--- /dev/null
+/**
+ * collectd - src/utils_avltree.c
+ * Copyright (C) 2006,2007 Florian octo Forster
+ *
+ * This program 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 of the License, or (at your
+ * option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Authors:
+ * Florian octo Forster <octo at verplant.org>
+ **/
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+
+#include "utils_avltree.h"
+
+#define BALANCE(n) ((((n)->left == NULL) ? 0 : (n)->left->height) \
+ - (((n)->right == NULL) ? 0 : (n)->right->height))
+
+/*
+ * private data types
+ */
+struct avl_node_s
+{
+ void *key;
+ void *value;
+
+ int height;
+ struct avl_node_s *left;
+ struct avl_node_s *right;
+ struct avl_node_s *parent;
+};
+typedef struct avl_node_s avl_node_t;
+
+struct avl_tree_s
+{
+ avl_node_t *root;
+ int (*compare) (const void *, const void *);
+};
+
+struct avl_iterator_s
+{
+ avl_tree_t *tree;
+ avl_node_t *node;
+};
+
+/*
+ * private functions
+ */
+#if 0
+static void verify_tree (avl_node_t *n)
+{
+ if (n == NULL)
+ return;
+
+ verify_tree (n->left);
+ verify_tree (n->right);
+
+ assert ((BALANCE (n) >= -1) && (BALANCE (n) <= 1));
+ assert ((n->parent == NULL) || (n->parent->right == n) || (n->parent->left == n));
+} /* void verify_tree */
+#else
+# define verify_tree(n) /**/
+#endif
+
+static void free_node (avl_node_t *n)
+{
+ if (n == NULL)
+ return;
+
+ if (n->left != NULL)
+ free_node (n->left);
+ if (n->right != NULL)
+ free_node (n->right);
+
+ free (n);
+}
+
+static int calc_height (avl_node_t *n)
+{
+ int height_left;
+ int height_right;
+
+ if (n == NULL)
+ return (0);
+
+ height_left = (n->left == NULL) ? 0 : n->left->height;
+ height_right = (n->right == NULL) ? 0 : n->right->height;
+
+ return (((height_left > height_right)
+ ? height_left
+ : height_right) + 1);
+} /* int calc_height */
+
+static avl_node_t *search (avl_tree_t *t, const void *key)
+{
+ avl_node_t *n;
+ int cmp;
+
+ n = t->root;
+ while (n != NULL)
+ {
+ cmp = t->compare (key, n->key);
+ if (cmp == 0)
+ return (n);
+ else if (cmp < 0)
+ n = n->left;
+ else
+ n = n->right;
+ }
+
+ return (NULL);
+}
+
+/* (x) (y)
+ * / \ / \
+ * (y) /\ /\ (x)
+ * / \ /_c\ ==> / a\ / \
+ * /\ /\ /____\/\ /\
+ * / a\ /_b\ /_b\ /_c\
+ * /____\
+ */
+static avl_node_t *rotate_right (avl_tree_t *t, avl_node_t *x)
+{
+ avl_node_t *p;
+ avl_node_t *y;
+ avl_node_t *b;
+
+ p = x->parent;
+ y = x->left;
+ b = y->right;
+
+ x->left = b;
+ if (b != NULL)
+ b->parent = x;
+
+ x->parent = y;
+ y->right = x;
+
+ y->parent = p;
+ assert ((p == NULL) || (p->left == x) || (p->right == x));
+ if (p == NULL)
+ t->root = y;
+ else if (p->left == x)
+ p->left = y;
+ else
+ p->right = y;
+
+ x->height = calc_height (x);
+ y->height = calc_height (y);
+
+ return (y);
+} /* void rotate_left */
+
+/*
+ * (x) (y)
+ * / \ / \
