--- /dev/null
+/*
+ * Copyright (c) 2004-2005, 2007, 2009-2011
+ * Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * Adapted from the following code written by Emin Martinian:
+ * http://web.mit.edu/~emin/www/source_code/red_black_tree/index.html
+ *
+ * Copyright (c) 2001 Emin Martinian
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that neither the name of Emin
+ * Martinian nor the names of any contributors are be used to endorse or
+ * promote products derived from this software without specific prior
+ * written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <sys/param.h>
+
+#include <stdio.h>
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# ifdef HAVE_STDLIB_H
+# include <stdlib.h>
+# endif
+#endif /* STDC_HEADERS */
+
+#include "missing.h"
+#include "alloc.h"
+#include "redblack.h"
+
+static void rbrepair(struct rbtree *, struct rbnode *);
+static void rotate_left(struct rbtree *, struct rbnode *);
+static void rotate_right(struct rbtree *, struct rbnode *);
+static void _rbdestroy(struct rbtree *, struct rbnode *, void (*)(void *));
+
+/*
+ * Red-Black tree, see http://en.wikipedia.org/wiki/Red-black_tree
+ *
+ * A red-black tree is a binary search tree where each node has a color
+ * attribute, the value of which is either red or black. Essentially, it
+ * is just a convenient way to express a 2-3-4 binary search tree where
+ * the color indicates whether the node is part of a 3-node or a 4-node.
+ * In addition to the ordinary requirements imposed on binary search
+ * trees, we make the following additional requirements of any valid
+ * red-black tree:
+ * 1) Every node is either red or black.
+ * 2) The root is black.
+ * 3) All leaves are black.
+ * 4) Both children of each red node are black.
+ * 5) The paths from each leaf up to the root each contain the same
+ * number of black nodes.
+ */
+
+/*
+ * Create a red black tree struct using the specified compare routine.
+ * Allocates and returns the initialized (empty) tree.
+ */
+struct rbtree *
+rbcreate(int (*compar)(const void *, const void*))
+{
+ struct rbtree *tree;
+
+ tree = (struct rbtree *) emalloc(sizeof(*tree));
+ tree->compar = compar;
+
+ /*
+ * We use a self-referencing sentinel node called nil to simplify the
+ * code by avoiding the need to check for NULL pointers.
+ */
+ tree->nil.left = tree->nil.right = tree->nil.parent = &tree->nil;
+ tree->nil.color = black;
+ tree->nil.data = NULL;
+
+ /*
+ * Similarly, the fake root node keeps us from having to worry
+ * about splitting the root.
+ */
+ tree->root.left = tree->root.right = tree->root.parent = &tree->nil;
+ tree->root.color = black;
+ tree->root.data = NULL;
+
+ return tree;
+}
+
+/*
+ * Perform a left rotation starting at node.
+ */
+static void
+rotate_left(struct rbtree *tree, struct rbnode *node)
+{
+ struct rbnode *child;
+
+ child = node->right;
+ node->right = child->left;
+
+ if (child->left != rbnil(tree))
+ child->left->parent = node;
+ child->parent = node->parent;
+
+ if (node == node->parent->left)
+ node->parent->left = child;
+ else
+ node->parent->right = child;
+ child->left = node;
+ node->parent = child;
+}
+
+/*
+ * Perform a right rotation starting at node.
+ */
+static void
+rotate_right(struct rbtree *tree, struct rbnode *node)
+{
+ struct rbnode *child;
+
+ child = node->left;
+ node->left = child->right;
+
+ if (child->right != rbnil(tree))
+ child->right->parent = node;
+ child->parent = node->parent;
+
+ if (node == node->parent->left)
+ node->parent->left = child;
+ else
+ node->parent->right = child;
+ child->right = node;
+ node->parent = child;
+}
+
+/*
+ * Insert data pointer into a redblack tree.
+ * Returns a NULL pointer on success. If a node matching "data"
+ * already exists, a pointer to the existant node is returned.
