Line data    Source code

       1             : //
       2             : // Copyright (c) 2019 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_SOURCE_HPP
      11             : #define BOOST_HTTP_PROTO_SOURCE_HPP
      12             : 
      13             : #include <boost/http_proto/detail/config.hpp>
      14             : #include <boost/http_proto/buffered_base.hpp>
      15             : #include <boost/buffers/mutable_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 producing buffers of data.
      25             : 
      26             :     This interface abstracts the production of
      27             :     a finite stream of data, returned by writing
      28             :     into caller-provided buffers until there
      29             :     is no more output 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             :     source
      37             : {
      38             :     /** The results of producing data.
      39             :     */
      40             :     struct results
      41             :     {
      42             :         /** The error, if any occurred.
      43             :         */
      44             :         system::error_code ec;
      45             : 
      46             :         /** The number of bytes produced in the output.
      47             :         */
      48             :         std::size_t bytes = 0;
      49             : 
      50             :         /** True if there will be no more output.
      51             :         */
      52             :         bool finished = false;
      53             : 
      54             :         /** Accumulate results.
      55             :         */
      56             :         results&
      57             :         operator+=(
      58             :             results const& rv) noexcept;
      59             :     };
      60             : 
      61             :     /** Produce data.
      62             : 
      63             :         This function attempts to read from the
      64             :         source, placing the data into the given
      65             :         mutable buffer sequence.
      66             :         The return value indicates the number of
      67             :         bytes placed into the buffers, the error
      68             :         if any occurred, and a `bool` indicating
      69             :         whether or not there is more data
      70             :         remaining in the source.
      71             : 
      72             :         @par Preconditions
      73             :         @li @ref init was called, and
      74             :         @li There is more data remaining.
      75             : 
      76             :         @return The result of the operation.
      77             : 
      78             :         @param bs The buffers to use.
      79             :             Each buffer in the sequence will
      80             :             be filled completely before data
      81             :             is placed in the next buffer.
      82             :     */
      83             :     template<class MutableBufferSequence>
      84             :     results
      85          24 :     read(MutableBufferSequence const& bs)
      86             :     {
      87             :         static_assert(
      88             :             buffers::is_mutable_buffer_sequence<
      89             :                 MutableBufferSequence>::value,
      90             :             "Type requirements not met");
      91             : 
      92          24 :         return read_impl(bs);
      93             :     }
      94             : 
      95             : #ifdef BOOST_HTTP_PROTO_DOCS
      96             : protected:
      97             : #else
      98             : private:
      99             : #endif
     100             :     /** Derived class override.
     101             : 
     102             :         This pure virtual function is called by
     103             :         the implementation and must be overriden.
     104             :         The callee should attempt to place data
     105             :         into the given mutable buffer.
     106             :         The return value must be set to indicate
     107             :         the number of bytes placed into the
     108             :         buffers, the error if any occurred,
     109             :         and a `bool` indicating whether or
     110             :         not there is more data remaining
     111             :         in the source.
     112             : 
     113             :         @par Preconditions
     114             :         @li @ref init was called, and
     115             :         @li There is more data remaining.
     116             : 
     117             :         @return The result of the operation.
     118             : 
     119             :         @param b The buffer to use.
     120             :             If this is not filled completely,
     121             :             then the result must indicate failure
     122             :             or that no more data remains (or both).
     123             :     */
     124             :     virtual
     125             :     results
     126             :     on_read(
     127             :         buffers::mutable_buffer b) = 0;
     128             : 
     129             :     /** Derived class override.
     130             : 
     131             :         This pure virtual function is called by
     132             :         the implementation and must be overriden.
     133             :         The callee should attempt to place data
     134             :         into the given mutable buffer sequence.
     135             :         The return value must be set to indicate
     136             :         the number of bytes placed into the
     137             :         buffers, the error if any occurred,
     138             :         and a `bool` indicating whether or
     139             :         not there is more data remaining
     140             :         in the source.
     141             : 
     142             :         @par Preconditions
     143             :         @li @ref init was called, and
     144             :         @li There is more data remaining.
     145             : 
     146             :         @return The result of the operation.
     147             : 
     148             :         @param bs The buffer sequence to use.
     149             :             Each buffer in the sequence must
     150             :             be filled completely before data
     151             :             is placed in the next buffer.
     152             :             If the buffers are not filled
     153             :             completely, then the result must
     154             :             indicate failure or that no more
     155             :             data remains (or both).
     156             :     */
     157             :     virtual
     158             :     results
     159             :     on_read(
     160             :         buffers::mutable_buffer_span bs);
     161             : 
     162             : private:
     163             :     results
     164           2 :     read_impl(
     165             :         buffers::mutable_buffer const& b)
     166             :     {
     167           2 :         return on_read(b);
     168             :     }
     169             : 
     170             :     results
     171           5 :     read_impl(
     172             :         buffers::mutable_buffer_span const& bs)
     173             :     {
     174           5 :         return on_read(bs);
     175             :     }
     176             : 
     177             :     template<class T>
     178             :     results
     179             :     read_impl(T const&);
     180             : };
     181             : 
     182             : //------------------------------------------------
     183             : 
     184             : /** Metafunction which determines if T is a source
     185             : 
     186             :     @see
     187             :         @ref source.
     188             : */
     189             : #ifdef BOOST_HTTP_PROTO_DOCS
     190             : template<class T>
     191             : using is_source = __see_below__;
     192             : #else
     193             : template<class T>
     194             : using is_source =
     195             :     std::is_convertible<
     196             :         typename std::decay<T>::type*,
     197             :         source*>;
     198             : #endif
     199             : 
     200             : } // http_proto
     201             : } // boost
     202             : 
     203             : #include <boost/http_proto/impl/source.hpp>
     204             : 
     205             : #endif