aboutsummaryrefslogtreecommitdiff
path: root/libiberty/splay-tree.c
blob: 22ea07d84adb5eada30579685da96e21d99f6841 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
/* A splay-tree datatype.  
   Copyright (C) 1998, 1999 Free Software Foundation, Inc.
   Contributed by Mark Mitchell (mark@markmitchell.com).

This file is part of GNU CC.
   
GNU CC 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.

GNU CC 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 GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* For an easily readable description of splay-trees, see:

     Lewis, Harry R. and Denenberg, Larry.  Data Structures and Their
     Algorithms.  Harper-Collins, Inc.  1991.  */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif

#include "libiberty.h"
#include "splay-tree.h"

static void splay_tree_delete_helper    PARAMS((splay_tree, 
						splay_tree_node));
static void splay_tree_splay            PARAMS((splay_tree,
						splay_tree_key));
static splay_tree_node splay_tree_splay_helper     
                                        PARAMS((splay_tree,
						splay_tree_key,
						splay_tree_node*,
						splay_tree_node*,
						splay_tree_node*));
static int splay_tree_foreach_helper    PARAMS((splay_tree,
					        splay_tree_node,
						splay_tree_foreach_fn,
						void*));

/* Deallocate NODE (a member of SP), and all its sub-trees.  */

static void 
splay_tree_delete_helper (sp, node)
     splay_tree sp;
     splay_tree_node node;
{
  if (!node)
    return;

  splay_tree_delete_helper (sp, node->left);
  splay_tree_delete_helper (sp, node->right);

  if (sp->delete_key)
    (*sp->delete_key)(node->key);
  if (sp->delete_value)
    (*sp->delete_value)(node->value);

  free ((char*) node);
}

/* Help splay SP around KEY.  PARENT and GRANDPARENT are the parent
   and grandparent, respectively, of NODE.  */

static splay_tree_node
splay_tree_splay_helper (sp, key, node, parent, grandparent)
     splay_tree sp;
     splay_tree_key key;
     splay_tree_node *node;
     splay_tree_node *parent;
     splay_tree_node *grandparent;
{
  splay_tree_node *next;
  splay_tree_node n;
  int comparison;
  
  n = *node;

  if (!n)
    return *parent;

  comparison = (*sp->comp) (key, n->key);

  if (comparison == 0)
    /* We've found the target.  */
    next = 0;
  else if (comparison < 0)
    /* The target is to the left.  */
    next = &n->left;
  else 
    /* The target is to the right.  */
    next = &n->right;

  if (next)
    {
      /* Continue down the tree.  */
      n = splay_tree_splay_helper (sp, key, next, node, parent);

      /* The recursive call will change the place to which NODE
	 points.  */
      if (*node != n)
	return n;
    }

  if (!parent)
    /* NODE is the root.  We are done.  */
    return n;

  /* First, handle the case where there is no grandparent (i.e.,
     *PARENT is the root of the tree.)  */
  if (!grandparent) 
    {
      if (n == (*parent)->left)
	{
	  *node = n->right;
	  n->right = *parent;
	}
      else
	{
	  *node = n->left;
	  n->left = *parent;
	}
      *parent = n;
      return n;
    }

  /* Next handle the cases where both N and *PARENT are left children,
     or where both are right children.  */
  if (n == (*parent)->left && *parent == (*grandparent)->left)
    {
      splay_tree_node p = *parent;

      (*grandparent)->left = p->right;
      p->right = *grandparent;
      p->left = n->right;
      n->right = p;
      *grandparent = n;
      return n; 
    }
  else if  (n == (*parent)->right && *parent == (*grandparent)->right)
    {
      splay_tree_node p = *parent;

      (*grandparent)->right = p->left;
      p->left = *grandparent;
      p->right = n->left;
      n->left = p;
      *grandparent = n;
      return n;
    }

  /* Finally, deal with the case where N is a left child, but *PARENT
     is a right child, or vice versa.  */
  if (n == (*parent)->left) 
    {
      (*parent)->left = n->right;
      n->right = *parent;
      (*grandparent)->right = n->left;
      n->left = *grandparent;
      *grandparent = n;
      return n;
    } 
  else
    {
      (*parent)->right = n->left;
      n->left = *parent;
      (*grandparent)->left = n->right;
      n->right = *grandparent;
      *grandparent = n;
      return n;
    }
}

