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1 | // |
2 | // detail/op_queue.hpp | |
3 | // ~~~~~~~~~~~~~~~~~~~ | |
4 | // | |
5 | // Copyright (c) 2003-2016 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 |