From: Florian Forster <octo@leeloo.lan.home.verplant.org>
Date: Tue, 21 Nov 2006 18:57:55 +0000 (+0100)
Subject: Added src/utils_avltree.[ch]: An implementation of an AVL-tree.
X-Git-Tag: collectd-4.0.0~187^2~7
X-Git-Url: https://git.octo.it/?p=collectd.git;a=commitdiff_plain;h=8e4ecdba481c776398685511c3c6e6e3e8e23bc7

Added src/utils_avltree.[ch]: An implementation of an AVL-tree.
---

diff --git a/src/utils_avltree.c b/src/utils_avltree.c
new file mode 100644
index 00000000..c3e83ae8
--- /dev/null
+++ b/src/utils_avltree.c
@@ -0,0 +1,418 @@
+#include <stdlib.h>
+#include <assert.h>
+
+#include "utils_avltree.h"
+
+#define BALANCE(n) ((((n)->right == NULL) ? 0 : (n)->right->height) \
+				 - (((n)->left == NULL) ? 0 : (n)->left->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
+ */
+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 avl_node_t *search (avl_tree_t *t, 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);
+}
+
+static void rebalance (avl_tree_t *t, avl_node_t *n)
+{
+	int height_left;
+	int height_right;
+	int height_new;
+	int cmp;
+
+	while (n != NULL)
+	{
+		height_left = (n->left == NULL) ? 0 : n->left->height;
+		height_right = (n->right == NULL) ? 0 : n->right->height;
+
+		height_new = 1 + ((height_left > height_right) ? height_left : height_right);
+
+		if (height_new == n->height)
+			break;
+
+		cmp = height_right - height_left;
+		if (cmp < -1)
+		{
+			avl_node_t *l;
+			avl_node_t *lr;
+
+			l = n->left;
+			lr = l->right;
+
+			l->right = n;
+			l->parent = n->parent;
+			n->parent = l;
+			n->left = lr;
+
+			if (n == t->root)
+				t->root = l;
+		}
+		else if (cmp > 1)
+		{
+			avl_node_t *r;
+			avl_node_t *rl;
+
+			r = n->right;
+			rl = r->left;
+
+			r->left = n;
+			r->parent = n->parent;
+			n->parent = r;
+			n->right = rl;
+
+			if (n == t->root)
+				t->root = r;
+		}
+		else
+		{
+			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);
+}
+
+static void *remove (avl_tree_t *t, avl_node_t *n)
+{
+	void *ret;
+
+	assert ((t != NULL) && (n != NULL));
+
+	ret = n->value;
+
+	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;
+		}
+
+		free_node (n);
+	}
+	else
+	{
+		avl_node_t *r; /* replacement node */
+		if (BALANCE (n) < 0)
+		{
+			assert (n->left != NULL);
+			r = avl_node_prev (t, n);
+		}
+		else
+		{
+			assert (n->right != NULL);
+			r = avl_node_next (t, n);
+		}
+		n->key   = r->key;
+		n->value = r->value;
+
+		remove (t, r);
+	}
+
+	return (ret);
+} /* 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 = 0;
+	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;
+				nptr = NULL;
+				break;
+			}
+			else
+			{
+				nptr = nptr->right;
+			}
+		}
+		else /* if (cmp > 0) */
+		{
+			/* nptr > new */
+			if (nptr->left == NULL)
+			{
+				nptr->left = new;
+				new->parent = nptr;
+				nptr = NULL;
+				break;
+			}
+			else
+			{
+				nptr = nptr->left;
+			}
+		}
+	} /* while (42) */
+
+	rebalance (t, new->parent);
+
+	return (0);
+} /* int avl_insert */
+
+void *avl_remove (avl_tree_t *t, void *key)
+{
+	avl_node_t *n;
+
+	assert (t != NULL);
+
+	n = search (t, key);
+	if (n == NULL)
+		return (NULL);
+
+	return (remove (t, n));
+} /* void *avl_remove */
+
+void *avl_get (avl_tree_t *t, void *key)
+{
+	avl_node_t *n;
+
+	n = search (t, key);
+	if (n == NULL)
+		return (NULL);
+
+	return (n->value);
+}
+
+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 */
+
+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);
+}
diff --git a/src/utils_avltree.h b/src/utils_avltree.h
new file mode 100644
index 00000000..5ffa696e
--- /dev/null
+++ b/src/utils_avltree.h
@@ -0,0 +1,23 @@
+#ifndef UTILS_AVLTREE_H
+#define UTILS_AVLTREE_H 1
+
+struct avl_tree_s;
+typedef struct avl_tree_s avl_tree_t;
+
+struct avl_iterator_s;
+typedef struct avl_iterator_s avl_iterator_t;
+
+avl_tree_t *avl_create (int (*compare) (const void *, const void *));
+void avl_destroy (avl_tree_t *t);
+
+int avl_insert (avl_tree_t *t, void *key, void *value);
+void *avl_remove (avl_tree_t *t, void *key);
+
+void *avl_get (avl_tree_t *t, void *key);
+
+avl_iterator_t *avl_get_iterator (avl_tree_t *t);
+void *avl_iterator_next (avl_iterator_t *iter);
+void *avl_iterator_prev (avl_iterator_t *iter);
+void avl_iterator_destroy (avl_iterator_t *iter);
+
+#endif /* UTILS_AVLTREE_H */