+ * /\ (y) (x) /\
+ * /_a\ / \ ==> / \ / c\
+ * /\ /\ /\ /\/____\
+ * /_b\ / c\ /_a\ /_b\
+ * /____\
+ */
+static avl_node_t *rotate_left (avl_tree_t *t, avl_node_t *x)
+{
+ avl_node_t *p;
+ avl_node_t *y;
+ avl_node_t *b;
+
+ p = x->parent;
+ y = x->right;
+ b = y->left;
+
+ x->right = b;
+ if (b != NULL)
+ b->parent = x;
+
+ x->parent = y;
+ y->left = x;
+
+ y->parent = p;
+ assert ((p == NULL) || (p->left == x) || (p->right == x));
+ if (p == NULL)
+ t->root = y;
+ else if (p->left == x)
+ p->left = y;
+ else
+ p->right = y;
+
+ x->height = calc_height (x);
+ y->height = calc_height (y);
+
+ return (y);
+} /* void rotate_left */
+
+static avl_node_t *rotate_left_right (avl_tree_t *t, avl_node_t *x)
+{
+ rotate_left (t, x->left);
+ return (rotate_right (t, x));
+} /* void rotate_left_right */
+
+static avl_node_t *rotate_right_left (avl_tree_t *t, avl_node_t *x)
+{
+ rotate_right (t, x->right);
+ return (rotate_left (t, x));
+} /* void rotate_right_left */
+
+static void rebalance (avl_tree_t *t, avl_node_t *n)
+{
+ int b_top;
+ int b_bottom;
+
+ while (n != NULL)
+ {
+ b_top = BALANCE (n);
+ assert ((b_top >= -2) && (b_top <= 2));
+
+ if (b_top == -2)
+ {
+ assert (n->right != NULL);
+ b_bottom = BALANCE (n->right);
+ assert ((b_bottom >= -1) || (b_bottom <= 1));
+ if (b_bottom == 1)
+ n = rotate_right_left (t, n);
+ else
+ n = rotate_left (t, n);
+ }
+ else if (b_top == 2)
+ {
+ assert (n->left != NULL);
+ b_bottom = BALANCE (n->left);
+ assert ((b_bottom >= -1) || (b_bottom <= 1));
+ if (b_bottom == -1)
+ n = rotate_left_right (t, n);
+ else
+ n = rotate_right (t, n);
+ }
+ else
+ {
+ int height = calc_height (n);
+ if (height == n->height)
+ break;
+ n->height = height;
+ }
+
+ assert (n->height == calc_height (n));
+
+ n = n->parent;
+ } /* while (n != NULL) */
+} /* void rebalance */
+
+static avl_iterator_t *avl_create_iterator (avl_tree_t *t, avl_node_t *n)
+{
+ avl_iterator_t *iter;
+
+ iter = (avl_iterator_t *) malloc (sizeof (avl_iterator_t));
+ if (iter == NULL)
+ return (NULL);
+
+ iter->tree = t;
+ iter->node = n;
+
+ return (iter);
+}
+
+void *avl_node_next (avl_tree_t *t, avl_node_t *n)
+{
+ avl_node_t *r; /* return node */
+
+ if (n == NULL)
+ {
+ return (NULL);
+ }
+ else if (n->right == NULL)
+ {
+
+ r = n->parent;
+ while (r != NULL)
+ {
+ /* stop if a bigger node is found */
+ if (t->compare (n, r) < 0) /* n < r */
+ break;
+ r = r->parent;
+ }
+ }
+ else
+ {
+ r = n->right;
+ while (r->left != NULL)
+ r = r->left;
+ }
+
+ return (r);
+}
+
+void *avl_node_prev (avl_tree_t *t, avl_node_t *n)
+{
+ avl_node_t *r; /* return node */
+
+ if (n == NULL)
+ {
+ return (NULL);
+ }
+ else if (n->left == NULL)
+ {
+
+ r = n->parent;
+ while (r != NULL)
+ {
+ /* stop if a smaller node is found */
+ if (t->compare (n, r) > 0) /* n > r */
+ break;
+ r = r->parent;
