/*************************************************************************** * _ _ ____ _ * 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 */