99 lines
3.0 KiB
C++
99 lines
3.0 KiB
C++
/*=============================================================================
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Copyright (c) 2002-2015 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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// A parser for summing a comma-separated list of numbers using phoenix.
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//
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// [ JDG June 28, 2002 ] spirit1
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// [ JDG March 24, 2007 ] spirit2
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// [ JDG May 12, 2015 ] spirit X3
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//
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///////////////////////////////////////////////////////////////////////////////
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#include <boost/config/warning_disable.hpp>
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#include <boost/spirit/home/x3.hpp>
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#include <iostream>
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#include <string>
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namespace client
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{
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namespace x3 = boost::spirit::x3;
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namespace ascii = boost::spirit::x3::ascii;
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using x3::double_;
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using ascii::space;
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using x3::_attr;
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///////////////////////////////////////////////////////////////////////////
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// Our adder
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///////////////////////////////////////////////////////////////////////////
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template <typename Iterator>
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bool adder(Iterator first, Iterator last, double& n)
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{
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auto assign = [&](auto& ctx){ n = _attr(ctx); };
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auto add = [&](auto& ctx){ n += _attr(ctx); };
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bool r = x3::phrase_parse(first, last,
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// Begin grammar
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(
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double_[assign] >> *(',' >> double_[add])
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)
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,
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// End grammar
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space);
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if (first != last) // fail if we did not get a full match
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return false;
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return r;
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}
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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 << "\t\tA parser for summing a list of numbers...\n\n";
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std::cout << "/////////////////////////////////////////////////////////\n\n";
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std::cout << "Give me a comma separated list of numbers.\n";
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std::cout << "The numbers are added using Phoenix.\n";
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std::cout << "Type [q or Q] to quit\n\n";
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std::string str;
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while (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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double n;
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if (client::adder(str.begin(), str.end(), n))
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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 << str << " Parses OK: " << std::endl;
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std::cout << "sum = " << n;
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std::cout << "\n-------------------------\n";
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}
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else
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{
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std::cout << "-------------------------\n";
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std::cout << "Parsing failed\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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