77 lines
2.8 KiB
C++
77 lines
2.8 KiB
C++
/*=============================================================================
|
|
Copyright (c) 2001-2003 Daniel Nuffer
|
|
http://spirit.sourceforge.net/
|
|
|
|
Use, modification and distribution is subject to 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)
|
|
=============================================================================*/
|
|
#ifndef BOOST_SPIRIT_TREE_CALC_GRAMMAR_HPP_
|
|
#define BOOST_SPIRIT_TREE_CALC_GRAMMAR_HPP_
|
|
|
|
using namespace BOOST_SPIRIT_CLASSIC_NS;
|
|
|
|
///////////////////////////////////////////////////////////////////////////////
|
|
//
|
|
// Demonstrates the AST and parse trees. This is discussed in the
|
|
// "Trees" chapter in the Spirit User's Guide.
|
|
//
|
|
///////////////////////////////////////////////////////////////////////////////
|
|
|
|
////////////////////////////////////////////////////////////////////////////
|
|
//
|
|
// Our calculator grammar
|
|
//
|
|
////////////////////////////////////////////////////////////////////////////
|
|
struct calculator : public grammar<calculator>
|
|
{
|
|
static const int integerID = 1;
|
|
static const int factorID = 2;
|
|
static const int termID = 3;
|
|
static const int expressionID = 4;
|
|
|
|
template <typename ScannerT>
|
|
struct definition
|
|
{
|
|
definition(calculator const& /*self*/)
|
|
{
|
|
// Start grammar definition
|
|
integer = leaf_node_d[ lexeme_d[
|
|
(!ch_p('-') >> +digit_p)
|
|
] ];
|
|
|
|
factor = integer
|
|
| inner_node_d[ch_p('(') >> expression >> ch_p(')')]
|
|
| (root_node_d[ch_p('-')] >> factor);
|
|
|
|
term = factor >>
|
|
*( (root_node_d[ch_p('*')] >> factor)
|
|
| (root_node_d[ch_p('/')] >> factor)
|
|
);
|
|
|
|
expression = term >>
|
|
*( (root_node_d[ch_p('+')] >> term)
|
|
| (root_node_d[ch_p('-')] >> term)
|
|
);
|
|
// End grammar definition
|
|
|
|
// turn on the debugging info.
|
|
BOOST_SPIRIT_DEBUG_RULE(integer);
|
|
BOOST_SPIRIT_DEBUG_RULE(factor);
|
|
BOOST_SPIRIT_DEBUG_RULE(term);
|
|
BOOST_SPIRIT_DEBUG_RULE(expression);
|
|
}
|
|
|
|
rule<ScannerT, parser_context<>, parser_tag<expressionID> > expression;
|
|
rule<ScannerT, parser_context<>, parser_tag<termID> > term;
|
|
rule<ScannerT, parser_context<>, parser_tag<factorID> > factor;
|
|
rule<ScannerT, parser_context<>, parser_tag<integerID> > integer;
|
|
|
|
rule<ScannerT, parser_context<>, parser_tag<expressionID> > const&
|
|
start() const { return expression; }
|
|
};
|
|
};
|
|
|
|
#endif
|
|
|