Line data Source code
1 : //
2 : // Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
3 : //
4 : // Distributed under the Boost Software License, Version 1.0. (See accompanying
5 : // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 : //
7 : // Official repository: https://github.com/cppalliance/http_proto
8 : //
9 :
10 : #ifndef BOOST_HTTP_PROTO_DETAIL_WORKSPACE_HPP
11 : #define BOOST_HTTP_PROTO_DETAIL_WORKSPACE_HPP
12 :
13 : #include <boost/http_proto/detail/config.hpp>
14 : #include <boost/http_proto/detail/except.hpp>
15 : #include <boost/assert.hpp>
16 : #include <cstdlib>
17 : #include <new>
18 : #include <utility>
19 : #include <stddef.h> // ::max_align_t
20 :
21 : namespace boost {
22 : namespace http_proto {
23 : namespace detail {
24 :
25 : /** A contiguous buffer of storage used by algorithms.
26 :
27 : Objects of this type retain ownership of a
28 : contiguous buffer of storage allocated upon
29 : construction. This storage is divided into
30 : three regions:
31 :
32 : @code
33 : | front | free | acquired | back |
34 : @endcode
35 :
36 : @li The reserved area, which starts at the
37 : beginning of the buffer and can grow
38 : upwards towards the end of the buffer.
39 :
40 : @li The acquired area, which starts at the
41 : end of the buffer and can grow downwards
42 : towards the beginning of the buffer.
43 :
44 : @li The unused area, which starts from the
45 : end of the reserved area and stretches
46 : until the beginning of the acquired area.
47 : */
48 : class BOOST_HTTP_PROTO_DECL workspace
49 : {
50 : unsigned char* begin_ = nullptr;
51 : unsigned char* front_ = nullptr;
52 : unsigned char* head_ = nullptr;
53 : unsigned char* back_ = nullptr;
54 : unsigned char* end_ = nullptr;
55 :
56 : template<class>
57 : struct any_impl;
58 : struct any;
59 : struct undo;
60 :
61 : public:
62 : /** Return the number of aligned bytes required for T
63 : */
64 : template<class T>
65 : static
66 : constexpr
67 : std::size_t
68 : space_needed();
69 :
70 : /** Destructor.
71 : */
72 : ~workspace();
73 :
74 : /** Constructor.
75 :
76 : @param n The number of bytes of storage
77 : to allocate for the internal buffer.
78 : */
79 : explicit
80 : workspace(
81 : std::size_t n);
82 :
83 : /** Constructor.
84 : */
85 1064 : workspace() = default;
86 :
87 : /** Constructor.
88 : */
89 : workspace(workspace&&) noexcept;
90 :
91 : /** Allocate internal storage.
92 :
93 : @throws std::logic_error this->size() > 0
94 :
95 : @throws std::invalid_argument n == 0
96 : */
97 : void
98 : allocate(
99 : std::size_t n);
100 :
101 : /** Return a pointer to the unused area.
102 : */
103 : unsigned char*
104 15819 : data() noexcept
105 : {
106 15819 : return front_;
107 : }
108 :
109 : /** Return the size of the unused area.
110 : */
111 : std::size_t
112 3567 : size() const noexcept
113 : {
114 3567 : return head_ - front_;
115 : }
116 :
117 : /** Clear the contents while preserving capacity.
118 : */
119 : void
120 : clear() noexcept;
121 :
122 : /** Convert unused storage to reserved storage.
123 :
124 : @throws std::invalid_argument n >= this->size()
125 : */
126 : unsigned char*
127 : reserve_front(
128 : std::size_t n);
129 :
130 : template<class T, class... Args>
131 : typename std::decay<T>::type&
132 : emplace(Args&&... args);
133 :
134 : template<class T>
135 : T*
136 : push_array(
137 : std::size_t n,
138 : T const& t);
139 :
140 : unsigned char*
141 : reserve_back(
142 : std::size_t n);
143 :
144 : private:
145 : unsigned char*
146 : bump_down(
147 : std::size_t size,
148 : std::size_t align);
149 : };
150 :
151 : } // detail
152 : } // http_proto
153 : } // boost
154 :
155 : #include <boost/http_proto/detail/impl/workspace.hpp>
156 :
157 : #endif
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