/*
* Copyright (c) 2010-2015 Richard Braun.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*
* Upstream site with license notes :
* http://git.sceen.net/rbraun/librbraun.git/
*
*
* Red-black tree.
*/
#ifndef KERN_RBTREE_H
#define KERN_RBTREE_H
#include
#include
#include
#include
/*
* Indexes of the left and right nodes in the children array of a node.
*/
#define RBTREE_LEFT 0
#define RBTREE_RIGHT 1
/*
* Red-black node.
*/
struct rbtree_node;
/*
* Red-black tree.
*/
struct rbtree;
/*
* Insertion point identifier.
*/
typedef uintptr_t rbtree_slot_t;
/*
* Static tree initializer.
*/
#define RBTREE_INITIALIZER { NULL }
#include
/*
* Initialize a tree.
*/
static inline void
rbtree_init(struct rbtree *tree)
{
tree->root = NULL;
}
/*
* Initialize a node.
*
* A node is in no tree when its parent points to itself.
*/
static inline void
rbtree_node_init(struct rbtree_node *node)
{
assert(rbtree_node_check_alignment(node));
node->parent = (uintptr_t)node | RBTREE_COLOR_RED;
node->children[RBTREE_LEFT] = NULL;
node->children[RBTREE_RIGHT] = NULL;
}
/*
* Return true if node is in no tree.
*/
static inline int
rbtree_node_unlinked(const struct rbtree_node *node)
{
return rbtree_node_parent(node) == node;
}
/*
* Macro that evaluates to the address of the structure containing the
* given node based on the given type and member.
*/
#define rbtree_entry(node, type, member) structof(node, type, member)
/*
* Return true if tree is empty.
*/
static inline int
rbtree_empty(const struct rbtree *tree)
{
return tree->root == NULL;
}
/*
* Look up a node in a tree.
*
* Note that implementing the lookup algorithm as a macro gives two benefits:
* First, it avoids the overhead of a callback function. Next, the type of the
* cmp_fn parameter isn't rigid. The only guarantee offered by this
* implementation is that the key parameter is the first parameter given to
* cmp_fn. This way, users can pass only the value they need for comparison
* instead of e.g. allocating a full structure on the stack.
*
* See rbtree_insert().
*/
#define rbtree_lookup(tree, key, cmp_fn) \
MACRO_BEGIN \
struct rbtree_node *cur_; \
int diff_; \
\
cur_ = (tree)->root; \
\
while (cur_ != NULL) { \
diff_ = cmp_fn(key, cur_); \
\
if (diff_ == 0) { \
break; \
} \
\
cur_ = cur_->children[rbtree_d2i(diff_)]; \
} \
\
cur_; \
MACRO_END
/*
* Look up a node or one of its nearest nodes in a tree.
*
* This macro essentially acts as rbtree_lookup() but if no entry matched
* the key, an additional step is performed to obtain the next or previous
* node, depending on the direction (left or right).
*
* The constraints that apply to the key parameter are the same as for
* rbtree_lookup().
*/
#define rbtree_lookup_nearest(tree, key, cmp_fn, dir) \
MACRO_BEGIN \
struct rbtree_node *cur_, *prev_; \
int diff_, index_; \
\
prev_ = NULL; \
index_ = -1; \
cur_ = (tree)->root; \
\
while (cur_ != NULL) { \
diff_ = cmp_fn(key, cur_); \
\
if (diff_ == 0) { \
break; \
} \
\
prev_ = cur_; \
index_ = rbtree_d2i(diff_); \
cur_ = cur_->children[index_]; \
} \
\
if (cur_ == NULL) { \
cur_ = rbtree_nearest(prev_, index_, dir); \
} \
\
cur_; \
MACRO_END
/*
* Insert a node in a tree.
*
* This macro performs a standard lookup to obtain the insertion point of
* the given node in the tree (it is assumed that the inserted node never
* compares equal to any other entry in the tree) and links the node. It
* then checks red-black rules violations, and rebalances the tree if
* necessary.
