libguile/variable.c

   1 /* Copyright (C) 1995,1996,1997,1998,2000,2001 Free Software Foundation, Inc.
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2, or (at your option)
   6  * any later version.
   7  *
   8  * This program 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
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this software; see the file COPYING.  If not, write to
  15  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  16  * Boston, MA 02111-1307 USA
  17  *
  18  * As a special exception, the Free Software Foundation gives permission
  19  * for additional uses of the text contained in its release of GUILE.
  20  *
  21  * The exception is that, if you link the GUILE library with other files
  22  * to produce an executable, this does not by itself cause the
  23  * resulting executable to be covered by the GNU General Public License.
  24  * Your use of that executable is in no way restricted on account of
  25  * linking the GUILE library code into it.
  26  *
  27  * This exception does not however invalidate any other reasons why
  28  * the executable file might be covered by the GNU General Public License.
  29  *
  30  * This exception applies only to the code released by the
  31  * Free Software Foundation under the name GUILE.  If you copy
  32  * code from other Free Software Foundation releases into a copy of
  33  * GUILE, as the General Public License permits, the exception does
  34  * not apply to the code that you add in this way.  To avoid misleading
  35  * anyone as to the status of such modified files, you must delete
  36  * this exception notice from them.
  37  *
  38  * If you write modifications of your own for GUILE, it is your choice
  39  * whether to permit this exception to apply to your modifications.
  40  * If you do not wish that, delete this exception notice.  */
  41
  42 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
  43    gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
  44
  45 \f
  46
  47 #include "libguile/_scm.h"
  48 #include "libguile/eq.h"
  49 #include "libguile/ports.h"
  50 #include "libguile/root.h"
  51 #include "libguile/smob.h"
  52 #include "libguile/deprecation.h"
  53
  54 #include "libguile/validate.h"
  55 #include "libguile/variable.h"
  56 \f
  57 scm_t_bits scm_tc16_variable;
  58
  59 static int
  60 variable_print (SCM exp, SCM port, scm_print_state *pstate)
  61 {
  62   scm_puts ("#<variable ", port);
  63   scm_intprint (SCM_UNPACK (exp), 16, port);
  64   scm_puts (" binding: ", port);
  65   scm_iprin1 (SCM_VARIABLE_REF (exp), port, pstate);
  66   scm_putc('>', port);
  67   return 1;
  68 }
  69
  70 static SCM
  71 variable_equalp (SCM var1, SCM var2)
  72 {
  73   return scm_equal_p (SCM_VARIABLE_REF (var1), SCM_VARIABLE_REF (var2));
  74 }
  75 \f
  76
  77 #if SCM_ENABLE_VCELLS
  78 SCM_SYMBOL (sym_huh, "???");
  79 #endif
  80
  81 static SCM
  82 make_variable (SCM init)
  83 {
  84 #if !SCM_ENABLE_VCELLS
  85   SCM_RETURN_NEWSMOB (scm_tc16_variable, SCM_UNPACK (init));
  86 #else
  87   SCM_RETURN_NEWSMOB (scm_tc16_variable, scm_cons (sym_huh, init));
  88 #endif
  89 }
  90
  91 SCM_DEFINE (scm_make_variable, "make-variable", 1, 0, 0,
  92             (SCM init),
  93             "Return a variable initialized to value @var{init}.\n")
  94 #define FUNC_NAME s_scm_make_variable
  95 {
  96   return make_variable (init);
  97 }
  98 #undef FUNC_NAME
  99
 100
 101 SCM_DEFINE (scm_make_undefined_variable, "make-undefined-variable", 0, 0, 0,
 102             (),
 103             "Return a variable that is initially unbound.\n")
 104 #define FUNC_NAME s_scm_make_undefined_variable
 105 {
 106   return make_variable (SCM_UNDEFINED);
 107 }
 108 #undef FUNC_NAME
 109
 110
 111 SCM_DEFINE (scm_variable_p, "variable?", 1, 0, 0,
 112             (SCM obj),
 113             "Return @code{#t} iff @var{obj} is a variable object, else\n"
 114             "return @code{#f}\n")
 115 #define FUNC_NAME s_scm_variable_p
 116 {
 117   return SCM_BOOL (SCM_VARIABLEP (obj));
 118 }
 119 #undef FUNC_NAME
 120
 121
 122 SCM_DEFINE (scm_variable_ref, "variable-ref", 1, 0, 0,
 123             (SCM var),
 124             "Dereference @var{var} and return its value.\n"
 125             "@var{var} must be a variable object; see @code{make-variable}\n"
 126             "and @code{make-undefined-variable}.")
