ceph/src/boost/libs/spirit/include/boost/spirit/home/qi/detail/pass_container.hpp

   1 /*=============================================================================
   2     Copyright (c) 2001-2011 Joel de Guzman
   3     Copyright (c) 2001-2011 Hartmut Kaiser
   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 #if !defined(SPIRIT_PASS_CONTAINER_JANUARY_06_2009_0802PM)
   9 #define SPIRIT_PASS_CONTAINER_JANUARY_06_2009_0802PM
  10
  11 #if defined(_MSC_VER)
  12 #pragma once
  13 #endif
  14
  15 #include <boost/spirit/home/qi/detail/attributes.hpp>
  16 #include <boost/spirit/home/support/container.hpp>
  17 #include <boost/spirit/home/support/handles_container.hpp>
  18 #include <boost/type_traits/is_base_of.hpp>
  19 #include <boost/type_traits/is_convertible.hpp>
  20 #include <boost/mpl/bool.hpp>
  21 #include <boost/mpl/and.hpp>
  22 #include <boost/mpl/or.hpp>
  23 #include <boost/preprocessor/cat.hpp>
  24 #include <boost/preprocessor/repetition/repeat.hpp>
  25
  26 namespace boost { namespace spirit { namespace qi { namespace detail
  27 {
  28     // Helper meta-function allowing to evaluate weak substitutability and
  29     // negate the result if the predicate (Sequence) is not true
  30     template <typename Sequence, typename Attribute, typename ValueType>
  31     struct negate_weak_substitute_if_not
  32       : mpl::if_<
  33             Sequence
  34           , typename traits::is_weak_substitute<Attribute, ValueType>::type
  35           , typename mpl::not_<
  36                 traits::is_weak_substitute<Attribute, ValueType>
  37             >::type>
  38     {};
  39
  40     // pass_through_container: utility to check decide whether a provided
  41     // container attribute needs to be passed through to the current component
  42     // or of we need to split the container by passing along instances of its
  43     // value type
  44
  45     // if the expected attribute of the current component is neither a Fusion
  46     // sequence nor a container, we will pass through the provided container
  47     // only if its value type is not compatible with the component
  48     template <typename Container, typename ValueType, typename Attribute
  49       , typename Sequence, typename Enable = void>
  50     struct pass_through_container_base
  51       : negate_weak_substitute_if_not<Sequence, Attribute, ValueType>
  52     {};
  53
  54     // Specialization for fusion sequences, in this case we check whether all
  55     // the types in the sequence are convertible to the lhs attribute.
  56     //
  57     // We return false if the rhs attribute itself is a fusion sequence, which
  58     // is compatible with the LHS sequence (we want to pass through this
  59     // attribute without it being split apart).
  60     template <typename Container, typename ValueType, typename Attribute
  61       , typename Sequence = mpl::true_>
  62     struct not_compatible_element
  63       : mpl::and_<
  64             negate_weak_substitute_if_not<Sequence, Attribute, Container>
  65           , negate_weak_substitute_if_not<Sequence, Attribute, ValueType> >
  66     {};
  67
  68     // If the value type of the container is not a Fusion sequence, we pass
  69     // through the container if each of the elements of the Attribute
  70     // sequence is compatible with either the container or its value type.
  71     template <typename Container, typename ValueType, typename Attribute
  72       , typename Sequence
  73       , bool IsSequence = fusion::traits::is_sequence<ValueType>::value>
  74     struct pass_through_container_fusion_sequence
  75     {
  76         typedef typename mpl::find_if<
  77             Attribute, not_compatible_element<Container, ValueType, mpl::_1>
  78         >::type iter;
  79         typedef typename mpl::end<Attribute>::type end;
  80
  81         typedef typename is_same<iter, end>::type type;
  82     };
  83
  84     // If both, the Attribute and the value type of the provided container
  85     // are Fusion sequences, we pass the container only if the two
  86     // sequences are not compatible.
