libs/capy/include/boost/capy/buffers/consuming_buffers.hpp
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| 1 | // | ||
| 2 | // Copyright (c) 2025 Vinnie Falco (vinnie dot falco at gmail dot 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_CONSUMING_BUFFERS_HPP | ||
| 11 | #define BOOST_CAPY_BUFFERS_CONSUMING_BUFFERS_HPP | ||
| 12 | |||
| 13 | #include <boost/capy/detail/config.hpp> | ||
| 14 | #include <boost/capy/buffers.hpp> | ||
| 15 | |||
| 16 | #include <cstddef> | ||
| 17 | #include <iterator> | ||
| 18 | #include <ranges> | ||
| 19 | #include <type_traits> | ||
| 20 | |||
| 21 | namespace boost { | ||
| 22 | namespace capy { | ||
| 23 | |||
| 24 | namespace detail { | ||
| 25 | |||
| 26 | template<class T> | ||
| 27 | struct buffer_type_for; | ||
| 28 | |||
| 29 | template<MutableBufferSequence T> | ||
| 30 | struct buffer_type_for<T> | ||
| 31 | { | ||
| 32 | using type = mutable_buffer; | ||
| 33 | }; | ||
| 34 | |||
| 35 | template<ConstBufferSequence T> | ||
| 36 | requires (!MutableBufferSequence<T>) | ||
| 37 | struct buffer_type_for<T> | ||
| 38 | { | ||
| 39 | using type = const_buffer; | ||
| 40 | }; | ||
| 41 | |||
| 42 | } // namespace detail | ||
| 43 | |||
| 44 | /** Wrapper for consuming a buffer sequence incrementally. | ||
| 45 | |||
| 46 | This class wraps a buffer sequence and tracks the current | ||
| 47 | position. It provides a `consume(n)` function that advances | ||
| 48 | through the sequence as bytes are processed. | ||
| 49 | |||
| 50 | Works with both mutable and const buffer sequences. | ||
| 51 | |||
| 52 | @tparam BufferSequence The buffer sequence type. | ||
| 53 | */ | ||
| 54 | template<class BufferSequence> | ||
| 55 | requires MutableBufferSequence<BufferSequence> || | ||
| 56 | ConstBufferSequence<BufferSequence> | ||
| 57 | class consuming_buffers | ||
| 58 | { | ||
| 59 | using iterator_type = decltype(capy::begin(std::declval<BufferSequence const&>())); | ||
| 60 | using end_iterator_type = decltype(capy::end(std::declval<BufferSequence const&>())); | ||
| 61 | using buffer_type = typename detail::buffer_type_for<BufferSequence>::type; | ||
| 62 | |||
| 63 | BufferSequence const& bufs_; | ||
| 64 | iterator_type it_; | ||
| 65 | end_iterator_type end_; | ||
| 66 | std::size_t consumed_ = 0; // Bytes consumed in current buffer | ||
| 67 | |||
| 68 | public: | ||
| 69 | /** Construct from a buffer sequence. | ||
| 70 | |||
| 71 | @param bufs The buffer sequence to wrap. | ||
| 72 | */ | ||
| 73 | 19 | explicit consuming_buffers(BufferSequence const& bufs) noexcept | |
| 74 | 19 | : bufs_(bufs) | |
| 75 | 19 | , it_(capy::begin(bufs)) | |
| 76 | 19 | , end_(capy::end(bufs)) | |
| 77 | { | ||
| 78 | 19 | } | |
| 79 | |||
| 80 | /** Consume n bytes from the buffer sequence. | ||
| 81 | |||
| 82 | Advances the current position by n bytes, moving to the | ||
| 83 | next buffer when the current one is exhausted. | ||
| 84 | |||
| 85 | @param n The number of bytes to consume. | ||
| 86 | */ | ||
| 87 | 29 | void consume(std::size_t n) noexcept | |
| 88 | { | ||
| 89 |
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boost::capy::consuming_buffers<boost::capy::mutable_buffer>::consume(unsigned long):
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boost::capy::consuming_buffers<std::array<boost::capy::const_buffer, 2ul> >::consume(unsigned long):
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boost::capy::consuming_buffers<std::array<boost::capy::mutable_buffer, 2ul> >::consume(unsigned long):
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58 | while (n > 0 && it_ != end_) |
| 90 | { | ||
| 91 | 29 | auto const& buf = *it_; | |
| 92 | 29 | std::size_t const buf_size = buf.size(); | |
| 93 | 29 | std::size_t const remaining = buf_size - consumed_; | |
| 94 | |||
| 95 |
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boost::capy::consuming_buffers<boost::capy::mutable_buffer>::consume(unsigned long):
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boost::capy::consuming_buffers<std::array<boost::capy::const_buffer, 2ul> >::consume(unsigned long):
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boost::capy::consuming_buffers<std::array<boost::capy::mutable_buffer, 2ul> >::consume(unsigned long):
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29 | if (n < remaining) |
| 96 | { | ||
| 97 | // Consume part of current buffer | ||
| 98 | 18 | consumed_ += n; | |
| 99 | 18 | n = 0; | |
| 100 | } | ||
| 101 | else | ||
| 102 | { | ||
