ceph/src/boost/libs/spirit/include/boost/spirit/home/classic/dynamic/rule_alias.hpp

   1 /*=============================================================================
   2     Copyright (c) 1998-2003 Joel de Guzman
   3     http://spirit.sourceforge.net/
   4
   5   Distributed under the Boost Software License, Version 1.0. (See accompanying
   6   file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   7 =============================================================================*/
   8 #if !defined(BOOST_SPIRIT_RULE_ALIAS_HPP)
   9 #define BOOST_SPIRIT_RULE_ALIAS_HPP
  10
  11 #include <boost/spirit/home/classic/namespace.hpp>
  12 #include <boost/spirit/home/classic/core/parser.hpp>
  13
  14 namespace boost { namespace spirit {
  15
  16 BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
  17
  18     ///////////////////////////////////////////////////////////////////////////
  19     //
  20     //  rule_alias class
  21     //
  22     ///////////////////////////////////////////////////////////////////////////
  23     template <typename ParserT>
  24     class rule_alias :
  25         public parser<rule_alias<ParserT> >
  26     {
  27     public:
  28
  29         typedef rule_alias<ParserT> self_t;
  30
  31         template <typename ScannerT>
  32         struct result
  33         {
  34             typedef typename parser_result<ParserT, ScannerT>::type type;
  35         };
  36
  37         rule_alias()
  38         : ptr(0) {}
  39
  40         rule_alias(ParserT const& p)
  41         : ptr(&p) {}
  42
  43         rule_alias&
  44         operator=(ParserT const& p)
  45         {
  46             ptr = &p;
  47             return *this;
  48         }
  49
  50         template <typename ScannerT>
  51         typename parser_result<ParserT, ScannerT>::type
  52         parse(ScannerT const& scan) const
  53         {
  54             if (ptr)
  55                 return ptr->parse(scan);
  56             else
  57                 return scan.no_match();
  58         }
  59
  60         ParserT const&
  61         get() const
  62         {
  63             BOOST_ASSERT(ptr != 0);
  64             return *ptr;
  65         }
  66
  67     private:
  68
  69         ParserT const* ptr; // hold it by pointer
  70     };
  71
  72 BOOST_SPIRIT_CLASSIC_NAMESPACE_END
  73
  74 }} // namespace BOOST_SPIRIT_CLASSIC_NS
  75
  76 #endif