[gcc.git] / libiberty / splay-tree.c

/* A splay-tree datatype.  
   Copyright (C) 1998 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, 675 Mass Ave, Cambridge, MA 02139, 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));
  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.  */

void 
splay_tree_insert (sp, key, value)
     splay_tree sp;
     splay_tree_key key;
     splay_tree_value value;
{
  int comparison;

  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));
      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;
  }
}

/* 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);
}
Commit	Line	Data
ed87f9c8 MM	1	/* A splay-tree datatype.
	2	Copyright (C) 1998 Free Software Foundation, Inc.
	3	Contributed by Mark Mitchell (mark@markmitchell.com).
	4
	5	This file is part of GNU CC.
	6
	7	GNU CC is free software; you can redistribute it and/or modify it
	8	under the terms of the GNU General Public License as published by
	9	the Free Software Foundation; either version 2, or (at your option)
	10	any later version.
	11
	12	GNU CC is distributed in the hope that it will be useful, but
	13	WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	15	General Public License for more details.
	16
	17	You should have received a copy of the GNU General Public License
	18	along with GNU CC; see the file COPYING. If not, write to the Free
	19	Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
	20
	21	For an easily readable description of splay-trees, see:
	22
	23	Lewis, Harry R. and Denenberg, Larry. Data Structures and Their
	24	Algorithms. Harper-Collins, Inc. 1991. */
	25
11a0bb74	26	#ifdef HAVE_CONFIG_H
ad3ef78e MM	27	#include "config.h"
	28	#endif
	29
	30	#ifdef HAVE_STDLIB_H
	31	#include <stdlib.h>
	32	#endif
	33
ed87f9c8	34	#include "libiberty.h"
ed87f9c8 MM	35	#include "splay-tree.h"
	36
	37	static void splay_tree_delete_helper PARAMS((splay_tree,
	38	splay_tree_node));
	39	static void splay_tree_splay PARAMS((splay_tree,
	40	splay_tree_key));
	41	static splay_tree_node splay_tree_splay_helper
	42	PARAMS((splay_tree,
	43	splay_tree_key,
	44	splay_tree_node*,
	45	splay_tree_node*,
	46	splay_tree_node*));
	47	static int splay_tree_foreach_helper PARAMS((splay_tree,
	48	splay_tree_node,
	49	splay_tree_foreach_fn,
	50	void*));
	51
	52	/* Deallocate NODE (a member of SP), and all its sub-trees. */
	53
	54	static void
	55	splay_tree_delete_helper (sp, node)
	56	splay_tree sp;
	57	splay_tree_node node;
	58	{
	59	if (!node)
	60	return;
	61
	62	splay_tree_delete_helper (sp, node->left);
	63	splay_tree_delete_helper (sp, node->right);
	64
	65	if (sp->delete_key)
	66	(*sp->delete_key)(node->key);
	67	if (sp->delete_value)
	68	(*sp->delete_value)(node->value);
	69
	70	free ((char*) node);
	71	}
	72
	73	/* Help splay SP around KEY. PARENT and GRANDPARENT are the parent
	74	and grandparent, respectively, of NODE. */
	75
	76	static splay_tree_node
	77	splay_tree_splay_helper (sp, key, node, parent, grandparent)
	78	splay_tree sp;
	79	splay_tree_key key;
	80	splay_tree_node *node;
	81	splay_tree_node *parent;
	82	splay_tree_node *grandparent;
	83	{
	84	splay_tree_node *next;
	85	splay_tree_node n;
	86	int comparison;
	87
	88	n = *node;
	89
	90	if (!n)
	91	return *parent;
	92
	93	comparison = (*sp->comp) (key, n->key);
	94
	95	if (comparison == 0)
	96	/* We've found the target. */
	97	next = 0;
	98	else if (comparison < 0)
99	/* The target is to the left. */
100	next = &n->left;
101	else
102	/* The target is to the right. */
103	next = &n->right;
104
105	if (next)
106	{
107	/* Continue down the tree. */
108	n = splay_tree_splay_helper (sp, key, next, node, parent);
109
110	/* The recursive call will change the place to which NODE
111	points. */
112	if (*node != n)
113	return n;
114	}
115
116	if (!parent)
117	/* NODE is the root. We are done. */
118	return n;
119
120	/* First, handle the case where there is no grandparent (i.e.,
121	PARENT is the root of the tree.) /
122	if (!grandparent)
123	{
124	if (n == (*parent)->left)
125	{
126	*node = n->right;
127	n->right = *parent;
128	}
129	else
130	{
131	*node = n->left;
132	n->left = *parent;
133	}
134	*parent = n;
135	return n;
136	}
137
138	/* Next handle the cases where both N and *PARENT are left children,
139	or where both are right children. */
140	if (n == (parent)->left && parent == (*grandparent)->left)
141	{
142	splay_tree_node p = *parent;
143
144	(*grandparent)->left = p->right;
145	p->right = *grandparent;
146	p->left = n->right;
147	n->right = p;
148	*grandparent = n;
149	return n;
150	}
