From 1a78a62555be32868418fe52f8e330c9d0f95d5a Mon Sep 17 00:00:00 2001 From: Anas Nashif Date: Tue, 30 Oct 2012 12:57:26 -0700 Subject: Imported Upstream version 1.49.0 --- boost/intrusive/sgtree_algorithms.hpp | 782 ++++++++++++++++++++++++++++++++++ 1 file changed, 782 insertions(+) create mode 100644 boost/intrusive/sgtree_algorithms.hpp (limited to 'boost/intrusive/sgtree_algorithms.hpp') diff --git a/boost/intrusive/sgtree_algorithms.hpp b/boost/intrusive/sgtree_algorithms.hpp new file mode 100644 index 0000000000..f3c433225e --- /dev/null +++ b/boost/intrusive/sgtree_algorithms.hpp @@ -0,0 +1,782 @@ +///////////////////////////////////////////////////////////////////////////// +// +// (C) Copyright Ion Gaztanaga 2007. +// +// Distributed under the Boost Software License, Version 1.0. +// (See accompanying file LICENSE_1_0.txt or copy at +// http://www.boost.org/LICENSE_1_0.txt) +// +// See http://www.boost.org/libs/intrusive for documentation. +// +///////////////////////////////////////////////////////////////////////////// +// +// Scapegoat tree algorithms are taken from the paper titled: +// "Scapegoat Trees" by Igal Galperin Ronald L. Rivest. +// +///////////////////////////////////////////////////////////////////////////// +#ifndef BOOST_INTRUSIVE_SGTREE_ALGORITHMS_HPP +#define BOOST_INTRUSIVE_SGTREE_ALGORITHMS_HPP + +#include + +#include +#include +#include +#include +#include +#include + + +namespace boost { +namespace intrusive { + +//! sgtree_algorithms is configured with a NodeTraits class, which encapsulates the +//! information about the node to be manipulated. NodeTraits must support the +//! following interface: +//! +//! Typedefs: +//! +//! node: The type of the node that forms the circular list +//! +//! node_ptr: A pointer to a node +//! +//! const_node_ptr: A pointer to a const node +//! +//! Static functions: +//! +//! static node_ptr get_parent(const_node_ptr n); +//! +//! static void set_parent(node_ptr n, node_ptr parent); +//! +//! static node_ptr get_left(const_node_ptr n); +//! +//! static void set_left(node_ptr n, node_ptr left); +//! +//! static node_ptr get_right(const_node_ptr n); +//! +//! static void set_right(node_ptr n, node_ptr right); +template +class sgtree_algorithms +{ + public: + typedef typename NodeTraits::node node; + typedef NodeTraits node_traits; + typedef typename NodeTraits::node_ptr node_ptr; + typedef typename NodeTraits::const_node_ptr const_node_ptr; + + /// @cond + private: + + typedef detail::tree_algorithms tree_algorithms; + + static node_ptr uncast(const const_node_ptr & ptr) + { return pointer_traits::const_cast_from(ptr); } + /// @endcond + + public: + static node_ptr begin_node(const const_node_ptr & header) + { return tree_algorithms::begin_node(header); } + + static node_ptr end_node(const const_node_ptr & header) + { return tree_algorithms::end_node(header); } + + //! This type is the information that will be + //! filled by insert_unique_check + struct insert_commit_data + : tree_algorithms::insert_commit_data + { + std::size_t depth; + }; + + //! Requires: header1 and header2 must be the header nodes + //! of two trees. + //! + //! Effects: Swaps two trees. After the function header1 will contain + //! links to the second tree and header2 will have links to the first tree. + //! + //! Complexity: Constant. + //! + //! Throws: Nothing. + static void swap_tree(const node_ptr & header1, const node_ptr & header2) + { return tree_algorithms::swap_tree(header1, header2); } + + //! Requires: node1 and node2 can't be header nodes + //! of two trees. + //! + //! Effects: Swaps two nodes. After the function node1 will be inserted + //! in the position node2 before the function. node2 will be inserted in the + //! position node1 had before the function. + //! + //! Complexity: Logarithmic. + //! + //! Throws: Nothing. + //! + //! Note: This function will break container ordering invariants if + //! node1 and node2 are not equivalent according to the ordering rules. + //! + //!Experimental function + static void swap_nodes(const node_ptr & node1, const node_ptr & node2) + { + if(node1 == node2) + return; + + node_ptr header1(tree_algorithms::get_header(node1)), header2(tree_algorithms::get_header(node2)); + swap_nodes(node1, header1, node2, header2); + } + + //! Requires: node1 and node2 can't be header nodes + //! of two trees with header header1 and header2. + //! + //! Effects: Swaps two nodes. After the function node1 will be inserted + //! in the position node2 before the function. node2 will be inserted in the + //! position node1 had before the function. + //! + //! Complexity: Constant. + //! + //! Throws: Nothing. + //! + //! Note: This function will break container ordering invariants if + //! node1 and node2 are not equivalent according to the ordering rules. + //! + //!Experimental