Chris@16: //
Chris@16: // detail/op_queue.hpp
Chris@16: // ~~~~~~~~~~~~~~~~~~~
Chris@16: //
Chris@101: // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: 
Chris@16: #ifndef BOOST_ASIO_DETAIL_OP_QUEUE_HPP
Chris@16: #define BOOST_ASIO_DETAIL_OP_QUEUE_HPP
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: # pragma once
Chris@16: #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
Chris@16: 
Chris@16: #include <boost/asio/detail/noncopyable.hpp>
Chris@16: 
Chris@16: #include <boost/asio/detail/push_options.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace asio {
Chris@16: namespace detail {
Chris@16: 
Chris@16: template <typename Operation>
Chris@16: class op_queue;
Chris@16: 
Chris@16: class op_queue_access
Chris@16: {
Chris@16: public:
Chris@16:   template <typename Operation>
Chris@16:   static Operation* next(Operation* o)
Chris@16:   {
Chris@16:     return static_cast<Operation*>(o->next_);
Chris@16:   }
Chris@16: 
Chris@16:   template <typename Operation1, typename Operation2>
Chris@16:   static void next(Operation1*& o1, Operation2* o2)
Chris@16:   {
Chris@16:     o1->next_ = o2;
Chris@16:   }
Chris@16: 
Chris@16:   template <typename Operation>
Chris@16:   static void destroy(Operation* o)
Chris@16:   {
Chris@16:     o->destroy();
Chris@16:   }
Chris@16: 
Chris@16:   template <typename Operation>
Chris@16:   static Operation*& front(op_queue<Operation>& q)
Chris@16:   {
Chris@16:     return q.front_;
Chris@16:   }
Chris@16: 
Chris@16:   template <typename Operation>
Chris@16:   static Operation*& back(op_queue<Operation>& q)
Chris@16:   {
Chris@16:     return q.back_;
Chris@16:   }
Chris@16: };
Chris@16: 
Chris@16: template <typename Operation>
Chris@16: class op_queue
Chris@16:   : private noncopyable
Chris@16: {
Chris@16: public:
Chris@16:   // Constructor.
Chris@16:   op_queue()
Chris@16:     : front_(0),
Chris@16:       back_(0)
Chris@16:   {
Chris@16:   }
Chris@16: 
Chris@16:   // Destructor destroys all operations.
Chris@16:   ~op_queue()
Chris@16:   {
Chris@16:     while (Operation* op = front_)
Chris@16:     {
Chris@16:       pop();
Chris@16:       op_queue_access::destroy(op);
Chris@16:     }
Chris@16:   }
Chris@16: 
Chris@16:   // Get the operation at the front of the queue.
Chris@16:   Operation* front()
Chris@16:   {
Chris@16:     return front_;
Chris@16:   }
Chris@16: 
Chris@16:   // Pop an operation from the front of the queue.
Chris@16:   void pop()
Chris@16:   {
Chris@16:     if (front_)
Chris@16:     {
Chris@16:       Operation* tmp = front_;
Chris@16:       front_ = op_queue_access::next(front_);
Chris@16:       if (front_ == 0)
Chris@16:         back_ = 0;
Chris@16:       op_queue_access::next(tmp, static_cast<Operation*>(0));
Chris@16:     }
Chris@16:   }
Chris@16: 
Chris@16:   // Push an operation on to the back of the queue.
Chris@16:   void push(Operation* h)
Chris@16:   {
Chris@16:     op_queue_access::next(h, static_cast<Operation*>(0));
Chris@16:     if (back_)
Chris@16:     {
Chris@16:       op_queue_access::next(back_, h);
Chris@16:       back_ = h;
Chris@16:     }
Chris@16:     else
Chris@16:     {
Chris@16:       front_ = back_ = h;
Chris@16:     }
Chris@16:   }
Chris@16: 
Chris@16:   // Push all operations from another queue on to the back of the queue. The
Chris@16:   // source queue may contain operations of a derived type.
Chris@16:   template <typename OtherOperation>
Chris@16:   void push(op_queue<OtherOperation>& q)
Chris@16:   {
Chris@16:     if (Operation* other_front = op_queue_access::front(q))
Chris@16:     {
Chris@16:       if (back_)
Chris@16:         op_queue_access::next(back_, other_front);
Chris@16:       else
Chris@16:         front_ = other_front;
Chris@16:       back_ = op_queue_access::back(q);
Chris@16:       op_queue_access::front(q) = 0;
Chris@16:       op_queue_access::back(q) = 0;
Chris@16:     }
Chris@16:   }
Chris@16: 
Chris@16:   // Whether the queue is empty.
Chris@16:   bool empty() const
Chris@16:   {
Chris@16:     return front_ == 0;
Chris@16:   }
Chris@16: 
Chris@16: private:
Chris@16:   friend class op_queue_access;
Chris@16: 
Chris@16:   // The front of the queue.
Chris@16:   Operation* front_;
Chris@16: 
Chris@16:   // The back of the queue.
Chris@16:   Operation* back_;
Chris@16: };
Chris@16: 
Chris@16: } // namespace detail
Chris@16: } // namespace asio
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/asio/detail/pop_options.hpp>
Chris@16: 
Chris@16: #endif // BOOST_ASIO_DETAIL_OP_QUEUE_HPP