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/*=============================================================================
Copyright (c) 2001-2014 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 ] spirit 1
// [ JDG March 4, 2007 ] spirit 2
// [ JDG February 21, 2011 ] spirit 2.5
// [ JDG June 6, 2014 ] spirit x3
//
///////////////////////////////////////////////////////////////////////////////
#include <boost/config/warning_disable.hpp>
#include <boost/spirit/home/x3.hpp>
#include <boost/spirit/home/x3/support/ast/variant.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
#include <iostream>
#include <string>
#include <list>
#include <numeric>
namespace x3 = boost::spirit::x3;
namespace client
{
///////////////////////////////////////////////////////////////////////////////
// The calculator grammar
///////////////////////////////////////////////////////////////////////////////
namespace calculator_grammar
{
using x3::uint_;
using x3::char_;
x3::rule<class expression> const expression("expression");
x3::rule<class term> const term("term");
x3::rule<class factor> const factor("factor");
auto const expression_def =
term
>> *( ('+' >> term)
| ('-' >> term)
)
;
auto const term_def =
factor
>> *( ('*' >> factor)
| ('/' >> factor)
)
;
auto const factor_def =
uint_
| '(' >> expression >> ')'
| ('-' >> factor)
| ('+' >> factor)
;
BOOST_SPIRIT_DEFINE(
expression
, term
, factor
);
auto calculator = expression;
}
using calculator_grammar::calculator;
}
///////////////////////////////////////////////////////////////////////////////
// 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";
typedef std::string::const_iterator iterator_type;
std::string str;
while (std::getline(std::cin, str))
{
if (str.empty() || str[0] == 'q' || str[0] == 'Q')
break;
auto& calc = client::calculator; // Our grammar
iterator_type iter = str.begin();
iterator_type end = str.end();
boost::spirit::x3::ascii::space_type space;
bool r = phrase_parse(iter, end, calc, space);
if (r && iter == end)
{
std::cout << "-------------------------\n";
std::cout << "Parsing succeeded\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;
}
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