1   
//
1   
//
2   
// Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
2   
// Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3   
//
3   
//
4   
// Distributed under the Boost Software License, Version 1.0. (See accompanying
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)
5   
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6   
//
6   
//
7   
// Official repository: https://github.com/cppalliance/capy
7   
// Official repository: https://github.com/cppalliance/capy
8   
//
8   
//
9  
9  
10   
#ifndef BOOST_CAPY_BUFFERS_SOME_BUFFERS_HPP
10   
#ifndef BOOST_CAPY_BUFFERS_SOME_BUFFERS_HPP
11   
#define BOOST_CAPY_BUFFERS_SOME_BUFFERS_HPP
11   
#define BOOST_CAPY_BUFFERS_SOME_BUFFERS_HPP
12  
12  
13   
#include <boost/capy/detail/config.hpp>
13   
#include <boost/capy/detail/config.hpp>
14   
#include <boost/capy/buffers.hpp>
14   
#include <boost/capy/buffers.hpp>
15  
15  
16   
#include <cstddef>
16   
#include <cstddef>
17   
#include <new>
17   
#include <new>
18  
18  
19   
namespace boost {
19   
namespace boost {
20   
namespace capy {
20   
namespace capy {
21  
21  
22   
namespace detail {
22   
namespace detail {
23  
23  
24   
template<class Buffer, class BS>
24   
template<class Buffer, class BS>
25   
std::size_t
25   
std::size_t
26   
fill_buffers(Buffer* arr, BS const& bs) noexcept
26   
fill_buffers(Buffer* arr, BS const& bs) noexcept
27   
{
27   
{
28   
    auto it = begin(bs);
28   
    auto it = begin(bs);
29   
    auto const last = end(bs);
29   
    auto const last = end(bs);
30   
    std::size_t n = 0;
30   
    std::size_t n = 0;
31   
    while(it != last && n < max_iovec_)
31   
    while(it != last && n < max_iovec_)
32   
    {
32   
    {
33   
        Buffer b(*it);
33   
        Buffer b(*it);
34   
        if(b.size() != 0)
34   
        if(b.size() != 0)
35   
            ::new(&arr[n++]) Buffer(b);
35   
            ::new(&arr[n++]) Buffer(b);
36   
        ++it;
36   
        ++it;
37   
    }
37   
    }
38   
    return n;
38   
    return n;
39   
}
39   
}
40  
40  
41   
} // detail
41   
} // detail
42  
42  
43   
//------------------------------------------------
43   
//------------------------------------------------
44  
44  
45   
/** A buffer sequence holding up to max_iovec_ const buffers.
45   
/** A buffer sequence holding up to max_iovec_ const buffers.
46  
46  
47   
    This class stores a fixed-size array of const_buffer
47   
    This class stores a fixed-size array of const_buffer
48   
    descriptors, populated from an arbitrary buffer sequence.
48   
    descriptors, populated from an arbitrary buffer sequence.
49   
    It provides efficient storage for small buffer sequences
49   
    It provides efficient storage for small buffer sequences
50   
    without dynamic allocation.
50   
    without dynamic allocation.
51  
51  
52   
    @par Usage
52   
    @par Usage
53  
53  
54   
    @code
54   
    @code
55   
    void process(ConstBufferSequence auto const& buffers)
55   
    void process(ConstBufferSequence auto const& buffers)
56   
    {
56   
    {
57   
        some_const_buffers bufs(buffers);
57   
        some_const_buffers bufs(buffers);
58   
        // use bufs.data(), bufs.size()
58   
        // use bufs.data(), bufs.size()
59   
    }
59   
    }
60   
    @endcode
60   
    @endcode
61   
*/
61   
*/
62   
class some_const_buffers
62   
class some_const_buffers
63   
{
63   
{
64   
    std::size_t n_ = 0;
64   
    std::size_t n_ = 0;
65   
    union {
65   
    union {
66   
        int dummy_;
66   
        int dummy_;
67   
        const_buffer arr_[detail::max_iovec_];
67   
        const_buffer arr_[detail::max_iovec_];
68   
    };
68   
    };
69  
69  
70   
public:
70   
public:
71   
    /** Default constructor.