*
* Unlike rbtree_lookup(), the cmp_fn parameter must compare two complete
* entries, so it is suggested to use two different comparison inline
* functions, such as myobj_cmp_lookup() and myobj_cmp_insert(). There is no
* guarantee about the order of the nodes given to the comparison function.
*
* See rbtree_lookup().
*/
#define rbtree_insert(tree, node, cmp_fn) \
MACRO_BEGIN \
struct rbtree_node *cur_, *prev_; \
int diff_, index_; \
\
prev_ = NULL; \
index_ = -1; \
cur_ = (tree)->root; \
\
while (cur_ != NULL) { \
diff_ = cmp_fn(node, cur_); \
assert(diff_ != 0); \
prev_ = cur_; \
index_ = rbtree_d2i(diff_); \
cur_ = cur_->children[index_]; \
} \
\
rbtree_insert_rebalance(tree, prev_, index_, node); \
MACRO_END
/*
* Look up a node/slot pair in a tree.
*
* This macro essentially acts as rbtree_lookup() but in addition to a node,
* it also returns a slot, which identifies an insertion point in the tree.
* If the returned node is NULL, the slot can be used by rbtree_insert_slot()
* to insert without the overhead of an additional lookup.
*
* The constraints that apply to the key parameter are the same as for
* rbtree_lookup().
*/
#define rbtree_lookup_slot(tree, key, cmp_fn, slot) \
MACRO_BEGIN \
struct rbtree_node *cur_, *prev_; \
int diff_, index_; \
\
prev_ = NULL; \
index_ = 0; \
cur_ = (tree)->root; \
\
while (cur_ != NULL) { \
diff_ = cmp_fn(key, cur_); \
\
if (diff_ == 0) { \
break; \
} \
\
prev_ = cur_; \
index_ = rbtree_d2i(diff_); \
cur_ = cur_->children[index_]; \
} \
\
(slot) = rbtree_slot(prev_, index_); \
cur_; \
MACRO_END
/*
* Insert a node at an insertion point in a tree.
*
* This macro essentially acts as rbtree_insert() except that it doesn't
* obtain the insertion point with a standard lookup. The insertion point
* is obtained by calling rbtree_lookup_slot(). In addition, the new node
* must not compare equal to an existing node in the tree (i.e. the slot
* must denote a NULL node).
*/
static inline void
rbtree_insert_slot(struct rbtree *tree, rbtree_slot_t slot,
struct rbtree_node *node)
{
struct rbtree_node *parent;
int index;
parent = rbtree_slot_parent(slot);
index = rbtree_slot_index(slot);
rbtree_insert_rebalance(tree, parent, index, node);
}
/*
* Replace a node at an insertion point in a tree.
*
* The given node must compare strictly equal to the previous node,
* which is returned on completion.
*/
void * rbtree_replace_slot(struct rbtree *tree, rbtree_slot_t slot,
struct rbtree_node *node);
/*
* Remove a node from a tree.
*
* After completion, the node is stale.
*/
void rbtree_remove(struct rbtree *tree, struct rbtree_node *node);
/*
* Return the first node of a tree.
*/
#define rbtree_first(tree) rbtree_firstlast(tree, RBTREE_LEFT)
/*
* Return the last node of a tree.
*/
#define rbtree_last(tree) rbtree_firstlast(tree, RBTREE_RIGHT)
/*
* Return the node previous to the given node.
*/
#define rbtree_prev(node) rbtree_walk(node, RBTREE_LEFT)
/*
* Return the node next to the given node.
*/
#define rbtree_next(node) rbtree_walk(node, RBTREE_RIGHT)
/*
* Forge a loop to process all nodes of a tree, removing them when visited.
*
* This macro can only be used to destroy a tree, so that the resources used
* by the entries can be released by the user. It basically removes all nodes
* without doing any color checking.
*
* After completion, all nodes and the tree root member are stale.
*/
#define rbtree_for_each_remove(tree, node, tmp) \
for (node = rbtree_postwalk_deepest(tree), \
tmp = rbtree_postwalk_unlink(node); \
node != NULL; \
node = tmp, tmp = rbtree_postwalk_unlink(node))
#endif /* KERN_RBTREE_H */