407 lines
15 KiB
Plaintext
407 lines
15 KiB
Plaintext
/////////////////////////////////////////////////////////////////////////////
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//
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// (C) Copyright Olaf Krzikalla 2004-2006.
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// (C) Copyright Ion Gaztanaga 2006-2014
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// See http://www.boost.org/libs/intrusive for documentation.
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//
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/////////////////////////////////////////////////////////////////////////////
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#ifndef BOOST_INTRUSIVE_CIRCULAR_SLIST_ALGORITHMS_HPP
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#define BOOST_INTRUSIVE_CIRCULAR_SLIST_ALGORITHMS_HPP
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#include <cstddef>
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#include <boost/intrusive/detail/config_begin.hpp>
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#include <boost/intrusive/intrusive_fwd.hpp>
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#include <boost/intrusive/detail/common_slist_algorithms.hpp>
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#include <boost/intrusive/detail/algo_type.hpp>
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#if defined(BOOST_HAS_PRAGMA_ONCE)
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# pragma once
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#endif
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namespace boost {
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namespace intrusive {
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//! circular_slist_algorithms provides basic algorithms to manipulate nodes
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//! forming a circular singly linked list. An empty circular list is formed by a node
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//! whose pointer to the next node points to itself.
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//!
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//! circular_slist_algorithms is configured with a NodeTraits class, which encapsulates the
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//! information about the node to be manipulated. NodeTraits must support the
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//! following interface:
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//!
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//! <b>Typedefs</b>:
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//!
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//! <tt>node</tt>: The type of the node that forms the circular list
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//!
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//! <tt>node_ptr</tt>: A pointer to a node
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//!
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//! <tt>const_node_ptr</tt>: A pointer to a const node
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//!
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//! <b>Static functions</b>:
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//!
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//! <tt>static node_ptr get_next(const_node_ptr n);</tt>
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//!
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//! <tt>static void set_next(node_ptr n, node_ptr next);</tt>
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template<class NodeTraits>
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class circular_slist_algorithms
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/// @cond
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: public detail::common_slist_algorithms<NodeTraits>
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/// @endcond
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{
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/// @cond
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typedef detail::common_slist_algorithms<NodeTraits> base_t;
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/// @endcond
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public:
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typedef typename NodeTraits::node node;
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typedef typename NodeTraits::node_ptr node_ptr;
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typedef typename NodeTraits::const_node_ptr const_node_ptr;
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typedef NodeTraits node_traits;
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#if defined(BOOST_INTRUSIVE_DOXYGEN_INVOKED)
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//! <b>Effects</b>: Constructs an non-used list element, putting the next
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//! pointer to null:
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//! <tt>NodeTraits::get_next(this_node) == node_ptr()</tt>
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//!
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//! <b>Complexity</b>: Constant
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//!
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//! <b>Throws</b>: Nothing.
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static void init(node_ptr this_node);
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//! <b>Requires</b>: this_node must be in a circular list or be an empty circular list.
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//!
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//! <b>Effects</b>: Returns true is "this_node" is the only node of a circular list:
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//! or it's a not inserted node:
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//! <tt>return node_ptr() == NodeTraits::get_next(this_node) || NodeTraits::get_next(this_node) == this_node</tt>
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//!
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//! <b>Complexity</b>: Constant
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//!
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//! <b>Throws</b>: Nothing.
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static bool unique(const_node_ptr this_node);
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//! <b>Effects</b>: Returns true is "this_node" has the same state as
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//! if it was inited using "init(node_ptr)"
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//!
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//! <b>Complexity</b>: Constant
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//!
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//! <b>Throws</b>: Nothing.
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static bool inited(const_node_ptr this_node);
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//! <b>Requires</b>: prev_node must be in a circular list or be an empty circular list.
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//!
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//! <b>Effects</b>: Unlinks the next node of prev_node from the circular list.
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//!
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//! <b>Complexity</b>: Constant
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//!
