Line data    Source code

       1              : //
       2              : // Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
       3              : // Copyright (c) 2022 Alan de Freitas (alandefreitas@gmail.com)
       4              : //
       5              : // Distributed under the Boost Software License, Version 1.0. (See accompanying
       6              : // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       7              : //
       8              : // Official repository: https://github.com/boostorg/url
       9              : //
      10              : 
      11              : #ifndef BOOST_URL_GRAMMAR_VARIANT_RULE_HPP
      12              : #define BOOST_URL_GRAMMAR_VARIANT_RULE_HPP
      13              : 
      14              : #include <boost/url/detail/config.hpp>
      15              : #include <boost/url/error_types.hpp>
      16              : #include <boost/url/variant.hpp>
      17              : #include <boost/url/grammar/detail/tuple.hpp>
      18              : #include <boost/url/grammar/type_traits.hpp>
      19              : 
      20              : namespace boost {
      21              : namespace urls {
      22              : namespace grammar {
      23              : 
      24              : namespace implementation_defined {
      25              : template<
      26              :     class R0, class... Rn>
      27              : class variant_rule_t
      28              : {
      29              : public:
      30              :     using value_type = variant2::variant<
      31              :         typename R0::value_type,
      32              :         typename Rn::value_type...>;
      33              : 
      34              :     BOOST_URL_CXX14_CONSTEXPR
      35              :     auto
      36              :     parse(
      37              :         char const*& it,
      38              :         char const* end) const ->
      39              :             system::result<value_type>;
      40              : 
      41              :     constexpr
      42            1 :     variant_rule_t(
      43              :         R0 const& r0,
      44              :         Rn const&... rn) noexcept
      45            1 :         : rn_(r0, rn...)
      46              :     {
      47            1 :     }
      48              : 
      49              : private:
      50              : 
      51              :     detail::tuple<R0, Rn...> rn_;
      52              : };
      53              : } // implementation_defined
      54              : 
      55              : /** Match one of a set of rules
      56              : 
      57              :     Each specified rule is tried in sequence.
      58              :     When the first match occurs, the result
      59              :     is stored and returned in the variant. If
      60              :     no match occurs, an error is returned.
      61              : 
      62              :     @param r0 The first rule to match
      63              :     @param rn A list of one or more rules to match
      64              :     @return The variant rule
      65              : 
      66              :     @par Value Type
      67              :     @code
      68              :     using value_type = variant< typename Rules::value_type... >;
      69              :     @endcode
      70              : 
      71              :     @par Example
      72              :     Rules are used with the function @ref parse.
      73              :     @code
      74              :     // request-target = origin-form
      75              :     //                / absolute-form
      76              :     //                / authority-form
      77              :     //                / asterisk-form
      78              : 
      79              :     system::result< variant< url_view, url_view, authority_view, core::string_view > > rv = grammar::parse(
      80              :         "/index.html?width=full",
      81              :         variant_rule(
      82              :             origin_form_rule,
      83              :             absolute_uri_rule,
      84              :             authority_rule,
      85              :             delim_rule('*') ) );
      86              :     @endcode
      87              : 
      88              :     @par BNF
      89              :     @code
      90              :     variant     = rule1 / rule2 / rule3...
      91              :     @endcode
      92              : 
      93              :     @par Specification
      94              :     @li <a href="https://datatracker.ietf.org/doc/html/rfc5234#section-3.2"
      95              :         >3.2.  Alternatives (rfc5234)</a>
      96              :     @li <a href="https://datatracker.ietf.org/doc/html/rfc7230#section-5.3"
      97              :         >5.3.  Request Target (rfc7230)</a>
      98              : 
      99              :     @see
     100              :         @ref absolute_uri_rule,
     101              :         @ref authority_rule,
     102              :         @ref delim_rule,
     103              :         @ref parse,
     104              :         @ref origin_form_rule,
     105              :         @ref url_view.
     106              : */
     107              : template<
     108              :     BOOST_URL_CONSTRAINT(Rule) R0,
     109              :     BOOST_URL_CONSTRAINT(Rule)... Rn>
     110              : constexpr
     111              : auto
     112              : variant_rule(
     113              :     R0 const& r0,
     114              :     Rn const&... rn) noexcept ->
     115              :         implementation_defined::variant_rule_t<R0, Rn...>;
     116              : 
     117              : } // grammar
     118              : } // urls
     119              : } // boost
     120              : 
     121              : #include <boost/url/grammar/impl/variant_rule.hpp>
     122              : 
     123              : #endif