| /*************************************************************************** |
| * _ _ ____ _ |
| * Project ___| | | | _ \| | |
| * / __| | | | |_) | | |
| * | (__| |_| | _ <| |___ |
| * \___|\___/|_| \_\_____| |
| * |
| * Copyright (C) 1997 - 2006, Daniel Stenberg, <daniel@haxx.se>, et al. |
| * |
| * This software is licensed as described in the file COPYING, which |
| * you should have received as part of this distribution. The terms |
| * are also available at http://curl.haxx.se/docs/copyright.html. |
| * |
| * You may opt to use, copy, modify, merge, publish, distribute and/or sell |
| * copies of the Software, and permit persons to whom the Software is |
| * furnished to do so, under the terms of the COPYING file. |
| * |
| * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY |
| * KIND, either express or implied. |
| * |
| * $Id$ |
| ***************************************************************************/ |
| |
| #include <stdio.h> |
| #include <stdlib.h> |
| |
| #include "splay.h" |
| |
| #define compare(i,j) ((i)-(j)) |
| |
| /* Set this to a key value that will *NEVER* appear otherwise */ |
| #define KEY_NOTUSED -1 |
| |
| /* |
| * Splay using the key i (which may or may not be in the tree.) The starting |
| * root is t. |
| */ |
| struct Curl_tree *Curl_splay(int i, struct Curl_tree *t) |
| { |
| struct Curl_tree N, *l, *r, *y; |
| int comp; |
| |
| if (t == NULL) |
| return t; |
| N.smaller = N.larger = NULL; |
| l = r = &N; |
| |
| for (;;) { |
| comp = compare(i, t->key); |
| if (comp < 0) { |
| if (t->smaller == NULL) |
| break; |
| if (compare(i, t->smaller->key) < 0) { |
| y = t->smaller; /* rotate smaller */ |
| t->smaller = y->larger; |
| y->larger = t; |
| t = y; |
| if (t->smaller == NULL) |
| break; |
| } |
| r->smaller = t; /* link smaller */ |
| r = t; |
| t = t->smaller; |
| } |
| else if (comp > 0) { |
| if (t->larger == NULL) |
| break; |
| if (compare(i, t->larger->key) > 0) { |
| y = t->larger; /* rotate larger */ |
| t->larger = y->smaller; |
| y->smaller = t; |
| t = y; |
| if (t->larger == NULL) |
| break; |
| } |
| l->larger = t; /* link larger */ |
| l = t; |
| t = t->larger; |
| } |
| else |
| break; |
| } |
| |
| l->larger = t->smaller; /* assemble */ |
| r->smaller = t->larger; |
| t->smaller = N.larger; |
| t->larger = N.smaller; |
| |
| return t; |
| } |
| |
| /* 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 *node) |
| { |
| if (node == NULL) |
| return t; |
| |
| if (t != NULL) { |
| t = Curl_splay(i,t); |
| if (compare(i, t->key)==0) { |
| /* 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) { |
| node->smaller = node->larger = NULL; |
| } |
| else if (compare(i, t->key) < 0) { |
| node->smaller = t->smaller; |
| node->larger = t; |
| t->smaller = NULL; |
| |
| } |
| else { |
| node->larger = t->larger; |
| node->smaller = t; |
| t->larger = NULL; |
| } |
| node->key = i; |
| |
| 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. |
| |
| Function not used in libcurl. |
| */ |
| struct Curl_tree *Curl_splayremove(int i, struct Curl_tree *t, |
| struct Curl_tree **removed) |
| { |
| struct Curl_tree *x; |
| |
| *removed = NULL; /* default to no removed */ |
| |
| if (t==NULL) |
| return NULL; |
| |
| t = Curl_splay(i,t); |
| if (compare(i, t->key) == 0) { /* found it */ |
| |
| /* FIRST! Check if there is a list with identical sizes */ |
| if((x = t->same)) { |
| /* there is, pick one from the list */ |
| |
| /* 'x' is the new root node */ |
| |
| x->key = t->key; |
| x->larger = t->larger; |
| x->smaller = t->smaller; |
| |
| *removed = t; |
| return x; /* new root */ |
| } |
| |
| if (t->smaller == NULL) { |
| x = t->larger; |
| } |
| else { |
| x = Curl_splay(i, t->smaller); |
| x->larger = t->larger; |
| } |
| *removed = t; |
| |
| return x; |
| } |
| 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 */ |
| struct Curl_tree *Curl_splaygetbest(int i, struct Curl_tree *t, |