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//! <b>Throws</b>: Nothing.
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static void unlink_after(node_ptr prev_node);
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//! <b>Requires</b>: prev_node and last_node must be in a circular list
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//! or be an empty circular list.
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//!
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//! <b>Effects</b>: Unlinks the range (prev_node, last_node) from the circular list.
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//!
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//! <b>Complexity</b>: Constant
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//!
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//! <b>Throws</b>: Nothing.
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static void unlink_after(node_ptr prev_node, node_ptr last_node);
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//! <b>Requires</b>: prev_node must be a node of a circular list.
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//!
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//! <b>Effects</b>: Links this_node after prev_node in the circular list.
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//!
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//! <b>Complexity</b>: Constant
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//!
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//! <b>Throws</b>: Nothing.
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static void link_after(node_ptr prev_node, node_ptr this_node);
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//! <b>Requires</b>: b and e must be nodes of the same circular list or an empty range.
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//! and p must be a node of a different circular list.
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//!
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//! <b>Effects</b>: Removes the nodes from (b, e] range from their circular list and inserts
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//! them after p in p's circular list.
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//!
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//! <b>Complexity</b>: Constant
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//!
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//! <b>Throws</b>: Nothing.
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static void transfer_after(node_ptr p, node_ptr b, node_ptr e);
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#endif //#if defined(BOOST_INTRUSIVE_DOXYGEN_INVOKED)
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//! <b>Effects</b>: Constructs an empty list, making this_node the only
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//! node of the circular list:
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//! <tt>NodeTraits::get_next(this_node) == this_node</tt>.
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//!
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//! <b>Complexity</b>: Constant
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//!
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//! <b>Throws</b>: Nothing.
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BOOST_INTRUSIVE_FORCEINLINE static void init_header(const node_ptr &this_node)
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{ NodeTraits::set_next(this_node, this_node); }
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//! <b>Requires</b>: this_node and prev_init_node must be in the same circular list.
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//!
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//! <b>Effects</b>: Returns the previous node of this_node in the circular list starting.
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//! the search from prev_init_node. The first node checked for equality
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//! is NodeTraits::get_next(prev_init_node).
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//!
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//! <b>Complexity</b>: Linear to the number of elements between prev_init_node and this_node.
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//!
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//! <b>Throws</b>: Nothing.
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BOOST_INTRUSIVE_FORCEINLINE static node_ptr get_previous_node(const node_ptr &prev_init_node, const node_ptr &this_node)
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{ return base_t::get_previous_node(prev_init_node, this_node); }
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//! <b>Requires</b>: this_node must be in a circular list or be an empty circular list.
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//!
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//! <b>Effects</b>: Returns the previous node of this_node in the circular list.
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//!
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//! <b>Complexity</b>: Linear to the number of elements in the circular list.
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//!
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//! <b>Throws</b>: Nothing.
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BOOST_INTRUSIVE_FORCEINLINE static node_ptr get_previous_node(const node_ptr & this_node)
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{ return base_t::get_previous_node(this_node, this_node); }
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//! <b>Requires</b>: this_node must be in a circular list or be an empty circular list.
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//!
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//! <b>Effects</b>: Returns the previous node of the previous node of this_node in the circular list.
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//!
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//! <b>Complexity</b>: Linear to the number of elements in the circular list.
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//!
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//! <b>Throws</b>: Nothing.
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BOOST_INTRUSIVE_FORCEINLINE static node_ptr get_previous_previous_node(const node_ptr & this_node)
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{ return get_previous_previous_node(this_node, this_node); }
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//! <b>Requires</b>: this_node and p must be in the same circular list.
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//!
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//! <b>Effects</b>: Returns the previous node of the previous node of this_node in the
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//! circular list starting. the search from p. The first node checked
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//! for equality is NodeTraits::get_next((NodeTraits::get_next(p)).
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//!
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//! <b>Complexity</b>: Linear to the number of elements in the circular list.
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//!
