ceph/src/boost/boost/spirit/home/x3/directive/with.hpp

   1 /*=============================================================================
   2     Copyright (c) 2014 Joel de Guzman
   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 #ifndef BOOST_SPIRIT_X3_DIRECTIVE_WITH_HPP
   8 #define BOOST_SPIRIT_X3_DIRECTIVE_WITH_HPP
   9
  10 #include <boost/spirit/home/x3/support/unused.hpp>
  11 #include <boost/spirit/home/x3/core/parser.hpp>
  12
  13 namespace boost { namespace spirit { namespace x3
  14 {
  15     ///////////////////////////////////////////////////////////////////////////
  16     // with directive injects a value into the context prior to parsing.
  17     ///////////////////////////////////////////////////////////////////////////
  18     template <typename Subject, typename Derived, typename T>
  19     struct with_value_holder
  20       : unary_parser<Subject, Derived>
  21     {
  22         typedef unary_parser<Subject, Derived> base_type;
  23         mutable T val;
  24         constexpr with_value_holder(Subject const& subject, T&& val)
  25           : base_type(subject)
  26           , val(std::forward<T>(val)) {}
  27     };
  28
  29     template <typename Subject, typename Derived, typename T>
  30     struct with_value_holder<Subject, Derived, T&>
  31       : unary_parser<Subject, Derived>
  32     {
  33         typedef unary_parser<Subject, Derived> base_type;
  34         T& val;
  35         constexpr with_value_holder(Subject const& subject, T& val)
  36           : base_type(subject)
  37           , val(val) {}
  38     };
  39
  40     template <typename Subject, typename ID, typename T>
  41     struct with_directive
  42       : with_value_holder<Subject, with_directive<Subject, ID, T>, T>
  43     {
  44         typedef with_value_holder<Subject, with_directive<Subject, ID, T>, T> base_type;
  45         static bool const is_pass_through_unary = true;
  46         static bool const handles_container = Subject::handles_container;
  47
  48         typedef Subject subject_type;
  49
  50         constexpr with_directive(Subject const& subject, T&& val)
  51           : base_type(subject, std::forward<T>(val)) {}
  52
  53         template <typename Iterator, typename Context
  54           , typename RContext, typename Attribute>
  55         bool parse(Iterator& first, Iterator const& last
  56           , Context const& context, RContext& rcontext, Attribute& attr) const
  57         {
  58             return this->subject.parse(
  59                 first, last
  60               , make_context<ID>(this->val, context)
  61               , rcontext
  62               , attr);
  63         }
  64     };
  65
  66     template <typename ID, typename T>
  67     struct with_gen
  68     {
  69         T&& val;
  70
  71         template <typename Subject>
  72         constexpr with_directive<typename extension::as_parser<Subject>::value_type, ID, T>
  73         operator[](Subject const& subject) const
  74         {
  75             return { as_parser(subject), std::forward<T>(val) };
  76         }
  77     };
  78
  79     template <typename ID, typename T>
  80     constexpr with_gen<ID, T> with(T&& val)
  81     {
  82         return { std::forward<T>(val) };
  83     }
  84 }}}
  85
  86 #endif