+ }
+ }
+ else
+ {
+ r = n->left;
+ while (r->right != NULL)
+ r = r->right;
+ }
+
+ return (r);
+} /* void *avl_node_prev */
+
+static int _remove (avl_tree_t *t, avl_node_t *n)
+{
+ assert ((t != NULL) && (n != NULL));
+
+ if ((n->left != NULL) && (n->right != NULL))
+ {
+ avl_node_t *r; /* replacement node */
+ if (BALANCE (n) > 0) /* left subtree is higher */
+ {
+ assert (n->left != NULL);
+ r = avl_node_prev (t, n);
+
+ }
+ else /* right subtree is higher */
+ {
+ assert (n->right != NULL);
+ r = avl_node_next (t, n);
+ }
+
+ assert ((r->left == NULL) || (r->right == NULL));
+
+ /* copy content */
+ n->key = r->key;
+ n->value = r->value;
+
+ n = r;
+ }
+
+ assert ((n->left == NULL) || (n->right == NULL));
+
+ if ((n->left == NULL) && (n->right == NULL))
+ {
+ /* Deleting a leave is easy */
+ if (n->parent == NULL)
+ {
+ assert (t->root == n);
+ t->root = NULL;
+ }
+ else
+ {
+ assert ((n->parent->left == n)
+ || (n->parent->right == n));
+ if (n->parent->left == n)
+ n->parent->left = NULL;
+ else
+ n->parent->right = NULL;
+
+ rebalance (t, n->parent);
+ }
+
+ free_node (n);
+ }
+ else if (n->left == NULL)
+ {
+ assert (BALANCE (n) == -1);
+ assert ((n->parent == NULL) || (n->parent->left == n) || (n->parent->right == n));
+ if (n->parent == NULL)
+ {
+ assert (t->root == n);
+ t->root = n->right;
+ }
+ else if (n->parent->left == n)
+ {
+ n->parent->left = n->right;
+ }
+ else
+ {
+ n->parent->right = n->right;
+ }
+ n->right->parent = n->parent;
+
+ if (n->parent != NULL)
+ rebalance (t, n->parent);
+
+ n->right = NULL;
+ free_node (n);
+ }
+ else if (n->right == NULL)
+ {
+ assert (BALANCE (n) == 1);
+ assert ((n->parent == NULL) || (n->parent->left == n) || (n->parent->right == n));
+ if (n->parent == NULL)
+ {
+ assert (t->root == n);
+ t->root = n->left;
+ }
+ else if (n->parent->left == n)
+ {
+ n->parent->left = n->left;
+ }
+ else
+ {
+ n->parent->right = n->left;
+ }
+ n->left->parent = n->parent;
+
+ if (n->parent != NULL)
+ rebalance (t, n->parent);
+
+ n->left = NULL;
+ free_node (n);
+ }
+ else
+ {
+ assert (0);
+ }
+
+ return (0);
+} /* void *_remove */
+
+/*
+ * public functions
+ */
+avl_tree_t *avl_create (int (*compare) (const void *, const void *))
+{
+ avl_tree_t *t;
+
+ if ((t = (avl_tree_t *) malloc (sizeof (avl_tree_t))) == NULL)
+ return (NULL);
+
+ t->root = NULL;
+ t->compare = compare;
+
+ return (t);
+}
+
+void avl_destroy (avl_tree_t *t)
+{
+ free_node (t->root);
+ free (t);
+}
+
+int avl_insert (avl_tree_t *t, void *key, void *value)
+{
+ avl_node_t *new;
+ avl_node_t *nptr;
+ int cmp;
+
+ if ((new = (avl_node_t *) malloc (sizeof (avl_node_t))) == NULL)
+ return (-1);
+
+ new->key = key;
+ new->value = value;
+ new->height = 1;
+ new->left = NULL;
+ new->right = NULL;
+
+ if (t->root == NULL)
+ {
+ new->parent = NULL;
+ t->root = new;
