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// Copyright (C) 2020 T. Zachary Laine
//
// 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)
//[ roman_numeral_example
#include <boost/parser/parser.hpp>
#include <iostream>
#include <string>
namespace bp = boost::parser;
int main()
{
std::cout << "Enter a number using Roman numerals. ";
std::string input;
std::getline(std::cin, input);
//[ roman_numeral_symbol_tables
bp::symbols<int> const ones = {
{"I", 1},
{"II", 2},
{"III", 3},
{"IV", 4},
{"V", 5},
{"VI", 6},
{"VII", 7},
{"VIII", 8},
{"IX", 9}};
bp::symbols<int> const tens = {
{"X", 10},
{"XX", 20},
{"XXX", 30},
{"XL", 40},
{"L", 50},
{"LX", 60},
{"LXX", 70},
{"LXXX", 80},
{"XC", 90}};
bp::symbols<int> const hundreds = {
{"C", 100},
{"CC", 200},
{"CCC", 300},
{"CD", 400},
{"D", 500},
{"DC", 600},
{"DCC", 700},
{"DCCC", 800},
{"CM", 900}};
//]
//[ roman_numeral_actions
int result = 0;
auto const add_1000 = [&result](auto & ctx) { result += 1000; };
auto const add = [&result](auto & ctx) { result += _attr(ctx); };
//]
//[ roman_numeral_parser
using namespace bp::literals;
auto const parser =
*'M'_l[add_1000] >> -hundreds[add] >> -tens[add] >> -ones[add];
//]
if (bp::parse(input, parser) && result != 0)
std::cout << "That's " << result << " in Arabic numerals.\n";
else
std::cout << "That's not a Roman number.\n";
}
//]
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