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350 lines
14 KiB
350 lines
14 KiB
/*============================================================================= |
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Copyright (c) 2001-2011 Hartmut Kaiser |
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Copyright (c) 2001-2011 Joel de Guzman |
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Distributed under the Boost Software License, Version 1.0. (See accompanying |
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
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=============================================================================*/ |
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#if !defined(SPIRIT_PASS_CONTAINER_MAR_15_2009_0114PM) |
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#define SPIRIT_PASS_CONTAINER_MAR_15_2009_0114PM |
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#if defined(_MSC_VER) |
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#pragma once |
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#endif |
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#include <boost/spirit/home/karma/detail/attributes.hpp> |
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#include <boost/spirit/home/support/container.hpp> |
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#include <boost/spirit/home/support/handles_container.hpp> |
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#include <boost/spirit/home/support/detail/hold_any.hpp> |
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#include <boost/type_traits/is_base_of.hpp> |
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#include <boost/type_traits/is_convertible.hpp> |
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#include <boost/mpl/bool.hpp> |
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#include <boost/mpl/and.hpp> |
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#include <boost/mpl/or.hpp> |
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#include <boost/preprocessor/cat.hpp> |
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#include <boost/preprocessor/repetition/repeat.hpp> |
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#include <boost/range/iterator_range.hpp> |
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#include <boost/fusion/include/deduce_sequence.hpp> |
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#include <boost/mpl/print.hpp> |
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namespace boost { namespace spirit { namespace karma { namespace detail |
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{ |
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// Helper meta-function allowing to evaluate weak substitutability and |
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// negate the result if the predicate (Sequence) is not true |
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template <typename Sequence, typename Attribute, typename ValueType> |
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struct negate_weak_substitute_if_not |
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: mpl::if_< |
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Sequence |
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, typename traits::is_weak_substitute<Attribute, ValueType>::type |
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, typename mpl::not_< |
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traits::is_weak_substitute<Attribute, ValueType> |
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>::type> |
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{}; |
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// pass_through_container: utility to check decide whether a provided |
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// container attribute needs to be passed through to the current component |
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// or of we need to split the container by passing along instances of its |
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// value type |
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// if the expected attribute of the current component is neither a Fusion |
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// sequence nor a container, we will pass through the provided container |
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// only if its value type is not compatible with the component |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence, typename Enable = void> |
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struct pass_through_container_base |
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: negate_weak_substitute_if_not<Sequence, ValueType, Attribute> |
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{}; |
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// Specialization for fusion sequences, in this case we check whether all |
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// the types in the sequence are convertible to the lhs attribute. |
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// |
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// We return false if the rhs attribute itself is a fusion sequence, which |
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// is compatible with the LHS sequence (we want to pass through this |
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// attribute without it being split apart). |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence = mpl::true_> |
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struct not_compatible_element |
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: mpl::and_< |
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negate_weak_substitute_if_not<Sequence, Container, Attribute> |
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, negate_weak_substitute_if_not<Sequence, ValueType, Attribute> > |
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{}; |
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// If the value type of the container is not a Fusion sequence, we pass |
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// through the container if each of the elements of the Attribute |
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// sequence is compatible with either the container or its value type. |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence |
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, bool IsSequence = fusion::traits::is_sequence<ValueType>::value> |
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struct pass_through_container_fusion_sequence |
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{ |
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typedef typename mpl::find_if< |
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Attribute, not_compatible_element<Container, ValueType, mpl::_1> |
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>::type iter; |
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typedef typename mpl::end<Attribute>::type end; |
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typedef typename is_same<iter, end>::type type; |
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}; |
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// If both, the Attribute and the value type of the provided container |
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// are Fusion sequences, we pass the container only if the two |
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// sequences are not compatible. |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence> |
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struct pass_through_container_fusion_sequence< |
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Container, ValueType, Attribute, Sequence, true> |
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{ |
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typedef typename mpl::find_if< |
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Attribute |
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, not_compatible_element<Container, ValueType, mpl::_1, Sequence> |
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>::type iter; |
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typedef typename mpl::end<Attribute>::type end; |
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typedef typename is_same<iter, end>::type type; |
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}; |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence> |
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struct pass_through_container_base<Container, ValueType, Attribute |
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, Sequence |
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, typename enable_if<fusion::traits::is_sequence<Attribute> >::type> |
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: pass_through_container_fusion_sequence< |
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Container, ValueType, Attribute, Sequence> |
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{}; |
