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