epoc32/include/stdapis/boost/pending/detail/property.hpp
author William Roberts <williamr@symbian.org>
Wed, 31 Mar 2010 12:33:34 +0100
branchSymbian3
changeset 4 837f303aceeb
parent 3 e1b950c65cb4
permissions -rw-r--r--
Current Symbian^3 public API header files (from PDK 3.0.h)
This is the epoc32/include tree with the "platform" subtrees removed, and
all but a selected few mbg and rsg files removed.
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//  (C) Copyright Jeremy Siek 2004 
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//  Distributed under the Boost Software License, Version 1.0. (See
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//  accompanying file LICENSE_1_0.txt or copy at
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//  http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_DETAIL_PROPERTY_HPP
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#define BOOST_DETAIL_PROPERTY_HPP
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#include <utility> // for std::pair
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#include <boost/type_traits/same_traits.hpp> // for is_same
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namespace boost {
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  namespace detail {
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    template <class PropertyTag1, class PropertyTag2>
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    struct same_property {
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      enum { value = is_same<PropertyTag1,PropertyTag2>::value };
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    };
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    struct error_property_not_found { };
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    template <int TagMatched>
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    struct property_value_dispatch {
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      template <class PropertyTag, class T, class Tag>
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      inline static T& get_value(PropertyTag& p, T*, Tag) {
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        return p.m_value; 
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      }
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      template <class PropertyTag, class T, class Tag>
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      inline static const T& const_get_value(const PropertyTag& p, T*, Tag) {
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        return p.m_value; 
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      }
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    };
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    template <class PropertyList>
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    struct property_value_end {
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      template <class T> struct result { typedef T type; };
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      template <class T, class Tag>
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      inline static T& get_value(PropertyList& p, T* t, Tag tag) {
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        typedef typename PropertyList::next_type Next;
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        typedef typename Next::tag_type Next_tag;
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        enum { match = same_property<Next_tag,Tag>::value };
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        return property_value_dispatch<match>
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          ::get_value(static_cast<Next&>(p), t, tag);
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      }
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      template <class T, class Tag>
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      inline static const T& const_get_value(const PropertyList& p, T* t, Tag tag) {
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        typedef typename PropertyList::next_type Next;
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        typedef typename Next::tag_type Next_tag;
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        enum { match = same_property<Next_tag,Tag>::value };
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        return property_value_dispatch<match>
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          ::const_get_value(static_cast<const Next&>(p), t, tag);
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      }
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    };
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    template <>
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    struct property_value_end<no_property> {
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      template <class T> struct result { 
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        typedef detail::error_property_not_found type; 
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      };
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      // Stop the recursion and return error
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      template <class T, class Tag>
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      inline static detail::error_property_not_found&
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      get_value(no_property&, T*, Tag) {
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        static error_property_not_found s_prop_not_found;
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        return s_prop_not_found;
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      }
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      template <class T, class Tag>
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      inline static const detail::error_property_not_found&
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      const_get_value(const no_property&, T*, Tag) {
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        static error_property_not_found s_prop_not_found;
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        return s_prop_not_found;
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      }
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    };
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    template <>
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    struct property_value_dispatch<0> {
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      template <class PropertyList, class T, class Tag>
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      inline static typename property_value_end<PropertyList>::template result<T>::type&
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      get_value(PropertyList& p, T* t, Tag tag) {
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        return property_value_end<PropertyList>::get_value(p, t, tag);
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      }
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      template <class PropertyList, class T, class Tag>
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      inline static const typename property_value_end<PropertyList>::template result<T>::type&
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      const_get_value(const PropertyList& p, T* t, Tag tag) {
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        return property_value_end<PropertyList>::const_get_value(p, t, tag);
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      }
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    };
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    template <class PropertyList>
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    struct build_property_tag_value_alist
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    {
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      typedef typename PropertyList::next_type NextProperty;
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      typedef typename PropertyList::value_type Value;
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      typedef typename PropertyList::tag_type Tag;
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      typedef typename build_property_tag_value_alist<NextProperty>::type Next;
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      typedef std::pair< std::pair<Tag,Value>, Next> type;
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    };
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    template <>
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    struct build_property_tag_value_alist<no_property>
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    {
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      typedef no_property type;
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    };
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#if !defined BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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    template <class TagValueAList, class Tag>
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    struct extract_value {
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      typedef error_property_not_found type;
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    };
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    template <class Value, class Tag1, class Tag2, class Rest>
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    struct extract_value< std::pair<std::pair<Tag1,Value>,Rest>, Tag2> {
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      typedef typename extract_value<Rest,Tag2>::type type;
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    };
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    template <class Value, class Tag, class Rest>
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    struct extract_value< std::pair<std::pair<Tag,Value>,Rest>, Tag> {
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      typedef Value type;
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    };
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#else
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    // VC++ workaround:
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    // The main idea here is to replace partial specialization with
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    // nested template member classes. Of course there is the
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    // further complication that the outer class of the nested
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    // template class cannot itself be a template class.
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    // Hence the need for the ev_selector. -JGS
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    struct recursive_extract;
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    struct end_extract;
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    template <class TagValueAList>
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    struct ev_selector { typedef recursive_extract type; };
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    template <>
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    struct ev_selector<no_property> { typedef end_extract type; };
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    struct recursive_extract {
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      template <class TagValueAList, class Tag1>
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      struct bind_ {
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        typedef typename TagValueAList::first_type AListFirst;
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        typedef typename AListFirst::first_type Tag2;
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        typedef typename AListFirst::second_type Value;
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        enum { match = same_property<Tag1,Tag2>::value };
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        typedef typename TagValueAList::second_type Next;
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        typedef typename ev_selector<Next>::type Extractor;
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        typedef typename boost::ct_if< match, Value, 
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          typename Extractor::template bind_<Next,Tag1>::type
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        >::type type;
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      };
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    };
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    struct end_extract {
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      template <class AList, class Tag1>
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      struct bind_ {
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        typedef error_property_not_found type;
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      };
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    };
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#endif //!defined BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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  } // namespace detail 
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} // namespace boost
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#endif // BOOST_DETAIL_PROPERTY_HPP