Chris@16: /////////////////////////////////////////////////////////////////////////////
Chris@16: //
Chris@101: // (C) Copyright Ion Gaztanaga 2007-2014
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0.
Chris@16: //    (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: //          http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: // See http://www.boost.org/libs/intrusive for documentation.
Chris@16: //
Chris@16: /////////////////////////////////////////////////////////////////////////////
Chris@16: //
Chris@16: // Scapegoat tree algorithms are taken from the paper titled:
Chris@16: // "Scapegoat Trees" by Igal Galperin Ronald L. Rivest.
Chris@16: //
Chris@16: /////////////////////////////////////////////////////////////////////////////
Chris@16: #ifndef BOOST_INTRUSIVE_SGTREE_ALGORITHMS_HPP
Chris@16: #define BOOST_INTRUSIVE_SGTREE_ALGORITHMS_HPP
Chris@16: 
Chris@16: #include <boost/intrusive/detail/config_begin.hpp>
Chris@101: #include <boost/intrusive/intrusive_fwd.hpp>
Chris@16: 
Chris@16: #include <cstddef>
Chris@101: #include <boost/intrusive/detail/algo_type.hpp>
Chris@16: #include <boost/intrusive/bstree_algorithms.hpp>
Chris@16: 
Chris@101: #if defined(BOOST_HAS_PRAGMA_ONCE)
Chris@101: #  pragma once
Chris@101: #endif
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace intrusive {
Chris@16: 
Chris@16: //! sgtree_algorithms is configured with a NodeTraits class, which encapsulates the
Chris@16: //! information about the node to be manipulated. NodeTraits must support the
Chris@16: //! following interface:
Chris@16: //!
Chris@16: //! <b>Typedefs</b>:
Chris@16: //!
Chris@16: //! <tt>node</tt>: The type of the node that forms the binary search tree
Chris@16: //!
Chris@16: //! <tt>node_ptr</tt>: A pointer to a node
Chris@16: //!
Chris@16: //! <tt>const_node_ptr</tt>: A pointer to a const node
Chris@16: //!
Chris@16: //! <b>Static functions</b>:
Chris@16: //!
Chris@16: //! <tt>static node_ptr get_parent(const_node_ptr n);</tt>
Chris@16: //!
Chris@16: //! <tt>static void set_parent(node_ptr n, node_ptr parent);</tt>
Chris@16: //!
Chris@16: //! <tt>static node_ptr get_left(const_node_ptr n);</tt>
Chris@16: //!
Chris@16: //! <tt>static void set_left(node_ptr n, node_ptr left);</tt>
Chris@16: //!
Chris@16: //! <tt>static node_ptr get_right(const_node_ptr n);</tt>
Chris@16: //!
Chris@16: //! <tt>static void set_right(node_ptr n, node_ptr right);</tt>
Chris@16: template<class NodeTraits>
Chris@16: class sgtree_algorithms
Chris@16:    #ifndef BOOST_INTRUSIVE_DOXYGEN_INVOKED
Chris@16:    : public bstree_algorithms<NodeTraits>
Chris@16:    #endif
Chris@16: {
Chris@16:    public:
Chris@16:    typedef typename NodeTraits::node            node;
Chris@16:    typedef NodeTraits                           node_traits;
Chris@16:    typedef typename NodeTraits::node_ptr        node_ptr;
Chris@16:    typedef typename NodeTraits::const_node_ptr  const_node_ptr;
Chris@16: 
Chris@16:    /// @cond
Chris@16:    private:
Chris@16: 
Chris@16:    typedef bstree_algorithms<NodeTraits>  bstree_algo;
Chris@16: 
Chris@16:    /// @endcond
Chris@16: 
Chris@16:    public:
Chris@16:    //! This type is the information that will be
Chris@16:    //! filled by insert_unique_check
Chris@16:    struct insert_commit_data
Chris@16:       : bstree_algo::insert_commit_data
Chris@16:    {
Chris@16:       std::size_t depth;
Chris@16:    };
Chris@16: 
Chris@16:    #ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::get_header(const const_node_ptr&)
Chris@16:    static node_ptr get_header(const const_node_ptr & n);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::begin_node
Chris@16:    static node_ptr begin_node(const const_node_ptr & header);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::end_node
Chris@16:    static node_ptr end_node(const const_node_ptr & header);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::swap_tree
Chris@16:    static void swap_tree(const node_ptr & header1, const node_ptr & header2);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::swap_nodes(const node_ptr&,const node_ptr&)
Chris@16:    static void swap_nodes(const node_ptr & node1, const node_ptr & node2);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::swap_nodes(const node_ptr&,const node_ptr&,const node_ptr&,const node_ptr&)
Chris@16:    static void swap_nodes(const node_ptr & node1, const node_ptr & header1, const node_ptr & node2, const node_ptr & header2);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::replace_node(const node_ptr&,const node_ptr&)
