1 files changed, 171 insertions, 0 deletions

diff --git a/src/search/tsearch_avl.c b/src/search/tsearch_avl.c
new file mode 100644
index 00000000..f5c2cf61
--- /dev/null
+++ b/src/search/tsearch_avl.c
@@ -0,0 +1,171 @@
+#include <stdlib.h>
+#include <search.h>
+
+struct node {
+	const void *key;
+	struct node *left;
+	struct node *right;
+	int height;
+};
+
+static int delta(struct node *n) {
+	return (n->left ? n->left->height:0) - (n->right ? n->right->height:0);
+}
+
+static void updateheight(struct node *n) {
+	n->height = 0;
+	if (n->left && n->left->height > n->height)
+		n->height = n->left->height;
+	if (n->right && n->right->height > n->height)
+		n->height = n->right->height;
+	n->height++;
+}
+
+static struct node *rotl(struct node *n) {
+	struct node *r = n->right;
+	n->right = r->left;
+	r->left = n;
+	updateheight(n);
+	updateheight(r);
+	return r;
+}
+
+static struct node *rotr(struct node *n) {
+	struct node *l = n->left;
+	n->left = l->right;
+	l->right = n;
+	updateheight(n);
+	updateheight(l);
+	return l;
+}
+
+static struct node *balance(struct node *n) {
+	int d = delta(n);
+
+	if (d < -1) {
+		if (delta(n->right) > 0)
+			n->right = rotr(n->right);
+		return rotl(n);
+	} else if (d > 1) {
+		if (delta(n->left) < 0)
+			n->left = rotl(n->left);
+		return rotr(n);
+	}
+	updateheight(n);
+	return n;
+}
+
+static struct node *find(struct node *n, const void *k,
+	int (*cmp)(const void *, const void *))
+{
+	int c;
+
+	if (!n)
+		return 0;
+	c = cmp(k, n->key);
+	if (c == 0)
+		return n;
+	if (c < 0)
+		return find(n->left, k, cmp);
+	else
+		return find(n->right, k, cmp);
+}
+
+static struct node *insert(struct node **n, const void *k,
+	int (*cmp)(const void *, const void *), int *new)
+{
+	struct node *r = *n;
+	int c;
+
+	if (!r) {
+		*n = r = malloc(sizeof **n);
+		if (r) {
+			r->key = k;
+			r->left = r->right = 0;
+			r->height = 1;
+		}
+		*new = 1;
+		return r;
+	}
+	c = cmp(k, r->key);
+	if (c == 0)
+		return r;
+	if (c < 0)
+		r = insert(&r->left, k, cmp, new);
+	else
+		r = insert(&r->right, k, cmp, new);
+	if (*new)
+		*n = balance(*n);
+	return r;
+}
+
+static struct node *movr(struct node *n, struct node *r) {
+	if (!n)
+		return r;
+	n->right = movr(n->right, r);
+	return balance(n);
+}
+
+static struct node *remove(struct node **n, const void *k,
+	int (*cmp)(const void *, const void *), struct node *parent)
+{
+	int c;
+
+	if (!*n)
+		return 0;
+	c = cmp(k, (*n)->key);
+	if (c == 0) {
+		struct node *r = *n;
+		*n = movr(r->left, r->right);
+		free(r);
+		return parent;
+	}
+	if (c < 0)
+		parent = remove(&(*n)->left, k, cmp, *n);
+	else
+		parent = remove(&(*n)->right, k, cmp, *n);
+	if (parent)
+		*n = balance(*n);
+	return parent;
+}
+
+void *tdelete(const void *restrict key, void **restrict rootp,
+	int(*compar)(const void *, const void *))
+{
+	/* last argument is arbitrary non-null pointer
+	   which is returned when the root node is deleted */
+	return remove((void*)rootp, key, compar, *rootp);
+}
+
+void *tfind(const void *key, void *const *rootp,
+	int(*compar)(const void *, const void *))
+{
+	return find(*rootp, key, compar);
+}
+
+void *tsearch(const void *key, void **rootp,
+	int (*compar)(const void *, const void *))
+{
+	int new = 0;
+	return insert((void*)rootp, key, compar, &new);
+}
+
+static void walk(const struct node *r, void (*action)(const void *, VISIT, int), int d)
+{
+	if (r == 0)
+		return;
+	if (r->left == 0 && r->right == 0)
+		action(r, leaf, d);
+	else {
+		action(r, preorder, d);
+		walk(r->left, action, d+1);
+		action(r, postorder, d);
+		walk(r->right, action, d+1);
+		action(r, endorder, d);
+	}
+}
+
+void twalk(const void *root, void (*action)(const void *, VISIT, int))
+{
+	walk(root, action, 0);
+}