  87     template <typename Container, typename ValueType, typename Attribute
  88       , typename Sequence>
  89     struct pass_through_container_fusion_sequence<
  90             Container, ValueType, Attribute, Sequence, true>
  91     {
  92         typedef typename mpl::find_if<
  93             Attribute
  94           , not_compatible_element<Container, ValueType, mpl::_1, Sequence>
  95         >::type iter;
  96         typedef typename mpl::end<Attribute>::type end;
  97
  98         typedef typename is_same<iter, end>::type type;
  99     };
 100
 101     template <typename Container, typename ValueType, typename Attribute
 102       , typename Sequence>
 103     struct pass_through_container_base<Container, ValueType, Attribute
 104           , Sequence
 105           , typename enable_if<fusion::traits::is_sequence<Attribute> >::type>
 106       : pass_through_container_fusion_sequence<
 107             Container, ValueType, Attribute, Sequence>
 108     {};
 109
 110     // Specialization for containers
 111     //
 112     // If the value type of the attribute of the current component is not
 113     // a Fusion sequence, we have to pass through the provided container if
 114     // both are compatible.
 115     template <typename Container, typename ValueType, typename Attribute
 116       , typename Sequence, typename AttributeValueType
 117       , bool IsSequence = fusion::traits::is_sequence<AttributeValueType>::value>
 118     struct pass_through_container_container
 119       : mpl::or_<
 120             traits::is_weak_substitute<Attribute, Container>
 121           , traits::is_weak_substitute<AttributeValueType, Container> >
 122     {};
 123
 124     // If the value type of the exposed container attribute is a Fusion
 125     // sequence, we use the already existing logic for those.
 126     template <typename Container, typename ValueType, typename Attribute
 127       , typename Sequence, typename AttributeValueType>
 128     struct pass_through_container_container<
 129             Container, ValueType, Attribute, Sequence, AttributeValueType, true>
 130       : pass_through_container_fusion_sequence<
 131             Container, ValueType, AttributeValueType, Sequence>
 132     {};
 133
 134     template <typename Container, typename ValueType, typename Attribute
 135       , typename Sequence>
 136     struct pass_through_container_base<
 137             Container, ValueType, Attribute, Sequence
 138           , typename enable_if<traits::is_container<Attribute> >::type>
 139       : detail::pass_through_container_container<
 140             Container, ValueType, Attribute, Sequence
 141           , typename traits::container_value<Attribute>::type>
 142     {};
 143
 144     // Specialization for exposed optional attributes
 145     //
 146     // If the type embedded in the exposed optional is not a Fusion
 147     // sequence we pass through the container attribute if it is compatible
 148     // either to the optionals embedded type or to the containers value
 149     // type.
 150     template <typename Container, typename ValueType, typename Attribute
 151       , typename Sequence
 152       , bool IsSequence = fusion::traits::is_sequence<Attribute>::value>
 153     struct pass_through_container_optional
 154       : mpl::or_<
 155             traits::is_weak_substitute<Attribute, Container>
 156           , traits::is_weak_substitute<Attribute, ValueType> >
 157     {};
 158
 159     // If the embedded type of the exposed optional attribute is a Fusion
 160     // sequence, we use the already existing logic for those.
 161     template <typename Container, typename ValueType, typename Attribute
 162       , typename Sequence>
 163     struct pass_through_container_optional<
 164                 Container, ValueType, Attribute, Sequence, true>
 165       : pass_through_container_fusion_sequence<
 166             Container, ValueType, Attribute, Sequence>
 167     {};
 168
 169     ///////////////////////////////////////////////////////////////////////////
 170     template <typename Container, typename ValueType, typename Attribute
 171       , typename Sequence>
 172     struct pass_through_container
 173       : pass_through_container_base<Container, ValueType, Attribute, Sequence>
 174     {};
 175
 176     // Handle optional attributes
 177     template <typename Container, typename ValueType, typename Attribute
 178       , typename Sequence>
 179     struct pass_through_container<
 180                 Container, ValueType, boost::optional<Attribute>, Sequence>
 181       : pass_through_container_optional<
 182             Container, ValueType, Attribute, Sequence>
 183     {};
 184
 185     // If both, the containers value type and the exposed attribute type are
 186     // optionals we are allowed to pass through the container only if the
 187     // embedded types of those optionals are not compatible.
