boost/intrusive/sgtree_algorithms.hpp
///////////////////////////////////////////////////////////////////////////// // // (C) Copyright Ion Gaztanaga 2007-2013 // // 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 <boost/intrusive/detail/config_begin.hpp> #include <boost/intrusive/intrusive_fwd.hpp> #include <cstddef> #include <boost/intrusive/detail/assert.hpp> #include <boost/intrusive/detail/utilities.hpp> #include <boost/intrusive/bstree_algorithms.hpp> #include <boost/intrusive/pointer_traits.hpp> 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: //! //! <b>Typedefs</b>: //! //! <tt>node</tt>: The type of the node that forms the binary search tree //! //! <tt>node_ptr</tt>: A pointer to a node //! //! <tt>const_node_ptr</tt>: A pointer to a const node //! //! <b>Static functions</b>: //! //! <tt>static node_ptr get_parent(const_node_ptr n);</tt> //! //! <tt>static void set_parent(node_ptr n, node_ptr parent);</tt> //! //! <tt>static node_ptr get_left(const_node_ptr n);</tt> //! //! <tt>static void set_left(node_ptr n, node_ptr left);</tt> //! //! <tt>static node_ptr get_right(const_node_ptr n);</tt> //! //! <tt>static void set_right(node_ptr n, node_ptr right);</tt> template<class NodeTraits> class sgtree_algorithms #ifndef BOOST_INTRUSIVE_DOXYGEN_INVOKED : public bstree_algorithms<NodeTraits> #endif { 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 bstree_algorithms<NodeTraits> bstree_algo; /// @endcond public: //! This type is the information that will be //! filled by insert_unique_check struct insert_commit_data : bstree_algo::insert_commit_data { std::size_t depth; }; #ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED //! @copydoc ::boost::intrusive::bstree_algorithms::get_header(const const_node_ptr&) static node_ptr get_header(const const_node_ptr & n); //! @copydoc ::boost::intrusive::bstree_algorithms::begin_node static node_ptr begin_node(const const_node_ptr & header); //! @copydoc ::boost::intrusive::bstree_algorithms::end_node static node_ptr end_node(const const_node_ptr & header); //! @copydoc ::boost::intrusive::bstree_algorithms::swap_tree static void swap_tree(const node_ptr & header1, const node_ptr & header2); //! @copydoc ::boost::intrusive::bstree_algorithms::swap_nodes(const node_ptr&,const node_ptr&) static void swap_nodes(const node_ptr & node1, const node_ptr & node2); //! @copydoc ::boost::intrusive::bstree_algorithms::swap_nodes(const node_ptr&,const node_ptr&,const node_ptr&,const node_ptr&) static void swap_nodes(const node_ptr & node1, const node_ptr & header1, const node_ptr & node2, const node_ptr & header2); //! @copydoc ::boost::intrusive::bstree_algorithms::replace_node(const node_ptr&,const node_ptr&) static void replace_node(const node_ptr & node_to_be_replaced, const node_ptr & new_node); //! @copydoc ::boost::intrusive::bstree_algorithms::replace_node(const node_ptr&,const node_ptr&,const node_ptr&) static void replace_node(const node_ptr & node_to_be_replaced, const node_ptr & header, const node_ptr & new_node); //Unlink is not possible since tree metadata is needed to update the tree //!static void unlink(const node_ptr & node); //! @copydoc ::boost::intrusive::bstree_algorithms::unlink_leftmost_without_rebalance static node_ptr unlink_leftmost_without_rebalance(const node_ptr & header); //! @copydoc ::boost::intrusive::bstree_algorithms::unique(const const_node_ptr&) static bool unique(const const_node_ptr & node); //! @copydoc ::boost::intrusive::bstree_algorithms::size(const const_node_ptr&) static std::size_t size(const const_node_ptr & header); //! @copydoc ::boost::intrusive::bstree_algorithms::next_node(const node_ptr&) static node_ptr next_node(const node_ptr & node); //! @copydoc ::boost::intrusive::bstree_algorithms::prev_node(const node_ptr&) static node_ptr prev_node(const node_ptr & node); //! @copydoc ::boost::intrusive::bstree_algorithms::init(const