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_SYMBOL_VISIBLE
      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             :         @return The result of the operation.
      73             : 
      74             :         @param bs The buffers to use.
      75             :             Each buffer in the sequence will be
      76             :             consumed completely before the next
      77             :             buffer is accessed.
      78             : 
      79             :         @param more `true` if there will be one
      80             :             or more subsequent calls to @ref write.
      81             :     */
      82             :     template<class ConstBufferSequence>
      83             :     results
      84           9 :     write(
      85             :         ConstBufferSequence const& bs,
      86             :         bool more)
      87             :     {
      88             :         static_assert(
      89             :             buffers::is_const_buffer_sequence<
      90             :                 ConstBufferSequence>::value,
      91             :             "Type requirements not met");
      92             : 
      93           9 :         return write_impl(bs, more);
      94             :     }
      95             : 
      96             : #ifdef BOOST_HTTP_PROTO_DOCS
      97             : protected:
      98             : #else
      99             : private:
     100             : #endif
     101             :     /** Derived class override.
     102             : 
     103             :         This pure virtual function is called by
     104             :         the implementation and must be overriden.
     105             :         The callee should attempt to consume data
     106             :         from the given constant buffer.
     107             :         The return value must be set to indicate
     108             :         the number of bytes consumed from the
     109             :         buffers, and the error if any occurred.
     110             : 
     111             :         @par Preconditions
     112             :         @li @ref init was called, and
     113             :         @li This is the first call to @ref on_write,
     114             :             or the last value of `more` was `true`.
     115             : 
     116             :         @return The result of the operation.
     117             : 
     118             :         @param b The buffer to use.
     119             :             If `more` is true then the results
     120             :             must indicate that the buffer was
     121             :             consumed completely, or that an error
     122             :             occurred.
     123             : 
     124             :         @param more `true` if there will be one
     125             :             or more subsequent calls to @ref write.
     126             :     */
     127             :     BOOST_HTTP_PROTO_DECL
     128             :     virtual
     129             :     results
     130             :     on_write(
     131             :         buffers::const_buffer b,
     132             :         bool more) = 0;
     133             : 
     134             :     /** Derived class override.
     135             : 
     136             :         This pure virtual function is called by
     137             :         the implementation and must be overriden.
     138             :         The callee should attempt to consume data
     139             :         from the given constant buffer sequence.
     140             :         The return value must be set to indicate
     141             :         the number of bytes consumed from the
     142             :         buffers, and the error if any occurred.
     143             : 
     144             :         @par Preconditions
     145             :         @li @ref init was called, and
     146             :         @li This is the first call to @ref on_write,
     147             :             or the last value of `more` was `true`.
     148             : 
     149             :         @return The result of the operation.
     150             : 
     151             :         @param bs The buffer sequence to use.
     152             :             Each buffer in the sequence must
     153             :             be completely consumed before data
     154             :             is consumed from the next buffer.
     155             :             If `more` is true then the results
     156             :             must indicate that the buffer was
     157             :             consumed completely, or that an error
     158             :             occurred.
     159             : 
     160             :         @param more `true` if there will be one
     161             :             or more subsequent calls to @ref write.
     162             :     */
     163             :     BOOST_HTTP_PROTO_DECL
     164             :     virtual
     165             :     results
     166             :     on_write(
     167             :         buffers::const_buffer_span bs,
     168             :         bool more);
     169             : 
     170             : private:
     171             :     results
     172           2 :     write_impl(
     173             :         buffers::const_buffer const& b,
     174             :         bool more)
     175             :     {
     176           2 :         return on_write(b, more);
     177             :     }
     178             : 
     179             :     results
     180           2 :     write_impl(
     181             :         buffers::mutable_buffer const& b,
     182             :         bool more)
     183             :     {
     184           2 :         return on_write(b, more);
     185             :     }
     186             : 
     187             :     results
     188           5 :     write_impl(
     189             :         buffers::const_buffer_span const& bs,
     190             :         bool more)
     191             :     {
     192           5 :         return on_write(bs, more);
     193             :     }
     194             : 
     195             :     template<class T>
     196             :     results
     197             :     write_impl(T const&, bool);
     198             : };
     199             : 
     200             : //------------------------------------------------
     201             : 
     202             : /** Metafunction which determines if T is a sink
     203             : 
     204             :     @see
     205             :         @ref sink.
     206             : */
     207             : #ifdef BOOST_HTTP_PROTO_DOCS
     208             : template<class T>
     209             : using is_sink = __see_below__;
     210             : #else
     211             : template<class T>
     212             : using is_sink =
     213             :     std::is_convertible<
     214             :         typename std::decay<T>::type*,
     215             :         sink*>;
     216             : #endif
     217             : 
     218             : } // http_proto
     219             : } // boost
     220             : 
     221             : #include <boost/http_proto/impl/sink.hpp>
     222             : 
     223             : #endif