Line data    Source code

       1             : //
       2             : // Copyright (c) 2021 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_RFC_LIST_RULE_HPP
      11             : #define BOOST_HTTP_PROTO_RFC_LIST_RULE_HPP
      12             : 
      13             : #include <boost/http_proto/detail/config.hpp>
      14             : #include <boost/http_proto/rfc/detail/rules.hpp>
      15             : #include <boost/url/grammar/range_rule.hpp>
      16             : #include <boost/core/empty_value.hpp>
      17             : 
      18             : namespace boost {
      19             : namespace http_proto {
      20             : 
      21             : /** Rule for a comma-delimited list of elements
      22             : 
      23             :     This rule defines a list containing
      24             :     at least n and at most m of Element,
      25             :     each separated by at least one comma
      26             :     and optional whitespace.
      27             : 
      28             :     @par BNF
      29             :     @code
      30             :     #element       => [ 1#element ]
      31             :     1#element      => element *( OWS "," OWS element )
      32             :     <n>#<m>element => element <n-1>*<m-1>( OWS "," OWS element )
      33             :     @endcode
      34             : 
      35             :     Senders must emit compliant values, but
      36             :     receivers should accept values generated
      37             :     with the legacy production rules:
      38             : 
      39             :     @par Legacy BNF
      40             :     @code
      41             :     #element    => [ ( "," / element ) *( OWS "," [ OWS element ] ) ]
      42             : 
      43             :     1#element   => *( "," OWS ) element *( OWS "," [ OWS element ] )
      44             :     @endcode
      45             : 
      46             :     @tparam R The rule to use for elements
      47             :     @tparam N The minimum number of elements, which may be zero
      48             :     @tparam M The maximum number of elements.
      49             : 
      50             :     @par Specification
      51             :     @li <a href="https://datatracker.ietf.org/doc/html/rfc7230#section-7"
      52             :         >5.6.1. Lists (#rule ABNF Extension) (rfc7230)</a>
      53             : */
      54             : #ifdef BOOST_HTTP_PROTO_DOCS
      55             : template<class Rule>
      56             : constexpr
      57             : __implementation_defined__
      58             : list_rule(
      59             :     Rule element,
      60             :     std::size_t N = 0,
      61             :     std::size_t M =
      62             :         std::size_t(-1)) noexcept;
      63             : #else
      64             : template<class Rule>
      65             : struct list_rule_t
      66             :     : private empty_value<Rule>
      67             : {
      68             :     using value_type = grammar::range<
      69             :         typename Rule::value_type>;
      70             : 
      71             :     constexpr
      72         152 :     list_rule_t(
      73             :         Rule const& r,
      74             :         std::size_t n,
      75             :         std::size_t m) noexcept
      76             :         : empty_value<Rule>(
      77             :             empty_init, r)
      78             :         , n_(n)
      79         152 :         , m_(m)
      80             :     {
      81         152 :     }
      82             : 
      83             :     auto
      84             :     parse(
      85             :         char const*& it,
      86             :         char const* end) const ->
      87             :             system::result<value_type>;
      88             : 
      89             : private:
      90             :     struct first_rule;
      91             :     struct next_rule;
      92             : 
      93             :     std::size_t n_;
      94             :     std::size_t m_;
      95             : };
      96             : 
      97             : template<class Rule>
      98             : constexpr
      99             : auto
     100         152 : list_rule(
     101             :     Rule const& r,
     102             :     std::size_t N = 0,
     103             :     std::size_t M =
     104             :         std::size_t(-1)) noexcept ->
     105             :     list_rule_t<Rule>
     106             : {
     107         152 :     return list_rule_t<Rule>(r, N, M);
     108             : }
     109             : #endif
     110             : 
     111             : } // http_proto
     112             : } // boost
     113             : 
     114             : #include <boost/http_proto/rfc/impl/list_rule.hpp>
     115             : 
     116             : #endif