node_ptr&) static void init(const node_ptr & node); //! @copydoc ::boost::intrusive::bstree_algorithms::init_header(const node_ptr&) static void init_header(const node_ptr & header); #endif //#ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED //! @copydoc ::boost::intrusive::bstree_algorithms::erase(const node_ptr&,const node_ptr&) template<class AlphaByMaxSize> 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 bstree_algo::data_for_rebalance info; bstree_algo::erase(header, z); --tree_size; if (tree_size > 0 && tree_size < alpha_by_maxsize(max_tree_size)){ bstree_algo::rebalance(header); max_tree_size = tree_size; } return z; } #ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED //! @copydoc ::boost::intrusive::bstree_algorithms::clone(const const_node_ptr&,const node_ptr&,Cloner,Disposer) template <class Cloner, class Disposer> static void clone (const const_node_ptr & source_header, const node_ptr & target_header, Cloner cloner, Disposer disposer); //! @copydoc ::boost::intrusive::bstree_algorithms::clear_and_dispose(const node_ptr&,Disposer) template<class Disposer> static void clear_and_dispose(const node_ptr & header, Disposer disposer); //! @copydoc ::boost::intrusive::bstree_algorithms::lower_bound(const const_node_ptr&,const KeyType&,KeyNodePtrCompare) template<class KeyType, class KeyNodePtrCompare> static node_ptr lower_bound (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp); //! @copydoc ::boost::intrusive::bstree_algorithms::upper_bound(const const_node_ptr&,const KeyType&,KeyNodePtrCompare) template<class KeyType, class KeyNodePtrCompare> static node_ptr upper_bound (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp); //! @copydoc ::boost::intrusive::bstree_algorithms::find(const const_node_ptr&, const KeyType&,KeyNodePtrCompare) template<class KeyType, class KeyNodePtrCompare> static node_ptr find (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp); //! @copydoc ::boost::intrusive::bstree_algorithms::equal_range(const const_node_ptr&,const KeyType&,KeyNodePtrCompare) template<class KeyType, class KeyNodePtrCompare> static std::pair<node_ptr, node_ptr> equal_range (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp); //! @copydoc ::boost::intrusive::bstree_algorithms::bounded_range(const const_node_ptr&,const KeyType&,const KeyType&,KeyNodePtrCompare,bool,bool) template<class KeyType, class KeyNodePtrCompare> static std::pair<node_ptr, node_ptr> bounded_range (const const_node_ptr & header, const KeyType &lower_key, const KeyType &upper_key, KeyNodePtrCompare comp , bool left_closed, bool right_closed); //! @copydoc ::boost::intrusive::bstree_algorithms::count(const const_node_ptr&,const KeyType&,KeyNodePtrCompare) template<class KeyType, class KeyNodePtrCompare> static std::size_t count(const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp); #endif //#ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED //! @copydoc ::boost::intrusive::bstree_algorithms::insert_equal_upper_bound(const node_ptr&,const node_ptr&,NodePtrCompare) template<class NodePtrCompare, class H_Alpha> 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; bstree_algo::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; } //! @copydoc ::boost::intrusive::bstree_algorithms::insert_equal_lower_bound(const node_ptr&,const node_ptr&,NodePtrCompare) template<class NodePtrCompare, class H_Alpha> 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; bstree_algo::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; } //! @copydoc ::boost::intrusive::bstree_algorithms::insert_equal(const node_ptr&,const node_ptr&,const node_ptr&,NodePtrCompare) template<class NodePtrCompare, class H_Alpha> 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; bstree_algo::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; } //! @copydoc ::boost::intrusive::bstree_algorithms::insert_before(const node_ptr&,const node_ptr&,const