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- /*=============================================================================
- Copyright (c) 2002-2003 Joel de Guzman
- 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)
- =============================================================================*/
- ///////////////////////////////////////////////////////////////////////////////
- //
- // A primitive calculator that knows how to add and subtract.
- // [ demonstrating phoenix ]
- //
- // [ JDG 6/28/2002 ]
- //
- ///////////////////////////////////////////////////////////////////////////////
- #include <boost/spirit/include/classic_core.hpp>
- #include <boost/spirit/include/phoenix1_primitives.hpp>
- #include <boost/spirit/include/phoenix1_operators.hpp>
- #include <iostream>
- #include <string>
- ///////////////////////////////////////////////////////////////////////////////
- using namespace std;
- using namespace BOOST_SPIRIT_CLASSIC_NS;
- using namespace phoenix;
- ///////////////////////////////////////////////////////////////////////////////
- //
- // Our primitive calculator
- //
- ///////////////////////////////////////////////////////////////////////////////
- template <typename IteratorT>
- bool primitive_calc(IteratorT first, IteratorT last, double& n)
- {
- return parse(first, last,
- // Begin grammar
- (
- real_p[var(n) = arg1]
- >> *( ('+' >> real_p[var(n) += arg1])
- | ('-' >> real_p[var(n) -= arg1])
- )
- )
- ,
- // End grammar
- space_p).full;
- }
- ////////////////////////////////////////////////////////////////////////////
- //
- // Main program
- //
- ////////////////////////////////////////////////////////////////////////////
- int
- main()
- {
- cout << "/////////////////////////////////////////////////////////\n\n";
- cout << "\t\tA primitive calculator...\n\n";
- cout << "/////////////////////////////////////////////////////////\n\n";
- cout << "Give me a list of numbers to be added or subtracted.\n";
- cout << "Example: 1 + 10 + 3 - 4 + 9\n";
- cout << "The result is computed using Phoenix.\n";
- cout << "Type [q or Q] to quit\n\n";
- string str;
- while (getline(cin, str))
- {
- if (str.empty() || str[0] == 'q' || str[0] == 'Q')
- break;
- double n;
- if (primitive_calc(str.begin(), str.end(), n))
- {
- cout << "-------------------------\n";
- cout << "Parsing succeeded\n";
- cout << str << " Parses OK: " << endl;
- cout << "result = " << n;
- cout << "\n-------------------------\n";
- }
- else
- {
- cout << "-------------------------\n";
- cout << "Parsing failed\n";
- cout << "-------------------------\n";
- }
- }
- cout << "Bye... :-) \n\n";
- return 0;
- }
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