+ return (0);
+ }
+
+ nptr = t->root;
+ while (42)
+ {
+ cmp = t->compare (nptr->key, new->key);
+ if (cmp == 0)
+ {
+ free_node (new);
+ return (-1);
+ }
+ else if (cmp < 0)
+ {
+ /* nptr < new */
+ if (nptr->right == NULL)
+ {
+ nptr->right = new;
+ new->parent = nptr;
+ rebalance (t, nptr);
+ break;
+ }
+ else
+ {
+ nptr = nptr->right;
+ }
+ }
+ else /* if (cmp > 0) */
+ {
+ /* nptr > new */
+ if (nptr->left == NULL)
+ {
+ nptr->left = new;
+ new->parent = nptr;
+ rebalance (t, nptr);
+ break;
+ }
+ else
+ {
+ nptr = nptr->left;
+ }
+ }
+ } /* while (42) */
+
+ verify_tree (t->root);
+ return (0);
+} /* int avl_insert */
+
+int avl_remove (avl_tree_t *t, void *key, void **rkey, void **rvalue)
+{
+ avl_node_t *n;
+ int status;
+
+ assert (t != NULL);
+
+ n = search (t, key);
+ if (n == NULL)
+ return (-1);
+
+ if (rkey != NULL)
+ *rkey = n->key;
+ if (rvalue != NULL)
+ *rvalue = n->value;
+
+ status = _remove (t, n);
+ verify_tree (t->root);
+ return (status);
+} /* void *avl_remove */
+
+int avl_get (avl_tree_t *t, const void *key, void **value)
+{
+ avl_node_t *n;
+
+ assert (value != NULL);
+
+ n = search (t, key);
+ if (n == NULL)
+ return (-1);
+
+ *value = n->value;
+
+ return (0);
+}
+
+avl_iterator_t *avl_get_iterator (avl_tree_t *t)
+{
+ avl_node_t *n;
+
+ if (t == NULL)
+ return (NULL);
+
+ for (n = t->root; n != NULL; n = n->left)
+ if (n->left == NULL)
+ break;
+
+ return (avl_create_iterator (t, n));
+} /* avl_iterator_t *avl_get_iterator */
+
+int avl_pick (avl_tree_t *, void **key, void **value)
+{
+ avl_node_t *n;
+ avl_node_t *p;
+
+ assert ((key != NULL) && (value != NULL));
+ if (t->root == NULL)
+ return (-1);
+
+ n = t->root;
+ while ((n->left != NULL) || (n->right != NULL))
+ {
+ int height_left = (n->left == NULL) ? 0 : n->left->traffic;
+ int height_right = (n->right == NULL) ? 0 : n->right->traffic;
+
+ if (height_left > height_right)
+ n = n->left;
+ else
+ n = n->right;
+ }
+
+ p = n->parent;
+ if (p == NULL)
+ t->root = NULL;
+ else if (p->left == n)
+ p->left = NULL;
+ else
+ p->right = NULL;
+
+ *key = n->key;
+ *value = n->value;
+
+ free_node (n);
+ rebalance (p);
+
+ return (0);
+} /* int avl_pick */
+
+void *avl_iterator_next (avl_iterator_t *iter)
+{
+ avl_node_t *n;
+
+ if ((iter == NULL) || (iter->node == NULL))
+ return (NULL);
+
+ n = avl_node_next (iter->tree, iter->node);
+
+ if (n == NULL)
+ return (NULL);
+
+ iter->node = n;
+ return (n);
+
+}
+
+void *avl_iterator_prev (avl_iterator_t *iter)
+{
+ avl_node_t *n;
+
+ if ((iter == NULL) || (iter->node == NULL))
+ return (NULL);
+
+ n = avl_node_prev (iter->tree, iter->node);
+
+ if (n == NULL)
+ return (NULL);
+
+ iter->node = n;
+ return (n);
+
+}
+
+void avl_iterator_destroy (avl_iterator_t *iter)
+{
+ free (iter);
+}
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