 127 #define FUNC_NAME s_scm_variable_ref
 128 {
 129   SCM val;
 130   SCM_VALIDATE_VARIABLE (1, var);
 131   val = SCM_VARIABLE_REF (var);
 132   if (val == SCM_UNDEFINED)
 133     SCM_MISC_ERROR ("variable is unbound: ~S", SCM_LIST1 (var));
 134   return val;
 135 }
 136 #undef FUNC_NAME
 137
 138 SCM_DEFINE (scm_variable_set_x, "variable-set!", 2, 0, 0,
 139             (SCM var, SCM val),
 140             "Set the value of the variable @var{var} to @var{val}.\n"
 141             "@var{var} must be a variable object, @var{val} can be any\n"
 142             "value. Return an unspecified value.\n")
 143 #define FUNC_NAME s_scm_variable_set_x
 144 {
 145   SCM_VALIDATE_VARIABLE (1, var);
 146   SCM_VARIABLE_SET (var, val);
 147   return SCM_UNSPECIFIED;
 148 }
 149 #undef FUNC_NAME
 150
 151 SCM_DEFINE (scm_variable_bound_p, "variable-bound?", 1, 0, 0,
 152             (SCM var),
 153             "Return @code{#t} iff @var{var} is bound to a value.\n"
 154             "Throws an error if @var{var} is not a variable object.\n")
 155 #define FUNC_NAME s_scm_variable_bound_p
 156 {
 157   SCM_VALIDATE_VARIABLE (1, var);
 158   return SCM_BOOL (SCM_VARIABLE_REF (var) != SCM_UNDEFINED);
 159 }
 160 #undef FUNC_NAME
 161
 162 SCM_DEFINE (scm_variable_set_name_hint, "variable-set-name-hint!", 2, 0, 0,
 163             (SCM var, SCM hint),
 164             "Do not use this function.")
 165 #define FUNC_NAME s_scm_variable_set_name_hint
 166 {
 167   SCM_VALIDATE_VARIABLE (1, var);
 168   SCM_VALIDATE_SYMBOL (2, hint);
 169 #if SCM_ENABLE_VCELLS
 170   SCM_SETCAR (SCM_SMOB_DATA (var), hint);
 171 #endif
 172   return SCM_UNSPECIFIED;
 173 }
 174 #undef FUNC_NAME
 175
 176 #if SCM_ENABLE_VCELLS
 177
 178 SCM_DEFINE (scm_builtin_variable, "builtin-variable", 1, 0, 0,
 179             (SCM name),
 180             "Return the built-in variable with the name @var{name}.\n"
 181             "@var{name} must be a symbol (not a string).\n"
 182             "Then use @code{variable-ref} to access its value.\n")
 183 #define FUNC_NAME s_scm_builtin_variable
 184 {
 185   SCM_VALIDATE_SYMBOL (1,name);
 186   scm_c_issue_deprecation_warning ("`builtin-variable' is deprecated. "
 187                                    "Use module system operations instead.");
 188   return scm_sym2var (name, SCM_BOOL_F, SCM_BOOL_T);
 189 }
 190 #undef FUNC_NAME
 191
 192 #endif /* SCM_ENABLE_VCELLS */
 193
 194 void
 195 scm_init_variable ()
 196 {
 197   scm_tc16_variable = scm_make_smob_type ("variable", 0);
 198   scm_set_smob_mark (scm_tc16_variable, scm_markcdr);
 199   scm_set_smob_print (scm_tc16_variable, variable_print);
 200   scm_set_smob_equalp (scm_tc16_variable, variable_equalp);
 201
 202 #ifndef SCM_MAGIC_SNARFER
 203 #include "libguile/variable.x"
 204 #endif
 205 }
 206
 207 /*
 208   Local Variables:
 209   c-file-style: "gnu"
 210   End:
 211 */