boost/intrusive/circular_list_algorithms.hpp
/////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Olaf Krzikalla 2004-2006.
// (C) Copyright Ion Gaztanaga 2006-2014
//
// 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 <boost/intrusive/detail/algo_type.hpp>
#include <boost/core/no_exceptions_support.hpp>
#include <cstddef>
#if defined(BOOST_HAS_PRAGMA_ONCE)
# pragma once
#endif
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 node;
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) BOOST_NOEXCEPT
{
const node_ptr null_node = node_ptr();
NodeTraits::set_next(this_node, null_node);
NodeTraits::set_previous(this_node, null_node);
}
//! <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.
BOOST_INTRUSIVE_FORCEINLINE static bool inited(const_node_ptr this_node) BOOST_NOEXCEPT
{ 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) BOOST_NOEXCEPT
{
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) BOOST_NOEXCEPT
{
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>: Linear
//!
//! <b>Throws</b>: Nothing.
static std::size_t count(const_node_ptr this_node) BOOST_NOEXCEPT
{
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) BOOST_NOEXCEPT
{
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;
}
//! <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) BOOST_NOEXCEPT
{
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) BOOST_NOEXCEPT
{
node_ptr prev(NodeTraits::get_previous(nxt_node));
NodeTraits::set_previous(this_node, prev);
NodeTraits::set_next(this_node, nxt_node);
//nxt_node might be an alias for prev->next_
//so use it before NodeTraits::set_next(prev, ...)
//is called and the reference changes its value
NodeTraits::set_previous(nxt_node, this_node);
NodeTraits::set_next(prev, this_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) BOOST_NOEXCEPT
{
node_ptr next(NodeTraits::get_next(prev_node));
NodeTraits::set_previous(this_node, prev_node);
NodeTraits::set_next(this_node, next);
//prev_node might be an alias for next->next_
//so use it before update it before NodeTraits::set_previous(next, ...)
//is called and the reference changes it's value
NodeTraits::set_next(prev_node, this_node);
NodeTraits::set_previous(next, 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) BOOST_NOEXCEPT
{
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) BOOST_NOEXCEPT
{
if (b != e && p != b && p != 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) BOOST_NOEXCEPT
{
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) BOOST_NOEXCEPT
{
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) BOOST_NOEXCEPT
{
//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) BOOST_NOEXCEPT
{
//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);
}
//! <b>Requires</b>: f and l must be in a circular list.
//!
//! <b>Effects</b>: Returns the number of nodes in the range [f, l).
//!
//! <b>Complexity</b>: Linear
//!
//! <b>Throws</b>: Nothing.
static std::size_t distance(const_node_ptr f, const_node_ptr l) BOOST_NOEXCEPT
{
std::size_t result = 0;
while(f != l){
f = NodeTraits::get_next(f);
++result;
}
return result;
}
struct stable_partition_info
{
std::size_t num_1st_partition;
std::size_t num_2nd_partition;
node_ptr beg_2st_partition;
};
template<class Pred>
static void stable_partition(node_ptr beg, node_ptr end, Pred pred, stable_partition_info &info)
{
node_ptr bcur = node_traits::get_previous(beg);
node_ptr cur = beg;
node_ptr new_f = end;
std::size_t num1 = 0, num2 = 0;
while(cur != end){
if(pred(cur)){
++num1;
bcur = cur;
cur = node_traits::get_next(cur);
}
else{
++num2;
node_ptr last_to_remove = bcur;
new_f = cur;
bcur = cur;
cur = node_traits::get_next(cur);
BOOST_TRY{
//Main loop
while(cur != end){
if(pred(cur)){ //Might throw
++num1;
//Process current node
node_traits::set_next (last_to_remove, cur);
node_traits::set_previous(cur, last_to_remove);
last_to_remove = cur;
node_ptr nxt = node_traits::get_next(cur);
node_traits::set_next (bcur, nxt);
node_traits::set_previous(nxt, bcur);
cur = nxt;
}
else{
++num2;
bcur = cur;
cur = node_traits::get_next(cur);
}
}
}
BOOST_CATCH(...){
node_traits::set_next (last_to_remove, new_f);
node_traits::set_previous(new_f, last_to_remove);
BOOST_RETHROW;
}
BOOST_CATCH_END
node_traits::set_next(last_to_remove, new_f);
node_traits::set_previous(new_f, last_to_remove);
break;
}
}
info.num_1st_partition = num1;
info.num_2nd_partition = num2;
info.beg_2st_partition = new_f;
}
private:
static void swap_prev(node_ptr this_node, node_ptr other_node) BOOST_NOEXCEPT
{
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) BOOST_NOEXCEPT
{
node_ptr temp(NodeTraits::get_next(this_node));
NodeTraits::set_next(this_node, NodeTraits::get_next(other_node));
NodeTraits::set_next(other_node, temp);
}
};
/// @cond
template<class NodeTraits>
struct get_algo<CircularListAlgorithms, NodeTraits>
{
typedef circular_list_algorithms<NodeTraits> type;
};
/// @endcond
} //namespace intrusive
} //namespace boost
#include <boost/intrusive/detail/config_end.hpp>
#endif //BOOST_INTRUSIVE_CIRCULAR_LIST_ALGORITHMS_HPP