   else
 120     result = scm_c_make_struct (scm_values_vtable, 0, 1, SCM_UNPACK (args));
 121
 122   return result;
 123 }
 124 #undef FUNC_NAME
 125
 126 SCM
 127 scm_c_values (SCM *base, size_t nvalues)
 128 {
 129   SCM ret, *walk;
 130
 131   if (nvalues == 1)
 132     return *base;
 133
 134   for (ret = SCM_EOL, walk = base + nvalues - 1; walk >= base; walk--)
 135     ret = scm_cons (*walk, ret);
 136
 137   return scm_values (ret);
 138 }
 139
 140 void
 141 scm_init_values (void)
 142 {
 143   SCM print = scm_c_define_gsubr ("%print-values", 2, 0, 0, print_values);
 144
 145   scm_values_vtable = scm_make_vtable (scm_from_locale_string ("pr"), print);
 146
 147   scm_add_feature ("values");
 148
 149 #include "libguile/values.x"
 150 }
 151
 152 /*
 153   Local Variables:
 154   c-file-style: "gnu"
 155   End:
 156 */