プログラマ専用SNS ミクプラ

コード:

// test1.cpp : コンソール アプリケーションのエントリ ポイントを定義します。
//

#include "stdafx.h"

#include <algorithm>
#include <cmath>
#include <limits>
#include <iterator>
#include <iostream>
#include <stdio.h>
#include <boost/fusion/tuple.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>

namespace qi = boost::spirit::qi;

namespace exprgrammar {	

	namespace {

		class lazy_pow_	//「^」の演算
		{
		public:
			double operator()(double x, double y) const
			{
				return std::pow(x, y);
			}
		};
		class lazy_puts_	//「put」の実験(文字列の扱い)
		{
		public:
			int operator[](char *x) const
			{
				return puts(x);
			}
		};
		class lazy_onefunc_	//引数１つのやつ
		{
		public:
			template <typename F, typename A1>
			A1 operator()(F f, A1 a1) const
			{
				return f(a1);
			}
		};

	}

	//メイン処理
	template <typename S, typename Iterator>
	struct grammar :public qi::grammar<Iterator, S(), qi::space_type>
	{

		// 定数
		struct constant_ :public qi::symbols<typename std::iterator_traits<Iterator>::value_type, S>
		{
			constant_()
			{
				this->add
					(_T("e"), 2.718281828459)
					(_T("pi"), 3.141592653589)
					;
			}
		} constant;

		// 引数１つのやつ
		struct onefunc_ :public qi::symbols<typename std::iterator_traits<Iterator>::value_type, S(*)(S)>
		{
			onefunc_()
			{
				this->add
					("cos", static_cast<S(*)(S)>(&std::cos))
					("sin", static_cast<S(*)(S)>(&std::sin))
					("tan", static_cast<S(*)(S)>(&std::tan))
					;
			}
		} onefunc;

		qi::rule<Iterator, S(), qi::space_type> expression, term, factor, primary;
		qi::rule<Iterator, char(), qi::space_type> character;

		grammar() : grammar::base_type(expression)
		{
			using boost::spirit::qi::real_parser;
			using boost::spirit::qi::real_policies;
			real_parser<S, real_policies<S> > real;

			using qi::_1;
			using qi::_2;
			using qi::no_case;
			using qi::_val;

			boost::phoenix::function<lazy_pow_>   lazy_pow;
			boost::phoenix::function<lazy_puts_>   lazy_puts;
			boost::phoenix::function<lazy_onefunc_> lazy_onefunc;

			expression = term[_val = _1] >> *(('+' >> term[_val += _1])
				| ('-' >> term[_val -= _1]))
				;

			term = factor[_val = _1] >> *(('*' >> factor[_val *= _1])
				| ('/' >> factor[_val /= _1]))
				;

			factor = primary[_val = _1] >> *('^' >> factor[_val = lazy_pow(_val, _1)])
				;

			primary = real[_val = _1]
				| ('(' >> expression[_val = _1] >> _T(')'))
				| ('-' >> primary[_val = -_1])
				| ('+' >> primary[_val = _1])
				| (no_case[onefunc] >> '(' >> expression >> ')')[_val = lazy_onefunc(_1, _2)]	//引数1つ
				| (no_case[constant])[_val = _1]	//定数
				//| ("puts(" >> character >> ')')[_val = lazy_puts[_1]]	//文字列の実験
				;

			character = '"' >> *(qi::char_)[_val = _1] >> '"'	//文字の読み込み
				;
		}
	};

}

int main(void) {

	std::string str;
	std::string::const_iterator first, last;

	exprgrammar::grammar<double, std::string::const_iterator> c;
	double Result;

	while (1)	//無限ループ
	{
		std::cin >> str;
		first = str.begin(); last = str.end();	//先頭と末尾の取得
		bool success = qi::phrase_parse(first, last, c,qi::space, Result);

		if ((success) && (first == last)) {
			std::cout << "Result: " << Result << std::endl;
		}// 計算結果が出力される
		else break;
	}

	system("pause");	//キー入力待ち
	return 0;
}