node_ptr&) template<class H_Alpha> 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; bstree_algo::insert_before(header, pos, new_node, &depth); rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size); return new_node; } //! @copydoc ::boost::intrusive::bstree_algorithms::push_back(const node_ptr&,const node_ptr&) template<class H_Alpha> 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; bstree_algo::push_back(header, new_node, &depth); rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size); } //! @copydoc ::boost::intrusive::bstree_algorithms::push_front(const node_ptr&,const node_ptr&) template<class H_Alpha> 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; bstree_algo::push_front(header, new_node, &depth); rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size); } //! @copydoc ::boost::intrusive::bstree_algorithms::insert_unique_check(const const_node_ptr&,const KeyType&,KeyNodePtrCompare,insert_commit_data&) template<class KeyType, class KeyNodePtrCompare> static std::pair<node_ptr, bool> insert_unique_check (const const_node_ptr & header, const KeyType &key ,KeyNodePtrCompare comp, insert_commit_data &commit_data) { std::size_t depth; std::pair<node_ptr, bool> ret = bstree_algo::insert_unique_check(header, key, comp, commit_data, &depth); commit_data.depth = depth; return ret; } //! @copydoc ::boost::intrusive::bstree_algorithms::insert_unique_check(const const_node_ptr&,const node_ptr&,const KeyType&,KeyNodePtrCompare,insert_commit_data&) template<class KeyType, class KeyNodePtrCompare> static std::pair<node_ptr, bool> 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<node_ptr, bool> ret = bstree_algo::insert_unique_check (header, hint, key, comp, commit_data, &depth); commit_data.depth = depth; return ret; } //! @copydoc ::boost::intrusive::bstree_algorithms::insert_unique_commit(const node_ptr&,const node_ptr&,const insert_commit_data&) template<class H_Alpha> 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) { bstree_algo::insert_unique_commit(header, new_value, commit_data); rebalance_after_insertion(new_value, commit_data.depth, tree_size+1, h_alpha, max_tree_size); } #ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED //! @copydoc ::boost::intrusive::bstree_algorithms::is_header static bool is_header(const const_node_ptr & p); //! @copydoc ::boost::intrusive::bstree_algorithms::is_header static void rebalance(const node_ptr & header); //! @copydoc ::boost::intrusive::bstree_algorithms::rebalance_subtree static node_ptr rebalance_subtree(const node_ptr & old_root) #endif //#ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED /// @cond private: template<class H_Alpha> 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 > 2 && //Nothing to do with only the root //Check if the root node is unbalanced //Scapegoat paper depth counts root depth as zero and "depth" counts root as 1, //but since "depth" is the depth of the ancestor of x, i == depth 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 ancestor = 1; ancestor != depth; ++ancestor){ const node_ptr s_parent = NodeTraits::get_parent(s); const node_ptr s_parent_left = NodeTraits::get_left(s_parent); //Obtain parent's size (previous size + parent + sibling tree) const node_ptr s_sibling = s_parent_left == s ? NodeTraits::get_right(s_parent) : s_parent_left; size += 1 + bstree_algo::subtree_size(s_sibling); s = s_parent; if(ancestor > h_alpha(size)){ //is 's' scapegoat? bstree_algo::rebalance_subtree(s); return; } } //The whole tree must be rebuilt max_tree_size = tree_size; bstree_algo::rebalance_subtree(NodeTraits::get_parent(s)); } } /// @endcond }; /// @cond template<class NodeTraits> struct get_algo<SgTreeAlgorithms, NodeTraits> { typedef sgtree_algorithms<NodeTraits> type; }; /// @endcond } //namespace intrusive } //namespace boost #include <boost/intrusive/detail/config_end.hpp> #endif //BOOST_INTRUSIVE_SGTREE_ALGORITHMS_HPP