Find file
Fetching contributors…
Cannot retrieve contributors at this time
167 lines (141 sloc) 5.33 KB
/*=============================================================================
Copyright (c) 2001-2011 Hartmut Kaiser
Copyright (c) 2001-2011 Joel de Guzman
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)
=============================================================================*/
///////////////////////////////////////////////////////////////////////////////
//
// Plain calculator example demonstrating the grammar. The parser is a
// syntax checker only and does not do any semantic evaluation.
//
// [ JDG May 10, 2002 ] spirit1
// [ JDG March 4, 2007 ] spirit2
// [ HK November 30, 2010 ] spirit2/utree
//
///////////////////////////////////////////////////////////////////////////////
// #define BOOST_SPIRIT_DEBUG
#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/support_utree.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
#include <boost/spirit/include/phoenix_function.hpp>
#include <iostream>
#include <string>
#if BOOST_PHOENIX_VERSION == 0x2000
namespace boost { namespace phoenix
{
// There's a bug in the Phoenix V2 type deduction mechanism that prevents
// correct return type deduction for for the math operations below. Newer
// versions of Phoenix will be switching to BOOST_TYPEOF. In the meantime,
// we will use the specializations helping with return type deduction
// below:
template <>
struct result_of_plus<spirit::utree&, spirit::utree&>
{
typedef spirit::utree type;
};
template <>
struct result_of_minus<spirit::utree&, spirit::utree&>
{
typedef spirit::utree type;
};
template <>
struct result_of_multiplies<spirit::utree&, spirit::utree&>
{
typedef spirit::utree type;
};
template <>
struct result_of_divides<spirit::utree&, spirit::utree&>
{
typedef spirit::utree type;
};
template <>
struct result_of_negate<spirit::utree&>
{
typedef spirit::utree type;
};
}}
#endif
namespace client
{
namespace qi = boost::spirit::qi;
namespace ascii = boost::spirit::ascii;
namespace spirit = boost::spirit;
///////////////////////////////////////////////////////////////////////////////
// Our calculator grammar
///////////////////////////////////////////////////////////////////////////////
template <typename Iterator>
struct calculator : qi::grammar<Iterator, ascii::space_type, spirit::utree()>
{
calculator() : calculator::base_type(expression)
{
using qi::uint_;
using qi::_val;
using qi::_1;
expression =
term [_val = _1]
>> *( ('+' >> term [_val = _val + _1])
| ('-' >> term [_val = _val - _1])
)
;
term =
factor [_val = _1]
>> *( ('*' >> factor [_val = _val * _1])
| ('/' >> factor [_val = _val / _1])
)
;
factor =
uint_ [_val = _1]
| '(' >> expression [_val = _1] >> ')'
| ('-' >> factor [_val = -_1])
| ('+' >> factor [_val = _1])
;
BOOST_SPIRIT_DEBUG_NODE(expression);
BOOST_SPIRIT_DEBUG_NODE(term);
BOOST_SPIRIT_DEBUG_NODE(factor);
}
qi::rule<Iterator, ascii::space_type, spirit::utree()> expression, term, factor;
};
}
///////////////////////////////////////////////////////////////////////////////
// Main program
///////////////////////////////////////////////////////////////////////////////
int main()
{
std::cout << "/////////////////////////////////////////////////////////\n\n";
std::cout << "Expression parser...\n\n";
std::cout << "/////////////////////////////////////////////////////////\n\n";
std::cout << "Type an expression...or [q or Q] to quit\n\n";
using boost::spirit::ascii::space;
using boost::spirit::utree;
typedef std::string::const_iterator iterator_type;
typedef client::calculator<iterator_type> calculator;
calculator calc; // Our grammar
std::string str;
while (std::getline(std::cin, str))
{
if (str.empty() || str[0] == 'q' || str[0] == 'Q')
break;
std::string::const_iterator iter = str.begin();
std::string::const_iterator end = str.end();
utree ut;
bool r = phrase_parse(iter, end, calc, space, ut);
if (r && iter == end)
{
std::cout << "-------------------------\n";
std::cout << "Parsing succeeded: " << ut << "\n";
std::cout << "-------------------------\n";
}
else
{
std::string rest(iter, end);
std::cout << "-------------------------\n";
std::cout << "Parsing failed\n";
std::cout << "stopped at: \": " << rest << "\"\n";
std::cout << "-------------------------\n";
}
}
std::cout << "Bye... :-) \n\n";
return 0;
}