/*=============================================================================
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Copyright (c) 1998-2003 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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#if !defined(BOOST_SPIRIT_RULE_ALIAS_HPP)
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#define BOOST_SPIRIT_RULE_ALIAS_HPP
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#include <boost/spirit/home/classic/namespace.hpp>
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#include <boost/spirit/home/classic/core/parser.hpp>
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namespace boost { namespace spirit {
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BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
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///////////////////////////////////////////////////////////////////////////
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//
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// rule_alias class
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//
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///////////////////////////////////////////////////////////////////////////
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template <typename ParserT>
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class rule_alias :
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public parser<rule_alias<ParserT> >
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{
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public:
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typedef rule_alias<ParserT> self_t;
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template <typename ScannerT>
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struct result
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{
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typedef typename parser_result<ParserT, ScannerT>::type type;
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};
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rule_alias()
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: ptr(0) {}
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rule_alias(ParserT const& p)
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: ptr(&p) {}
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rule_alias&
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operator=(ParserT const& p)
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{
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ptr = &p;
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return *this;
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}
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template <typename ScannerT>
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typename parser_result<ParserT, ScannerT>::type
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parse(ScannerT const& scan) const
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{
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if (ptr)
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return ptr->parse(scan);
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else
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return scan.no_match();
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}
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ParserT const&
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get() const
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{
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BOOST_ASSERT(ptr != 0);
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return *ptr;
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}
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private:
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ParserT const* ptr; // hold it by pointer
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};
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BOOST_SPIRIT_CLASSIC_NAMESPACE_END
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}} // namespace BOOST_SPIRIT_CLASSIC_NS
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#endif
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