function + static void swap_nodes(const node_ptr & node1, const node_ptr & header1, const node_ptr & node2, const node_ptr & header2) + { tree_algorithms::swap_nodes(node1, header1, node2, header2); } + + //! Requires: node_to_be_replaced must be inserted in a tree + //! and new_node must not be inserted in a tree. + //! + //! Effects: Replaces node_to_be_replaced in its position in the + //! tree with new_node. The tree does not need to be rebalanced + //! + //! Complexity: Logarithmic. + //! + //! Throws: Nothing. + //! + //! Note: This function will break container ordering invariants if + //! new_node is not equivalent to node_to_be_replaced according to the + //! ordering rules. This function is faster than erasing and inserting + //! the node, since no rebalancing and comparison is needed. + //! + //!Experimental function + static void replace_node(const node_ptr & node_to_be_replaced, const node_ptr & new_node) + { + if(node_to_be_replaced == new_node) + return; + replace_node(node_to_be_replaced, tree_algorithms::get_header(node_to_be_replaced), new_node); + } + + //! Requires: node_to_be_replaced must be inserted in a tree + //! with header "header" and new_node must not be inserted in a tree. + //! + //! Effects: Replaces node_to_be_replaced in its position in the + //! tree with new_node. The tree does not need to be rebalanced + //! + //! Complexity: Constant. + //! + //! Throws: Nothing. + //! + //! Note: This function will break container ordering invariants if + //! new_node is not equivalent to node_to_be_replaced according to the + //! ordering rules. This function is faster than erasing and inserting + //! the node, since no rebalancing or comparison is needed. + //! + //!Experimental function + static void replace_node(const node_ptr & node_to_be_replaced, const node_ptr & header, const node_ptr & new_node) + { tree_algorithms::replace_node(node_to_be_replaced, header, new_node); } + + //! Requires: node is a tree node but not the header. + //! + //! Effects: Unlinks the node and rebalances the tree. + //! + //! Complexity: Average complexity is constant time. + //! + //! Throws: Nothing. + static void unlink(const node_ptr & node) + { + node_ptr x = NodeTraits::get_parent(node); + if(x){ + while(!is_header(x)) + x = NodeTraits::get_parent(x); + tree_algorithms::erase(x, node); + } + } + + //! Requires: header is the header of a tree. + //! + //! Effects: Unlinks the leftmost node from the tree, and + //! updates the header link to the new leftmost node. + //! + //! Complexity: Average complexity is constant time. + //! + //! Throws: Nothing. + //! + //! Notes: This function breaks the tree and the tree can + //! only be used for more unlink_leftmost_without_rebalance calls. + //! This function is normally used to achieve a step by step + //! controlled destruction of the tree. + static node_ptr unlink_leftmost_without_rebalance(const node_ptr & header) + { return tree_algorithms::unlink_leftmost_without_rebalance(header); } + + //! Requires: node is a node of the tree or an node initialized + //! by init(...). + //! + //! Effects: Returns true if the node is initialized by init(). + //! + //! Complexity: Constant time. + //! + //! Throws: Nothing. + static bool unique(const const_node_ptr & node) + { return tree_algorithms::unique(node); } + + //! Requires: node is a node of the tree but it's not the header. + //! + //! Effects: Returns the number of nodes of the subtree. + //! + //! Complexity: Linear time. + //! + //! Throws: Nothing. + static std::size_t count(const const_node_ptr & node) + { return tree_algorithms::count(node); } + + //! Requires: header is the header node of the tree. + //! + //! Effects: Returns the number of nodes above the header. + //! + //! Complexity: Linear time. + //! + //! Throws: Nothing. + static std::size_t size(const const_node_ptr & header) + { return tree_algorithms::size(header); } + + //! Requires: p is a node from the tree except the header. + //! + //! Effects: Returns the next node of the tree. + //! + //! Complexity: Average constant time. + //! + //! Throws: Nothing. + static node_ptr next_node(const node_ptr & p) + { return tree_algorithms::next_node(p); } + + //! Requires: p is a node from the tree except the leftmost node. + //! + //! Effects: Returns the previous node of the tree. + //! + //! Complexity: Average constant time. + //! + //! Throws: Nothing. + static node_ptr prev_node(const node_ptr & p) + { return tree_algorithms::prev_node(p); } + + //! Requires: node must not be part of any tree. + //! + //! Effects: After the function unique(node) == true. + //! + //! Complexity: Constant. + //! + //! Throws: Nothing. + //! + //! Nodes: If node is inserted in a tree, this function corrupts the tree. + static void init(const node_ptr & node) + { tree_algorithms::init(node); } + + //! Requires: