mirror of
https://github.com/boostorg/spirit.git
synced 2026-01-19 04:42:11 +00:00
127 lines
4.1 KiB
C++
127 lines
4.1 KiB
C++
/*=============================================================================
|
|
Copyright (c) 2001-2007 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)
|
|
=============================================================================*/
|
|
///////////////////////////////////////////////////////////////////////////////
|
|
//
|
|
// This time, we'll incorporate error handling and reporting.
|
|
//
|
|
// [ JDG June 29, 2002 ] spirit1
|
|
// [ JDG March 5, 2007 ] spirit2
|
|
//
|
|
///////////////////////////////////////////////////////////////////////////////
|
|
#include <boost/spirit/include/qi.hpp>
|
|
#include <boost/spirit/include/phoenix_operator.hpp>
|
|
#include <boost/spirit/include/phoenix_object.hpp>
|
|
|
|
#include <iostream>
|
|
#include <string>
|
|
|
|
using namespace boost::spirit;
|
|
using namespace boost::spirit::qi;
|
|
using namespace boost::spirit::ascii;
|
|
using namespace boost::spirit::arg_names;
|
|
|
|
using boost::phoenix::val;
|
|
using boost::phoenix::construct;
|
|
|
|
///////////////////////////////////////////////////////////////////////////////
|
|
// Our calculator grammar
|
|
///////////////////////////////////////////////////////////////////////////////
|
|
template <typename Iterator>
|
|
struct calculator : grammar_def<Iterator, int(), space_type>
|
|
{
|
|
calculator()
|
|
{
|
|
expression =
|
|
term [_val = _1]
|
|
>> *( ('+' > term [_val += _1])
|
|
| ('-' > term [_val -= _1])
|
|
)
|
|
;
|
|
|
|
term =
|
|
factor [_val = _1]
|
|
>> *( ('*' > factor [_val *= _1])
|
|
| ('/' > factor [_val /= _1])
|
|
)
|
|
;
|
|
|
|
factor =
|
|
uint_ [_val = _1]
|
|
| '(' > expression [_val = _1] > ')'
|
|
| ('-' > factor [_val = -_1])
|
|
| ('+' > factor [_val = _1])
|
|
;
|
|
|
|
expression.name("expression");
|
|
term.name("term");
|
|
factor.name("factor");
|
|
|
|
on_error<fail>
|
|
(
|
|
expression
|
|
, std::cout
|
|
<< val("Error! Expecting ")
|
|
<< _4 // what failed?
|
|
<< val(" here: \"")
|
|
<< construct<std::string>(_3, _2) // iterators to error-pos, end
|
|
<< val("\"")
|
|
<< std::endl
|
|
);
|
|
}
|
|
|
|
rule<Iterator, int(), space_type> 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";
|
|
|
|
typedef std::string::const_iterator iterator_type;
|
|
typedef calculator<iterator_type> calculator;
|
|
|
|
calculator def; // Our grammar definition
|
|
grammar<calculator> calc(def, def.expression); // Our grammar
|
|
|
|
std::string str;
|
|
int result;
|
|
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();
|
|
bool r = phrase_parse(iter, end, calc, result, space);
|
|
|
|
if (r && iter == end)
|
|
{
|
|
std::cout << "-------------------------\n";
|
|
std::cout << "Parsing succeeded\n";
|
|
std::cout << "result = " << result << std::endl;
|
|
std::cout << "-------------------------\n";
|
|
}
|
|
else
|
|
{
|
|
std::cout << "-------------------------\n";
|
|
std::cout << "Parsing failed\n";
|
|
std::cout << "-------------------------\n";
|
|
}
|
|
}
|
|
|
|
std::cout << "Bye... :-) \n\n";
|
|
return 0;
|
|
}
|
|
|
|
|