Chris@16:    static void replace_node(const node_ptr & node_to_be_replaced, const node_ptr & new_node);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::replace_node(const node_ptr&,const node_ptr&,const node_ptr&)
Chris@16:    static void replace_node(const node_ptr & node_to_be_replaced, const node_ptr & header, const node_ptr & new_node);
Chris@16: 
Chris@16:    //Unlink is not possible since tree metadata is needed to update the tree
Chris@16:    //!static void unlink(const node_ptr & node);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::unlink_leftmost_without_rebalance
Chris@16:    static node_ptr unlink_leftmost_without_rebalance(const node_ptr & header);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::unique(const const_node_ptr&)
Chris@16:    static bool unique(const const_node_ptr & node);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::size(const const_node_ptr&)
Chris@16:    static std::size_t size(const const_node_ptr & header);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::next_node(const node_ptr&)
Chris@16:    static node_ptr next_node(const node_ptr & node);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::prev_node(const node_ptr&)
Chris@16:    static node_ptr prev_node(const node_ptr & node);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::init(const node_ptr&)
Chris@16:    static void init(const node_ptr & node);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::init_header(const node_ptr&)
Chris@16:    static void init_header(const node_ptr & header);
Chris@16:    #endif   //#ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::erase(const node_ptr&,const node_ptr&)
Chris@16:    template<class AlphaByMaxSize>
Chris@16:    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)
Chris@16:    {
Chris@16:       //typename bstree_algo::data_for_rebalance info;
Chris@16:       bstree_algo::erase(header, z);
Chris@16:       --tree_size;
Chris@16:       if (tree_size > 0 &&
Chris@16:           tree_size < alpha_by_maxsize(max_tree_size)){
Chris@16:          bstree_algo::rebalance(header);
Chris@16:          max_tree_size = tree_size;
Chris@16:       }
Chris@16:       return z;
Chris@16:    }
Chris@16: 
Chris@16:    #ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::clone(const const_node_ptr&,const node_ptr&,Cloner,Disposer)
Chris@16:    template <class Cloner, class Disposer>
Chris@16:    static void clone
Chris@16:       (const const_node_ptr & source_header, const node_ptr & target_header, Cloner cloner, Disposer disposer);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::clear_and_dispose(const node_ptr&,Disposer)
Chris@16:    template<class Disposer>
Chris@16:    static void clear_and_dispose(const node_ptr & header, Disposer disposer);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::lower_bound(const const_node_ptr&,const KeyType&,KeyNodePtrCompare)
Chris@16:    template<class KeyType, class KeyNodePtrCompare>
Chris@16:    static node_ptr lower_bound
Chris@16:       (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::upper_bound(const const_node_ptr&,const KeyType&,KeyNodePtrCompare)
Chris@16:    template<class KeyType, class KeyNodePtrCompare>
Chris@16:    static node_ptr upper_bound
Chris@16:       (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::find(const const_node_ptr&, const KeyType&,KeyNodePtrCompare)
Chris@16:    template<class KeyType, class KeyNodePtrCompare>
Chris@16:    static node_ptr find
Chris@16:       (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::equal_range(const const_node_ptr&,const KeyType&,KeyNodePtrCompare)
Chris@16:    template<class KeyType, class KeyNodePtrCompare>
Chris@16:    static std::pair<node_ptr, node_ptr> equal_range
Chris@16:       (const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::bounded_range(const const_node_ptr&,const KeyType&,const KeyType&,KeyNodePtrCompare,bool,bool)
Chris@16:    template<class KeyType, class KeyNodePtrCompare>
Chris@16:    static std::pair<node_ptr, node_ptr> bounded_range
Chris@16:       (const const_node_ptr & header, const KeyType &lower_key, const KeyType &upper_key, KeyNodePtrCompare comp
Chris@16:       , bool left_closed, bool right_closed);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::count(const const_node_ptr&,const KeyType&,KeyNodePtrCompare)
Chris@16:    template<class KeyType, class KeyNodePtrCompare>
Chris@16:    static std::size_t count(const const_node_ptr & header, const KeyType &key, KeyNodePtrCompare comp);
Chris@101: 
Chris@16:    #endif   //#ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::insert_equal_upper_bound(const node_ptr&,const node_ptr&,NodePtrCompare)
