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217 lines
7.5 KiB
217 lines
7.5 KiB
///////////////////////////////////////////////////////////////////////////////
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// is_pure.hpp
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//
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// Copyright 2008 Eric Niebler. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_XPRESSIVE_DETAIL_STATIC_IS_PURE_HPP_EAN_10_04_2005
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#define BOOST_XPRESSIVE_DETAIL_STATIC_IS_PURE_HPP_EAN_10_04_2005
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// MS compatible compilers support #pragma once
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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/ref.hpp>
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#include <boost/mpl/and.hpp>
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#include <boost/mpl/bool.hpp>
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#include <boost/mpl/assert.hpp>
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#include <boost/mpl/not_equal_to.hpp>
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#include <boost/xpressive/detail/detail_fwd.hpp>
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#include <boost/xpressive/detail/static/width_of.hpp>
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namespace boost { namespace xpressive { namespace detail
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{
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///////////////////////////////////////////////////////////////////////////////
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// use_simple_repeat_terminal
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//
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template<typename Expr, typename Char, bool IsXpr = is_xpr<Expr>::value>
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struct use_simple_repeat_terminal
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: mpl::bool_<
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Expr::quant == quant_fixed_width
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|| (Expr::width != unknown_width::value && Expr::pure)
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>
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_terminal<Expr, Char, false>
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: mpl::true_ // char literals, string literals, etc.
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{};
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template<typename BidiIter, typename Char>
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struct use_simple_repeat_terminal<tracking_ptr<regex_impl<BidiIter> >, Char, false>
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: mpl::false_ // basic_regex
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{};
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template<typename BidiIter, typename Char>
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struct use_simple_repeat_terminal<reference_wrapper<basic_regex<BidiIter> >, Char, false>
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: mpl::false_ // basic_regex
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{};
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template<typename BidiIter, typename Char>
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struct use_simple_repeat_terminal<reference_wrapper<basic_regex<BidiIter> const>, Char, false>
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: mpl::false_ // basic_regex
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{};
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///////////////////////////////////////////////////////////////////////////////
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// use_simple_repeat_
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//
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template<typename Expr, typename Char, typename Tag = typename Expr::proto_tag>
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struct use_simple_repeat_
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, proto::tag::terminal>
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: use_simple_repeat_terminal<typename proto::result_of::value<Expr>::type, Char>
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, proto::tag::shift_right>
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: mpl::and_<
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use_simple_repeat_<typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr, Char>
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, use_simple_repeat_<typename remove_reference<typename Expr::proto_child1>::type::proto_base_expr, Char>
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>
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, proto::tag::bitwise_or>
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: mpl::and_<
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mpl::not_equal_to<unknown_width, width_of<Expr, Char> >
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, use_simple_repeat_<typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr, Char>
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, use_simple_repeat_<typename remove_reference<typename Expr::proto_child1>::type::proto_base_expr, Char>
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>
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{};
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template<typename Left>
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struct use_simple_repeat_assign
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{};
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template<>
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struct use_simple_repeat_assign<mark_placeholder>
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: mpl::false_
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{};
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template<>
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struct use_simple_repeat_assign<set_initializer>
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: mpl::true_
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{};
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template<typename Nbr>
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struct use_simple_repeat_assign<attribute_placeholder<Nbr> >
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: mpl::false_
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{};
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// either (s1 = ...) or (a1 = ...) or (set = ...)
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, proto::tag::assign>
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: use_simple_repeat_assign<
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typename proto::result_of::value<
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typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr
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>::type
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>
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, modifier_tag>
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: use_simple_repeat_<typename remove_reference<typename Expr::proto_child1>::type::proto_base_expr, Char>
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, lookahead_tag>
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: mpl::false_
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, lookbehind_tag>
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: mpl::false_
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, keeper_tag>
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: mpl::false_
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{};
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// when complementing a set or an assertion, the purity is that of the set (true) or the assertion
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, proto::tag::complement>
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: use_simple_repeat_<typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr, Char>
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{};
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// The comma is used in list-initialized sets, which are pure
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, proto::tag::comma>
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: mpl::true_
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{};
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// The subscript operator[] is used for sets, as in set['a' | range('b','h')]
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// It is also used for actions, which by definition have side-effects and thus are impure
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template<typename Expr, typename Char, typename Left>
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struct use_simple_repeat_subscript
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: mpl::false_
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_subscript<Expr, Char, set_initializer_type>
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: mpl::true_
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, proto::tag::subscript>
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: use_simple_repeat_subscript<Expr, Char, typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr>
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{};
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// Quantified expressions are variable-width and cannot use the simple quantifier
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, proto::tag::unary_plus>
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: mpl::false_
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, proto::tag::dereference>
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: mpl::false_
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, proto::tag::logical_not>
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: mpl::false_
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{};
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template<typename Expr, typename Char, uint_t Min, uint_t Max>
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struct use_simple_repeat_<Expr, Char, generic_quant_tag<Min, Max> >
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: mpl::false_
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{};
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template<typename Expr, typename Char, uint_t Count>
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struct use_simple_repeat_<Expr, Char, generic_quant_tag<Count, Count> >
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: use_simple_repeat_<typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr, Char>
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{};
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template<typename Expr, typename Char>
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struct use_simple_repeat_<Expr, Char, proto::tag::negate>
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: use_simple_repeat_<typename remove_reference<typename Expr::proto_child0>::type::proto_base_expr, Char>
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{};
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///////////////////////////////////////////////////////////////////////////////
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// use_simple_repeat
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//
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template<typename Expr, typename Char>
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struct use_simple_repeat
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: use_simple_repeat_<Expr, Char>
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{
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// should never try to repeat something of 0-width
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BOOST_MPL_ASSERT_RELATION(0, !=, (width_of<Expr, Char>::value));
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};
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template<typename Expr, typename Char>
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struct use_simple_repeat<Expr &, Char>
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: use_simple_repeat_<Expr, Char>
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{
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// should never try to repeat something of 0-width
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BOOST_MPL_ASSERT_RELATION(0, !=, (width_of<Expr, Char>::value));
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};
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}}} // namespace boost::xpressive::detail
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#endif
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