176 lines
5.9 KiB
Plaintext
176 lines
5.9 KiB
Plaintext
/*=============================================================================
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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_HPP)
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#define BOOST_SPIRIT_RULE_HPP
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#include <boost/static_assert.hpp>
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///////////////////////////////////////////////////////////////////////////////
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//
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// Spirit predefined maximum number of simultaneously usable different
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// scanner types.
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//
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// This limit defines the maximum number of possible different scanner
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// types for which a specific rule<> may be used. If this isn't defined, a
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// rule<> may be used with one scanner type only (multiple scanner support
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// is disabled).
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//
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///////////////////////////////////////////////////////////////////////////////
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#if !defined(BOOST_SPIRIT_RULE_SCANNERTYPE_LIMIT)
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# define BOOST_SPIRIT_RULE_SCANNERTYPE_LIMIT 1
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#endif
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// Ensure a meaningful maximum number of simultaneously usable scanner types
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BOOST_STATIC_ASSERT(BOOST_SPIRIT_RULE_SCANNERTYPE_LIMIT > 0);
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#include <boost/scoped_ptr.hpp>
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#include <boost/spirit/home/classic/namespace.hpp>
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#include <boost/spirit/home/classic/core/non_terminal/impl/rule.ipp>
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#if BOOST_SPIRIT_RULE_SCANNERTYPE_LIMIT > 1
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# include <boost/preprocessor/enum_params.hpp>
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#endif
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///////////////////////////////////////////////////////////////////////////////
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namespace boost { namespace spirit {
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BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
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#if BOOST_SPIRIT_RULE_SCANNERTYPE_LIMIT > 1
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///////////////////////////////////////////////////////////////////////////
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//
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// scanner_list (a fake scanner)
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//
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// Typically, rules are tied to a specific scanner type and
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// a particular rule cannot be used with anything else. Sometimes
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// there's a need for rules that can accept more than one scanner
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// type. The scanner_list<S0, ...SN> can be used as a template
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// parameter to the rule class to specify up to the number of
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// scanner types defined by the BOOST_SPIRIT_RULE_SCANNERTYPE_LIMIT
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// constant. Example:
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//
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// rule<scanner_list<ScannerT0, ScannerT1> > r;
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//
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// *** This feature is available only to compilers that support
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// partial template specialization. ***
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//
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///////////////////////////////////////////////////////////////////////////
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template <
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BOOST_PP_ENUM_PARAMS(
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BOOST_SPIRIT_RULE_SCANNERTYPE_LIMIT,
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typename ScannerT
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)
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>
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struct scanner_list : scanner_base {};
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#endif
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///////////////////////////////////////////////////////////////////////////
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//
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// rule class
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//
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// The rule is a polymorphic parser that acts as a named place-
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// holder capturing the behavior of an EBNF expression assigned to
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// it.
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//
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// The rule is a template class parameterized by:
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//
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// 1) scanner (scanner_t, see scanner.hpp),
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// 2) the rule's context (context_t, see parser_context.hpp)
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// 3) an arbitrary tag (tag_t, see parser_id.hpp) that allows
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// a rule to be tagged for identification.
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//
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// These template parameters may be specified in any order. The
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// scanner will default to scanner<> when it is not specified.
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// The context will default to parser_context when not specified.
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// The tag will default to parser_address_tag when not specified.
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//
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// The definition of the rule (its right hand side, RHS) held by
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// the rule through a scoped_ptr. When a rule is seen in the RHS
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// of an assignment or copy construction EBNF expression, the rule
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// is held by the LHS rule by reference.
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//
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///////////////////////////////////////////////////////////////////////////
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template <
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typename T0 = nil_t
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, typename T1 = nil_t
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, typename T2 = nil_t
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>
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class rule
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: public impl::rule_base<
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rule<T0, T1, T2>
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, rule<T0, T1, T2> const&
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, T0, T1, T2>
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{
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public:
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typedef rule<T0, T1, T2> self_t;
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typedef impl::rule_base<
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self_t
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, self_t const&
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, T0, T1, T2>
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base_t;
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typedef typename base_t::scanner_t scanner_t;
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typedef typename base_t::attr_t attr_t;
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typedef impl::abstract_parser<scanner_t, attr_t> abstract_parser_t;
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rule() : ptr() {}
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~rule() {}
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rule(rule const& r)
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: ptr(new impl::concrete_parser<rule, scanner_t, attr_t>(r)) {}
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template <typename ParserT>
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rule(ParserT const& p)
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: ptr(new impl::concrete_parser<ParserT, scanner_t, attr_t>(p)) {}
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template <typename ParserT>
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rule& operator=(ParserT const& p)
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{
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ptr.reset(new impl::concrete_parser<ParserT, scanner_t, attr_t>(p));
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return *this;
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}
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rule& operator=(rule const& r)
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{
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ptr.reset(new impl::concrete_parser<rule, scanner_t, attr_t>(r));
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return *this;
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}
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rule<T0, T1, T2>
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copy() const
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{
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return rule<T0, T1, T2>(ptr.get() ? ptr->clone() : 0);
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}
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private:
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friend class impl::rule_base_access;
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abstract_parser_t*
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get() const
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{
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return ptr.get();
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}
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rule(abstract_parser_t* ptr_)
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: ptr(ptr_) {}
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rule(abstract_parser_t const* ptr_)
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: ptr(ptr_) {}
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scoped_ptr<abstract_parser_t> ptr;
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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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