freebsd-dev/contrib/gcc/et-forest.c
2003-07-11 03:40:53 +00:00

681 lines
16 KiB
C

/* ET-trees datastructure implementation.
Contributed by Pavel Nejedly
Copyright (C) 2002 Free Software Foundation, Inc.
This file is part of the libiberty library.
Libiberty is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
Libiberty 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with libiberty; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
The ET-forest structure is described in:
D. D. Sleator and R. E. Tarjan. A data structure for dynamic trees.
J. G'omput. System Sci., 26(3):362 381, 1983.
*/
#include "config.h"
#include "system.h"
#include "et-forest.h"
struct et_forest_occurrence;
typedef struct et_forest_occurrence* et_forest_occurrence_t;
/* The ET-forest type. */
struct et_forest
{
/* Linked list of nodes is used to destroy the structure. */
int nnodes;
};
/* Single occurrence of node in ET-forest.
A single node may have multiple occurrences.
*/
struct et_forest_occurrence
{
/* Parent in the splay-tree. */
et_forest_occurrence_t parent;
/* Children in the splay-tree. */
et_forest_occurrence_t left, right;
/* Counts of vertices in the two splay-subtrees. */
int count_left, count_right;
/* Next occurrence of this node in the sequence. */
et_forest_occurrence_t next;
/* The node, which this occurrence is of. */
et_forest_node_t node;
};
/* ET-forest node. */
struct et_forest_node
{
et_forest_t forest;
void *value;
/* First and last occurrence of this node in the sequence. */
et_forest_occurrence_t first, last;
};
static et_forest_occurrence_t splay PARAMS ((et_forest_occurrence_t));
static void remove_all_occurrences PARAMS ((et_forest_node_t));
static inline et_forest_occurrence_t find_leftmost_node
PARAMS ((et_forest_occurrence_t));
static inline et_forest_occurrence_t find_rightmost_node
PARAMS ((et_forest_occurrence_t));
static int calculate_value PARAMS ((et_forest_occurrence_t));
/* Return leftmost node present in the tree roted by OCC. */
static inline et_forest_occurrence_t
find_leftmost_node (occ)
et_forest_occurrence_t occ;
{
while (occ->left)
occ = occ->left;
return occ;
}
/* Return rightmost node present in the tree roted by OCC. */
static inline et_forest_occurrence_t
find_rightmost_node (occ)
et_forest_occurrence_t occ;
{
while (occ->right)
occ = occ->right;
return occ;
}
/* Operation splay for splay tree structure representing ocuurences. */
static et_forest_occurrence_t
splay (node)
et_forest_occurrence_t node;
{
et_forest_occurrence_t parent;
et_forest_occurrence_t grandparent;
while (1)
{
parent = node->parent;
if (! parent)
return node; /* node == root. */
grandparent = parent->parent;
if (! grandparent)
break;
/* Now there are four possible combinations: */
if (node == parent->left)
{
if (parent == grandparent->left)
{
et_forest_occurrence_t node1, node2;
int count1, count2;
node1 = node->right;
count1 = node->count_right;
node2 = parent->right;
count2 = parent->count_right;
grandparent->left = node2;
grandparent->count_left = count2;
if (node2)
node2->parent = grandparent;
parent->left = node1;
parent->count_left = count1;
if (node1)
node1->parent = parent;
parent->right = grandparent;
parent->count_right = count2 + grandparent->count_right + 1;
node->right = parent;
node->count_right = count1 + parent->count_right + 1;
node->parent = grandparent->parent;
parent->parent = node;
grandparent->parent = parent;
if (node->parent)
{
if (node->parent->left == grandparent)
node->parent->left = node;
else
node->parent->right = node;
}
}
else
{
/* parent == grandparent->right && node == parent->left*/
et_forest_occurrence_t node1, node2;
int count1, count2;
node1 = node->left;
count1 = node->count_left;
node2 = node->right;
count2 = node->count_right;
grandparent->right = node1;
grandparent->count_right = count1;
if (node1)
node1->parent = grandparent;
parent->left = node2;
parent->count_left = count2;
if (node2)
node2->parent = parent;
node->left = grandparent;
node->count_left = grandparent->count_left + count1 + 1;
node->right = parent;
node->count_right = parent->count_right + count2 + 1;
node->parent = grandparent->parent;
parent->parent = node;
grandparent->parent = node;
if (node->parent)
{
if (node->parent->left == grandparent)
node->parent->left = node;
else
node->parent->right = node;
}
}
}
else
{
/* node == parent->right. */
if (parent == grandparent->left)
{
et_forest_occurrence_t node1, node2;
int count1, count2;
node1 = node->left;
count1 = node->count_left;
node2 = node->right;
count2 = node->count_right;
parent->right = node1;
parent->count_right = count1;
if (node1)
node1->parent = parent;
grandparent->left = node2;
grandparent->count_left = count2;
if (node2)
node2->parent = grandparent;
node->left = parent;
node->count_left = parent->count_left + count1 + 1;
