// Copyright (c) 2001 Daniel C. Nuffer
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// Copyright (c) 2001-2011 Hartmut Kaiser
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//
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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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#if !defined(BOOST_SPIRIT_ITERATOR_LEX_INPUT_POLICY_MAR_16_2007_1205PM)
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#define BOOST_SPIRIT_ITERATOR_LEX_INPUT_POLICY_MAR_16_2007_1205PM
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#include <boost/spirit/home/support/iterators/multi_pass_fwd.hpp>
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#include <boost/spirit/home/support/iterators/detail/multi_pass.hpp>
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namespace boost { namespace spirit { namespace iterator_policies
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{
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///////////////////////////////////////////////////////////////////////////////
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// class lex_input
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// Implementation of the InputPolicy used by multi_pass
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//
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// The lex_input class gets tokens (integers) from yylex()
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///////////////////////////////////////////////////////////////////////////
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struct lex_input
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{
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typedef int value_type;
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///////////////////////////////////////////////////////////////////////
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template <typename T>
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class unique : public detail::default_input_policy
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{
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public:
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typedef std::ptrdiff_t difference_type;
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typedef std::ptrdiff_t distance_type;
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typedef int* pointer;
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typedef int& reference;
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protected:
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unique() {}
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explicit unique(T) {}
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public:
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template <typename MultiPass>
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static typename MultiPass::reference get_input(MultiPass& mp)
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{
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value_type& curtok = mp.shared()->curtok;
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if (-1 == curtok)
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{
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extern int yylex();
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curtok = yylex();
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}
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return curtok;
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}
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template <typename MultiPass>
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static void advance_input(MultiPass& mp)
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{
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extern int yylex();
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mp.shared()->curtok = yylex();
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}
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// test, whether we reached the end of the underlying stream
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template <typename MultiPass>
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static bool input_at_eof(MultiPass const& mp)
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{
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return mp.shared()->curtok == 0;
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}
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template <typename MultiPass>
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static bool input_is_valid(MultiPass const&, value_type const& t)
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{
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return -1 != t;
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}
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};
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///////////////////////////////////////////////////////////////////////
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template <typename T>
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struct shared
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{
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explicit shared(T) : curtok(-1) {}
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value_type curtok;
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};
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};
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}}}
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#endif
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