| /*============================================================================= |
| 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) |
| =============================================================================*/ |
| /////////////////////////////////////////////////////////////////////////////// |
| // |
| // This calculator example demontrates the use of subrules. |
| // This is discussed in the "Subrule" chapter in the Spirit User's Guide. |
| // |
| // [ JDG 4/11/2002 ] |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| //#define BOOST_SPIRIT_DEBUG // define this for debug output |
| |
| #include <boost/spirit/include/classic_core.hpp> |
| #include <iostream> |
| #include <string> |
| |
| using namespace std; |
| using namespace BOOST_SPIRIT_CLASSIC_NS; |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // |
| // Semantic actions |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| namespace |
| { |
| void do_int(char const* str, char const* end) |
| { |
| string s(str, end); |
| cout << "PUSH(" << s << ')' << endl; |
| } |
| |
| void do_add(char const*, char const*) { cout << "ADD\n"; } |
| void do_subt(char const*, char const*) { cout << "SUBTRACT\n"; } |
| void do_mult(char const*, char const*) { cout << "MULTIPLY\n"; } |
| void do_div(char const*, char const*) { cout << "DIVIDE\n"; } |
| void do_neg(char const*, char const*) { cout << "NEGATE\n"; } |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // |
| // Our calculator grammar (using subrules) |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| struct calculator : public grammar<calculator> |
| { |
| template <typename ScannerT> |
| struct definition { |
| |
| definition(calculator const& /*self*/) |
| { |
| first = ( |
| |
| expression = |
| term |
| >> *( ('+' >> term)[&do_add] |
| | ('-' >> term)[&do_subt] |
| ) |
| , |
| |
| term = |
| factor |
| >> *( ('*' >> factor)[&do_mult] |
| | ('/' >> factor)[&do_div] |
| ) |
| , |
| |
| factor |
| = lexeme_d[(+digit_p)[&do_int]] |
| | '(' >> expression >> ')' |
| | ('-' >> factor)[&do_neg] |
| | ('+' >> factor) |
| ); |
| |
| BOOST_SPIRIT_DEBUG_NODE(first); |
| BOOST_SPIRIT_DEBUG_NODE(expression); |
| BOOST_SPIRIT_DEBUG_NODE(term); |
| BOOST_SPIRIT_DEBUG_NODE(factor); |
| } |
| |
| subrule<0> expression; |
| subrule<1> term; |
| subrule<2> factor; |
| |
| rule<ScannerT> first; |
| rule<ScannerT> const& |
| start() const { return first; } |
| }; |
| }; |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // |
| // Main program |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| int |
| main() |
| { |
| cout << "/////////////////////////////////////////////////////////\n\n"; |
| cout << "\t\tA calculator using subrules...\n\n"; |
| cout << "/////////////////////////////////////////////////////////\n\n"; |
| cout << "Type an expression...or [q or Q] to quit\n\n"; |
| |
| calculator calc; // Our parser |
| |
| string str; |
| while (getline(cin, str)) |
| { |
| if (str.empty() || str[0] == 'q' || str[0] == 'Q') |
| break; |
| |
| parse_info<> info = parse(str.c_str(), calc, space_p); |
| |
| if (info.full) |
| { |
| cout << "-------------------------\n"; |
| cout << "Parsing succeeded\n"; |
| cout << "-------------------------\n"; |
| } |
| else |
| { |
| cout << "-------------------------\n"; |
| cout << "Parsing failed\n"; |
| cout << "stopped at: \": " << info.stop << "\"\n"; |
| cout << "-------------------------\n"; |
| } |
| } |
| |
| cout << "Bye... :-) \n\n"; |
| return 0; |
| } |
| |
| |