1 /*=============================================================================
2     Copyright (c) 2001-2011 Hartmut Kaiser
3     Copyright (c) 2001-2011 Joel de Guzman
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_KARMA_DETAIL_PASS_CONTAINER_HPP
9 #define BOOST_SPIRIT_KARMA_DETAIL_PASS_CONTAINER_HPP
10 
11 #if defined(_MSC_VER)
12 #pragma once
13 #endif
14 
15 #include <boost/spirit/home/karma/detail/attributes.hpp>
16 #include <boost/spirit/home/support/container.hpp>
17 #include <boost/spirit/home/support/handles_container.hpp>
18 #include <boost/spirit/home/support/detail/hold_any.hpp>
19 #include <boost/type_traits/is_base_of.hpp>
20 #include <boost/type_traits/is_convertible.hpp>
21 #include <boost/mpl/bool.hpp>
22 #include <boost/mpl/and.hpp>
23 #include <boost/mpl/or.hpp>
24 #include <boost/preprocessor/cat.hpp>
25 #include <boost/preprocessor/repetition/repeat.hpp>
26 #include <boost/range/iterator_range_core.hpp>
27 #include <boost/fusion/include/deduce_sequence.hpp>
28 
29 #include <boost/mpl/print.hpp>
30 
31 namespace boost { namespace spirit { namespace karma { namespace detail
32 {
33     // Helper meta-function allowing to evaluate weak substitutability and
34     // negate the result if the predicate (Sequence) is not true
35     template <typename Sequence, typename Attribute, typename ValueType>
36     struct negate_weak_substitute_if_not
37       : mpl::if_<
38             Sequence
39           , typename traits::is_weak_substitute<Attribute, ValueType>::type
40           , typename mpl::not_<
41                 traits::is_weak_substitute<Attribute, ValueType>
42             >::type>
43     {};
44 
45     // pass_through_container: utility to check decide whether a provided
46     // container attribute needs to be passed through to the current component
47     // or of we need to split the container by passing along instances of its
48     // value type
49 
50     // if the expected attribute of the current component is neither a Fusion
51     // sequence nor a container, we will pass through the provided container
52     // only if its value type is not compatible with the component
53     template <typename Container, typename ValueType, typename Attribute
54       , typename Sequence, typename Enable = void>
55     struct pass_through_container_base
56       : negate_weak_substitute_if_not<Sequence, ValueType, Attribute>
57     {};
58 
59     // Specialization for fusion sequences, in this case we check whether all
60     // the types in the sequence are convertible to the lhs attribute.
61     //
62     // We return false if the rhs attribute itself is a fusion sequence, which
63     // is compatible with the LHS sequence (we want to pass through this
64     // attribute without it being split apart).
65     template <typename Container, typename ValueType, typename Attribute
66       , typename Sequence = mpl::true_>
67     struct not_compatible_element
68       : mpl::and_<
69             negate_weak_substitute_if_not<Sequence, Container, Attribute>
70           , negate_weak_substitute_if_not<Sequence, ValueType, Attribute> >
71     {};
72 
73     // If the value type of the container is not a Fusion sequence, we pass
74     // through the container if each of the elements of the Attribute
75     // sequence is compatible with either the container or its value type.
76     template <typename Container, typename ValueType, typename Attribute
77       , typename Sequence
78       , bool IsSequence = fusion::traits::is_sequence<ValueType>::value>
79     struct pass_through_container_fusion_sequence
80     {
81         typedef typename mpl::find_if<
82             Attribute, not_compatible_element<Container, ValueType, mpl::_1>
83         >::type iter;
84         typedef typename mpl::end<Attribute>::type end;
85 
86         typedef typename is_same<iter, end>::type type;
87     };
88 
89     // If both, the Attribute and the value type of the provided container
90     // are Fusion sequences, we pass the container only if the two
91     // sequences are not compatible.
92     template <typename Container, typename ValueType, typename Attribute
93       , typename Sequence>
94     struct pass_through_container_fusion_sequence<
95             Container, ValueType, Attribute, Sequence, true>
96     {
97         typedef typename mpl::find_if<
98             Attribute
99           , not_compatible_element<Container, ValueType, mpl::_1, Sequence>
100         >::type iter;
101         typedef typename mpl::end<Attribute>::type end;
102 
103         typedef typename is_same<iter, end>::type type;
104     };
105 
106     template <typename Container, typename ValueType, typename Attribute
107       , typename Sequence>
108     struct pass_through_container_base<Container, ValueType, Attribute
109           , Sequence
110           , typename enable_if<fusion::traits::is_sequence<Attribute> >::type>
111       : pass_through_container_fusion_sequence<
112             Container, ValueType, Attribute, Sequence>
113     {};
114 
115     // Specialization for containers
116     //
117     // If the value type of the attribute of the current component is not
118     // a Fusion sequence, we have to pass through the provided container if
119     // both are compatible.