71   
    /** Default constructor.
72  
72  
73   
        Constructs an empty buffer sequence.
73   
        Constructs an empty buffer sequence.
74   
    */
74   
    */
75   
    some_const_buffers() noexcept
75   
    some_const_buffers() noexcept
76   
        : dummy_(0)
76   
        : dummy_(0)
77   
    {
77   
    {
78   
    }
78   
    }
79  
79  
80   
    /** Copy constructor.
80   
    /** Copy constructor.
81   
    */
81   
    */
82   
    some_const_buffers(some_const_buffers const& other) noexcept
82   
    some_const_buffers(some_const_buffers const& other) noexcept
83   
        : n_(other.n_)
83   
        : n_(other.n_)
84   
    {
84   
    {
85   
        for(std::size_t i = 0; i < n_; ++i)
85   
        for(std::size_t i = 0; i < n_; ++i)
86   
            ::new(&arr_[i]) const_buffer(other.arr_[i]);
86   
            ::new(&arr_[i]) const_buffer(other.arr_[i]);
87   
    }
87   
    }
88  
88  
89   
    /** Construct from a buffer sequence.
89   
    /** Construct from a buffer sequence.
90  
90  
91   
        Copies up to @ref detail::max_iovec_ buffer descriptors
91   
        Copies up to @ref detail::max_iovec_ buffer descriptors
92   
        from the source sequence into the internal array.
92   
        from the source sequence into the internal array.
93  
93  
94   
        @param bs The buffer sequence to copy from.
94   
        @param bs The buffer sequence to copy from.
95   
    */
95   
    */
96   
    template<ConstBufferSequence BS>
96   
    template<ConstBufferSequence BS>
97   
    some_const_buffers(BS const& bs) noexcept
97   
    some_const_buffers(BS const& bs) noexcept
98   
        : n_(detail::fill_buffers(arr_, bs))
98   
        : n_(detail::fill_buffers(arr_, bs))
99   
    {
99   
    {
100   
    }
100   
    }
101  
101  
102   
    /** Destructor.
102   
    /** Destructor.
103   
    */
103   
    */
104   
    ~some_const_buffers()
104   
    ~some_const_buffers()
105   
    {
105   
    {
106   
        while(n_--)
106   
        while(n_--)
107   
            arr_[n_].~const_buffer();
107   
            arr_[n_].~const_buffer();
108   
    }
108   
    }
109  
109  
110   
    /** Return a pointer to the buffer array.
110   
    /** Return a pointer to the buffer array.
111   
    */
111   
    */
112   
    const_buffer*
112   
    const_buffer*
113   
    data() noexcept
113   
    data() noexcept
114   
    {
114   
    {
115   
        return arr_;
115   
        return arr_;
116   
    }
116   
    }
117  
117  
118   
    /** Return a pointer to the buffer array.
118   
    /** Return a pointer to the buffer array.
119   
    */
119   
    */
120   
    const_buffer const*
120   
    const_buffer const*
121   
    data() const noexcept
121   
    data() const noexcept
122   
    {
122   
    {
123   
        return arr_;
123   
        return arr_;
124   
    }
124   
    }
125  
125  
126   
    /** Return the number of buffers.
126   
    /** Return the number of buffers.
127   
    */
127   
    */
128   
    std::size_t
128   
    std::size_t
129   
    size() const noexcept
129   
    size() const noexcept
130   
    {
130   
    {
131   
        return n_;
131   
        return n_;
132   
    }
132   
    }
133  
133  
134   
    /** Return an iterator to the beginning.
134   
    /** Return an iterator to the beginning.
135   
    */
135   
    */
136   
    const_buffer*
136   
    const_buffer*
137   
    begin() noexcept
137   
    begin() noexcept
138   
    {
138   
    {
139   
        return arr_;
139   
        return arr_;
140   
    }
140   
    }
141  
141  
142   
    /** Return an iterator to the beginning.
142   
    /** Return an iterator to the beginning.