node must not be part of any tree. + //! + //! Effects: Initializes the header to represent an empty tree. + //! unique(header) == true. + //! + //! Complexity: Constant. + //! + //! Throws: Nothing. + //! + //! Nodes: If node is inserted in a tree, this function corrupts the tree. + static void init_header(const node_ptr & header) + { tree_algorithms::init_header(header); } + + //! Requires: header must be the header of a tree, z a node + //! of that tree and z != header. + //! + //! Effects: Erases node "z" from the tree with header "header". + //! + //! Complexity: Amortized constant time. + //! + //! Throws: Nothing. + template + static node_ptr erase(const node_ptr & header, const node_ptr & z, std::size_t tree_size, std::size_t &max_tree_size, AlphaByMaxSize alpha_by_maxsize) + { + //typename tree_algorithms::data_for_rebalance info; + tree_algorithms::erase(header, z); + --tree_size; + if (tree_size > 0 && + tree_size < alpha_by_maxsize(max_tree_size)){ + tree_algorithms::rebalance(header); + max_tree_size = tree_size; + } + return z; + } + + //! Requires: "cloner" must be a function + //! object taking a node_ptr and returning a new cloned node of it. "disposer" must + //! take a node_ptr and shouldn't throw. + //! + //! Effects: First empties target tree calling + //! void disposer::operator()(const node_ptr &) for every node of the tree + //! except the header. + //! + //! Then, duplicates the entire tree pointed by "source_header" cloning each + //! source node with node_ptr Cloner::operator()(const node_ptr &) to obtain + //! the nodes of the target tree. If "cloner" throws, the cloned target nodes + //! are disposed using void disposer(const node_ptr &). + //! + //! Complexity: Linear to the number of element of the source tree plus the. + //! number of elements of tree target tree when calling this function. + //! + //! Throws: If cloner functor throws. If this happens target nodes are disposed. + template + static void clone + (const const_node_ptr & source_header, const node_ptr & target_header, Cloner cloner, Disposer disposer) + { + tree_algorithms::clone(source_header, target_header, cloner, disposer); + } + + //! Requires: "disposer" must be an object function + //! taking a node_ptr parameter and shouldn't throw. + //! + //! Effects: Empties the target tree calling + //! void disposer::operator()(const node_ptr &) for every node of the tree + //! except the header. + //! + //! Complexity: Linear to the number of element of the source tree plus the. + //! number of elements of tree target tree when calling this function. + //! + //! Throws: If cloner functor throws. If this happens target nodes are disposed. + template + static void clear_and_dispose(const node_ptr & header, Disposer disposer) + { tree_algorithms::clear_and_dispose(header, disposer); } + + //! Requires: "header" must be the header node of a tree. + //! KeyNodePtrCompare is a function object that induces a strict weak + //! ordering compatible with the strict weak ordering used to create the + //! the tree. KeyNodePtrCompare can compare KeyType with tree's node_ptrs. + //! + //! Effects: Returns an node_ptr to the first element that is + //! not less than "key" according to "comp" or "header" if that element does + //! not exist. + //! + //! Complexity: Logarithmic. + //! + //! Throws: If "comp" throws. + template + static node_ptr lower_bound + (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp) + { return tree_algorithms::lower_bound(header, key, comp); } + + //! Requires: "header" must be the header node of a tree. + //! KeyNodePtrCompare is a function object that induces a strict weak + //! ordering compatible with the strict weak ordering used to create the + //! the tree. KeyNodePtrCompare can compare KeyType with tree's node_ptrs. + //! + //! Effects: Returns an node_ptr to the first element that is greater + //! than "key" according to "comp" or "header" if that element does not exist. + //! + //! Complexity: Logarithmic. + //! + //! Throws: If "comp" throws. + template + static node_ptr upper_bound + (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp) + { return tree_algorithms::upper_bound(header, key, comp); } + + //! Requires: "header" must be the header node of a tree. + //! KeyNodePtrCompare is a function object that induces a strict weak + //! ordering compatible with the strict weak ordering used to create the + //! the tree. KeyNodePtrCompare can compare KeyType with tree's node_ptrs. + //! + //! Effects: Returns an node_ptr to the element that is equivalent to + //! "key" according to "comp" or "header" if that element does not exist. + //! + //! Complexity: Logarithmic. + //! + //! Throws: If "comp" throws. + template + static node_ptr find + (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp) + { return