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