Line data Source code
1 : //
2 : // Copyright (c) 2025 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/capy
8 : //
9 :
10 : #ifndef BOOST_CAPY_BUFFERS_SPAN_HPP
11 : #define BOOST_CAPY_BUFFERS_SPAN_HPP
12 :
13 : #include <boost/capy/detail/config.hpp>
14 : #include <boost/capy/buffers.hpp>
15 : #include <span>
16 :
17 : namespace boost {
18 : namespace capy {
19 :
20 : /** Remove bytes from the beginning of a span of const buffers.
21 :
22 : Modifies the span and its buffer contents in-place to
23 : remove the first `n` bytes.
24 :
25 : @param bs The span to modify.
26 : @param n The number of bytes to remove.
27 : */
28 : inline
29 : void
30 12 : remove_span_prefix(
31 : std::span<const_buffer>& bs,
32 : std::size_t n) noexcept
33 : {
34 19 : while(bs.size() > 0)
35 : {
36 15 : if(n < bs.front().size())
37 : {
38 8 : bs.front() += n;
39 8 : return;
40 : }
41 7 : n -= bs.front().size();
42 7 : bs = bs.subspan(1);
43 : }
44 : }
45 :
46 : /** Remove bytes from the beginning of a span of mutable buffers.
47 :
48 : Modifies the span and its buffer contents in-place to
49 : remove the first `n` bytes.
50 :
51 : @param bs The span to modify.
52 : @param n The number of bytes to remove.
53 : */
54 : inline
55 : void
56 4 : remove_span_prefix(
57 : std::span<mutable_buffer>& bs,
58 : std::size_t n) noexcept
59 : {
60 6 : while(bs.size() > 0)
61 : {
62 4 : if(n < bs.front().size())
63 : {
64 2 : bs.front() += n;
65 2 : return;
66 : }
67 2 : n -= bs.front().size();
68 2 : bs = bs.subspan(1);
69 : }
70 : }
71 :
72 : /** Remove bytes from the end of a span of const buffers.
73 :
74 : Modifies the span and its buffer contents in-place to
75 : remove the last `n` bytes.
76 :
77 : @param bs The span to modify.
78 : @param n The number of bytes to remove.
79 : */
80 : inline
81 : void
82 12 : remove_span_suffix(
83 : std::span<const_buffer>& bs,
84 : std::size_t n) noexcept
85 : {
86 19 : while(bs.size() > 0)
87 : {
88 15 : if(n < bs.back().size())
89 : {
90 8 : auto& b = bs.back();
91 8 : b = const_buffer(b.data(), b.size() - n);
92 8 : return;
93 : }
94 7 : n -= bs.back().size();
95 7 : bs = bs.subspan(0, bs.size() - 1);
96 : }
97 : }
98 :
99 : /** Remove bytes from the end of a span of mutable buffers.
100 :
101 : Modifies the span and its buffer contents in-place to
102 : remove the last `n` bytes.
103 :
104 : @param bs The span to modify.
105 : @param n The number of bytes to remove.
106 : */
107 : inline
108 : void
109 4 : remove_span_suffix(
110 : std::span<mutable_buffer>& bs,
111 : std::size_t n) noexcept
112 : {
113 6 : while(bs.size() > 0)
114 : {
115 4 : if(n < bs.back().size())
116 : {
117 2 : auto& b = bs.back();
118 2 : b = mutable_buffer(b.data(), b.size() - n);
119 2 : return;
120 : }
121 2 : n -= bs.back().size();
122 2 : bs = bs.subspan(0, bs.size() - 1);
123 : }
124 : }
125 :
126 : /** Keep only the first bytes of a span of const buffers.
127 :
128 : Modifies the span and its buffer contents in-place to
129 : keep only the first `n` bytes.
130 :
131 : @param bs The span to modify.
132 : @param n The number of bytes to keep.
133 : */
134 : inline
135 : void
136 5 : keep_span_prefix(
137 : std::span<const_buffer>& bs,
138 : std::size_t n) noexcept
139 : {
140 5 : auto total = buffer_size(bs);
141 5 : if(n < total)
142 3 : remove_span_suffix(bs, total - n);
143 5 : }
144 :
145 : /** Keep only the first bytes of a span of mutable buffers.
146 :
147 : Modifies the span and its buffer contents in-place to
148 : keep only the first `n` bytes.
149 :
150 : @param bs The span to modify.
151 : @param n The number of bytes to keep.
152 : */
153 : inline
154 : void
155 2 : keep_span_prefix(
156 : std::span<mutable_buffer>& bs,
157 : std::size_t n) noexcept
158 : {
159 2 : auto total = buffer_size(bs);
160 2 : if(n < total)
161 2 : remove_span_suffix(bs, total - n);
162 2 : }
163 :
164 : /** Keep only the last bytes of a span of const buffers.
165 :
166 : Modifies the span and its buffer contents in-place to
167 : keep only the last `n` bytes.
168 :
169 : @param bs The span to modify.
170 : @param n The number of bytes to keep.
171 : */
172 : inline
173 : void
174 5 : keep_span_suffix(
175 : std::span<const_buffer>& bs,
176 : std::size_t n) noexcept
177 : {
178 5 : auto total = buffer_size(bs);
179 5 : if(n < total)
180 3 : remove_span_prefix(bs, total - n);
181 5 : }
182 :
183 : /** Keep only the last bytes of a span of mutable buffers.
184 :
185 : Modifies the span and its buffer contents in-place to
186 : keep only the last `n` bytes.
187 :
188 : @param bs The span to modify.
189 : @param n The number of bytes to keep.
190 : */
191 : inline
192 : void
193 2 : keep_span_suffix(
194 : std::span<mutable_buffer>& bs,
195 : std::size_t n) noexcept
196 : {
197 2 : auto total = buffer_size(bs);
198 2 : if(n < total)
199 2 : remove_span_prefix(bs, total - n);
200 2 : }
201 :
202 : } // capy
203 : } // boost
204 :
205 : #endif
|
