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-rw-r--r--src/search/tsearch_avl.c171
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);
+}