tree_algorithms::find(header, key, comp); } + + //! Requires: "header" must be the header node of a tree. + //! KeyNodePtrCompare is a function object that induces a strict weak + //! ordering compatible with the strict weak ordering used to create the + //! the tree. KeyNodePtrCompare can compare KeyType with tree's node_ptrs. + //! + //! Effects: Returns an a pair of node_ptr delimiting a range containing + //! all elements that are equivalent to "key" according to "comp" or an + //! empty range that indicates the position where those elements would be + //! if they there are no equivalent elements. + //! + //! Complexity: Logarithmic. + //! + //! Throws: If "comp" throws. + template + static std::pair equal_range + (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp) + { return tree_algorithms::equal_range(header, key, comp); } + + //! Requires: "h" must be the header node of a tree. + //! NodePtrCompare is a function object that induces a strict weak + //! ordering compatible with the strict weak ordering used to create the + //! the tree. NodePtrCompare compares two node_ptrs. + //! + //! Effects: Inserts new_node into the tree before the upper bound + //! according to "comp". + //! + //! Complexity: Average complexity for insert element is at + //! most logarithmic. + //! + //! Throws: If "comp" throws. + template + static node_ptr insert_equal_upper_bound + (const node_ptr & h, const node_ptr & new_node, NodePtrCompare comp + ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size) + { + std::size_t depth; + tree_algorithms::insert_equal_upper_bound(h, new_node, comp, &depth); + rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size); + return new_node; + } + + //! Requires: "h" must be the header node of a tree. + //! NodePtrCompare is a function object that induces a strict weak + //! ordering compatible with the strict weak ordering used to create the + //! the tree. NodePtrCompare compares two node_ptrs. + //! + //! Effects: Inserts new_node into the tree before the lower bound + //! according to "comp". + //! + //! Complexity: Average complexity for insert element is at + //! most logarithmic. + //! + //! Throws: If "comp" throws. + template + static node_ptr insert_equal_lower_bound + (const node_ptr & h, const node_ptr & new_node, NodePtrCompare comp + ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size) + { + std::size_t depth; + tree_algorithms::insert_equal_lower_bound(h, new_node, comp, &depth); + rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size); + return new_node; + } + + //! Requires: "header" must be the header node of a tree. + //! NodePtrCompare is a function object that induces a strict weak + //! ordering compatible with the strict weak ordering used to create the + //! the tree. NodePtrCompare compares two node_ptrs. "hint" is node from + //! the "header"'s tree. + //! + //! Effects: Inserts new_node into the tree, using "hint" as a hint to + //! where it will be inserted. If "hint" is the upper_bound + //! the insertion takes constant time (two comparisons in the worst case). + //! + //! Complexity: Logarithmic in general, but it is amortized + //! constant time if new_node is inserted immediately before "hint". + //! + //! Throws: If "comp" throws. + template + static node_ptr insert_equal + (const node_ptr & header, const node_ptr & hint, const node_ptr & new_node, NodePtrCompare comp + ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size) + { + std::size_t depth; + tree_algorithms::insert_equal(header, hint, new_node, comp, &depth); + rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size); + return new_node; + } + + //! Requires: "header" must be the header node of a tree. + //! KeyNodePtrCompare is a function object that induces a strict weak + //! ordering compatible with the strict weak ordering used to create the + //! the tree. NodePtrCompare compares KeyType with a node_ptr. + //! + //! Effects: Checks if there is an equivalent node to "key" in the + //! tree according to "comp" and obtains the needed information to realize + //! a constant-time node insertion if there is no equivalent node. + //! + //! Returns: If there is an equivalent value + //! returns a pair containing a node_ptr to the already present node + //! and false. If there is not equivalent key can be inserted returns true + //! in the returned pair's boolean and fills "commit_data" that is meant to + //! be used with the "insert_commit" function to achieve a constant-time + //! insertion function. + //! + //! Complexity: Average complexity is at most logarithmic. + //! + //! Throws: If "comp" throws. + //! + //! Notes: This function is used to improve performance when constructing + //! a node is expensive and the user does not want to have two equivalent nodes + //! in the tree: if there is an