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 #ifndef BOOST_SPIRIT_QI_DETAIL_PASS_CONTAINER_HPP
9 #define BOOST_SPIRIT_QI_DETAIL_PASS_CONTAINER_HPP
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 
pass_containerboost::spirit::qi::detail::pass_container270         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>
dispatch_containerboost::spirit::qi::detail::pass_container276         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>
dispatch_containerboost::spirit::qi::detail::pass_container298         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>
dispatch_attributeboost::spirit::qi::detail::pass_container307         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>
dispatch_attributeboost::spirit::qi::detail::pass_container314         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>
operator ()boost::spirit::qi::detail::pass_container337         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         // silence MSVC warning C4512: assignment operator could not be generated
358         BOOST_DELETED_FUNCTION(pass_container& operator= (pass_container const&))
359     };
360 
361     ///////////////////////////////////////////////////////////////////////////
362     // Utility function to make a pass_container for container components
363     // (kleene, list, plus, repeat)
364     template <typename F, typename Attr>
365     inline pass_container<F, Attr, mpl::false_>
make_pass_container(F const & f,Attr & attr)366     make_pass_container(F const& f, Attr& attr)
367     {
368         return pass_container<F, Attr, mpl::false_>(f, attr);
369     }
370 
371     // Utility function to make a pass_container for sequences
372     template <typename F, typename Attr>
373     inline pass_container<F, Attr, mpl::true_>
make_sequence_pass_container(F const & f,Attr & attr)374     make_sequence_pass_container(F const& f, Attr& attr)
375     {
376         return pass_container<F, Attr, mpl::true_>(f, attr);
377     }
378 }}}}
379 
380 #endif
381 
382