boost/spirit/home/classic/dynamic/rule_alias.hpp
/*=============================================================================
Copyright (c) 1998-2003 Joel de Guzman
http://spirit.sourceforge.net/
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#if !defined(BOOST_SPIRIT_RULE_ALIAS_HPP)
#define BOOST_SPIRIT_RULE_ALIAS_HPP
#include <boost/spirit/home/classic/namespace.hpp>
#include <boost/spirit/home/classic/core/parser.hpp>
namespace boost { namespace spirit {
BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
///////////////////////////////////////////////////////////////////////////
//
// rule_alias class
//
///////////////////////////////////////////////////////////////////////////
template <typename ParserT>
class rule_alias :
public parser<rule_alias<ParserT> >
{
public:
typedef rule_alias<ParserT> self_t;
template <typename ScannerT>
struct result
{
typedef typename parser_result<ParserT, ScannerT>::type type;
};
rule_alias()
: ptr(0) {}
rule_alias(ParserT const& p)
: ptr(&p) {}
rule_alias&
operator=(ParserT const& p)
{
ptr = &p;
return *this;
}
template <typename ScannerT>
typename parser_result<ParserT, ScannerT>::type
parse(ScannerT const& scan) const
{
if (ptr)
return ptr->parse(scan);
else
return scan.no_match();
}
ParserT const&
get() const
{
assert(ptr != 0);
return *ptr;
}
private:
ParserT const* ptr; // hold it by pointer
};
BOOST_SPIRIT_CLASSIC_NAMESPACE_END
}} // namespace BOOST_SPIRIT_CLASSIC_NS
#endif