node->right = grandparent;
node->count_right = grandparent->count_right + count2 + 1;
node->parent = grandparent->parent;
parent->parent = node;
grandparent->parent = node;
if (node->parent)
{
if (node->parent->left == grandparent)
node->parent->left = node;
else
node->parent->right = node;
}
}
else
{
/* parent == grandparent->right && node == parent->right*/
et_forest_occurrence_t node1, node2;
int count1, count2;
node1 = node->left;
count1 = node->count_left;
node2 = parent->left;
count2 = parent->count_left;
grandparent->right = node2;
grandparent->count_right = count2;
if (node2)
node2->parent = grandparent;
parent->right = node1;
parent->count_right = count1;
if (node1)
node1->parent = parent;
parent->left = grandparent;
parent->count_left = count2 + grandparent->count_left + 1;
node->left = parent;
node->count_left = count1 + parent->count_left + 1;
node->parent = grandparent->parent;
parent->parent = node;
grandparent->parent = parent;
if (node->parent)
{
if (node->parent->left == grandparent)
node->parent->left = node;
else
node->parent->right = node;
}
}
}
}
/* parent == root. */
/* There are two possible combinations: */
if (node == parent->left)
{
et_forest_occurrence_t node1;
int count1;
node1 = node->right;
count1 = node->count_right;
parent->left = node1;
parent->count_left = count1;
if (node1)
node1->parent = parent;
node->right = parent;
node->count_right = parent->count_right + 1 + count1;
node->parent = parent->parent; /* the same as = 0; */
parent->parent = node;
if (node->parent)
{
if (node->parent->left == parent)
node->parent->left = node;
else
node->parent->right = node;
}
}
else
{
/* node == parent->right. */
et_forest_occurrence_t node1;
int count1;
node1 = node->left;
count1 = node->count_left;
parent->right = node1;
parent->count_right = count1;
if (node1)
node1->parent = parent;
node->left = parent;
node->count_left = parent->count_left + 1 + count1;
node->parent = parent->parent; /* the same as = 0; */
parent->parent = node;
if (node->parent)
{
if (node->parent->left == parent)
node->parent->left = node;
else
node->parent->right = node;
}
}
return node;
}
/* Remove all occurences of the given node before destroying the node. */
static void
remove_all_occurrences (forest_node)
et_forest_node_t forest_node;
{
et_forest_occurrence_t first = forest_node->first;
et_forest_occurrence_t last = forest_node->last;
et_forest_occurrence_t node;
splay (first);
if (first->left)
first->left->parent = 0;
if (first->right)
first->right->parent = 0;
if (last != first)
{
splay (last);
if (last->left)
last->left->parent = 0;
if (last->right)
last->right->parent = 0;
}
if (last->right && first->left) /* actually, first->left would suffice. */
{
/* Need to join them. */
et_forest_occurrence_t prev_node, next_node;
prev_node = splay (find_rightmost_node (first->left));
next_node = splay (find_leftmost_node (last->right));
/* prev_node and next_node are consecutive occurencies
of the same node. */
if (prev_node->next != next_node)
abort ();
prev_node->right = next_node->right;
prev_node->count_right = next_node->count_right;
prev_node->next = next_node->next;
if (prev_node->right)
prev_node->right->parent = prev_node;
if (prev_node->node->last == next_node)
prev_node->node->last = prev_node;
free (next_node);
}
if (first != last)
{
node = first->next;
while (node != last)
{
et_forest_occurrence_t next_node;
splay (node);
if (node->left)
node->left->parent = 0;
if (node->right)
node->right->parent = 0;
next_node = node->next;
free (node);
node = next_node;
}
}
free (first);
if (first != last)
free (last);
}
/* Calculate ET value of the given node. */
static inline int
calculate_value (node)
et_forest_occurrence_t node;
{
int value = node->count_left;
while (node->parent)
{
if (node == node->parent->right)
value += node->parent->count_left + 1;
node = node->parent;
}
return value;
}
/* Create ET-forest structure. */
et_forest_t
et_forest_create ()
{
et_forest_t forest = xmalloc (sizeof (struct et_forest));
forest->nnodes = 0;
return forest;
}
/* Deallocate the structure. */
void
et_forest_delete (forest)
et_forest_t forest;
{
if (forest->nnodes)
abort ();
free (forest);
}
/* Create new node with VALUE and return the edge.
Return NULL when memory allocation failed. */
et_forest_node_t
et_forest_add_node (forest, value)
et_forest_t forest;
void *value;
{
/* Create node with one occurrence. */
et_forest_node_t node;
et_forest_occurrence_t occ;
node = xmalloc (sizeof (struct et_forest_node));
occ = xmalloc (sizeof (struct et_forest_occurrence));
node->first = node->last = occ;
node->value = value;
forest->nnodes++;
occ->node = node;
occ->left = occ->right = occ->parent = 0;
occ->next = 0;
occ->count_left = occ->count_right = 0;
return node;
}
/* Add new edge to the tree, return 1 if succesfull.