 188     template <typename Container, typename ValueType, typename Attribute
 189       , typename Sequence>
 190     struct pass_through_container<
 191             Container, boost::optional<ValueType>, boost::optional<Attribute>
 192           , Sequence>
 193       : mpl::not_<traits::is_weak_substitute<Attribute, ValueType> >
 194     {};
 195
 196     // Specialization for exposed variant attributes
 197     //
 198     // We pass through the container attribute if at least one of the embedded
 199     // types in the variant requires to pass through the attribute
 200
 201 #if !defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES)
 202     template <typename Container, typename ValueType, typename Sequence
 203       , typename T>
 204     struct pass_through_container<Container, ValueType, boost::variant<T>
 205           , Sequence>
 206       : pass_through_container<Container, ValueType, T, Sequence>
 207     {};
 208
 209     template <typename Container, typename ValueType, typename Sequence
 210       , typename T0, typename ...TN>
 211     struct pass_through_container<Container, ValueType
 212           , boost::variant<T0, TN...>, Sequence>
 213       : mpl::bool_<pass_through_container<
 214             Container, ValueType, T0, Sequence
 215             >::type::value || pass_through_container<
 216                 Container, ValueType, boost::variant<TN...>, Sequence
 217             >::type::value>
 218     {};
 219 #else
 220 #define BOOST_SPIRIT_PASS_THROUGH_CONTAINER(z, N, _)                          \
 221     pass_through_container<Container, ValueType,                              \
 222         BOOST_PP_CAT(T, N), Sequence>::type::value ||                         \
 223     /***/
 224
 225     // make sure unused variant parameters do not affect the outcome
 226     template <typename Container, typename ValueType, typename Sequence>
 227     struct pass_through_container<Container, ValueType
 228           , boost::detail::variant::void_, Sequence>
 229       : mpl::false_
 230     {};
 231
 232     template <typename Container, typename ValueType, typename Sequence
 233       , BOOST_VARIANT_ENUM_PARAMS(typename T)>
 234     struct pass_through_container<Container, ValueType
 235           , boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Sequence>
 236       : mpl::bool_<BOOST_PP_REPEAT(BOOST_VARIANT_LIMIT_TYPES
 237           , BOOST_SPIRIT_PASS_THROUGH_CONTAINER, _) false>
 238     {};
 239
 240 #undef BOOST_SPIRIT_PASS_THROUGH_CONTAINER
 241 #endif
 242 }}}}
 243
 244 ///////////////////////////////////////////////////////////////////////////////
 245 namespace boost { namespace spirit { namespace traits
 246 {
 247     ///////////////////////////////////////////////////////////////////////////
 248     // forwarding customization point for domain qi::domain
 249     template <typename Container, typename ValueType, typename Attribute
 250       , typename Sequence>
 251     struct pass_through_container<
 252             Container, ValueType, Attribute, Sequence, qi::domain>
 253       : qi::detail::pass_through_container<
 254             Container, ValueType, Attribute, Sequence>
 255     {};
 256 }}}
 257
 258 namespace boost { namespace spirit { namespace qi { namespace detail
 259 {
 260     ///////////////////////////////////////////////////////////////////////////
 261     // This function handles the case where the attribute (Attr) given
 262     // the sequence is an STL container. This is a wrapper around F.
 263     // The function F does the actual parsing.