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// Specialization for containers |
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// |
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// If the value type of the attribute of the current component is not |
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// a Fusion sequence, we have to pass through the provided container if |
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// both are compatible. |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence, typename AttributeValueType |
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, bool IsSequence = fusion::traits::is_sequence<AttributeValueType>::value> |
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struct pass_through_container_container |
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: mpl::or_< |
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traits::is_weak_substitute<Container, Attribute> |
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, traits::is_weak_substitute<Container, AttributeValueType> > |
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{}; |
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// If the value type of the exposed container attribute is a Fusion |
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// sequence, we use the already existing logic for those. |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence, typename AttributeValueType> |
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struct pass_through_container_container< |
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Container, ValueType, Attribute, Sequence, AttributeValueType, true> |
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: pass_through_container_fusion_sequence< |
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Container, ValueType, AttributeValueType, Sequence> |
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{}; |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence> |
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struct pass_through_container_base<Container, ValueType, Attribute |
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, Sequence |
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, typename enable_if<traits::is_container<Attribute> >::type> |
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: detail::pass_through_container_container< |
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Container, ValueType, Attribute, Sequence |
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, typename traits::container_value<Attribute>::type> |
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{}; |
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// Specialization for exposed optional attributes |
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// |
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// If the type embedded in the exposed optional is not a Fusion |
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// sequence we pass through the container attribute if it is compatible |
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// either to the optionals embedded type or to the containers value |
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// type. |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence |
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, bool IsSequence = fusion::traits::is_sequence<Attribute>::value> |
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struct pass_through_container_optional |
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: mpl::or_< |
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traits::is_weak_substitute<Container, Attribute> |
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, traits::is_weak_substitute<ValueType, Attribute> > |
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{}; |
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// If the embedded type of the exposed optional attribute is a Fusion |
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// sequence, we use the already existing logic for those. |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence> |
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struct pass_through_container_optional< |
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Container, ValueType, Attribute, Sequence, true> |
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: pass_through_container_fusion_sequence< |
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Container, ValueType, Attribute, Sequence> |
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{}; |
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/////////////////////////////////////////////////////////////////////////// |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence> |
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struct pass_through_container |
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: pass_through_container_base<Container, ValueType, Attribute, Sequence> |
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{}; |
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// Handle optional attributes |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence> |
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struct pass_through_container< |
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Container, ValueType, boost::optional<Attribute>, Sequence> |
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: pass_through_container_optional< |
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Container, ValueType, Attribute, Sequence> |
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{}; |
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// If both, the containers value type and the exposed attribute type are |
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// optionals we are allowed to pass through the the container only if the |
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// embedded types of those optionals are not compatible. |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence> |
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struct pass_through_container< |
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Container, boost::optional<ValueType>, boost::optional<Attribute> |
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, Sequence> |
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: mpl::not_<traits::is_weak_substitute<ValueType, Attribute> > |
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{}; |
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// Specialization for exposed variant attributes |
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// |
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// We pass through the container attribute if at least one of the embedded |
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// types in the variant requires to pass through the attribute |
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#define BOOST_SPIRIT_PASS_THROUGH_CONTAINER(z, N, _) \ |
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pass_through_container<Container, ValueType, \ |
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BOOST_PP_CAT(T, N), Sequence>::type::value || \ |
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/***/ |
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// make sure unused variant parameters do not affect the outcome |
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template <typename Container, typename ValueType, typename Sequence> |
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struct pass_through_container<Container, ValueType |
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, boost::detail::variant::void_, Sequence> |
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: mpl::false_ |
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{}; |
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template <typename Container, typename ValueType, typename Sequence |
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, BOOST_VARIANT_ENUM_PARAMS(typename T)> |
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struct pass_through_container<Container, ValueType |
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, boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Sequence> |
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: mpl::bool_<BOOST_PP_REPEAT(BOOST_VARIANT_LIMIT_TYPES |
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, BOOST_SPIRIT_PASS_THROUGH_CONTAINER, _) false> |
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{}; |
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#undef BOOST_SPIRIT_PASS_THROUGH_CONTAINER |
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}}}} |
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/////////////////////////////////////////////////////////////////////////////// |
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namespace boost { namespace spirit { namespace traits |
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{ |
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/////////////////////////////////////////////////////////////////////////// |
