boost/intrusive/circular_list_algorithms.hpp
///////////////////////////////////////////////////////////////////////////// // // (C) Copyright Olaf Krzikalla 2004-2006. // (C) Copyright Ion Gaztanaga 2006-2007 // // 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. // ///////////////////////////////////////////////////////////////////////////// #ifndef BOOST_INTRUSIVE_CIRCULAR_LIST_ALGORITHMS_HPP #define BOOST_INTRUSIVE_CIRCULAR_LIST_ALGORITHMS_HPP #include <boost/intrusive/detail/config_begin.hpp> #include <boost/intrusive/intrusive_fwd.hpp> #include <cstddef> namespace boost { namespace intrusive { //! circular_list_algorithms provides basic algorithms to manipulate nodes //! forming a circular doubly linked list. An empty circular list is formed by a node //! whose pointers point to itself. //! //! circular_list_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 circular list //! //! <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_previous(const_node_ptr n);</tt> //! //! <tt>static void set_previous(node_ptr n, node_ptr prev);</tt> //! //! <tt>static node_ptr get_next(const_node_ptr n);</tt> //! //! <tt>static void set_next(node_ptr n, node_ptr next);</tt> template<class NodeTraits> class circular_list_algorithms { public: typedef typename NodeTraits::node_ptr node_ptr; typedef typename NodeTraits::const_node_ptr const_node_ptr; typedef NodeTraits node_traits; //! <b>Effects</b>: Constructs an non-used list element, so that //! inited(this_node) == true //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. static void init(node_ptr this_node) { NodeTraits::set_next(this_node, 0); NodeTraits::set_previous(this_node, 0); } //! <b>Effects</b>: Returns true is "this_node" is in a non-used state //! as if it was initialized by the "init" function. //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. static bool inited(const_node_ptr this_node) { return !NodeTraits::get_next(this_node); } //! <b>Effects</b>: Constructs an empty list, making this_node the only //! node of the circular list: //! <tt>NodeTraits::get_next(this_node) == NodeTraits::get_previous(this_node) //! == this_node</tt>. //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. static void init_header(node_ptr this_node) { NodeTraits::set_next(this_node, this_node); NodeTraits::set_previous(this_node, this_node); } //! <b>Requires</b>: this_node must be in a circular list or be an empty circular list. //! //! <b>Effects</b>: Returns true is "this_node" is the only node of a circular list: //! <tt>return NodeTraits::get_next(this_node) == this_node</tt> //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. static bool unique(const_node_ptr this_node) { node_ptr next = NodeTraits::get_next(this_node); return !next || next == this_node; } //! <b>Requires</b>: this_node must be in a circular list or be an empty circular list. //! //! <b>Effects</b>: Returns the number of nodes in a circular list. If the circular list //! is empty, returns 1. //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. static std::size_t count(const_node_ptr this_node) { std::size_t result = 0; const_node_ptr p = this_node; do{ p = NodeTraits::get_next(p); ++result; }while (p != this_node); return result; } //! <b>Requires</b>: this_node must be in a circular list or be an empty circular list. //! //! <b>Effects</b>: Unlinks the node from the circular list. //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. static node_ptr unlink(node_ptr this_node) { if(NodeTraits::get_next(this_node)){ node_ptr next(NodeTraits::get_next(this_node)); node_ptr prev(NodeTraits::get_previous(this_node)); NodeTraits::set_next(prev, next); NodeTraits::set_previous(next, prev); return next; } else{ return this_node; } } //! <b>Requires</b>: b and e must be nodes of the same circular list or an empty range. //! //! <b>Effects</b>: Unlinks the node [b, e) from the circular list. //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. static void unlink(node_ptr b, node_ptr e) { if (b != e) { node_ptr prevb(NodeTraits::get_previous(b)); NodeTraits::set_previous(e, prevb); NodeTraits::set_next(prevb, e); } } //! <b>Requires</b>: nxt_node must be a node of a circular list. //! //! <b>Effects</b>: Links this_node before nxt_node in the circular list. //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. static void link_before(node_ptr nxt_node, node_ptr this_node) { node_ptr prev(NodeTraits::get_previous(nxt_node)); NodeTraits::set_previous(this_node, prev); NodeTraits::set_next(prev, this_node); NodeTraits::set_previous(nxt_node, this_node); NodeTraits::set_next(this_node, nxt_node); } //! <b>Requires</b>: prev_node must be a node of a circular list. //! //! <b>Effects</b>: Links this_node after prev_node in the circular list. //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. static void link_after(node_ptr prev_node, node_ptr this_node) { node_ptr next(NodeTraits::get_next(prev_node)); NodeTraits::set_previous(this_node, prev_node); NodeTraits::set_next(this_node, next); NodeTraits::set_previous(next, this_node); NodeTraits::set_next(prev_node, this_node); } //! <b>Requires</b>: this_node and other_node must be nodes inserted //! in circular lists or be empty circular lists. //! //! <b>Effects</b>: Swaps the position of the nodes: this_node is inserted in //! other_nodes position in the second circular list and the other_node