Chris@16:    template<class NodePtrCompare, class H_Alpha>
Chris@16:    static node_ptr insert_equal_upper_bound
Chris@16:       (const node_ptr & h, const node_ptr & new_node, NodePtrCompare comp
Chris@16:       ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size)
Chris@16:    {
Chris@16:       std::size_t depth;
Chris@16:       bstree_algo::insert_equal_upper_bound(h, new_node, comp, &depth);
Chris@16:       rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size);
Chris@16:       return new_node;
Chris@16:    }
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::insert_equal_lower_bound(const node_ptr&,const node_ptr&,NodePtrCompare)
Chris@16:    template<class NodePtrCompare, class H_Alpha>
Chris@16:    static node_ptr insert_equal_lower_bound
Chris@16:       (const node_ptr & h, const node_ptr & new_node, NodePtrCompare comp
Chris@16:       ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size)
Chris@16:    {
Chris@16:       std::size_t depth;
Chris@16:       bstree_algo::insert_equal_lower_bound(h, new_node, comp, &depth);
Chris@16:       rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size);
Chris@16:       return new_node;
Chris@16:    }
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::insert_equal(const node_ptr&,const node_ptr&,const node_ptr&,NodePtrCompare)
Chris@16:    template<class NodePtrCompare, class H_Alpha>
Chris@16:    static node_ptr insert_equal
Chris@16:       (const node_ptr & header, const node_ptr & hint, const node_ptr & new_node, NodePtrCompare comp
Chris@16:       ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size)
Chris@16:    {
Chris@16:       std::size_t depth;
Chris@16:       bstree_algo::insert_equal(header, hint, new_node, comp, &depth);
Chris@16:       rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size);
Chris@16:       return new_node;
Chris@16:    }
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::insert_before(const node_ptr&,const node_ptr&,const node_ptr&)
Chris@16:    template<class H_Alpha>
Chris@16:    static node_ptr insert_before
Chris@16:       (const node_ptr & header, const node_ptr & pos, const node_ptr & new_node
Chris@16:       ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size)
Chris@16:    {
Chris@16:       std::size_t depth;
Chris@16:       bstree_algo::insert_before(header, pos, new_node, &depth);
Chris@16:       rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size);
Chris@16:       return new_node;
Chris@16:    }
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::push_back(const node_ptr&,const node_ptr&)
Chris@16:    template<class H_Alpha>
Chris@16:    static void push_back(const node_ptr & header, const node_ptr & new_node
Chris@16:          ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size)
Chris@16:    {
Chris@16:       std::size_t depth;
Chris@16:       bstree_algo::push_back(header, new_node, &depth);
Chris@16:       rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size);
Chris@16:    }
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::push_front(const node_ptr&,const node_ptr&)
Chris@16:    template<class H_Alpha>
Chris@16:    static void push_front(const node_ptr & header, const node_ptr & new_node
Chris@16:          ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size)
Chris@16:    {
Chris@16:       std::size_t depth;
Chris@16:       bstree_algo::push_front(header, new_node, &depth);
Chris@16:       rebalance_after_insertion(new_node, depth, tree_size+1, h_alpha, max_tree_size);
Chris@16:    }
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::insert_unique_check(const const_node_ptr&,const KeyType&,KeyNodePtrCompare,insert_commit_data&)
Chris@16:    template<class KeyType, class KeyNodePtrCompare>
Chris@16:    static std::pair<node_ptr, bool> insert_unique_check
Chris@16:       (const const_node_ptr & header,  const KeyType &key
Chris@16:       ,KeyNodePtrCompare comp, insert_commit_data &commit_data)
Chris@16:    {
Chris@16:       std::size_t depth;
Chris@16:       std::pair<node_ptr, bool> ret =
Chris@16:          bstree_algo::insert_unique_check(header, key, comp, commit_data, &depth);
Chris@16:       commit_data.depth = depth;
Chris@16:       return ret;
Chris@16:    }
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::insert_unique_check(const const_node_ptr&,const node_ptr&,const KeyType&,KeyNodePtrCompare,insert_commit_data&)
Chris@16:    template<class KeyType, class KeyNodePtrCompare>
Chris@16:    static std::pair<node_ptr, bool> insert_unique_check
Chris@16:       (const const_node_ptr & header, const node_ptr &hint, const KeyType &key