 264     template <typename F, typename Attr, typename Sequence>
 265     struct pass_container
 266     {
 267         typedef typename F::context_type context_type;
 268         typedef typename F::iterator_type iterator_type;
 269
 270         pass_container(F const& f_, Attr& attr_)
 271           : f(f_), attr(attr_) {}
 272
 273         // this is for the case when the current element exposes an attribute
 274         // which is pushed back onto the container
 275         template <typename Component>
 276         bool dispatch_container(Component const& component, mpl::false_) const
 277         {
 278             // synthesized attribute needs to be default constructed
 279             typename traits::container_value<Attr>::type val =
 280                 typename traits::container_value<Attr>::type();
 281
 282             iterator_type save = f.first;
 283             bool r = f(component, val);
 284             if (!r)
 285             {
 286                 // push the parsed value into our attribute
 287                 r = !traits::push_back(attr, val);
 288                 if (r)
 289                     f.first = save;
 290             }
 291             return r;
 292         }
 293
 294         // this is for the case when the current element is able to handle an
 295         // attribute which is a container itself, this element will push its
 296         // data directly into the attribute container
 297         template <typename Component>
 298         bool dispatch_container(Component const& component, mpl::true_) const
 299         {
 300             return f(component, attr);
 301         }
 302
 303         ///////////////////////////////////////////////////////////////////////
 304         // this is for the case when the current element doesn't expect an
 305         // attribute
 306         template <typename Component>
 307         bool dispatch_attribute(Component const& component, mpl::false_) const
 308         {
 309             return f(component, unused);
 310         }
 311
 312         // the current element expects an attribute
 313         template <typename Component>
 314         bool dispatch_attribute(Component const& component, mpl::true_) const
 315         {
 316             typedef typename traits::container_value<Attr>::type value_type;
 317             typedef typename traits::attribute_of<
 318                 Component, context_type, iterator_type>::type
 319             rhs_attribute;
 320
 321             // this predicate detects, whether the attribute of the current
 322             // element is a substitute for the value type of the container
 323             // attribute
 324             typedef mpl::and_<
 325                 traits::handles_container<
 326                     Component, Attr, context_type, iterator_type>
 327               , traits::pass_through_container<
 328                     Attr, value_type, rhs_attribute, Sequence, qi::domain>
 329             > predicate;
 330
 331             return dispatch_container(component, predicate());
 332         }
 333
 334         // Dispatches to dispatch_main depending on the attribute type
 335         // of the Component
 336         template <typename Component>
 337         bool operator()(Component const& component) const
 338         {
 339             // we need to dispatch depending on the type of the attribute
 340             // of the current element (component). If this is has no attribute
 341             // we shouldn't pass an attribute at all.
 342             typedef typename traits::not_is_unused<
 343                 typename traits::attribute_of<
 344                     Component, context_type, iterator_type
 345                 >::type
 346             >::type predicate;
 347
 348             // ensure the attribute is actually a container type
 349             traits::make_container(attr);
 350
 351             return dispatch_attribute(component, predicate());
 352         }
 353
 354         F f;
 355         Attr& attr;
 356
 357     private:
 358         // silence MSVC warning C4512: assignment operator could not be generated
 359         pass_container& operator= (pass_container const&);
 360     };
 361
 362     ///////////////////////////////////////////////////////////////////////////
 363     // Utility function to make a pass_container for container components
 364     // (kleene, list, plus, repeat)
 365     template <typename F, typename Attr>
 366     inline pass_container<F, Attr, mpl::false_>
 367     make_pass_container(F const& f, Attr& attr)
 368     {
 369         return pass_container<F, Attr, mpl::false_>(f, attr);
 370     }
 371
 372     // Utility function to make a pass_container for sequences
 373     template <typename F, typename Attr>
 374     inline pass_container<F, Attr, mpl::true_>
 375     make_sequence_pass_container(F const& f, Attr& attr)
 376     {
 377         return pass_container<F, Attr, mpl::true_>(f, attr);
 378     }
 379 }}}}
 380
 381 #endif
 382