143   
    */
143   
    */
144   
    const_buffer const*
144   
    const_buffer const*
145   
    begin() const noexcept
145   
    begin() const noexcept
146   
    {
146   
    {
147   
        return arr_;
147   
        return arr_;
148   
    }
148   
    }
149  
149  
150   
    /** Return an iterator to the end.
150   
    /** Return an iterator to the end.
151   
    */
151   
    */
152   
    const_buffer*
152   
    const_buffer*
153   
    end() noexcept
153   
    end() noexcept
154   
    {
154   
    {
155   
        return arr_ + n_;
155   
        return arr_ + n_;
156   
    }
156   
    }
157  
157  
158   
    /** Return an iterator to the end.
158   
    /** Return an iterator to the end.
159   
    */
159   
    */
160   
    const_buffer const*
160   
    const_buffer const*
161   
    end() const noexcept
161   
    end() const noexcept
162   
    {
162   
    {
163   
        return arr_ + n_;
163   
        return arr_ + n_;
164   
    }
164   
    }
165   
};
165   
};
166  
166  
167   
//------------------------------------------------
167   
//------------------------------------------------
168  
168  
169   
/** A buffer sequence holding up to max_iovec_ mutable buffers.
169   
/** A buffer sequence holding up to max_iovec_ mutable buffers.
170  
170  
171   
    This class stores a fixed-size array of mutable_buffer
171   
    This class stores a fixed-size array of mutable_buffer
172   
    descriptors, populated from an arbitrary buffer sequence.
172   
    descriptors, populated from an arbitrary buffer sequence.
173   
    It provides efficient storage for small buffer sequences
173   
    It provides efficient storage for small buffer sequences
174   
    without dynamic allocation.
174   
    without dynamic allocation.
175  
175  
176   
    @par Usage
176   
    @par Usage
177  
177  
178   
    @code
178   
    @code
179   
    void process(MutableBufferSequence auto const& buffers)
179   
    void process(MutableBufferSequence auto const& buffers)
180   
    {
180   
    {
181   
        some_mutable_buffers bufs(buffers);
181   
        some_mutable_buffers bufs(buffers);
182   
        // use bufs.data(), bufs.size()
182   
        // use bufs.data(), bufs.size()
183   
    }
183   
    }
184   
    @endcode
184   
    @endcode
185   
*/
185   
*/
186   
class some_mutable_buffers
186   
class some_mutable_buffers
187   
{
187   
{
188   
    std::size_t n_ = 0;
188   
    std::size_t n_ = 0;
189   
    union {
189   
    union {
190   
        int dummy_;
190   
        int dummy_;
191   
        mutable_buffer arr_[detail::max_iovec_];
191   
        mutable_buffer arr_[detail::max_iovec_];
192   
    };
192   
    };
193  
193  
194   
public:
194   
public:
195   
    /** Default constructor.
195   
    /** Default constructor.
196  
196  
197   
        Constructs an empty buffer sequence.
197   
        Constructs an empty buffer sequence.
198   
    */
198   
    */
199   
    some_mutable_buffers() noexcept
199   
    some_mutable_buffers() noexcept
200   
        : dummy_(0)
200   
        : dummy_(0)
201   
    {
201   
    {
202   
    }
202   
    }
203  
203  
204   
    /** Copy constructor.
204   
    /** Copy constructor.
205   
    */
205   
    */
206   
    some_mutable_buffers(some_mutable_buffers const& other) noexcept
206   
    some_mutable_buffers(some_mutable_buffers const& other) noexcept
207   
        : n_(other.n_)
207   
        : n_(other.n_)
208   
    {
208   
    {
209   
        for(std::size_t i = 0; i < n_; ++i)
209   
        for(std::size_t i = 0; i < n_; ++i)
210   
            ::new(&arr_[i]) mutable_buffer(other.arr_[i]);
210   
            ::new(&arr_[i]) mutable_buffer(other.arr_[i]);
211   
    }
211   
    }
212  
212  
213   
    /** Construct from a buffer sequence.
213   
    /** Construct from a buffer sequence.