| 103 | // Consume rest of current buffer and move to next | ||
| 104 | 11 | n -= remaining; | |
| 105 | 11 | consumed_ = 0; | |
| 106 | 11 | ++it_; | |
| 107 | } | ||
| 108 | } | ||
| 109 | 29 | } | |
| 110 | |||
| 111 | /** Iterator for the consuming buffer sequence. | ||
| 112 | |||
| 113 | Returns buffers starting from the current position, | ||
| 114 | with the first buffer adjusted for consumed bytes. | ||
| 115 | */ | ||
| 116 | class const_iterator | ||
| 117 | { | ||
| 118 | iterator_type it_; | ||
| 119 | end_iterator_type end_; | ||
| 120 | std::size_t consumed_; | ||
| 121 | |||
| 122 | public: | ||
| 123 | using iterator_category = std::bidirectional_iterator_tag; | ||
| 124 | using value_type = buffer_type; | ||
| 125 | using difference_type = std::ptrdiff_t; | ||
| 126 | using pointer = value_type*; | ||
| 127 | using reference = value_type; | ||
| 128 | |||
| 129 | // Default constructor required for forward_iterator | ||
| 130 | const_iterator() noexcept = default; | ||
| 131 | |||
| 132 | 40 | const_iterator( | |
| 133 | iterator_type it, | ||
| 134 | end_iterator_type end, | ||
| 135 | std::size_t consumed) noexcept | ||
| 136 | 40 | : it_(it) | |
| 137 | 40 | , end_(end) | |
| 138 | 40 | , consumed_(consumed) | |
| 139 | { | ||
| 140 | 40 | } | |
| 141 | |||
| 142 | 6 | bool operator==(const_iterator const& other) const noexcept | |
| 143 | { | ||
| 144 |
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boost::capy::consuming_buffers<std::array<boost::capy::mutable_buffer, 2ul> >::const_iterator::operator==(boost::capy::consuming_buffers<std::array<boost::capy::mutable_buffer, 2ul> >::const_iterator const&) const:
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6 | return it_ == other.it_ && consumed_ == other.consumed_; |
| 145 | } | ||
| 146 | |||
| 147 | // != operator required for equality_comparable | ||
| 148 | 6 | bool operator!=(const_iterator const& other) const noexcept | |
| 149 | { | ||
| 150 | 6 | return !(*this == other); | |
| 151 | } | ||
| 152 | |||
| 153 | 37 | value_type operator*() const noexcept | |
| 154 | { | ||
| 155 | 37 | auto const& buf = *it_; | |
| 156 | if constexpr (std::is_same_v<buffer_type, mutable_buffer>) | ||
| 157 | { | ||
| 158 | 48 | return buffer_type( | |
| 159 | 16 | static_cast<char*>(buf.data()) + consumed_, | |
| 160 | 32 | buf.size() - consumed_); | |
| 161 | } | ||
| 162 | else | ||
| 163 | { | ||
| 164 | 63 | return buffer_type( | |
| 165 | 21 | static_cast<char const*>(buf.data()) + consumed_, | |
| 166 | 42 | buf.size() - consumed_); | |
| 167 | } | ||
| 168 | } | ||
| 169 | |||
| 170 | 3 | const_iterator& operator++() noexcept | |
| 171 | { | ||
| 172 | 3 | consumed_ = 0; | |
| 173 | 3 | ++it_; | |
| 174 | 3 | return *this; | |
| 175 | } | ||
| 176 | |||
| 177 | const_iterator operator++(int) noexcept | ||
| 178 | { | ||
| 179 | const_iterator tmp = *this; | ||
| 180 | ++*this; | ||
| 181 | return tmp; | ||
| 182 | } | ||
| 183 | |||
| 184 | const_iterator& operator--() noexcept | ||
| 185 | { | ||
| 186 | if (consumed_ == 0) | ||
| 187 | { | ||
| 188 | --it_; | ||
| 189 | // Set consumed_ to the size of the previous buffer | ||
| 190 | // This is a simplified implementation for bidirectional requirement | ||
| 191 | if (it_ != end_) | ||
| 192 | { | ||
| 193 | auto const& buf = *it_; | ||
| 194 | consumed_ = buf.size(); | ||
| 195 | } | ||
| 196 | } | ||
| 197 | else | ||
| 198 | { | ||
| 199 | consumed_ = 0; | ||
| 200 | } | ||
| 201 | return *this; | ||
| 202 | } | ||
| 203 | |||
| 204 | const_iterator operator--(int) noexcept | ||
| 205 | { | ||
| 206 | const_iterator tmp = *this; | ||
| 207 | --*this; | ||
| 208 | return tmp; | ||
| 209 | } | ||
| 210 | }; | ||
| 211 | |||
| 212 | /** Return iterator to beginning of remaining buffers. | ||
| 213 | |||
| 214 | @return Iterator pointing to the first remaining buffer, | ||
| 215 | adjusted for consumed bytes in the current buffer. | ||
| 216 | */ | ||
| 217 | 37 | const_iterator begin() const noexcept | |
| 218 | { | ||
| 219 | 37 | return const_iterator(it_, end_, consumed_); | |
| 220 | } | ||
| 221 | |||
| 222 | /** Return iterator to end of buffer sequence. | ||
| 223 | |||
| 224 | @return End iterator. | ||
| 225 | */ | ||
| 226 | 3 | const_iterator end() const noexcept | |
| 227 | { | ||
| 228 | 3 | return const_iterator(end_, end_, 0); | |
| 229 | } | ||
| 230 | }; | ||
| 231 | |||
| 232 | } // namespace capy | ||
| 233 | } // namespace boost | ||
| 234 | |||
| 235 | #endif | ||
| 236 |