1/* gc.c -- Functions to remember and garbage collect unused node contents.
2   $Id: gc.c,v 1.3 2004/04/11 17:56:45 karl Exp $
3
4   Copyright (C) 1993, 2004 Free Software Foundation, Inc.
5
6   This program is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 2, or (at your option)
9   any later version.
10
11   This program is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   You should have received a copy of the GNU General Public License
17   along with this program; if not, write to the Free Software
18   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19
20   Written by Brian Fox (bfox@ai.mit.edu). */
21
22#include "info.h"
23
24/* Array of pointers to the contents of gc-able nodes.  A pointer on this
25   list can be garbage collected when no info window contains a node whose
26   contents member match the pointer. */
27static char **gcable_pointers = (char **)NULL;
28static int gcable_pointers_index = 0;
29static int gcable_pointers_slots = 0;
30
31/* Add POINTER to the list of garbage collectible pointers.  A pointer
32   is not actually garbage collected until no info window contains a node
33   whose contents member is equal to the pointer. */
34void
35add_gcable_pointer (char *pointer)
36{
37  gc_pointers ();
38  add_pointer_to_array (pointer, gcable_pointers_index, gcable_pointers,
39			gcable_pointers_slots, 10, char *);
40}
41
42/* Grovel the list of info windows and gc-able pointers finding those
43   node->contents which are collectible, and free them. */
44void
45gc_pointers (void)
46{
47  register int i, j, k;
48  INFO_WINDOW *iw;
49  char **new = (char **)NULL;
50  int new_index = 0;
51  int new_slots = 0;
52
53  if (!info_windows || !gcable_pointers_index)
54    return;
55
56  for (i = 0; (iw = info_windows[i]); i++)
57    {
58      for (j = 0; j < iw->nodes_index; j++)
59	{
60	  NODE *node = iw->nodes[j];
61
62	  /* If this node->contents appears in our list of gcable_pointers,
63	     it is not gc-able, so save it. */
64	  for (k = 0; k < gcable_pointers_index; k++)
65	    if (gcable_pointers[k] == node->contents)
66	      {
67		add_pointer_to_array
68		  (node->contents, new_index, new, new_slots, 10, char *);
69		break;
70	      }
71	}
72    }
73
74  /* We have gathered all of the pointers which need to be saved.  Free any
75     of the original pointers which do not appear in the new list. */
76  for (i = 0; i < gcable_pointers_index; i++)
77    {
78      for (j = 0; j < new_index; j++)
79	if (gcable_pointers[i] == new[j])
80	  break;
81
82      /* If we got all the way through the new list, then the old pointer
83	 can be garbage collected. */
84      if (new && !new[j])
85	free (gcable_pointers[i]);
86    }
87
88  free (gcable_pointers);
89  gcable_pointers = new;
90  gcable_pointers_slots = new_slots;
91  gcable_pointers_index = new_index;
92}
93