| Line | Branch | Exec | Source |
|---|---|---|---|
| 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_ANY_BUFREF_HPP | ||
| 11 | #define BOOST_CAPY_ANY_BUFREF_HPP | ||
| 12 | |||
| 13 | #include <boost/capy/detail/config.hpp> | ||
| 14 | #include <boost/capy/buffers.hpp> | ||
| 15 | |||
| 16 | #include <cstddef> | ||
| 17 | |||
| 18 | namespace boost { | ||
| 19 | namespace capy { | ||
| 20 | |||
| 21 | /** A type-erased buffer sequence I/O parameter. | ||
| 22 | |||
| 23 | This class provides a type-erased interface for iterating | ||
| 24 | over buffer sequences without knowing the concrete type. | ||
| 25 | It allows asynchronous operations to efficiently type-erase | ||
| 26 | the buffer sequence parameter, avoiding the need to | ||
| 27 | templatize the implementation. | ||
| 28 | |||
| 29 | @par Example | ||
| 30 | The following shows the minimal form of an awaitable, templated on the | ||
| 31 | buffer sequence type, with only an `await_suspend` method. The example | ||
| 32 | demonstrates that you can construct an `any_bufref` in the parameter | ||
| 33 | list when calling a virtual interface; there is no need to create a | ||
| 34 | separate variable if not desired. | ||
| 35 | |||
| 36 | @code | ||
| 37 | template<class Buffers> | ||
| 38 | struct awaitable | ||
| 39 | { | ||
| 40 | Buffers b; | ||
| 41 | |||
| 42 | void await_suspend( std::coroutine_handle<> ) | ||
| 43 | { | ||
| 44 | my_virtual_engine_submit( any_bufref( b ) ); | ||
| 45 | } | ||
| 46 | }; | ||
| 47 | |||
| 48 | // Example virtual interface accepting any_bufref | ||
| 49 | void my_virtual_engine_submit( any_bufref p ) | ||
| 50 | { | ||
| 51 | capy::mutable_buffer temp[8]; | ||
| 52 | std::size_t n = p.copy_to( temp, 8 ); | ||
| 53 | // ... handle the buffers ... | ||
| 54 | } | ||
| 55 | @endcode | ||
| 56 | */ | ||
| 57 | class any_bufref | ||
| 58 | { | ||
| 59 | public: | ||
| 60 | /** Construct from a const buffer sequence. | ||
| 61 | |||
| 62 | @param bs The buffer sequence to adapt. | ||
| 63 | */ | ||
| 64 | template<ConstBufferSequence BS> | ||
| 65 | explicit | ||
| 66 | 18 | any_bufref(BS const& bs) noexcept | |
| 67 | 18 | : bs_(&bs) | |
| 68 | 18 | , fn_(©_impl<BS>) | |
| 69 | { | ||
| 70 | 18 | } | |
| 71 | |||
| 72 | /** Fill an array with buffers from the sequence. | ||
| 73 | |||
| 74 | @param dest Pointer to array of mutable buffer descriptors. | ||
| 75 | @param n Maximum number of buffers to copy. | ||
| 76 | |||
| 77 | @return The number of buffers actually copied. | ||
| 78 | */ | ||
| 79 | std::size_t | ||
| 80 | 9 | copy_to( | |
| 81 | mutable_buffer* dest, | ||
| 82 | std::size_t n) const noexcept | ||
| 83 | { | ||
| 84 | 9 | return fn_(bs_, dest, n); | |
| 85 | } | ||
| 86 | |||
| 87 | private: | ||
| 88 | template<ConstBufferSequence BS> | ||
| 89 | static std::size_t | ||
| 90 | 9 | copy_impl( | |
| 91 | void const* p, | ||
| 92 | mutable_buffer* dest, | ||
| 93 | std::size_t n) | ||
| 94 | { | ||
| 95 | 9 | auto const& bs = *static_cast<BS const*>(p); | |
| 96 | 9 | auto it = begin(bs); | |
| 97 | 9 | auto const end_it = end(bs); | |
| 98 | |||
| 99 | 9 | std::size_t i = 0; | |
| 100 | if constexpr (MutableBufferSequence<BS>) | ||
| 101 | { | ||
| 102 | 5 | for(; it != end_it && i < n; ++it, ++i) | |
| 103 | 3 | dest[i] = *it; | |
| 104 | } | ||
| 105 | else | ||
| 106 | { | ||
| 107 | 22 | for(; it != end_it && i < n; ++it, ++i) | |
| 108 | { | ||
| 109 | 15 | auto const& buf = *it; | |
| 110 | 30 | dest[i] = mutable_buffer( | |
| 111 | const_cast<char*>( | ||
| 112 | 15 | static_cast<char const*>(buf.data())), | |
| 113 | buf.size()); | ||
| 114 | } | ||
| 115 | } | ||
| 116 | 9 | return i; | |
| 117 | } | ||
| 118 | |||
| 119 | using fn_t = std::size_t(*)(void const*, | ||
| 120 | mutable_buffer*, std::size_t); | ||
| 121 | |||
| 122 | void const* bs_; | ||
| 123 | fn_t fn_; | ||
| 124 | }; | ||
| 125 | |||
| 126 | } // namespace capy | ||
| 127 | } // namespace boost | ||
| 128 | |||
| 129 | #endif | ||
| 130 |