Line data    Source code

       1             : //
       2             : // Copyright (c) 2023 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_SINK_HPP
      11             : #define BOOST_HTTP_PROTO_SINK_HPP
      12             : 
      13             : #include <boost/http_proto/detail/config.hpp>
      14             : #include <boost/http_proto/buffered_base.hpp>
      15             : #include <boost/buffers/const_buffer_span.hpp>
      16             : #include <boost/buffers/type_traits.hpp>
      17             : #include <boost/system/error_code.hpp>
      18             : #include <cstddef>
      19             : #include <type_traits>
      20             : 
      21             : namespace boost {
      22             : namespace http_proto {
      23             : 
      24             : /** An algorithm for consuming buffers of data.
      25             : 
      26             :     This interface abstracts the consumption of
      27             :     a finite stream of data, passed by reading
      28             :     from caller-provided buffers until there
      29             :     is no more input data.
      30             : 
      31             :     @par Thread Safety
      32             :     Non-const member functions may not be
      33             :     called concurrently on the same instance.
      34             : */
      35             : struct BOOST_HTTP_PROTO_DECL
      36             :     sink
      37             :     : buffered_base
      38             : {
      39             :     /** The results of consuming data.
      40             :     */
      41             :     struct results
      42             :     {
      43             :         /** The error, if any occurred.
      44             :         */
      45             :         system::error_code ec;
      46             : 
      47             :         /** The number of bytes consumed in the input.
      48             :         */
      49             :         std::size_t bytes = 0;
      50             : 
      51             :         /** Accumulate results.
      52             :         */
      53             :         results&
      54             :         operator+=(
      55             :             results const& rv) noexcept;
      56             :     };
      57             : 
      58             :     /** Consume data.
      59             : 
      60             :         This function attempts to write to the
      61             :         sink, by transferring data from the given
      62             :         constant buffer sequence.
      63             :         The return value indicates the number of
      64             :         bytes consumed from the buffers and the
      65             :         error if any occurred.
      66             : 
      67             :         @par Preconditions
      68             :         @li @ref init was called, and
      69             :         @li This is the first call to @ref write,
      70             :             or the last value of `more` was `true`.
      71             : 
      72             :         @par Postconditions
      73             :         @code
      74             :         rv.ec.failed() == true || rv.bytes == buffer_size(bs)
      75             :         @endcode
      76             : 
      77             :         @return The result of the operation.
      78             : 
      79             :         @param bs The buffers to use.
      80             :             Each buffer in the sequence will be
      81             :             consumed completely before the next
      82             :             buffer is accessed.
      83             : 
      84             :         @param more `true` if there will be one
      85             :             or more subsequent calls to @ref write.
      86             :     */
      87             :     template<class ConstBufferSequence>
      88             :     results
      89           9 :     write(
      90             :         ConstBufferSequence const& bs,
      91             :         bool more)
      92             :     {
      93             :         static_assert(
      94             :             buffers::is_const_buffer_sequence<
      95             :                 ConstBufferSequence>::value,
      96             :             "Type requirements not met");
      97             : 
      98           9 :         return write_impl(bs, more);
      99             :     }
     100             : 
     101             : #ifdef BOOST_HTTP_PROTO_DOCS
     102             : protected:
     103             : #else
     104             : private:
     105             : #endif
     106             :     /** Derived class override.
     107             : 
     108             :         This pure virtual function is called by
     109             :         the implementation and must be overriden.
     110             :         The callee should attempt to consume data
     111             :         from the given constant buffer.
     112             :         The return value must be set to indicate
     113             :         the number of bytes consumed from the
     114             :         buffers, and the error if any occurred.
     115             : 
     116             :         @par Preconditions
     117             :         @li @ref init was called, and
     118             :         @li This is the first call to @ref on_write,
     119             :             or the last value of `more` was `true`.
     120             : 
     121             :         @return The result of the operation.
     122             : 
     123             :         @param b The buffer to use.
     124             :             If `more` is true then the results
     125             :             must indicate that the buffer was
     126             :             consumed completely, or that an error
     127             :             occurred.
     128             : 
     129             :         @param more `true` if there will be one
     130             :             or more subsequent calls to @ref write.
     131             :     */
     132             :     virtual
     133             :     results
     134             :     on_write(
     135             :         buffers::const_buffer b,
     136             :         bool more) = 0;
     137             : 
     138             :     /** Derived class override.
     139             : 
     140             :         This pure virtual function is called by
     141             :         the implementation and must be overriden.
     142             :         The callee should attempt to consume data
     143             :         from the given constant buffer sequence.
     144             :         The return value must be set to indicate
     145             :         the number of bytes consumed from the
     146             :         buffers, and the error if any occurred.
     147             : 
     148             :         @par Preconditions
     149             :         @li @ref init was called, and
     150             :         @li This is the first call to @ref on_write,
     151             :             or the last value of `more` was `true`.
     152             : 
     153             :         @return The result of the operation.
     154             : 
     155             :         @param bs The buffer sequence to use.
     156             :             Each buffer in the sequence must
     157             :             be completely consumed before data
     158             :             is consumed from the next buffer.
     159             :             If `more` is true then the results
     160             :             must indicate that the buffer was
     161             :             consumed completely, or that an error
     162             :             occurred.
     163             : 
     164             :         @param more `true` if there will be one
     165             :             or more subsequent calls to @ref write.
     166             :     */
     167             :     virtual
     168             :     results
     169             :     on_write(
     170             :         buffers::const_buffer_span bs,
     171             :         bool more);
     172             : 
     173             : private:
     174             :     results
     175           2 :     write_impl(
     176             :         buffers::const_buffer const& b,
     177             :         bool more)
     178             :     {
     179           2 :         return on_write(b, more);
     180             :     }
     181             : 
     182             :     results
     183           2 :     write_impl(
     184             :         buffers::mutable_buffer const& b,
     185             :         bool more)
     186             :     {
     187           2 :         return on_write(b, more);
     188             :     }
     189             : 
     190             :     results
     191           5 :     write_impl(
     192             :         buffers::const_buffer_span const& bs,
     193             :         bool more)
     194             :     {
     195           5 :         return on_write(bs, more);
     196             :     }
     197             : 
     198             :     template<class T>
     199             :     results
     200             :     write_impl(T const&, bool);
     201             : };
     202             : 
     203             : //------------------------------------------------
     204             : 
     205             : /** Metafunction which determines if T is a sink
     206             : 
     207             :     @see
     208             :         @ref sink.
     209             : */
     210             : #ifdef BOOST_HTTP_PROTO_DOCS
     211             : template<class T>
     212             : using is_sink = __see_below__;
     213             : #else
     214             : template<class T>
     215             : using is_sink =
     216             :     std::is_convertible<
     217             :         typename std::decay<T>::type*,
     218             :         sink*>;
     219             : #endif
     220             : 
     221             : } // http_proto
     222             : } // boost
     223             : 
     224             : #include <boost/http_proto/impl/sink.hpp>
     225             : 
     226             : #endif