l = t;
t = t->larger;
}
- else {
+ else
break;
- }
}
l->larger = r->smaller = NULL;
/* Insert key i into the tree t. Return a pointer to the resulting tree or
NULL if something went wrong. */
-struct Curl_tree *Curl_splayinsert(int i, struct Curl_tree *t,
- struct Curl_tree *area)
+struct Curl_tree *Curl_splayinsert(int i,
+ struct Curl_tree *t,
+ struct Curl_tree *node)
{
- if (area == NULL)
+ if (node == NULL)
return t;
if (t != NULL) {
t = Curl_splay(i,t);
if (compare(i, t->key)==0) {
- /* it already exists one of this size */
-
- area->same = t;
- area->key = i;
- area->smaller = t->smaller;
- area->larger = t->larger;
-
- t->smaller = area;
- t->key = KEY_NOTUSED;
-
- return area; /* new root node */
+ /* There already exists a node in the tree with the very same key. Build
+ a linked list of nodes. We make the new 'node' struct the new master
+ node and make the previous node the first one in the 'same' list. */
+
+ node->same = t;
+ node->key = i;
+ node->smaller = t->smaller;
+ node->larger = t->larger;
+
+ t->smaller = node; /* in the sub node for this same key, we use the
+ smaller pointer to point back to the master
+ node */
+ t->key = KEY_NOTUSED; /* and we set the key in the sub node to NOTUSED
+ to quickly identify this node as a subnode */
+
+ return node; /* new root node */
}
}
if (t == NULL) {
- area->smaller = area->larger = NULL;
+ node->smaller = node->larger = NULL;
}
else if (compare(i, t->key) < 0) {
- area->smaller = t->smaller;
- area->larger = t;
+ node->smaller = t->smaller;
+ node->larger = t;
t->smaller = NULL;
}
else {
- area->larger = t->larger;
- area->smaller = t;
+ node->larger = t->larger;
+ node->smaller = t;
t->larger = NULL;
}
- area->key = i;
+ node->key = i;
- area->same = NULL; /* no identical node (yet) */
- return area;
+ node->same = NULL; /* no identical node (yet) */
+ return node;
}
+#if 0
/* Deletes 'i' from the tree if it's there (with an exact match). Returns a
- pointer to the resulting tree. */
+ pointer to the resulting tree.
+
+ Function not used in libcurl.
+*/
struct Curl_tree *Curl_splayremove(int i, struct Curl_tree *t,
struct Curl_tree **removed)
{
else
return t; /* It wasn't there */
}
+#endif
/* Finds and deletes the best-fit node from the tree. Return a pointer to the
resulting tree. best-fit means the node with the given or lower number */
}
-/* Deletes the node we point out from the tree if it's there. Return a pointer
- to the resulting tree. */
-struct Curl_tree *Curl_splayremovebyaddr(struct Curl_tree *t,
- struct Curl_tree *remove)
+/* Deletes the very node we point out from the tree if it's there. Stores a
+ pointer to the new resulting tree in 'newroot'.
+
+ Returns zero on success and non-zero on errors! TODO: document error codes.
+ When returning error, it does not touch the 'newroot' pointer.
+
+ NOTE: when the last node of the tree is removed, there's no tree left so
+ 'newroot' will be made to point to NULL.
+*/
+int Curl_splayremovebyaddr(struct Curl_tree *t,
+ struct Curl_tree *remove,
+ struct Curl_tree **newroot)
{
struct Curl_tree *x;
if (!t || !remove)
- return NULL;
+ return 1;
if(KEY_NOTUSED == remove->key) {
- /* just unlink ourselves nice and quickly: */
+ /* Key set to NOTUSED means it is a subnode within a 'same' linked list
+ and thus we can unlink it easily. The 'smaller' link of a subnode
+ links to the parent node. */
remove->smaller->same = remove->same;
if(remove->same)
remove->same->smaller = remove->smaller;
/* voila, we're done! */
- return t;
+ *newroot = t; /* return the same root */
+ return 0;
}
t = Curl_splay(remove->key, t);
- /* Check if there is a list with identical sizes */
+ /* First make sure that we got a root node witht he same key as the one we
+ want to remove, as otherwise we might be trying to remove a node that
+ isn't actually in the tree. */
+ if(t->key != remove->key)
+ return 2;
