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-rw-r--r--Utilities/cmcurl/lib/splay.c278
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diff --git a/Utilities/cmcurl/lib/splay.c b/Utilities/cmcurl/lib/splay.c
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+/***************************************************************************
+ * _ _ ____ _
+ * Project ___| | | | _ \| |
+ * / __| | | | |_) | |
+ * | (__| |_| | _ <| |___
+ * \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 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 https://curl.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.
+ *
+ * SPDX-License-Identifier: curl
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#include "splay.h"
+
+/*
+ * This macro compares two node keys i and j and returns:
+ *
+ * negative value: when i is smaller than j
+ * zero : when i is equal to j
+ * positive when : when i is larger than j
+ */
+#define compare(i,j) Curl_splaycomparekeys((i),(j))
+
+/*
+ * Splay using the key i (which may or may not be in the tree.) The starting
+ * root is t.
+ */
+struct Curl_tree *Curl_splay(struct curltime i,
+ struct Curl_tree *t)
+{
+ struct Curl_tree N, *l, *r, *y;
+
+ if(!t)
+ return t;
+ N.smaller = N.larger = NULL;
+ l = r = &N;
+
+ for(;;) {
+ long comp = compare(i, t->key);
+ if(comp < 0) {
+ if(!t->smaller)
+ 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)
+ break;
+ }
+ r->smaller = t; /* link smaller */
+ r = t;
+ t = t->smaller;
+ }
+ else if(comp > 0) {
+ if(!t->larger)
+ 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)
+ 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.
+ *
+ * @unittest: 1309
+ */
+struct Curl_tree *Curl_splayinsert(struct curltime i,
+ struct Curl_tree *t,
+ struct Curl_tree *node)
+{
+ static const struct curltime KEY_NOTUSED = {
+ ~0, -1
+ }; /* will *NEVER* appear */
+
+ if(!node)
+ return t;
+
+ if(t) {
+ 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 doubly-linked circular list of nodes. We add the new 'node' struct
+ to the end of this list. */
+
+ node->key = KEY_NOTUSED; /* we set the key in the sub node to NOTUSED
+ to quickly identify this node as a subnode */
+ node->samen = t;
+ node->samep = t->samep;
+ t->samep->samen = node;
+ t->samep = node;
+
+ return t; /* the root node always stays the same */
+ }
+ }
+
+ if(!t) {
+ 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;
+
+ /* no identical nodes (yet), we are the only one in the list of nodes */
+ node->samen = node;
+ node->samep = node;
+ return node;
+}
+
+/* Finds and deletes the best-fit node from the tree. Return a pointer to the
+ resulting tree. best-fit means the smallest node if it is not larger than
+ the key */
+struct Curl_tree *Curl_splaygetbest(struct curltime i,
+ struct Curl_tree *t,
+ struct Curl_tree **removed)
+{
+ static const struct curltime tv_zero = {0, 0};
+ struct Curl_tree *x;
+
+ if(!t) {
+ *removed = NULL; /* none removed since there was no root */
+ return NULL;
+ }
+
+ /* find smallest */
+ t = Curl_splay(tv_zero, t);
+ if(compare(i, t->key) < 0) {
+ /* even the smallest is too big */
+ *removed = NULL;
+ return t;
+ }
+
+ /* FIRST! Check if there is a list with identical keys */
+ x = t->samen;
+ if(x != t) {
+ /* 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;
+ x->samep = t->samep;
+ t->samep->samen = x;
+
+ *removed = t;
+ return x; /* new root */
+ }
+
+ /* we splayed the tree to the smallest element, there is no smaller */
+ x = t->larger;
+ *removed = t;
+
+ return x;
+}
+
+
+/* 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!
+ * 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.
+ *
+ * @unittest: 1309
+ */
+int Curl_splayremove(struct Curl_tree *t,
+ struct Curl_tree *removenode,
+ struct Curl_tree **newroot)
+{
+ static const struct curltime KEY_NOTUSED = {
+ ~0, -1
+ }; /* will *NEVER* appear */
+ struct Curl_tree *x;
+
+ if(!t || !removenode)
+ return 1;
+
+ if(compare(KEY_NOTUSED, removenode->key) == 0) {
+ /* Key set to NOTUSED means it is a subnode within a 'same' linked list
+ and thus we can unlink it easily. */
+ if(removenode->samen == removenode)
+ /* A non-subnode should never be set to KEY_NOTUSED */
+ return 3;
+
+ removenode->samep->samen = removenode->samen;
+ removenode->samen->samep = removenode->samep;
+
+ /* Ensures that double-remove gets caught. */
+ removenode->samen = removenode;
+
+ *newroot = t; /* return the same root */
+ return 0;
+ }
+
+ t = Curl_splay(removenode->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 != removenode)
+ 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->samen;
+ if(x != t) {
+ /* '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;
+ x->samep = t->samep;
+ t->samep->samen = x;
+ }
+ else {
+ /* Remove the root node */
+ if(!t->smaller)
+ x = t->larger;
+ else {
+ x = Curl_splay(removenode->key, t->smaller);
+ x->larger = t->larger;
+ }
+ }
+
+ *newroot = x; /* store new root pointer */
+
+ return 0;
+}
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