1 | // |
2 | // detail/op_queue.hpp |
3 | // ~~~~~~~~~~~~~~~~~~~ |
4 | // |
5 | // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com) |
6 | // |
7 | // Distributed under the Boost Software License, Version 1.0. (See accompanying |
8 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
9 | // |
10 | |
11 | #ifndef BOOST_ASIO_DETAIL_OP_QUEUE_HPP |
12 | #define BOOST_ASIO_DETAIL_OP_QUEUE_HPP |
13 | |
14 | #if defined(_MSC_VER) && (_MSC_VER >= 1200) |
15 | # pragma once |
16 | #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) |
17 | |
18 | #include <boost/asio/detail/noncopyable.hpp> |
19 | |
20 | #include <boost/asio/detail/push_options.hpp> |
21 | |
22 | namespace boost { |
23 | namespace asio { |
24 | namespace detail { |
25 | |
26 | template <typename Operation> |
27 | class op_queue; |
28 | |
29 | class op_queue_access |
30 | { |
31 | public: |
32 | template <typename Operation> |
33 | static Operation* next(Operation* o) |
34 | { |
35 | return static_cast<Operation*>(o->next_); |
36 | } |
37 | |
38 | template <typename Operation1, typename Operation2> |
39 | static void next(Operation1*& o1, Operation2* o2) |
40 | { |
41 | o1->next_ = o2; |
42 | } |
43 | |
44 | template <typename Operation> |
45 | static void destroy(Operation* o) |
46 | { |
47 | o->destroy(); |
48 | } |
49 | |
50 | template <typename Operation> |
51 | static Operation*& front(op_queue<Operation>& q) |
52 | { |
53 | return q.front_; |
54 | } |
55 | |
56 | template <typename Operation> |
57 | static Operation*& back(op_queue<Operation>& q) |
58 | { |
59 | return q.back_; |
60 | } |
61 | }; |
62 | |
63 | template <typename Operation> |
64 | class op_queue |
65 | : private noncopyable |
66 | { |
67 | public: |
68 | // Constructor. |
69 | op_queue() |
70 | : front_(0), |
71 | back_(0) |
72 | { |
73 | } |
74 | |
75 | // Destructor destroys all operations. |
76 | ~op_queue() |
77 | { |
78 | while (Operation* op = front_) |
79 | { |
80 | pop(); |
81 | op_queue_access::destroy(op); |
82 | } |
83 | } |
84 | |
85 | // Get the operation at the front of the queue. |
86 | Operation* front() |
87 | { |
88 | return front_; |
89 | } |
90 | |
91 | // Pop an operation from the front of the queue. |
92 | void pop() |
93 | { |
94 | if (front_) |
95 | { |
96 | Operation* tmp = front_; |
97 | front_ = op_queue_access::next(front_); |
98 | if (front_ == 0) |
99 | back_ = 0; |
100 | op_queue_access::next(tmp, static_cast<Operation*>(0)); |
101 | } |
102 | } |
103 | |
104 | // Push an operation on to the back of the queue. |
105 | void push(Operation* h) |
106 | { |
107 | op_queue_access::next(h, static_cast<Operation*>(0)); |
108 | if (back_) |
109 | { |
110 | op_queue_access::next(back_, h); |
111 | back_ = h; |
112 | } |
113 | else |
114 | { |
115 | front_ = back_ = h; |
116 | } |
117 | } |
118 | |
119 | // Push all operations from another queue on to the back of the queue. The |
120 | // source queue may contain operations of a derived type. |
121 | template <typename OtherOperation> |
122 | void push(op_queue<OtherOperation>& q) |
123 | { |
124 | if (Operation* other_front = op_queue_access::front(q)) |
125 | { |
126 | if (back_) |
127 | op_queue_access::next(back_, other_front); |
128 | else |
129 | front_ = other_front; |
130 | back_ = op_queue_access::back(q); |
131 | op_queue_access::front(q) = 0; |
132 | op_queue_access::back(q) = 0; |
133 | } |
134 | } |
135 | |
136 | // Whether the queue is empty. |
137 | bool empty() const |
138 | { |
139 | return front_ == 0; |
140 | } |
141 | |
142 | private: |
143 | friend class op_queue_access; |
144 | |
145 | // The front of the queue. |
146 | Operation* front_; |
147 | |
148 | // The back of the queue. |
149 | Operation* back_; |
150 | }; |
151 | |
152 | } // namespace detail |
153 | } // namespace asio |
154 | } // namespace boost |
155 | |
156 | #include <boost/asio/detail/pop_options.hpp> |
157 | |
158 | #endif // BOOST_ASIO_DETAIL_OP_QUEUE_HPP |
159 | |