+ */
+struct rbnode *
+rbinsert(struct rbtree *tree, void *data)
+{
+ struct rbnode *node = rbfirst(tree);
+ struct rbnode *parent = rbroot(tree);
+ int res;
+
+ /* Find correct insertion point. */
+ while (node != rbnil(tree)) {
+ parent = node;
+ if ((res = tree->compar(data, node->data)) == 0)
+ return node;
+ node = res < 0 ? node->left : node->right;
+ }
+
+ node = (struct rbnode *) emalloc(sizeof(*node));
+ node->data = data;
+ node->left = node->right = rbnil(tree);
+ node->parent = parent;
+ if (parent == rbroot(tree) || tree->compar(data, parent->data) < 0)
+ parent->left = node;
+ else
+ parent->right = node;
+ node->color = red;
+
+ /*
+ * If the parent node is black we are all set, if it is red we have
+ * the following possible cases to deal with. We iterate through
+ * the rest of the tree to make sure none of the required properties
+ * is violated.
+ *
+ * 1) The uncle is red. We repaint both the parent and uncle black
+ * and repaint the grandparent node red.
+ *
+ * 2) The uncle is black and the new node is the right child of its
+ * parent, and the parent in turn is the left child of its parent.
+ * We do a left rotation to switch the roles of the parent and
+ * child, relying on further iterations to fixup the old parent.
+ *
+ * 3) The uncle is black and the new node is the left child of its
+ * parent, and the parent in turn is the left child of its parent.
+ * We switch the colors of the parent and grandparent and perform
+ * a right rotation around the grandparent. This makes the former
+ * parent the parent of the new node and the former grandparent.
+ *
+ * Note that because we use a sentinel for the root node we never
+ * need to worry about replacing the root.
+ */
+ while (node->parent->color == red) {
+ struct rbnode *uncle;
+ if (node->parent == node->parent->parent->left) {
+ uncle = node->parent->parent->right;
+ if (uncle->color == red) {
+ node->parent->color = black;
+ uncle->color = black;
+ node->parent->parent->color = red;
+ node = node->parent->parent;
+ } else /* if (uncle->color == black) */ {
+ if (node == node->parent->right) {
+ node = node->parent;
+ rotate_left(tree, node);
+ }
+ node->parent->color = black;
+ node->parent->parent->color = red;
+ rotate_right(tree, node->parent->parent);
+ }
+ } else { /* if (node->parent == node->parent->parent->right) */
+ uncle = node->parent->parent->left;
+ if (uncle->color == red) {
+ node->parent->color = black;
+ uncle->color = black;
+ node->parent->parent->color = red;
+ node = node->parent->parent;
+ } else /* if (uncle->color == black) */ {
+ if (node == node->parent->left) {
+ node = node->parent;
+ rotate_right(tree, node);
+ }
+ node->parent->color = black;
+ node->parent->parent->color = red;
+ rotate_left(tree, node->parent->parent);
+ }
+ }
+ }
+ rbfirst(tree)->color = black; /* first node is always black */
+ return NULL;
+}
+
+/*
+ * Look for a node matching key in tree.
+ * Returns a pointer to the node if found, else NULL.
+ */
+struct rbnode *
+rbfind(struct rbtree *tree, void *key)
+{
+ struct rbnode *node = rbfirst(tree);
+ int res;
+
+ while (node != rbnil(tree)) {
+ if ((res = tree->compar(key, node->data)) == 0)
+ return node;
+ node = res < 0 ? node->left : node->right;
+ }
+ return NULL;
+}
+
+/*
+ * Call func() for each node, passing it the node data and a cookie;
+ * If func() returns non-zero for a node, the traversal stops and the
+ * error value is returned. Returns 0 on successful traversal.
+ */
+int
+rbapply_node(struct rbtree *tree, struct rbnode *node,
+ int (*func)(void *, void *), void *cookie, enum rbtraversal order)
+{
+ int error;
+
+ if (node != rbnil(tree)) {
+ if (order == preorder)
+ if ((error = func(node->data, cookie)) != 0)
+ return error;
+ if ((error = rbapply_node(tree, node->left, func, cookie, order)) != 0)
+ return error;
+ if (order == inorder)
+ if ((error = func(node->data, cookie)) != 0)
+ return error;
+ if ((error = rbapply_node(tree, node->right, func, cookie, order)) != 0)
+ return error;
+ if (order == postorder)
+ if ((error = func(node->data, cookie)) != 0)
+ return error;
+ }
+ return 0;
+}
+
+/*
+ * Returns the successor of node, or nil if there is none.