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// forwarding customization point for domain karma::domain |
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template <typename Container, typename ValueType, typename Attribute |
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, typename Sequence> |
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struct pass_through_container< |
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Container, ValueType, Attribute, Sequence, karma::domain> |
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: karma::detail::pass_through_container< |
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Container, ValueType, Attribute, Sequence> |
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{}; |
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}}} |
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namespace boost { namespace spirit { namespace karma { namespace detail |
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{ |
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/////////////////////////////////////////////////////////////////////////// |
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// This function handles the case where the attribute (Attr) given |
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// to the sequence is an STL container. This is a wrapper around F. |
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// The function F does the actual generating. |
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template <typename F, typename Attr, typename Iterator, typename Sequence> |
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struct pass_container |
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{ |
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typedef typename F::context_type context_type; |
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pass_container(F const& f, Iterator begin, Iterator end) |
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: f(f), iter(begin), end(end) |
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{} |
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bool is_at_end() const |
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{ |
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return traits::compare(iter, end); |
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} |
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void next() |
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{ |
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traits::next(iter); |
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} |
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// this is for the case when the current element expects an attribute |
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// which is taken from the next entry in the container |
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template <typename Component> |
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bool dispatch_container(Component const& component, mpl::false_) const |
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{ |
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// get the next value to generate from container |
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if (!is_at_end() && !f(component, traits::deref(iter))) |
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{ |
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// needs to return false as long as everything is ok |
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traits::next(iter); |
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return false; |
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} |
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// either no elements available any more or generation failed |
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return true; |
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} |
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// this is for the case when the current element is able to handle an |
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// attribute which is a container itself, this element will push its |
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// data directly into the attribute container |
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template <typename Component> |
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bool dispatch_container(Component const& component, mpl::true_) const |
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{ |
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return f(component, make_iterator_range(iter, end)); |
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} |
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/////////////////////////////////////////////////////////////////////// |
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// this is for the case when the current element doesn't expect an |
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// attribute |
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template <typename Component> |
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bool dispatch_attribute(Component const& component, mpl::false_) const |
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{ |
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return f(component, unused); |
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} |
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// the current element expects an attribute |
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template <typename Component> |
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bool dispatch_attribute(Component const& component, mpl::true_) const |
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{ |
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typedef typename traits::container_value<Attr>::type value_type; |
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typedef typename |
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traits::attribute_of<Component, context_type>::type |
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lhs_attribute; |
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// this predicate detects, whether the value type of the container |
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// attribute is a substitute for the attribute of the current |
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// element |
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typedef mpl::and_< |
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traits::handles_container<Component, Attr, context_type> |
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, traits::pass_through_container< |
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Attr, value_type, lhs_attribute, Sequence, karma::domain> |
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> predicate; |
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return dispatch_container(component, predicate()); |
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} |
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// Dispatches to dispatch_main depending on the attribute type |
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// of the Component |
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template <typename Component> |
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bool operator()(Component const& component) const |
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{ |
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// we need to dispatch depending on the type of the attribute |
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// of the current element (component). If this is has no attribute |
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// we shouldn't use an element of the container but unused_type |
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// instead |
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typedef traits::not_is_unused< |
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typename traits::attribute_of<Component, context_type>::type |
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> predicate; |
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return dispatch_attribute(component, predicate()); |
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} |
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F f; |
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mutable Iterator iter; |
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mutable Iterator end; |
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private: |
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// silence MSVC warning C4512: assignment operator could not be generated |
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pass_container& operator= (pass_container const&); |
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}; |
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}}}} |
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#endif
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