Chris@16:       ,KeyNodePtrCompare comp, insert_commit_data &commit_data)
Chris@16:    {
Chris@16:       std::size_t depth;
Chris@16:       std::pair<node_ptr, bool> ret =
Chris@16:          bstree_algo::insert_unique_check
Chris@16:             (header, hint, key, comp, commit_data, &depth);
Chris@16:       commit_data.depth = depth;
Chris@16:       return ret;
Chris@16:    }
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::insert_unique_commit(const node_ptr&,const node_ptr&,const insert_commit_data&)
Chris@16:    template<class H_Alpha>
Chris@16:    static void insert_unique_commit
Chris@16:       (const node_ptr & header, const node_ptr & new_value, const insert_commit_data &commit_data
Chris@16:       ,std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size)
Chris@16:    {
Chris@16:       bstree_algo::insert_unique_commit(header, new_value, commit_data);
Chris@16:       rebalance_after_insertion(new_value, commit_data.depth, tree_size+1, h_alpha, max_tree_size);
Chris@16:    }
Chris@16: 
Chris@16:    #ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::is_header
Chris@16:    static bool is_header(const const_node_ptr & p);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::is_header
Chris@16:    static void rebalance(const node_ptr & header);
Chris@16: 
Chris@16:    //! @copydoc ::boost::intrusive::bstree_algorithms::rebalance_subtree
Chris@16:    static node_ptr rebalance_subtree(const node_ptr & old_root)
Chris@16:    #endif   //#ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED
Chris@16: 
Chris@16:    /// @cond
Chris@16:    private:
Chris@16: 
Chris@16:    template<class H_Alpha>
Chris@16:    static void rebalance_after_insertion
Chris@16:       (const node_ptr &x, std::size_t depth
Chris@16:       , std::size_t tree_size, H_Alpha h_alpha, std::size_t &max_tree_size)
Chris@16:    {
Chris@16:       if(tree_size > max_tree_size)
Chris@16:          max_tree_size = tree_size;
Chris@16: 
Chris@101:       if(tree_size > 2 && //Nothing to do with only the root
Chris@16:          //Check if the root node is unbalanced
Chris@16:          //Scapegoat paper depth counts root depth as zero and "depth" counts root as 1,
Chris@16:          //but since "depth" is the depth of the ancestor of x, i == depth
Chris@16:          depth > h_alpha(tree_size)){
Chris@101: 
Chris@16:          //Find the first non height-balanced node
Chris@16:          //as described in the section 4.2 of the paper.
Chris@16:          //This method is the alternative method described
Chris@16:          //in the paper. Authors claim that this method
Chris@16:          //may tend to yield more balanced trees on the average
Chris@16:          //than the weight balanced method.
Chris@16:          node_ptr s = x;
Chris@16:          std::size_t size = 1;
Chris@101:          for(std::size_t ancestor = 1; ancestor != depth; ++ancestor){
Chris@101:             const node_ptr s_parent = NodeTraits::get_parent(s);
Chris@101:             const node_ptr s_parent_left = NodeTraits::get_left(s_parent);
Chris@101:             //Obtain parent's size (previous size + parent + sibling tree)
Chris@101:             const node_ptr s_sibling = s_parent_left == s ? NodeTraits::get_right(s_parent) : s_parent_left;
Chris@101:             size += 1 + bstree_algo::subtree_size(s_sibling);
Chris@101:             s = s_parent;
Chris@101:             if(ancestor > h_alpha(size)){ //is 's' scapegoat?
Chris@101:                bstree_algo::rebalance_subtree(s);
Chris@101:                return;
Chris@16:             }
Chris@16:          }
Chris@101:          //The whole tree must be rebuilt
Chris@101:          max_tree_size = tree_size;
Chris@101:          bstree_algo::rebalance_subtree(NodeTraits::get_parent(s));
Chris@16:       }
Chris@16:    }
Chris@16:    /// @endcond
Chris@16: };
Chris@16: 
Chris@16: /// @cond
Chris@16: 
Chris@16: template<class NodeTraits>
Chris@16: struct get_algo<SgTreeAlgorithms, NodeTraits>
Chris@16: {
Chris@16:    typedef sgtree_algorithms<NodeTraits> type;
Chris@16: };
Chris@16: 
Chris@101: template <class ValueTraits, class NodePtrCompare, class ExtraChecker>
Chris@101: struct get_node_checker<SgTreeAlgorithms, ValueTraits, NodePtrCompare, ExtraChecker>
Chris@101: {
Chris@101:    typedef detail::bstree_node_checker<ValueTraits, NodePtrCompare, ExtraChecker> type;
Chris@101: };
Chris@101: 
Chris@16: /// @endcond
Chris@16: 
Chris@16: } //namespace intrusive
Chris@16: } //namespace boost
Chris@16: 
Chris@16: #include <boost/intrusive/detail/config_end.hpp>
Chris@16: 
Chris@16: #endif //BOOST_INTRUSIVE_SGTREE_ALGORITHMS_HPP