+ */
+static struct rbnode *
+rbsuccessor(struct rbtree *tree, struct rbnode *node)
+{
+ struct rbnode *succ;
+
+ if ((succ = node->right) != rbnil(tree)) {
+ while (succ->left != rbnil(tree))
+ succ = succ->left;
+ } else {
+ /* No right child, move up until we find it or hit the root */
+ for (succ = node->parent; node == succ->right; succ = succ->parent)
+ node = succ;
+ if (succ == rbroot(tree))
+ succ = rbnil(tree);
+ }
+ return succ;
+}
+
+/*
+ * Recursive portion of rbdestroy().
+ */
+static void
+_rbdestroy(struct rbtree *tree, struct rbnode *node, void (*destroy)(void *))
+{
+ if (node != rbnil(tree)) {
+ _rbdestroy(tree, node->left, destroy);
+ _rbdestroy(tree, node->right, destroy);
+ if (destroy != NULL)
+ destroy(node->data);
+ efree(node);
+ }
+}
+
+/*
+ * Destroy the specified tree, calling the destructor destroy
+ * for each node and then freeing the tree itself.
+ */
+void
+rbdestroy(struct rbtree *tree, void (*destroy)(void *))
+{
+ _rbdestroy(tree, rbfirst(tree), destroy);
+ efree(tree);
+}
+
+/*
+ * Delete node 'z' from the tree and return its data pointer.
+ */
+void *rbdelete(struct rbtree *tree, struct rbnode *z)
+{
+ struct rbnode *x, *y;
+ void *data = z->data;
+
+ if (z->left == rbnil(tree) || z->right == rbnil(tree))
+ y = z;
+ else
+ y = rbsuccessor(tree, z);
+ x = (y->left == rbnil(tree)) ? y->right : y->left;
+
+ if ((x->parent = y->parent) == rbroot(tree)) {
+ rbfirst(tree) = x;
+ } else {
+ if (y == y->parent->left)
+ y->parent->left = x;
+ else
+ y->parent->right = x;
+ }
+ if (y->color == black)
+ rbrepair(tree, x);
+ if (y != z) {
+ y->left = z->left;
+ y->right = z->right;
+ y->parent = z->parent;
+ y->color = z->color;
+ z->left->parent = z->right->parent = y;
+ if (z == z->parent->left)
+ z->parent->left = y;
+ else
+ z->parent->right = y;
+ }
+ free(z);
+
+ return data;
+}
+
+/*
+ * Repair the tree after a node has been deleted by rotating and repainting
+ * colors to restore the 4 properties inherent in red-black trees.
+ */
+static void
+rbrepair(struct rbtree *tree, struct rbnode *node)
+{
+ struct rbnode *sibling;
+
+ while (node->color == black && node != rbroot(tree)) {
+ if (node == node->parent->left) {
+ sibling = node->parent->right;
+ if (sibling->color == red) {
+ sibling->color = black;
+ node->parent->color = red;
+ rotate_left(tree, node->parent);
+ sibling = node->parent->right;
+ }
+ if (sibling->right->color == black && sibling->left->color == black) {
+ sibling->color = red;
+ node = node->parent;
+ } else {
+ if (sibling->right->color == black) {
+ sibling->left->color = black;
+ sibling->color = red;
+ rotate_right(tree, sibling);
+ sibling = node->parent->right;
+ }
+ sibling->color = node->parent->color;
+ node->parent->color = black;
+ sibling->right->color = black;
+ rotate_left(tree, node->parent);
+ node = rbroot(tree); /* exit loop */
+ }
+ } else { /* if (node == node->parent->right) */
+ sibling = node->parent->left;
+ if (sibling->color == red) {
+ sibling->color = black;
+ node->parent->color = red;
+ rotate_right(tree, node->parent);
+ sibling = node->parent->left;
+ }
+ if (sibling->right->color == black && sibling->left->color == black) {
+ sibling->color = red;
+ node = node->parent;
+ } else {
+ if (sibling->left->color == black) {
+ sibling->right->color = black;
+ sibling->color = red;
+ rotate_left(tree, sibling);
+ sibling = node->parent->left;
+ }
+ sibling->color = node->parent->color;
+ node->parent->color = black;
+ sibling->left->color = black;
+ rotate_right(tree, node->parent);
+ node = rbroot(tree); /* exit loop */
+ }
+ }
+ }
+ node->color = black;
+}
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