guile/libguile/properties.c

/* Copyright (C) 1995,1996,2000,2001 Free Software Foundation, Inc.
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this software; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307 USA
 *
 * As a special exception, the Free Software Foundation gives permission
 * for additional uses of the text contained in its release of GUILE.
 *
 * The exception is that, if you link the GUILE library with other files
 * to produce an executable, this does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * Your use of that executable is in no way restricted on account of
 * linking the GUILE library code into it.
 *
 * This exception does not however invalidate any other reasons why
 * the executable file might be covered by the GNU General Public License.
 *
 * This exception applies only to the code released by the
 * Free Software Foundation under the name GUILE.  If you copy
 * code from other Free Software Foundation releases into a copy of
 * GUILE, as the General Public License permits, the exception does
 * not apply to the code that you add in this way.  To avoid misleading
 * anyone as to the status of such modified files, you must delete
 * this exception notice from them.
 *
 * If you write modifications of your own for GUILE, it is your choice
 * whether to permit this exception to apply to your modifications.
 * If you do not wish that, delete this exception notice.  */

/* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
   gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */



#include "libguile/_scm.h"
#include "libguile/hashtab.h"
#include "libguile/alist.h"
#include "libguile/root.h"
#include "libguile/weaks.h"
#include "libguile/validate.h"
#include "libguile/eval.h"

#include "libguile/properties.h"


/* {Properties}
 */

SCM_DEFINE (scm_primitive_make_property, "primitive-make-property", 1, 0, 0,
	    (SCM not_found_proc),
	    "Create a @dfn{property token} that can be used with\n"
	    "@code{primitive-property-ref} and @code{primitive-property-set!}.\n"
	    "See @code{primitive-property-ref} for the significance of\n"
	    "@var{not_found_proc}.")
#define FUNC_NAME s_scm_primitive_make_property
{
  if (not_found_proc != SCM_BOOL_F)
    SCM_VALIDATE_PROC (SCM_ARG1, not_found_proc);
  return scm_cons (not_found_proc, SCM_EOL);
}
#undef FUNC_NAME


SCM_DEFINE (scm_primitive_property_ref, "primitive-property-ref", 2, 0, 0,
	    (SCM prop, SCM obj),
	    "Return the property @var{prop} of @var{obj}.  When no value\n"
            "has yet been associated with @var{prop} and @var{obj}, call\n"
	    "@var{not-found-proc} instead (see @code{primitive-make-property})\n"
	    "and use its return value.  That value is also associated with\n"
	    "@var{obj} via @code{primitive-property-set!}.  When\n"
            "@var{not-found-proc} is @code{#f}, use @code{#f} as the\n"
	    "default value of @var{prop}.")
#define FUNC_NAME s_scm_primitive_property_ref
{
  SCM h;

  SCM_VALIDATE_CONS (SCM_ARG1, prop);

  h = scm_hashq_get_handle (scm_properties_whash, obj);
  if (!SCM_FALSEP (h))
    {
      SCM assoc = scm_assq (prop, SCM_CDR (h));
      if (!SCM_FALSEP (assoc))
	return SCM_CDR (assoc);
    }

  if (SCM_FALSEP (SCM_CAR (prop)))
    return SCM_BOOL_F;
  else
    {
      SCM val = scm_apply (SCM_CAR (prop), SCM_LIST2 (prop, obj), SCM_EOL);
      if (SCM_FALSEP (h))
	h = scm_hashq_create_handle_x (scm_properties_whash, obj, SCM_EOL);
      SCM_SETCDR (h, scm_acons (prop, val, SCM_CDR (h)));
      return val;
    }
}
#undef FUNC_NAME


SCM_DEFINE (scm_primitive_property_set_x, "primitive-property-set!", 3, 0, 0,
	    (SCM prop, SCM obj, SCM val),
	    "Associate @var{code} with @var{prop} and @var{obj}.")
#define FUNC_NAME s_scm_primitive_property_set_x
{
  SCM h, assoc;
  SCM_VALIDATE_CONS (SCM_ARG1, prop);
  h = scm_hashq_create_handle_x (scm_properties_whash, obj, SCM_EOL);
  assoc = scm_assq (prop, SCM_CDR (h));
  if (SCM_NIMP (assoc))
    SCM_SETCDR (assoc, val);
  else
    {
      assoc = scm_acons (prop, val, SCM_CDR (h));
      SCM_SETCDR (h, assoc);
    }
  return SCM_UNSPECIFIED;
}
#undef FUNC_NAME


SCM_DEFINE (scm_primitive_property_del_x, "primitive-property-del!", 2, 0, 0,
	    (SCM prop, SCM obj),
	    "Remove any value associated with @var{prop} and @var{obj}.")
#define FUNC_NAME s_scm_primitive_property_del_x
{
  SCM h;
  SCM_VALIDATE_CONS (SCM_ARG1, prop);
  h = scm_hashq_get_handle (scm_properties_whash, obj);
  if (!SCM_FALSEP (h))
    SCM_SETCDR (h, scm_assq_remove_x (SCM_CDR (h), prop));
  return SCM_UNSPECIFIED;
}
#undef FUNC_NAME


void
scm_init_properties ()
{
  scm_properties_whash = scm_make_weak_key_hash_table (SCM_MAKINUM (511));
#ifndef SCM_MAGIC_SNARFER
#include "libguile/properties.x"
#endif
}


/*
  Local Variables:
  c-file-style: "gnu"
  End:
*/