214  
214  
215   
        Copies up to @ref detail::max_iovec_ buffer descriptors
215   
        Copies up to @ref detail::max_iovec_ buffer descriptors
216   
        from the source sequence into the internal array.
216   
        from the source sequence into the internal array.
217  
217  
218   
        @param bs The buffer sequence to copy from.
218   
        @param bs The buffer sequence to copy from.
219   
    */
219   
    */
220   
    template<MutableBufferSequence BS>
220   
    template<MutableBufferSequence BS>
221   
    some_mutable_buffers(BS const& bs) noexcept
221   
    some_mutable_buffers(BS const& bs) noexcept
222   
        : n_(detail::fill_buffers(arr_, bs))
222   
        : n_(detail::fill_buffers(arr_, bs))
223   
    {
223   
    {
224   
    }
224   
    }
225  
225  
226   
    /** Destructor.
226   
    /** Destructor.
227   
    */
227   
    */
228   
    ~some_mutable_buffers()
228   
    ~some_mutable_buffers()
229   
    {
229   
    {
230   
        while(n_--)
230   
        while(n_--)
231   
            arr_[n_].~mutable_buffer();
231   
            arr_[n_].~mutable_buffer();
232   
    }
232   
    }
233  
233  
234   
    /** Return a pointer to the buffer array.
234   
    /** Return a pointer to the buffer array.
235   
    */
235   
    */
236   
    mutable_buffer*
236   
    mutable_buffer*
237   
    data() noexcept
237   
    data() noexcept
238   
    {
238   
    {
239   
        return arr_;
239   
        return arr_;
240   
    }
240   
    }
241  
241  
242   
    /** Return a pointer to the buffer array.
242   
    /** Return a pointer to the buffer array.
243   
    */
243   
    */
244   
    mutable_buffer const*
244   
    mutable_buffer const*
245   
    data() const noexcept
245   
    data() const noexcept
246   
    {
246   
    {
247   
        return arr_;
247   
        return arr_;
248   
    }
248   
    }
249  
249  
250   
    /** Return the number of buffers.
250   
    /** Return the number of buffers.
251   
    */
251   
    */
252   
    std::size_t
252   
    std::size_t
253   
    size() const noexcept
253   
    size() const noexcept
254   
    {
254   
    {
255   
        return n_;
255   
        return n_;
256   
    }
256   
    }
257  
257  
258   
    /** Return an iterator to the beginning.
258   
    /** Return an iterator to the beginning.
259   
    */
259   
    */
260   
    mutable_buffer*
260   
    mutable_buffer*
261   
    begin() noexcept
261   
    begin() noexcept
262   
    {
262   
    {
263   
        return arr_;
263   
        return arr_;
264   
    }
264   
    }
265  
265  
266   
    /** Return an iterator to the beginning.
266   
    /** Return an iterator to the beginning.
267   
    */
267   
    */
268   
    mutable_buffer const*
268   
    mutable_buffer const*
269   
    begin() const noexcept
269   
    begin() const noexcept
270   
    {
270   
    {
271   
        return arr_;
271   
        return arr_;
272   
    }
272   
    }
273  
273  
274   
    /** Return an iterator to the end.
274   
    /** Return an iterator to the end.
275   
    */
275   
    */
276   
    mutable_buffer*
276   
    mutable_buffer*
277   
    end() noexcept
277   
    end() noexcept
278   
    {
278   
    {
279   
        return arr_ + n_;
279   
        return arr_ + n_;
280   
    }
280   
    }
281  
281  
282   
    /** Return an iterator to the end.
282   
    /** Return an iterator to the end.
283   
    */
283   
    */
284   
    mutable_buffer const*
284   
    mutable_buffer const*
285   
    end() const noexcept
285   
    end() const noexcept
286   
    {
286   
    {
287   
        return arr_ + n_;
287   
        return arr_ + n_;
288   
    }
288   
    }
289   
};
289   
};
290  
290  
291   
} // namespace capy
291   
} // namespace capy
292   
} // namespace boost
292   
} // namespace boost
293  
293  
294   
#endif
294   
#endif