| struct Curl_tree **removed) |
| { |
| struct Curl_tree *x; |
| |
| if (!t) { |
| *removed = NULL; /* none removed since there was no root */ |
| return NULL; |
| } |
| |
| t = Curl_splay(i,t); |
| if(compare(i, t->key) < 0) { |
| /* too big node, try the smaller chain */ |
| if(t->smaller) |
| t=Curl_splay(t->smaller->key, t); |
| else { |
| /* fail */ |
| *removed = NULL; |
| return t; |
| } |
| } |
| |
| if (compare(i, t->key) >= 0) { /* found it */ |
| /* FIRST! Check if there is a list with identical sizes */ |
| x = t->same; |
| if(x) { |
| /* there is, pick one from the list */ |
| |
| /* 'x' is the new root node */ |
| |
| x->key = t->key; |
| x->larger = t->larger; |
| x->smaller = t->smaller; |
| |
| *removed = t; |
| return x; /* new root */ |
| } |
| |
| if (t->smaller == NULL) { |
| x = t->larger; |
| } |
| else { |
| x = Curl_splay(i, t->smaller); |
| x->larger = t->larger; |
| } |
| *removed = t; |
| |
| return x; |
| } |
| else { |
| *removed = NULL; /* no match */ |
| return t; /* It wasn't there */ |
| } |
| } |
| |
| |
| /* 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 1; |
| |
| if(KEY_NOTUSED == remove->key) { |
| /* 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. */ |
| if (remove->smaller == NULL) |
| return 3; |
| |
| remove->smaller->same = remove->same; |
| if(remove->same) |
| remove->same->smaller = remove->smaller; |
| |
| /* Ensures that double-remove gets caught. */ |
| remove->smaller = NULL; |
| |
| /* voila, we're done! */ |
| *newroot = t; /* return the same root */ |
| return 0; |
| } |
| |
| t = Curl_splay(remove->key, t); |
| |
| /* First make sure that we got the same root node as the one we want |
| to remove, as otherwise we might be trying to remove a node that |
| isn't actually in the tree. |
| |
| We cannot just compare the keys here as a double remove in quick |
| succession of a node with key != KEY_NOTUSED && same != NULL |
| could return the same key but a different node. */ |
| if(t != remove) |
| 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, we just make it use the root node's |
| smaller/larger links */ |
| |
| x->key = t->key; |
| x->larger = t->larger; |
| x->smaller = t->smaller; |
| } |
| else { |
| /* Remove the root node */ |
| if (t->smaller == NULL) |
| x = t->larger; |
| else { |
| x = Curl_splay(remove->key, t->smaller); |
| x->larger = t->larger; |
| } |
| } |
| |
| *newroot = x; /* store new root pointer */ |
| |
| return 0; |
| } |
| |
| #ifdef CURLDEBUG |
| |
| void Curl_splayprint(struct Curl_tree * t, int d, char output) |
| { |
| struct Curl_tree *node; |
| int i; |
| int count; |
| if (t == NULL) |
| return; |
| |
| Curl_splayprint(t->larger, d+1, output); |
| for (i=0; i<d; i++) |
| if(output) |
| printf(" "); |
| |
| if(output) { |
| printf("%d[%d]", t->key, i); |
| } |
| |
| for(count=0, node = t->same; node; node = node->same, count++) |
| ; |
| |
| if(output) { |
| if(count) |
| printf(" [%d more]\n", count); |
| else |
| printf("\n"); |
| } |
| |
| Curl_splayprint(t->smaller, d+1, output); |
| } |
| #endif |
| |
| #ifdef TEST_SPLAY |
| |
| /*#define TEST2 */ |
| #define MAX 50 |
| #define TEST2 |
| |
| /* A sample use of these functions. Start with the empty tree, insert some |
| stuff into it, and then delete it */ |
| int main(int argc, char **argv) |
| { |
| 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, |
| 220, 80, 90, 50, 100, 60, 200, 120, 300, 400, 200, 256, 122, 60, 120, 200, |
| 300, 220, 80, 90, 50, 100, 60, 200, 120, 300, 400, 200, 256, 122, 60, 120, |
| 200, 300, 220, 80, 90}; |
| int i; |
| 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; |
| } |
| root = Curl_splayinsert(key, root, t); |
| } |
| |
| #if 0 |
| puts("Result:"); |
| Curl_splayprint(root, 0, 1); |
| #endif |
| |
| #if 1 |
| for (i = 0; i < MAX; 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 |
| |
| return 0; |
| } |
| |
| #endif /* TEST_SPLAY */ |