0 indicates that creation of the edge will close the cycle in graph. */
int
et_forest_add_edge (forest, parent_node, child_node)
et_forest_t forest ATTRIBUTE_UNUSED;
et_forest_node_t parent_node;
et_forest_node_t child_node;
{
et_forest_occurrence_t new_occ, parent_occ, child_occ;
if (! parent_node || ! child_node)
abort ();
parent_occ = parent_node->first;
child_occ = child_node->first;
splay (parent_occ);
splay (child_occ);
if (parent_occ->parent)
return 0; /* Both child and parent are in the same tree. */
if (child_occ->left)
abort (); /* child must be root of its containing tree. */
new_occ = xmalloc (sizeof (struct et_forest_occurrence));
new_occ->node = parent_node;
new_occ->left = child_occ;
new_occ->count_left = child_occ->count_right + 1; /* count_left is 0. */
new_occ->right = parent_occ->right;
new_occ->count_right = parent_occ->count_right;
new_occ->parent = parent_occ;
new_occ->next = parent_occ->next;
child_occ->parent = new_occ;
parent_occ->right = new_occ;
parent_occ->count_right = new_occ->count_left + new_occ->count_right + 1;
parent_occ->next = new_occ;
if (new_occ->right)
new_occ->right->parent = new_occ;
if (parent_node->last == parent_occ)
parent_node->last = new_occ;
return 1;
}
/* Remove NODE from the tree and all connected edges. */
void
et_forest_remove_node (forest, node)
et_forest_t forest;
et_forest_node_t node;
{
remove_all_occurrences (node);
forest->nnodes--;
free (node);
}
/* Remove edge from the tree, return 1 if sucesfull,
0 indicates nonexisting edge. */
int
et_forest_remove_edge (forest, parent_node, child_node)
et_forest_t forest ATTRIBUTE_UNUSED;
et_forest_node_t parent_node;
et_forest_node_t child_node;
{
et_forest_occurrence_t parent_pre_occ, parent_post_occ;
splay (child_node->first);
if (! child_node->first->left)
return 0;
parent_pre_occ = find_rightmost_node (child_node->first->left);
if (parent_pre_occ->node != parent_node)
abort ();
splay (parent_pre_occ);
parent_pre_occ->right->parent = 0;
parent_post_occ = parent_pre_occ->next;
splay (parent_post_occ);
parent_post_occ->left->parent = 0;
parent_pre_occ->right = parent_post_occ->right;
parent_pre_occ->count_right = parent_post_occ->count_right;
if (parent_post_occ->right)
parent_post_occ->right->parent = parent_pre_occ;
parent_pre_occ->next = parent_post_occ->next;
if (parent_post_occ == parent_node->last)
parent_node->last = parent_pre_occ;
free (parent_post_occ);
return 1;
}
/* Return the parent of the NODE if any, NULL otherwise. */
et_forest_node_t
et_forest_parent (forest, node)
et_forest_t forest ATTRIBUTE_UNUSED;
et_forest_node_t node;
{
splay (node->first);
if (node->first->left)
return find_rightmost_node (node->first->left)->node;
else
return 0;
}
/* Return nearest common ancestor of NODE1 and NODE2.
Return NULL of they are in different trees. */
et_forest_node_t
et_forest_common_ancestor (forest, node1, node2)
et_forest_t forest ATTRIBUTE_UNUSED;
et_forest_node_t node1;
et_forest_node_t node2;
{
int value1, value2, max_value;
et_forest_node_t ancestor;
if (node1 == node2)
return node1;
if (! node1 || ! node2)
abort ();
splay (node1->first);
splay (node2->first);
if (! node1->first->parent) /* The two vertices are in different trees. */
return 0;
value2 = calculate_value (node2->first);
value1 = calculate_value (node1->first);
if (value1 < value2)
{
ancestor = node1;
max_value = value2;
}
else
{
ancestor = node2;
max_value = value1;
}
while (calculate_value (ancestor->last) < max_value)
{
/* Find parent node. */
splay (ancestor->first);
ancestor = find_rightmost_node (ancestor->first->left) ->node;
}
return ancestor;
}
/* Return the value pointer of node set during it's creation. */
void *
et_forest_node_value (forest, node)
et_forest_t forest ATTRIBUTE_UNUSED;
et_forest_node_t node;
{
/* Alloc threading NULL as a special node of the forest. */
if (!node)
return NULL;
return node->value;
}
/* Find all sons of NODE and store them into ARRAY allocated by the caller.
Return number of nodes found. */
int
et_forest_enumerate_sons (forest, node, array)
et_forest_t forest ATTRIBUTE_UNUSED;
et_forest_node_t node;
et_forest_node_t *array;
{
int n = 0;
et_forest_occurrence_t occ = node->first, stop = node->last, occ1;
/* Parent is the rightmost node of the left successor.
Look for all occurences having no right succesor
and lookup the sons. */
while (occ != stop)
{
splay (occ);
if (occ->right)
{
occ1 = find_leftmost_node (occ->right);
if (occ1->node->first == occ1)
array[n++] = occ1->node;
}
occ = occ->next;
}
return n;
}