151	else if (n == (parent)->right && parent == (*grandparent)->right)
152	{
153	splay_tree_node p = *parent;
154
155	(*grandparent)->right = p->left;
156	p->left = *grandparent;
157	p->right = n->left;
158	n->left = p;
159	*grandparent = n;
160	return n;
161	}
162
163	/* Finally, deal with the case where N is a left child, but *PARENT
164	is a right child, or vice versa. */
165	if (n == (*parent)->left)
166	{
167	(*parent)->left = n->right;
168	n->right = *parent;
169	(*grandparent)->right = n->left;
170	n->left = *grandparent;
171	*grandparent = n;
172	return n;
173	}
174	else
175	{
176	(*parent)->right = n->left;
177	n->left = *parent;
178	(*grandparent)->left = n->right;
179	n->right = *grandparent;
180	*grandparent = n;
181	return n;
182	}
183	}
184
185	/* Splay SP around KEY. */
186
187	static void
188	splay_tree_splay (sp, key)
189	splay_tree sp;
190	splay_tree_key key;
191	{
192	if (sp->root == 0)
193	return;
194
195	splay_tree_splay_helper (sp, key, &sp->root,
196	/grandparent=/0, /parent=/0);
197	}
198
199	/* Call FN, passing it the DATA, for every node below NODE, all of
200	which are from SP, following an in-order traversal. If FN every
201	returns a non-zero value, the iteration ceases immediately, and the
202	value is returned. Otherwise, this function returns 0. */
203
b056ad1c	204	static int
ed87f9c8 MM	205	splay_tree_foreach_helper (sp, node, fn, data)
	206	splay_tree sp;
	207	splay_tree_node node;
	208	splay_tree_foreach_fn fn;
	209	void* data;
	210	{
	211	int val;
	212
	213	if (!node)
	214	return 0;
	215
	216	val = splay_tree_foreach_helper (sp, node->left, fn, data);
	217	if (val)
	218	return val;
	219
	220	val = (*fn)(node, data);
	221	if (val)
	222	return val;
	223
	224	return splay_tree_foreach_helper (sp, node->right, fn, data);
	225	}
	226
	227	/* Allocate a new splay tree, using COMPARE_FN to compare nodes,
	228	DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate
	229	values. */
	230
	231	splay_tree
	232	splay_tree_new (compare_fn, delete_key_fn, delete_value_fn)
	233	splay_tree_compare_fn compare_fn;
	234	splay_tree_delete_key_fn delete_key_fn;
	235	splay_tree_delete_value_fn delete_value_fn;
	236	{
	237	splay_tree sp = (splay_tree) xmalloc (sizeof (struct splay_tree));
	238	sp->root = 0;
	239	sp->comp = compare_fn;
	240	sp->delete_key = delete_key_fn;
	241	sp->delete_value = delete_value_fn;
	242
	243	return sp;
	244	}
	245
	246	/* Deallocate SP. */
	247
	248	void
	249	splay_tree_delete (sp)
	250	splay_tree sp;
	251	{
	252	splay_tree_delete_helper (sp, sp->root);
	253	free ((char*) sp);
	254	}
	255
	256	/* Insert a new node (associating KEY with DATA) into SP. If a
	257	previous node with the indicated KEY exists, its data is replaced
	258	with the new value. */
	259
	260	void
	261	splay_tree_insert (sp, key, value)
	262	splay_tree sp;
	263	splay_tree_key key;
	264	splay_tree_value value;
	265	{
	266	int comparison;
	267
	268	splay_tree_splay (sp, key);
269
270	if (sp->root)
271	comparison = (*sp->comp)(sp->root->key, key);
272
273	if (sp->root && comparison == 0)
274	{
275	/* If the root of the tree already has the indicated KEY, just
276	replace the value with VALUE. */
277	if (sp->delete_value)
278	(*sp->delete_value)(sp->root->value);
279	sp->root->value = value;
280	}
281	else
282	{
283	/* Create a new node, and insert it at the root. */
284	splay_tree_node node;
285
286	node = (splay_tree_node) xmalloc (sizeof (struct splay_tree_node));
287	node->key = key;
288	node->value = value;
289
290	if (!sp->root)
291	node->left = node->right = 0;
292	else if (comparison < 0)
293	{
294	node->left = sp->root;
295	node->right = node->left->right;
296	node->left->right = 0;
297	}
298	else
299	{
300	node->right = sp->root;
301	node->left = node->right->left;
302	node->right->left = 0;
303	}
304
305	sp->root = node;
306	}
307	}
308
309	/* Lookup KEY in SP, returning VALUE if present, and NULL
310	otherwise. */
311
312	splay_tree_node
313	splay_tree_lookup (sp, key)
314	splay_tree sp;
315	splay_tree_key key;
316	{
317	splay_tree_splay (sp, key);
318
319	if (sp->root && (*sp->comp)(sp->root->key, key) == 0)
320	return sp->root;
321	else
322	return 0;
323	}
324
325	/* Call FN, passing it the DATA, for every node in SP, following an
326	in-order traversal. If FN every returns a non-zero value, the
327	iteration ceases immediately, and the value is returned.
328	Otherwise, this function returns 0. */
329
330	int
331	splay_tree_foreach (sp, fn, data)
332	splay_tree sp;
333	splay_tree_foreach_fn fn;
334	void *data;
335	{
336	return splay_tree_foreach_helper (sp, sp->root, fn, data);
337	}