equivalent value + //! the constructed object must be discarded. Many times, the part of the + //! node that is used to impose the order is much cheaper to construct + //! than the node and this function offers the possibility to use that part + //! to check if the insertion will be successful. + //! + //! If the check is successful, the user can construct the node and use + //! "insert_commit" to insert the node in constant-time. This gives a total + //! logarithmic complexity to the insertion: check(O(log(N)) + commit(O(1)). + //! + //! "commit_data" remains valid for a subsequent "insert_unique_commit" only + //! if no more objects are inserted or erased from the set. + template + static std::pair insert_unique_check + (const const_node_ptr & header, const KeyType &key + ,KeyNodePtrCompare comp, insert_commit_data &commit_data) + { + std::size_t depth; + std::pair ret = + tree_algorithms::insert_unique_check(header, key, comp, commit_data, &depth); + commit_data.depth = depth; + return ret; + } + + + //! Requires: "header" must be the header node of a tree. + //! "pos" must be a valid iterator or header (end) node. + //! "pos" must be an iterator pointing to the successor to "new_node" + //! once inserted according to the order of already inserted nodes. This function does not + //! check "pos" and this precondition must be guaranteed by the caller. + //! + //! Effects: Inserts new_node into the tree before "pos". + //! + //! Complexity: Constant-time. + //! + //! Throws: Nothing. + //! + //! Note: If "pos" is not the successor of the newly inserted "new_node" + //! tree invariants might be broken. + template + static node_ptr insert_before + (const node_ptr & header, const node_ptr & pos, const node_ptr & new_node + ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size) + { + std::size_t depth; + tree_algorithms::insert_before(header, pos, new_node, &depth); + rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size); + return new_node; + } + + //! Requires: "header" must be the header node of a tree. + //! "new_node" must be, according to the used ordering no less than the + //! greatest inserted key. + //! + //! Effects: Inserts new_node into the tree before "pos". + //! + //! Complexity: Constant-time. + //! + //! Throws: Nothing. + //! + //! Note: If "new_node" is less than the greatest inserted key + //! tree invariants are broken. This function is slightly faster than + //! using "insert_before". + template + static void push_back(const node_ptr & header, const node_ptr & new_node + ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size) + { + std::size_t depth; + tree_algorithms::push_back(header, new_node, &depth); + rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size); + } + + //! Requires: "header" must be the header node of a tree. + //! "new_node" must be, according to the used ordering, no greater than the + //! lowest inserted key. + //! + //! Effects: Inserts new_node into the tree before "pos". + //! + //! Complexity: Constant-time. + //! + //! Throws: Nothing. + //! + //! Note: If "new_node" is greater than the lowest inserted key + //! tree invariants are broken. This function is slightly faster than + //! using "insert_before". + template + static void push_front(const node_ptr & header, const node_ptr & new_node + ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size) + { + std::size_t depth; + tree_algorithms::push_front(header, new_node, &depth); + rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size); + } + + //! Requires: "header" must be the header node of a tree. + //! KeyNodePtrCompare is a function object that induces a strict weak + //! ordering compatible with the strict weak ordering used to create the + //! the tree. NodePtrCompare compares KeyType with a node_ptr. + //! "hint" is node from the "header"'s tree. + //! + //! Effects: Checks if there is an equivalent node to "key" in the + //! tree according to "comp" using "hint" as a hint to where it should be + //! inserted and obtains the needed information to realize + //! a constant-time node insertion if there is no equivalent node. + //! If "hint" is the upper_bound the function has constant time + //! complexity (two comparisons in the worst case). + //! + //! Returns: If there is an equivalent value + //! returns a pair containing a node_ptr to the already present node + //! and false. If there is not equivalent key can be inserted returns true + //! in the returned pair's boolean and fills "commit_data" that is meant to + //! be used with the "insert_commit" function to achieve a constant-time + //! insertion function. + //! + //! Complexity: Average complexity is at most logarithmic, but it is + //! amortized constant time if new_node should be inserted immediately before "hint". + //! + //! Throws: If "comp" throws. + //! + //! Notes: This function is used to improve performance when constructing + //! a node is expensive and the user does not want to have two equivalent nodes + //! in the tree: if there is an equivalent value + //! the constructed object must be discarded. Many times, the part of the + //! node that is used to impose the order is much cheaper to construct + //! than the node and this function offers the possibility to use that part + //! to check if the insertion will be successful. + //! + //! If the check is successful, the user can construct the node and use + //! "insert_commit" to insert the node in constant-time. This gives a total + //! logarithmic complexity to the insertion: check(O(log(N)) + commit(O(1)). + //! + //! "commit_data" remains valid for a subsequent "insert_unique_commit" only + //! if no more objects are inserted or erased from the set. + template + static std::pair insert_unique_check + (const const_node_ptr & header, const node_ptr &hint, const KeyType &key + ,KeyNodePtrCompare comp, insert_commit_data &commit_data) + { + std::size_t depth; + std::pair ret = + tree_algorithms::insert_unique_check + (header, hint, key, comp, commit_data, &depth); + commit_data.depth = depth; + return ret; + } + + //! Requires: "header" must be the header node of a tree. + //! "commit_data" must have been obtained from a previous call to + //! "insert_unique_check". No objects should have been inserted or erased + //! from the set between the "insert_unique_check" that filled "commit_data" + //! and the call to "insert_commit". + //! + //! + //! Effects: Inserts new_node in the set using the information obtained + //! from the "commit_data" that a previous "insert_check" filled. + //! + //! Complexity: Constant time. + //! + //! Throws: Nothing. + //! + //! Notes: This function has only sense if a "insert_unique_check" has been + //! previously executed to fill "commit_data". No value should be inserted or + //! erased between the "insert_check" and "insert_commit" calls. + template + static void insert_unique_commit + (const node_ptr & header, const node_ptr & new_value, const insert_commit_data &commit_data + ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size) + { + tree_algorithms::insert_unique_commit(header, new_value, commit_data); + rebalance_after_insertion(new_value, commit_data.depth, tree_size+1, h_alpha, max_tree_size); + } + + //! Requires: header must be the header of a tree. + //! + //! Effects: Rebalances the tree. + //! + //! Throws: Nothing. + //! + //! Complexity: Linear. + static void rebalance(const node_ptr & header) + { tree_algorithms::rebalance(header); } + + //! Requires: old_root is a node of a tree. + //! + //! Effects: Rebalances the subtree rooted at old_root. + //! + //! Returns: The new root of the subtree. + //! + //! Throws: Nothing. + //! + //! Complexity: Linear. + static node_ptr rebalance_subtree(const node_ptr & old_root) + { return tree_algorithms::rebalance_subtree(old_root); } + + //! Requires: "n" must be a node inserted in a tree. + //! + //! Effects: Returns a pointer to the header node of the tree. + //! + //! Complexity: Logarithmic. + //! + //! Throws: Nothing. + static node_ptr get_header(const node_ptr & n) + { return tree_algorithms::get_header(n); } + + /// @cond + private: + + //! Requires: p is a node of a tree. + //! + //! Effects: Returns true if p is the header of the tree. + //! + //! Complexity: Constant. + //! + //! Throws: Nothing. + static bool is_header(const const_node_ptr & p) + { return tree_algorithms::is_header(p); } + + template + static void rebalance_after_insertion + (const node_ptr &x, std::size_t depth + , std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size) + { + if(tree_size > max_tree_size) + max_tree_size = tree_size; + + if(tree_size != 1 && depth > h_alpha(tree_size)){ + //Find the first non height-balanced node + //as described in the section 4.2 of the paper. + //This method is the alternative method described + //in the paper. Authors claim that this method + //may tend to yield more balanced trees on the average + //than the weight balanced method. + node_ptr s = x; + std::size_t size = 1; + + for(std::size_t i = 1; true; ++i){ + bool rebalance = false; + if(i == depth){ + BOOST_INTRUSIVE_INVARIANT_ASSERT(tree_size == count(s)); + rebalance = true; + } + else if(i > h_alpha(size)){ + node_ptr s_parent = NodeTraits::get_parent(s); + node_ptr s_parent_left = NodeTraits::get_left(s_parent); + size += 1 + tree_algorithms::count + ( s_parent_left == s ? NodeTraits::get_right(s_parent) : s_parent_left ); + s = s_parent; + rebalance = true; + } + if(rebalance){ + rebalance_subtree(s); + break; + } + } + } + } + + /// @endcond +}; + +} //namespace intrusive +} //namespace boost + +#include + +#endif //BOOST_INTRUSIVE_SGTREE_ALGORITHMS_HPP -- cgit v1.2.3