is inserted //! in this_node's position in the first circular list. //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. /* static void swap_nodes(node_ptr this_node, node_ptr other_node) { if (other_node == this_node) return; bool empty1 = unique(this_node); bool empty2 = unique(other_node); node_ptr next_this(NodeTraits::get_next(this_node)); node_ptr prev_this(NodeTraits::get_previous(this_node)); node_ptr next_other(NodeTraits::get_next(other_node)); node_ptr prev_other(NodeTraits::get_previous(other_node)); //Do the swap NodeTraits::set_next(this_node, next_other); NodeTraits::set_next(other_node, next_this); NodeTraits::set_previous(this_node, prev_other); NodeTraits::set_previous(other_node, prev_this); if (empty2){ init(this_node); } else{ NodeTraits::set_next(prev_other, this_node); NodeTraits::set_previous(next_other, this_node); } if (empty1){ init(other_node); } else{ NodeTraits::set_next(prev_this, other_node); NodeTraits::set_previous(next_this, other_node); } } */ //Watanabe version private: static void swap_prev(node_ptr this_node, node_ptr other_node) { node_ptr temp(NodeTraits::get_previous(this_node)); NodeTraits::set_previous(this_node, NodeTraits::get_previous(other_node)); NodeTraits::set_previous(other_node, temp); } static void swap_next(node_ptr this_node, node_ptr other_node) { node_ptr temp(NodeTraits::get_next(this_node)); NodeTraits::set_next(this_node, NodeTraits::get_next(other_node)); NodeTraits::set_next(other_node, temp); } public: static void swap_nodes(node_ptr this_node, node_ptr other_node) { if (other_node == this_node) return; bool this_inited = inited(this_node); bool other_inited = inited(other_node); if(this_inited){ init_header(this_node); } if(other_inited){ init_header(other_node); } node_ptr next_this(NodeTraits::get_next(this_node)); node_ptr prev_this(NodeTraits::get_previous(this_node)); node_ptr next_other(NodeTraits::get_next(other_node)); node_ptr prev_other(NodeTraits::get_previous(other_node)); //these first two swaps must happen before the other two swap_prev(next_this, next_other); swap_next(prev_this, prev_other); swap_next(this_node, other_node); swap_prev(this_node, other_node); if(this_inited){ init(other_node); } if(other_inited){ init(this_node); } } //! <b>Requires</b>: b and e must be nodes of the same circular list or an empty range. //! and p must be a node of a different circular list or may not be an iterator in // [b, e). //! //! <b>Effects</b>: Removes the nodes from [b, e) range from their circular list and inserts //! them before p in p's circular list. //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. static void transfer(node_ptr p, node_ptr b, node_ptr e) { if (b != e) { node_ptr prev_p(NodeTraits::get_previous(p)); node_ptr prev_b(NodeTraits::get_previous(b)); node_ptr prev_e(NodeTraits::get_previous(e)); NodeTraits::set_next(prev_e, p); NodeTraits::set_previous(p, prev_e); NodeTraits::set_next(prev_b, e); NodeTraits::set_previous(e, prev_b); NodeTraits::set_next(prev_p, b); NodeTraits::set_previous(b, prev_p); } } //! <b>Requires</b>: i must a node of a circular list //! and p must be a node of a different circular list. //! //! <b>Effects</b>: Removes the node i from its circular list and inserts //! it before p in p's circular list. //! If p == i or p == NodeTraits::get_next(i), this function is a null operation. //! //! <b>Complexity</b>: Constant //! //! <b>Throws</b>: Nothing. static void transfer(node_ptr p, node_ptr i) { node_ptr n(NodeTraits::get_next(i)); if(n != p && i != p){ node_ptr prev_p(NodeTraits::get_previous(p)); node_ptr prev_i(NodeTraits::get_previous(i)); NodeTraits::set_next(prev_p, i); NodeTraits::set_previous(i, prev_p); NodeTraits::set_next(i, p); NodeTraits::set_previous(p, i); NodeTraits::set_previous(n, prev_i); NodeTraits::set_next(prev_i, n); } } //! <b>Effects</b>: Reverses the order of elements in the list. //! //! <b>Throws</b>: Nothing. //! //! <b>Complexity</b>: This function is linear time. static void reverse(node_ptr p) { node_ptr f(NodeTraits::get_next(p)); node_ptr i(NodeTraits::get_next(f)), e(p); while(i != e) { node_ptr n = i; i = NodeTraits::get_next(i); transfer(f, n, i); f = n; } } //! <b>Effects</b>: Moves the node p n positions towards the end of the list. //! //! <b>Throws</b>: Nothing. //! //! <b>Complexity</b>: Linear to the number of moved positions. static void move_backwards(node_ptr p, std::size_t n) { //Null shift, nothing to do if(!n) return; node_ptr first = NodeTraits::get_next(p); //size() == 0 or 1, nothing to do if(first == NodeTraits::get_previous(p)) return; unlink(p); //Now get the new first node while(n--){ first = NodeTraits::get_next(first); } link_before(first, p); } //! <b>Effects</b>: Moves the node p n positions towards the beginning of the list. //! //! <b>Throws</b>: Nothing. //! //! <b>Complexity</b>: Linear to the number of moved positions. static void move_forward(node_ptr p, std::size_t n) { //Null shift, nothing to do if(!n) return; node_ptr last = NodeTraits::get_previous(p); //size() == 0 or 1, nothing to do if(last == NodeTraits::get_next(p)) return; unlink(p); //Now get the new last node while(n--){ last = NodeTraits::get_previous(last); } link_after(last, p); } }; } //namespace intrusive } //namespace boost #include <boost/intrusive/detail/config_end.hpp> #endif //BOOST_INTRUSIVE_CIRCULAR_LIST_ALGORITHMS_HPP