120     template <typename Container, typename ValueType, typename Attribute
121       , typename Sequence, typename AttributeValueType
122       , bool IsSequence = fusion::traits::is_sequence<AttributeValueType>::value>
123     struct pass_through_container_container
124       : mpl::or_<
125             traits::is_weak_substitute<Container, Attribute>
126           , traits::is_weak_substitute<Container, AttributeValueType> >
127     {};
128 
129     // If the value type of the exposed container attribute is a Fusion
130     // sequence, we use the already existing logic for those.
131     template <typename Container, typename ValueType, typename Attribute
132       , typename Sequence, typename AttributeValueType>
133     struct pass_through_container_container<
134             Container, ValueType, Attribute, Sequence, AttributeValueType, true>
135       : pass_through_container_fusion_sequence<
136             Container, ValueType, AttributeValueType, Sequence>
137     {};
138 
139     template <typename Container, typename ValueType, typename Attribute
140       , typename Sequence>
141     struct pass_through_container_base<Container, ValueType, Attribute
142           , Sequence
143           , typename enable_if<traits::is_container<Attribute> >::type>
144       : detail::pass_through_container_container<
145           Container, ValueType, Attribute, Sequence
146         , typename traits::container_value<Attribute>::type>
147     {};
148 
149     // Specialization for exposed optional attributes
150     //
151     // If the type embedded in the exposed optional is not a Fusion
152     // sequence we pass through the container attribute if it is compatible
153     // either to the optionals embedded type or to the containers value
154     // type.
155     template <typename Container, typename ValueType, typename Attribute
156       , typename Sequence
157       , bool IsSequence = fusion::traits::is_sequence<Attribute>::value>
158     struct pass_through_container_optional
159       : mpl::or_<
160             traits::is_weak_substitute<Container, Attribute>
161           , traits::is_weak_substitute<ValueType, Attribute> >
162     {};
163 
164     // If the embedded type of the exposed optional attribute is a Fusion
165     // sequence, we use the already existing logic for those.
166     template <typename Container, typename ValueType, typename Attribute
167       , typename Sequence>
168     struct pass_through_container_optional<
169             Container, ValueType, Attribute, Sequence, true>
170       : pass_through_container_fusion_sequence<
171             Container, ValueType, Attribute, Sequence>
172     {};
173 
174     ///////////////////////////////////////////////////////////////////////////
175     template <typename Container, typename ValueType, typename Attribute
176       , typename Sequence>
177     struct pass_through_container
178       : pass_through_container_base<Container, ValueType, Attribute, Sequence>
179     {};
180 
181     // Handle optional attributes
182     template <typename Container, typename ValueType, typename Attribute
183       , typename Sequence>
184     struct pass_through_container<
185             Container, ValueType, boost::optional<Attribute>, Sequence>
186       : pass_through_container_optional<
187             Container, ValueType, Attribute, Sequence>
188     {};
189 
190     // If both, the containers value type and the exposed attribute type are
191     // optionals we are allowed to pass through the container only if the
192     // embedded types of those optionals are not compatible.
193     template <typename Container, typename ValueType, typename Attribute
194       , typename Sequence>
195     struct pass_through_container<
196             Container, boost::optional<ValueType>, boost::optional<Attribute>
197           , Sequence>
198       : mpl::not_<traits::is_weak_substitute<ValueType, Attribute> >
199     {};
200 
201     // Specialization for exposed variant attributes
202     //
203     // We pass through the container attribute if at least one of the embedded
204     // types in the variant requires to pass through the attribute
205 
206 #if !defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES)
207     template <typename Container, typename ValueType, typename Sequence
208       , typename T>
209     struct pass_through_container<Container, ValueType, boost::variant<T>
210           , Sequence>
211       : pass_through_container<Container, ValueType, T, Sequence>
212     {};
213 
214     template <typename Container, typename ValueType, typename Sequence
215       , typename T0, typename ...TN>
216     struct pass_through_container<Container, ValueType
217           , boost::variant<T0, TN...>, Sequence>
218       : mpl::bool_<pass_through_container<
219             Container, ValueType, T0, Sequence
220             >::type::value || pass_through_container<
221                 Container, ValueType, boost::variant<TN...>, Sequence
222             >::type::value>
223     {};
224 #else
225 #define BOOST_SPIRIT_PASS_THROUGH_CONTAINER(z, N, _)                          \
226     pass_through_container<Container, ValueType,                              \
227         BOOST_PP_CAT(T, N), Sequence>::type::value ||                         \
228     /***/
229 
230     // make sure unused variant parameters do not affect the outcome
231     template <typename Container, typename ValueType, typename Sequence>
232     struct pass_through_container<Container, ValueType
233           , boost::detail::variant::void_, Sequence>
234       : mpl::false_
235     {};
236 
237     template <typename Container, typename ValueType, typename Sequence
238       , BOOST_VARIANT_ENUM_PARAMS(typename T)>
239     struct pass_through_container<Container, ValueType
240           , boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Sequence>
241       : mpl::bool_<BOOST_PP_REPEAT(BOOST_VARIANT_LIMIT_TYPES
242           , BOOST_SPIRIT_PASS_THROUGH_CONTAINER, _) false>
243     {};
244 
245 #undef BOOST_SPIRIT_PASS_THROUGH_CONTAINER
246 #endif
247 }}}}
248 
249 ///////////////////////////////////////////////////////////////////////////////
250 namespace boost { namespace spirit { namespace traits
251 {
252     ///////////////////////////////////////////////////////////////////////////
253     // forwarding customization point for domain karma::domain
254     template <typename Container, typename ValueType, typename Attribute
255       , typename Sequence>
256     struct pass_through_container<
257             Container, ValueType, Attribute, Sequence, karma::domain>
258       : karma::detail::pass_through_container<
259             Container, ValueType, Attribute, Sequence>
260     {};
261 }}}
262 
263 namespace boost { namespace spirit { namespace karma { namespace detail
264 {
265     template <typename Iterator>
266     struct pass_container_base
267     {
pass_container_baseboost::spirit::karma::detail::pass_container_base268         pass_container_base(Iterator begin, Iterator end)
269           : iter(begin), end(end)
270         {}
271 
272         mutable Iterator iter;
273         mutable Iterator end;
274     };
275 
276     template <typename Iterator>
277     struct pass_container_base<Iterator&>
278     {
pass_container_baseboost::spirit::karma::detail::pass_container_base279         pass_container_base(Iterator& begin, Iterator& end)
280           : iter(begin), end(end)
281         {}
282 
283         Iterator& iter;
284         Iterator& end;
285     };
286 
287     ///////////////////////////////////////////////////////////////////////////
288     // This function handles the case where the attribute (Attr) given
289     // to the sequence is an STL container. This is a wrapper around F.