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//! <b>Throws</b>: Nothing.
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static node_ptr get_previous_previous_node(node_ptr p, const node_ptr & this_node)
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{
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node_ptr p_next = NodeTraits::get_next(p);
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node_ptr p_next_next = NodeTraits::get_next(p_next);
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while (this_node != p_next_next){
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p = p_next;
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p_next = p_next_next;
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p_next_next = NodeTraits::get_next(p_next);
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}
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return p;
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}
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//! <b>Requires</b>: this_node must be in a circular list or be an empty circular list.
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//!
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//! <b>Effects</b>: Returns the number of nodes in a circular list. If the circular list
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//! is empty, returns 1.
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//!
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//! <b>Complexity</b>: Linear
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//!
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//! <b>Throws</b>: Nothing.
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static std::size_t count(const const_node_ptr & this_node)
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{
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std::size_t result = 0;
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const_node_ptr p = this_node;
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do{
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p = NodeTraits::get_next(p);
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++result;
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} while (p != this_node);
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return result;
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}
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//! <b>Requires</b>: this_node must be in a circular list, be an empty circular list or be inited.
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//!
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//! <b>Effects</b>: Unlinks the node from the circular list.
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//!
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//! <b>Complexity</b>: Linear to the number of elements in the circular list
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//!
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//! <b>Throws</b>: Nothing.
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BOOST_INTRUSIVE_FORCEINLINE static void unlink(const node_ptr & this_node)
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{
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if(NodeTraits::get_next(this_node))
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base_t::unlink_after(get_previous_node(this_node));
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}
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//! <b>Requires</b>: nxt_node must be a node of a circular list.
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//!
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//! <b>Effects</b>: Links this_node before nxt_node in the circular list.
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//!
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//! <b>Complexity</b>: Linear to the number of elements in the circular list.
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//!
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//! <b>Throws</b>: Nothing.
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BOOST_INTRUSIVE_FORCEINLINE static void link_before (const node_ptr & nxt_node, const node_ptr & this_node)
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{ base_t::link_after(get_previous_node(nxt_node), this_node); }
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//! <b>Requires</b>: this_node and other_node must be nodes inserted
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//! in circular lists or be empty circular lists.
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//!
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//! <b>Effects</b>: Swaps the position of the nodes: this_node is inserted in
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//! other_nodes position in the second circular list and the other_node is inserted
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//! in this_node's position in the first circular list.
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//!
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//! <b>Complexity</b>: Linear to number of elements of both lists
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//!
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//! <b>Throws</b>: Nothing.
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static void swap_nodes(const node_ptr & this_node, const node_ptr & other_node)
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{
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if (other_node == this_node)
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return;
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const node_ptr this_next = NodeTraits::get_next(this_node);
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const node_ptr other_next = NodeTraits::get_next(other_node);
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const bool this_null = !this_next;
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const bool other_null = !other_next;
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const bool this_empty = this_next == this_node;
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const bool other_empty = other_next == other_node;
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if(!(other_null || other_empty)){
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NodeTraits::set_next(this_next == other_node ? other_node : get_previous_node(other_node), this_node );
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}
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if(!(this_null | this_empty)){
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NodeTraits::set_next(other_next == this_node ? this_node : get_previous_node(this_node), other_node );
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}
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NodeTraits::set_next(this_node, other_empty ? this_node : (other_next == this_node ? other_node : other_next) );
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NodeTraits::set_next(other_node, this_empty ? other_node : (this_next == other_node ? this_node : this_next ) );
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}
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//! <b>Effects</b>: Reverses the order of elements in the list.
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//!
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//! <b>Throws</b>: Nothing.
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//!
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//! <b>Complexity</b>: This function is linear to the contained elements.
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static void reverse(const node_ptr & p)
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{
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node_ptr i = NodeTraits::get_next(p), e(p);
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for (;;) {
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node_ptr nxt(NodeTraits::get_next(i));
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if (nxt == e)
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break;
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base_t::transfer_after(e, i, nxt);
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}
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}
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//! <b>Effects</b>: Moves the node p n positions towards the end of the list.