/* Splay SP around KEY.  */

static void
splay_tree_splay (sp, key)
     splay_tree sp;
     splay_tree_key key;
{
  if (sp->root == 0)
    return;

  splay_tree_splay_helper (sp, key, &sp->root, 
			   /*grandparent=*/0, /*parent=*/0); 
}

/* Call FN, passing it the DATA, for every node below NODE, all of
   which are from SP, following an in-order traversal.  If FN every
   returns a non-zero value, the iteration ceases immediately, and the
   value is returned.  Otherwise, this function returns 0.  */

static int
splay_tree_foreach_helper (sp, node, fn, data)
     splay_tree sp;
     splay_tree_node node;
     splay_tree_foreach_fn fn;
     void* data;
{
  int val;

  if (!node)
    return 0;

  val = splay_tree_foreach_helper (sp, node->left, fn, data);
  if (val)
    return val;

  val = (*fn)(node, data);
  if (val)
    return val;

  return splay_tree_foreach_helper (sp, node->right, fn, data);
}

/* Allocate a new splay tree, using COMPARE_FN to compare nodes,
   DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate
   values.  */

splay_tree 
splay_tree_new (compare_fn, delete_key_fn, delete_value_fn)
     splay_tree_compare_fn compare_fn;
     splay_tree_delete_key_fn delete_key_fn;
     splay_tree_delete_value_fn delete_value_fn;
{
  splay_tree sp = (splay_tree) xmalloc (sizeof (struct splay_tree_s));
  sp->root = 0;
  sp->comp = compare_fn;
  sp->delete_key = delete_key_fn;
  sp->delete_value = delete_value_fn;

  return sp;
}

/* Deallocate SP.  */

void 
splay_tree_delete (sp)
     splay_tree sp;
{
  splay_tree_delete_helper (sp, sp->root);
  free ((char*) sp);
}

/* Insert a new node (associating KEY with DATA) into SP.  If a
   previous node with the indicated KEY exists, its data is replaced
   with the new value.  Returns the new node.  */

splay_tree_node
splay_tree_insert (sp, key, value)
     splay_tree sp;
     splay_tree_key key;
     splay_tree_value value;
{
  int comparison = 0;

  splay_tree_splay (sp, key);

  if (sp->root)
    comparison = (*sp->comp)(sp->root->key, key);

  if (sp->root && comparison == 0)
    {
      /* If the root of the tree already has the indicated KEY, just
	 replace the value with VALUE.  */
      if (sp->delete_value)
	(*sp->delete_value)(sp->root->value);
      sp->root->value = value;
    } 
  else 
    {
      /* Create a new node, and insert it at the root.  */
      splay_tree_node node;
      
      node = (splay_tree_node) xmalloc (sizeof (struct splay_tree_node_s));
      node->key = key;
      node->value = value;
      
      if (!sp->root)
	node->left = node->right = 0;
      else if (comparison < 0)
	{
	  node->left = sp->root;
	  node->right = node->left->right;
	  node->left->right = 0;
	}
      else
	{
	  node->right = sp->root;
	  node->left = node->right->left;
	  node->right->left = 0;
	}

    sp->root = node;
  }

  return sp->root;
}

/* Lookup KEY in SP, returning VALUE if present, and NULL 
   otherwise.  */

splay_tree_node
splay_tree_lookup (sp, key)
     splay_tree sp;
     splay_tree_key key;
{
  splay_tree_splay (sp, key);

  if (sp->root && (*sp->comp)(sp->root->key, key) == 0)
    return sp->root;
  else
    return 0;
}

/* Call FN, passing it the DATA, for every node in SP, following an
   in-order traversal.  If FN every returns a non-zero value, the
   iteration ceases immediately, and the value is returned.
   Otherwise, this function returns 0.  */

int
splay_tree_foreach (sp, fn, data)
     splay_tree sp;
     splay_tree_foreach_fn fn;
     void *data;
{
  return splay_tree_foreach_helper (sp, sp->root, fn, data);
}

/* Splay-tree comparison function, treating the keys as ints.  */

int
splay_tree_compare_ints (k1, k2)
     splay_tree_key k1;
     splay_tree_key k2;
{
  if ((int) k1 < (int) k2)
    return -1;
  else if ((int) k1 > (int) k2)
    return 1;
  else 
    return 0;
}

/* Splay-tree comparison function, treating the keys as pointers.  */

int
splay_tree_compare_pointers (k1, k2)
     splay_tree_key k1;
     splay_tree_key k2;
{
  if ((char*) k1 < (char*) k2)
    return -1;
  else if ((char*) k1 > (char*) k2)
    return 1;
  else 
    return 0;
}