290     // The function F does the actual generating.
291     template <typename F, typename Attr, typename Iterator, typename Sequence>
292     struct pass_container : pass_container_base<Iterator>
293     {
294         typedef pass_container_base<Iterator> base_type;
295         typedef typename F::context_type context_type;
296 
pass_containerboost::spirit::karma::detail::pass_container297         pass_container(F const& f, Iterator begin, Iterator end)
298           : base_type(begin, end)
299           , f(f)
300         {}
301 
is_at_endboost::spirit::karma::detail::pass_container302         bool is_at_end() const
303         {
304             return traits::compare(this->iter, this->end);
305         }
306 
nextboost::spirit::karma::detail::pass_container307         void next()
308         {
309             traits::next(this->iter);
310         }
311 
312         // this is for the case when the current element expects an attribute
313         // which is taken from the next entry in the container
314         template <typename Component>
dispatch_containerboost::spirit::karma::detail::pass_container315         bool dispatch_container(Component const& component, mpl::false_) const
316         {
317             // get the next value to generate from container
318             if (!is_at_end() && !f(component, traits::deref(this->iter)))
319             {
320                 // needs to return false as long as everything is ok
321                 traits::next(this->iter);
322                 return false;
323             }
324 
325             // either no elements available any more or generation failed
326             return true;
327         }
328 
329         // this is for the case when the current element is able to handle an
330         // attribute which is a container itself, this element will push its
331         // data directly into the attribute container
332         template <typename Component>
dispatch_containerboost::spirit::karma::detail::pass_container333         bool dispatch_container(Component const& component, mpl::true_) const
334         {
335             return f(component, make_iterator_range(this->iter, this->end));
336         }
337 
338         ///////////////////////////////////////////////////////////////////////
339         // this is for the case when the current element doesn't expect an
340         // attribute
341         template <typename Component>
dispatch_attributeboost::spirit::karma::detail::pass_container342         bool dispatch_attribute(Component const& component, mpl::false_) const
343         {
344             return f(component, unused);
345         }
346 
347         // the current element expects an attribute
348         template <typename Component>
dispatch_attributeboost::spirit::karma::detail::pass_container349         bool dispatch_attribute(Component const& component, mpl::true_) const
350         {
351             typedef typename traits::container_value<Attr>::type value_type;
352             typedef typename
353                 traits::attribute_of<Component, context_type>::type
354             lhs_attribute;
355 
356             // this predicate detects, whether the value type of the container
357             // attribute is a substitute for the attribute of the current
358             // element
359             typedef mpl::and_<
360                 traits::handles_container<Component, Attr, context_type>
361               , traits::pass_through_container<
362                     Attr, value_type, lhs_attribute, Sequence, karma::domain>
363             > predicate;
364 
365             return dispatch_container(component, predicate());
366         }
367 
368         // Dispatches to dispatch_main depending on the attribute type
369         // of the Component
370         template <typename Component>
operator ()boost::spirit::karma::detail::pass_container371         bool operator()(Component const& component) const
372         {
373             // we need to dispatch depending on the type of the attribute
374             // of the current element (component). If this is has no attribute
375             // we shouldn't use an element of the container but unused_type
376             // instead
377             typedef traits::not_is_unused<
378                 typename traits::attribute_of<Component, context_type>::type
379             > predicate;
380 
381             return dispatch_attribute(component, predicate());
382         }
383 
384         F f;
385 
386         // silence MSVC warning C4512: assignment operator could not be generated
387         BOOST_DELETED_FUNCTION(pass_container& operator= (pass_container const&))
388     };
389 }}}}
390 
391 #endif
392