ceph/src/boost/boost/spirit/home/qi/detail/alternative_function.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2011 Hartmut Kaiser
   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 #if !defined(SPIRIT_ALTERNATIVE_FUNCTION_APRIL_23_2007_1046AM)
   8 #define SPIRIT_ALTERNATIVE_FUNCTION_APRIL_23_2007_1046AM
   9
  10 #if defined(_MSC_VER)
  11 #pragma once
  12 #endif
  13
  14 #include <boost/spirit/home/qi/domain.hpp>
  15 #include <boost/spirit/home/qi/detail/assign_to.hpp>
  16 #include <boost/spirit/home/support/unused.hpp>
  17 #include <boost/spirit/home/qi/detail/attributes.hpp>
  18 #include <boost/variant.hpp>
  19 #include <boost/mpl/bool.hpp>
  20
  21 namespace boost { namespace spirit { namespace qi { namespace detail
  22 {
  23     template <typename Variant, typename Expected>
  24     struct find_substitute
  25     {
  26         // Get the type from the variant that can be a substitute for Expected.
  27         // If none is found, just return Expected
  28
  29         typedef Variant variant_type;
  30         typedef typename variant_type::types types;
  31         typedef typename mpl::end<types>::type end;
  32
  33         typedef typename
  34             mpl::find_if<types, is_same<mpl::_1, Expected> >::type
  35         iter_1;
  36
  37         typedef typename
  38             mpl::eval_if<
  39                 is_same<iter_1, end>,
  40                 mpl::find_if<types, traits::is_substitute<mpl::_1, Expected> >,
  41                 mpl::identity<iter_1>
  42             >::type
  43         iter;
  44
  45         typedef typename
  46             mpl::eval_if<
  47                 is_same<iter, end>,
  48                 mpl::identity<Expected>,
  49                 mpl::deref<iter>
  50             >::type
  51         type;
  52     };
  53
  54     template <typename Iterator, typename Context, typename Skipper,
  55         typename Attribute>
  56     struct alternative_function
  57     {
  58         alternative_function(
  59             Iterator& first_, Iterator const& last_, Context& context_,
  60             Skipper const& skipper_, Attribute& attr_)
  61           : first(first_), last(last_), context(context_), skipper(skipper_),
  62             attr(attr_)
  63         {
  64         }
  65
  66         template <typename Component>
  67         bool call(Component const& component, mpl::true_) const
  68         {
  69             // if Attribute is not a variant, then pass it as-is
  70             return component.parse(first, last, context, skipper, attr);
  71         }
  72
  73         template <typename Component>
  74         bool call_optional_or_variant(Component const& component, mpl::true_) const
  75         {
  76             // If Attribute is an optional, then create an attribute for the Component
  77             // with the type optional::value_type. If the expected attribute is unused type,
  78             // use it instead.
  79             typedef typename
  80                 traits::attribute_of<Component, Context, Iterator>::type
  81             expected_type;
  82
  83             typename mpl::if_<
  84                 is_same<expected_type, unused_type>,
  85                 unused_type,
  86                 typename Attribute::value_type>::type
  87             val;
  88
  89             if (component.parse(first, last, context, skipper, val))
  90             {
  91                 traits::assign_to(val, attr);
  92                 return true;
  93             }
  94             return false;
  95         }
  96
  97         template <typename Component>
  98         bool call_variant(Component const& component, mpl::false_) const
  99         {
 100             // If Attribute is a variant, then search the variant types for a
 101             // suitable substitute type.
 102
 103             typename
 104                 find_substitute<Attribute,
 105                     typename traits::attribute_of<Component, Context, Iterator>::type
 106                 >::type
 107             val;
 108
 109             if (component.parse(first, last, context, skipper, val))
 110             {
 111                 traits::assign_to(val, attr);
 112                 return true;
 113             }
 114             return false;
 115         }
 116
 117         template <typename Component>
 118         bool call_variant(Component const& component, mpl::true_) const
 119         {
 120             // If Attribute is a variant and the expected attribute is
 121             // the same type (pass the variant as-is).
 122
 123             return component.parse(first, last, context, skipper, attr);
 124         }
 125
 126         template <typename Component>
 127         bool call_optional_or_variant(Component const& component, mpl::false_) const
 128         {
 129             // Attribute is a variant...
 130
 131             typedef typename
 132                 traits::attribute_of<Component, Context, Iterator>::type
 133             expected;
 134             return call_variant(component,
 135                 is_same<Attribute, expected>());
 136         }
 137
 138         template <typename Component>
 139         bool call(Component const& component, mpl::false_) const
 140         {
 141             // fix for alternative.cpp test case, FHE 2016-07-28
 142             return call_optional_or_variant(
 143                 component, mpl::not_<spirit::traits::not_is_optional<Attribute, qi::domain> >());
 144         }
 145
 146         template <typename Component>
 147         bool call_unused(Component const& component, mpl::true_) const
 148         {
 149             // return true if the parser succeeds
 150             return call(component,
 151                 mpl::and_<
 152                     spirit::traits::not_is_variant<Attribute, qi::domain>,
 153                     spirit::traits::not_is_optional<Attribute, qi::domain>
 154                 >());
 155         }
 156
 157         template <typename Component>
 158         bool call_unused(Component const& component, mpl::false_) const
 159         {
 160             return component.parse(first, last, context, skipper, unused);
 161         }
 162
 163         template <typename Component>
 164         bool operator()(Component const& component) const
 165         {
 166             // return true if the parser succeeds
 167             typedef typename traits::not_is_unused<
 168                 typename traits::attribute_of<Component, Context, Iterator>::type
 169             >::type predicate;
 170
 171             return call_unused(component, predicate());
 172         }
 173
 174         Iterator& first;
 175         Iterator const& last;
 176         Context& context;
 177         Skipper const& skipper;
 178         Attribute& attr;
 179
 180     private:
 181         // silence MSVC warning C4512: assignment operator could not be generated
 182         alternative_function& operator= (alternative_function const&);
 183     };
 184
 185     template <typename Iterator, typename Context, typename Skipper>
 186     struct alternative_function<Iterator, Context, Skipper, unused_type const>
 187     {
 188         alternative_function(
 189             Iterator& first_, Iterator const& last_, Context& context_,
 190             Skipper const& skipper_, unused_type)
 191           : first(first_), last(last_), context(context_), skipper(skipper_)
 192         {
 193         }
 194
 195         template <typename Component>
 196         bool operator()(Component const& component) const
 197         {
 198             // return true if the parser succeeds
 199             return component.parse(first, last, context, skipper,
 200                 unused);
 201         }
 202
 203         Iterator& first;
 204         Iterator const& last;
 205         Context& context;
 206         Skipper const& skipper;
 207
 208     private:
 209         // silence MSVC warning C4512: assignment operator could not be generated
 210         alternative_function& operator= (alternative_function const&);
 211     };
 212
 213 }}}}
 214
 215 #endif