libguile/properties.c

   1 /* Copyright (C) 1995,1996,2000,2001 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/hashtab.h"
  49 #include "libguile/alist.h"
  50 #include "libguile/root.h"
  51 #include "libguile/weaks.h"
  52 #include "libguile/validate.h"
  53 #include "libguile/eval.h"
  54
  55 #include "libguile/properties.h"
  56 \f
  57
  58 /* {Properties}
  59  */
  60
  61 SCM_DEFINE (scm_primitive_make_property, "primitive-make-property", 1, 0, 0,
  62             (SCM not_found_proc),
  63             "Create a @dfn{property token} that can be used with\n"
  64             "@code{primitive-property-ref} and @code{primitive-property-set!}.\n"
  65             "See @code{primitive-property-ref} for the significance of\n"
  66             "@var{not_found_proc}.")
  67 #define FUNC_NAME s_scm_primitive_make_property
  68 {
  69   if (not_found_proc != SCM_BOOL_F)
  70     SCM_VALIDATE_PROC (SCM_ARG1, not_found_proc);
  71   return scm_cons (not_found_proc, SCM_EOL);
  72 }
  73 #undef FUNC_NAME
  74
  75
  76 SCM_DEFINE (scm_primitive_property_ref, "primitive-property-ref", 2, 0, 0,
  77             (SCM prop, SCM obj),
  78             "Return the property @var{prop} of @var{obj}.  When no value\n"
  79             "has yet been associated with @var{prop} and @var{obj}, call\n"
  80             "@var{not-found-proc} instead (see @code{primitive-make-property})\n"
  81             "and use its return value.  That value is also associated with\n"
  82             "@var{obj} via @code{primitive-property-set!}.  When\n"
  83             "@var{not-found-proc} is @code{#f}, use @code{#f} as the\n"
  84             "default value of @var{prop}.")
  85 #define FUNC_NAME s_scm_primitive_property_ref
  86 {
  87   SCM h;
  88
  89   SCM_VALIDATE_CONS (SCM_ARG1, prop);
  90
  91   h = scm_hashq_get_handle (scm_properties_whash, obj);
  92   if (!SCM_FALSEP (h))
  93     {
  94       SCM assoc = scm_assq (prop, SCM_CDR (h));
  95       if (!SCM_FALSEP (assoc))
  96         return SCM_CDR (assoc);
  97     }
  98
  99   if (SCM_FALSEP (SCM_CAR (prop)))
 100     return SCM_BOOL_F;
 101   else
 102     {
 103       SCM val = scm_call_2 (SCM_CAR (prop), prop, obj);
 104       if (SCM_FALSEP (h))
 105         h = scm_hashq_create_handle_x (scm_properties_whash, obj, SCM_EOL);
 106       SCM_SETCDR (h, scm_acons (prop, val, SCM_CDR (h)));
 107       return val;
 108     }
 109 }
 110 #undef FUNC_NAME
 111
 112
 113 SCM_DEFINE (scm_primitive_property_set_x, "primitive-property-set!", 3, 0, 0,
 114             (SCM prop, SCM obj, SCM val),
 115             "Associate @var{code} with @var{prop} and @var{obj}.")
 116 #define FUNC_NAME s_scm_primitive_property_set_x
 117 {
 118   SCM h, assoc;
 119   SCM_VALIDATE_CONS (SCM_ARG1, prop);
 120   h = scm_hashq_create_handle_x (scm_properties_whash, obj, SCM_EOL);
 121   assoc = scm_assq (prop, SCM_CDR (h));
 122   if (SCM_NIMP (assoc))
 123     SCM_SETCDR (assoc, val);
 124   else
 125     {
 126       assoc = scm_acons (prop, val, SCM_CDR (h));
 127       SCM_SETCDR (h, assoc);
 128     }
 129   return SCM_UNSPECIFIED;
 130 }
 131 #undef FUNC_NAME
 132
 133
 134 SCM_DEFINE (scm_primitive_property_del_x, "primitive-property-del!", 2, 0, 0,
 135             (SCM prop, SCM obj),
 136             "Remove any value associated with @var{prop} and @var{obj}.")
 137 #define FUNC_NAME s_scm_primitive_property_del_x
 138 {
 139   SCM h;
 140   SCM_VALIDATE_CONS (SCM_ARG1, prop);
 141   h = scm_hashq_get_handle (scm_properties_whash, obj);
 142   if (!SCM_FALSEP (h))
 143     SCM_SETCDR (h, scm_assq_remove_x (SCM_CDR (h), prop));
 144   return SCM_UNSPECIFIED;
 145 }
 146 #undef FUNC_NAME
 147
 148
 149 void
 150 scm_init_properties ()
 151 {
 152   scm_properties_whash = scm_make_weak_key_hash_table (SCM_MAKINUM (511));
 153 #ifndef SCM_MAGIC_SNARFER
 154 #include "libguile/properties.x"
 155 #endif
 156 }
 157
 158
 159 /*
 160   Local Variables:
 161   c-file-style: "gnu"
 162   End:
 163 */