rtorrent/rak/priority_queue_default.h

// rak - Rakshasa's toolbox
// Copyright (C) 2005, Jari Sundell
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// In addition, as a special exception, the copyright holders give
// permission to link the code of portions of this program with the
// OpenSSL library under certain conditions as described in each
// individual source file, and distribute linked combinations
// including the two.
//
// You must obey the GNU General Public License in all respects for
// all of the code used other than OpenSSL.  If you modify file(s)
// with this exception, you may extend this exception to your version
// of the file(s), but you are not obligated to do so.  If you do not
// wish to do so, delete this exception statement from your version.
// If you delete this exception statement from all source files in the
// program, then also delete it here.
//
// Contact:  Jari Sundell <jaris@ifi.uio.no>
//
//           Skomakerveien 33
//           3185 Skoppum, NORWAY

#ifndef RAK_PRIORITY_QUEUE_DEFAULT_H
#define RAK_PRIORITY_QUEUE_DEFAULT_H

#include <stdexcept>
#include <rak/functional.h>
#include <rak/functional_fun.h>
#include <rak/priority_queue.h>
#include <rak/timer.h>

namespace rak {

class priority_item {
public:
  bool                is_queued() const           { return m_time != timer(); }

  void                call()                      { m_slot(); }
  void                set_slot(function<void> s)  { m_slot = s; }
  
  const timer&        time() const                { return m_time; }
  void                clear_time()                { m_time = timer(); }

  priority_item*      prepare(const timer& t);

private:
  timer               m_time;
  function<void>      m_slot;
};

inline priority_item*
priority_item::prepare(const timer& t) {
  if (is_queued())
    throw std::logic_error("priority_item::prepare(rak::timer) called on an already queued item.");

  m_time = t;
  return this;
}

struct priority_compare {
  bool operator () (const priority_item* p1, const priority_item* p2) const {
    return p1->time() > p2->time();
  }
};

struct priority_erase {
  void operator () (priority_item* p1) const {
    p1->clear_time();
  }
};

typedef std::equal_to<priority_item*> priority_equal;
typedef priority_queue<priority_item*, priority_compare, priority_equal, priority_erase> priority_queue_default;

template <typename Queue, typename Compare>
class queue_pop_iterator
  : public std::iterator<std::forward_iterator_tag, void, void, void, void> {
public:
  typedef Queue container_type;

  queue_pop_iterator() : m_queue(NULL) {}
  queue_pop_iterator(Queue* q, Compare c) : m_queue(q), m_compare(c) {}

  queue_pop_iterator& operator ++ ()                     { m_queue->pop(); return *this; }
  queue_pop_iterator& operator ++ (int)                  { m_queue->pop(); return *this; }

  typename container_type::const_reference operator * () { return m_queue->top(); }

  bool operator != (const queue_pop_iterator& itr)       { return !m_queue->empty() && m_compare(m_queue->top()); }
  bool operator == (const queue_pop_iterator& itr)       { return m_queue->empty() || !m_compare(m_queue->top()); }

private:
  Queue*  m_queue;
  Compare m_compare;
};

struct priority_ready {
  priority_ready() {}
  priority_ready(timer t) : m_timer(t) {}

  bool operator () (const priority_item* p1) const {
    return p1->time() <= m_timer;
  }

  timer m_timer;
};

inline queue_pop_iterator<priority_queue_default, priority_ready>
queue_popper(priority_queue_default& queue, priority_ready comp) {
  return queue_pop_iterator<priority_queue_default, priority_ready>(&queue, comp);
}

inline queue_pop_iterator<priority_queue_default, priority_ready>
queue_popper() {
  return queue_pop_iterator<priority_queue_default, priority_ready>();
}

}

#endif