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124 lines
3.9 KiB
124 lines
3.9 KiB
/*============================================================================= |
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Copyright (c) 2001-2011 Joel de Guzman |
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http://spirit.sourceforge.net/ |
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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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#ifndef BOOST_SPIRIT_MODIFY_OCTOBER_25_2008_0142PM |
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#define BOOST_SPIRIT_MODIFY_OCTOBER_25_2008_0142PM |
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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/include/phoenix_limits.hpp> // needs to be included before proto |
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#include <boost/proto/proto.hpp> |
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#include <boost/mpl/if.hpp> |
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#include <boost/type_traits/is_base_of.hpp> |
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#include <boost/spirit/home/support/unused.hpp> |
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namespace boost { namespace spirit |
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{ |
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template <typename Domain, typename T, typename Enable = void> |
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struct is_modifier_directive; |
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// Testing if a modifier set includes a modifier T involves |
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// checking for inheritance (i.e. Modifiers is derived from T) |
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template <typename Modifiers, typename T> |
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struct has_modifier |
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: is_base_of<T, Modifiers> {}; |
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// Adding modifiers is done using multi-inheritance |
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template <typename Current, typename New, typename Enable = void> |
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struct compound_modifier : Current, New |
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{ |
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compound_modifier() |
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: Current(), New() {} |
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compound_modifier(Current const& current, New const& new_) |
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: Current(current), New(new_) {} |
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}; |
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// Don't add if New is already in Current |
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template <typename Current, typename New> |
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struct compound_modifier< |
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Current, New, typename enable_if<has_modifier<Current, New> >::type> |
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: Current |
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{ |
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compound_modifier() |
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: Current() {} |
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compound_modifier(Current const& current, New const&) |
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: Current(current) {} |
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}; |
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// Special case if Current is unused_type |
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template <typename New, typename Enable> |
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struct compound_modifier<unused_type, New, Enable> : New |
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{ |
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compound_modifier() |
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: New() {} |
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compound_modifier(unused_type, New const& new_) |
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: New(new_) {} |
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}; |
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// Domains may specialize this modify metafunction to allow |
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// directives to add information to the Modifier template |
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// parameter that is passed to the make_component metafunction. |
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// By default, we return the modifiers untouched |
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template <typename Domain, typename Enable = void> |
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struct modify |
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{ |
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template <typename Sig> |
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struct result; |
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template <typename This, typename Tag, typename Modifiers> |
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struct result<This(Tag, Modifiers)> |
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{ |
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typedef typename remove_const< |
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typename remove_reference<Tag>::type>::type |
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tag_type; |
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typedef typename remove_const< |
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typename remove_reference<Modifiers>::type>::type |
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modifiers_type; |
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typedef typename mpl::if_< |
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is_modifier_directive<Domain, tag_type> |
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, compound_modifier<modifiers_type, tag_type> |
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, Modifiers>::type |
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type; |
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}; |
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template <typename Tag, typename Modifiers> |
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typename result<modify(Tag, Modifiers)>::type |
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operator()(Tag tag, Modifiers modifiers) const |
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{ |
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return op(tag, modifiers, is_modifier_directive<Domain, Tag>()); |
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} |
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template <typename Tag, typename Modifiers> |
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Modifiers |
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op(Tag /*tag*/, Modifiers modifiers, mpl::false_) const |
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{ |
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return modifiers; |
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} |
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template <typename Tag, typename Modifiers> |
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compound_modifier<Modifiers, Tag> |
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op(Tag tag, Modifiers modifiers, mpl::true_) const |
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{ |
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return compound_modifier<Modifiers, Tag>(modifiers, tag); |
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} |
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}; |
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}} |
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namespace boost { namespace proto |
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{ |
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template <typename Domain, typename Enable> |
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struct is_callable<spirit::modify<Domain, Enable> > |
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: mpl::true_ {}; |
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}} |
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#endif
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