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f44479bcd3
It is better to manage warnings on our side to know what warnings we need to fix or suppress, and the only thing that header does is disabling deprecation warnings on MSVC and ICC which we would prefer to not show to users.
123 lines
3.6 KiB
C++
123 lines
3.6 KiB
C++
/*=============================================================================
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Copyright (c) 2001-2014 Joel de Guzman
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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///////////////////////////////////////////////////////////////////////////////
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//
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// Plain calculator example demonstrating the grammar. The parser is a
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// syntax checker only and does not do any semantic evaluation.
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//
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// [ JDG May 10, 2002 ] spirit 1
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// [ JDG March 4, 2007 ] spirit 2
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// [ JDG February 21, 2011 ] spirit 2.5
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// [ JDG June 6, 2014 ] spirit x3
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//
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///////////////////////////////////////////////////////////////////////////////
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#include <boost/spirit/home/x3.hpp>
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#include <boost/spirit/home/x3/support/ast/variant.hpp>
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#include <boost/fusion/include/adapt_struct.hpp>
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#include <iostream>
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#include <string>
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#include <list>
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#include <numeric>
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namespace x3 = boost::spirit::x3;
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namespace client
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{
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///////////////////////////////////////////////////////////////////////////////
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// The calculator grammar
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///////////////////////////////////////////////////////////////////////////////
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namespace calculator_grammar
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{
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using x3::uint_;
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using x3::char_;
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x3::rule<class expression> const expression("expression");
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x3::rule<class term> const term("term");
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x3::rule<class factor> const factor("factor");
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auto const expression_def =
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term
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>> *( ('+' >> term)
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| ('-' >> term)
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)
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;
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auto const term_def =
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factor
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>> *( ('*' >> factor)
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| ('/' >> factor)
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)
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;
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auto const factor_def =
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uint_
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| '(' >> expression >> ')'
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| ('-' >> factor)
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| ('+' >> factor)
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;
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BOOST_SPIRIT_DEFINE(
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expression
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, term
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, factor
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);
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auto calculator = expression;
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}
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using calculator_grammar::calculator;
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}
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///////////////////////////////////////////////////////////////////////////////
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// Main program
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///////////////////////////////////////////////////////////////////////////////
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int
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main()
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{
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std::cout << "/////////////////////////////////////////////////////////\n\n";
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std::cout << "Expression parser...\n\n";
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std::cout << "/////////////////////////////////////////////////////////\n\n";
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std::cout << "Type an expression...or [q or Q] to quit\n\n";
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typedef std::string::const_iterator iterator_type;
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std::string str;
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while (std::getline(std::cin, str))
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{
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if (str.empty() || str[0] == 'q' || str[0] == 'Q')
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break;
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auto& calc = client::calculator; // Our grammar
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iterator_type iter = str.begin();
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iterator_type end = str.end();
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boost::spirit::x3::ascii::space_type space;
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bool r = phrase_parse(iter, end, calc, space);
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if (r && iter == end)
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{
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std::cout << "-------------------------\n";
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std::cout << "Parsing succeeded\n";
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std::cout << "-------------------------\n";
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}
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else
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{
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std::string rest(iter, end);
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std::cout << "-------------------------\n";
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std::cout << "Parsing failed\n";
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std::cout << "stopped at: \"" << rest << "\"\n";
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std::cout << "-------------------------\n";
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}
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}
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std::cout << "Bye... :-) \n\n";
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return 0;
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}
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