+ /* Check if there is a list with identical sizes, as then we're trying to
+ remove the root node of a list of nodes with identical keys. */
x = t->same;
if(x) {
- /* 'x' is the new root node */
+ /* 'x' is the new root node, we just make it use the root node's
+ smaller/larger links */
x->key = t->key;
x->larger = t->larger;
x->smaller = t->smaller;
-
- return x; /* new root */
}
-
- /* Remove the actualy root node: */
- if (t->smaller == NULL)
- x = t->larger;
else {
- x = Curl_splay(remove->key, t->smaller);
- x->larger = t->larger;
+ /* Remove the root node */
+ if (t->smaller == NULL)
+ x = t->larger;
+ else {
+ x = Curl_splay(remove->key, t->smaller);
+ x->larger = t->larger;
+ }
}
- return x;
+ *newroot = x; /* store new root pointer */
+
+ return 0;
}
#ifdef CURLDEBUG
-int Curl_splayprint(struct Curl_tree * t, int d, char output)
+void Curl_splayprint(struct Curl_tree * t, int d, char output)
{
- int distance=0;
struct Curl_tree *node;
int i;
+ int count;
if (t == NULL)
- return 0;
- distance += Curl_splayprint(t->larger, d+1, output);
+ return;
+
+ Curl_splayprint(t->larger, d+1, output);
for (i=0; i<d; i++)
if(output)
printf(" ");
printf("%d[%d]", t->key, i);
}
- for(node = t->same; node; node = node->same) {
- distance += i; /* this has the same "virtual" distance */
+ for(count=0, node = t->same; node; node = node->same, count++)
+ ;
- if(output)
- printf(" [+]");
+ if(output) {
+ if(count)
+ printf(" [%d more]\n", count);
+ else
+ printf("\n");
}
- if(output)
- puts("");
- distance += i;
-
- distance += Curl_splayprint(t->smaller, d+1, output);
-
- return distance;
+ Curl_splayprint(t->smaller, d+1, output);
}
#endif
/*#define TEST2 */
#define MAX 50
-#define OUTPUT 0 /* 1 enables, 0 disables */
+#define TEST2
/* A sample use of these functions. Start with the empty tree, insert some
stuff into it, and then delete it */
{
struct Curl_tree *root, *t;
void *ptrs[MAX];
+ int adds=0;
+ int rc;
long sizes[]={
50, 60, 50, 100, 60, 200, 120, 300, 400, 200, 256, 122, 60, 120, 200, 300,
root = NULL; /* the empty tree */
for (i = 0; i < MAX; i++) {
+ int key;
ptrs[i] = t = (struct Curl_tree *)malloc(sizeof(struct Curl_tree));
+
+#ifdef TEST2
+ key = sizes[i];
+#elif defined(TEST1)
+ key = (541*i)%1023;
+#elif defined(TEST3)
+ key = 100;
+#endif
+
+ t->payload = (void *)key; /* for simplicity */
if(!t) {
puts("out of memory!");
return 0;
}
-#ifdef TEST2
- root = Curl_splayinsert(sizes[i], root, t);
-#else
- root = Curl_splayinsert((541*i)&1023, root, t);
-#endif
+ root = Curl_splayinsert(key, root, t);
}
#if 0
puts("Result:");
- printtree(root, 0, 1);
+ Curl_splayprint(root, 0, 1);
#endif
#if 1
- for (i=0; root; i+=30) {
- Curl_splayprint(root, 0, 1);
- do {
- root = Curl_splaygetbest(i, root, &t);
- if(t)
- printf("bestfit %d became %d\n", i, t->key);
- else
- printf("bestfit %d failed!\n", i);
- } while(t && root);
- }
-#endif
-#if 0
for (i = 0; i < MAX; i++) {
- printf("remove pointer %d size %d\n", i, sizes[i]);
- root = removebyaddr(root, (struct Curl_tree *)ptrs[i]);
+ int rem = (i+7)%MAX;
+ struct Curl_tree *r;
+ printf("Tree look:\n");
Curl_splayprint(root, 0, 1);
+ printf("remove pointer %d, payload %d\n", rem,
+ (int)((struct Curl_tree *)ptrs[rem])->payload);
+ rc = Curl_splayremovebyaddr(root, (struct Curl_tree *)ptrs[rem], &root);
+ if(rc)
+ /* failed! */
+ printf("remove %d failed!\n", rem);
}
#endif
-#if 0
-#ifdef WEIGHT
- for (i = -1; i<=root->weight; i++) {
- t = find_rank(i, root);
- if (t == NULL) {
- printf("could not find a node of rank %d.\n", i);
- } else {
- printf("%d is of rank %d\n", t->key, i);
- }
- }
-#endif
-#endif
-
-#if 0
-#ifdef TEST2
- for (i = 0; i < MAX; i++) {
- printf("remove size %d\n", sizes[i]);
- root = Curl_splayremove(sizes[i], root, &t);
- free(t);
- Curl_splayprint(root, 0, 1);
- }
-#endif
-#endif
return 0;
}
projects / thirdparty / curl.git / commitdiff