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//!
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//! <b>Returns</b>: The previous node of p after the function if there has been any movement,
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//! Null if n leads to no movement.
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//!
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//! <b>Throws</b>: Nothing.
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//!
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//! <b>Complexity</b>: Linear to the number of elements plus the number moved positions.
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static node_ptr move_backwards(const node_ptr & p, std::size_t n)
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{
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//Null shift, nothing to do
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if(!n) return node_ptr();
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node_ptr first = NodeTraits::get_next(p);
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//count() == 1 or 2, nothing to do
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if(NodeTraits::get_next(first) == p)
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return node_ptr();
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bool end_found = false;
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node_ptr new_last = node_ptr();
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//Now find the new last node according to the shift count.
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//If we find p before finding the new last node
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//unlink p, shortcut the search now that we know the size of the list
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//and continue.
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for(std::size_t i = 1; i <= n; ++i){
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new_last = first;
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first = NodeTraits::get_next(first);
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if(first == p){
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//Shortcut the shift with the modulo of the size of the list
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n %= i;
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if(!n)
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return node_ptr();
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i = 0;
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//Unlink p and continue the new first node search
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first = NodeTraits::get_next(p);
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base_t::unlink_after(new_last);
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end_found = true;
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}
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}
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//If the p has not been found in the previous loop, find it
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//starting in the new first node and unlink it
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if(!end_found){
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base_t::unlink_after(base_t::get_previous_node(first, p));
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}
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//Now link p after the new last node
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base_t::link_after(new_last, p);
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return new_last;
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}
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//! <b>Effects</b>: Moves the node p n positions towards the beginning of the list.
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//!
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//! <b>Returns</b>: The previous node of p after the function if there has been any movement,
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//! Null if n leads equals to no movement.
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//!
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//! <b>Throws</b>: Nothing.
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//!
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//! <b>Complexity</b>: Linear to the number of elements plus the number moved positions.
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static node_ptr move_forward(const node_ptr & p, std::size_t n)
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{
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//Null shift, nothing to do
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if(!n) return node_ptr();
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node_ptr first = node_traits::get_next(p);
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//count() == 1 or 2, nothing to do
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if(node_traits::get_next(first) == p) return node_ptr();
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//Iterate until p is found to know where the current last node is.
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//If the shift count is less than the size of the list, we can also obtain
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//the position of the new last node after the shift.
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node_ptr old_last(first), next_to_it, new_last(p);
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std::size_t distance = 1;
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while(p != (next_to_it = node_traits::get_next(old_last))){
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if(++distance > n)
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new_last = node_traits::get_next(new_last);
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old_last = next_to_it;
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}
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//If the shift was bigger or equal than the size, obtain the equivalent
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//forward shifts and find the new last node.
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if(distance <= n){
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//Now find the equivalent forward shifts.
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//Shortcut the shift with the modulo of the size of the list
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std::size_t new_before_last_pos = (distance - (n % distance))% distance;
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//If the shift is a multiple of the size there is nothing to do
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if(!new_before_last_pos) return node_ptr();
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for( new_last = p
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; new_before_last_pos--
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; new_last = node_traits::get_next(new_last)){
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//empty
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}
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}
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//Now unlink p and link it after the new last node
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base_t::unlink_after(old_last);
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base_t::link_after(new_last, p);
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return new_last;
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}
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};
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/// @cond
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template<class NodeTraits>
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struct get_algo<CircularSListAlgorithms, NodeTraits>
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{
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typedef circular_slist_algorithms<NodeTraits> type;
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};
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/// @endcond
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} //namespace intrusive
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} //namespace boost
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#include <boost/intrusive/detail/config_end.hpp>
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#endif //BOOST_INTRUSIVE_CIRCULAR_SLIST_ALGORITHMS_HPP
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