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鑰屼粖澶╂垜瑕佸仛鐨勬槸錛屼嬌鐢╞oost::spirit鏉ュ疄鐜板悓鏍風(fēng)殑琛ㄨ揪寮忓垎鏋愬拰璁＄畻銆備紬鎵鍛ㄧ煡錛宐oost鏄疌++涓川閲忓緢楂樼殑搴擄紝琚О涓哄噯鏍囧噯搴擄紝鍥犱負(fù)鍏跺瓨鍦ㄧ殑涓涓緢閲嶈鐨勭洰鐨勫氨鏄負(fù)涓嬩竴浠++搴撴彁渚涢妗堛傜洰鍓嶅凡緇忔湁澶ч噺鐨刡oost搴撴垚涓轟簡(jiǎn)C++鏍囧噯搴撶殑涓閮ㄥ垎銆傛垜鐜板湪瑕佺敤鐨勬槸Boost鐨凷pirit搴?/a>銆傝繖涓簱鍙互鐩存帴鍦–++浠ｇ爜涓挵鍐橢BNF銆傚榪囩紪璇戝師鐞嗙殑鏈嬪弸搴旇瀵規(guī)閮藉緢鐔熸?zhèn)夊Q岃繖鏄竴縐嶆瘮鍫嗘爤鏇寸伒媧葷殑瑙ｆ瀽琛ㄨ揪寮忕敋鑷崇▼搴忕殑鏂瑰紡銆?br>
濡傛灉鎴戜滑瑕佸鐞嗗洓鍒欒繍綆楃殑琛ㄨ揪寮忥紝閭ｄ箞鎴戜滑鍙渶瑕佸湪C++涓啓鍏ヤ笅鍒桬BNF鐨勫畾涔夛細(xì)
group = '(' >> expression >> ')';
factor = integer | group;
term = factor >> *(('*' >> factor) | ('/' >> factor));
expression = term >> *(('+' >> term) | ('-' >> term));
factor = integer | group;
term = factor >> *(('*' >> factor) | ('/' >> factor));
expression = term >> *(('+' >> term) | ('-' >> term));
鎴戜滑灝辨瀯鎴愪簡(jiǎn)榪欎釜琛ㄨ揪寮忕殑鏍煎紡瀹氫箟錛屽畠鍙互寰堣交鏉劇殑澶勭悊涓嬪垪琛ㄨ揪寮忕殑榪愮畻錛?br>
12345
-12345
+12345
1 + 2
1 * 2
1/2 + 3/4
1 + 2 + 3 + 4
1 * 2 * 3 * 4
(1 + 2) * (3 + 4)
(-1 + 2) * (3 + -4)
1 + ((6 * 200) - 20) / 6
(1 + (2 + (3 + (4 + 5))))
-12345
+12345
1 + 2
1 * 2
1/2 + 3/4
1 + 2 + 3 + 4
1 * 2 * 3 * 4
(1 + 2) * (3 + 4)
(-1 + 2) * (3 + -4)
1 + ((6 * 200) - 20) / 6
(1 + (2 + (3 + (4 + 5))))
寰堢畝鍗曞惂錛?br>
浣跨敤榪噛acc鎴栬?lex鐨勬湅鍙嬪榪欑被瀹氫箟鑲畾寰堢啛鎮(zhèn)夈備絾鏄墍涓嶅悓鐨勬槸錛屼粬浠兘鏄鐢ㄦ埛鍐欎竴涓ā鏉匡紝鐒跺悗鐢▂acc鎴栬?lex澶勭悊妯℃澘鐢熸垚鐩稿簲璇█鐨勭▼搴忋傜▼搴忚噧鑲夸笖寰堥毦闃呰銆傝屼笖鐢變簬涓嶆槸鑷繁鍐欑殑紼嬪簭錛岃皟鏁磋搗鏉ユ昏緇忚繃涓姝ユ墜緇紝姣旇緝綣佺悙銆?br>
鑰屼嬌鐢–++鐨勬湅鍙嬪垯涓嶇敤鏈夎繖縐嶇儲(chǔ)鎭鹼紝Boost鐨凷pirit鍏呭垎鍒╃敤浜?jiǎn)C++寮哄ぇ鐨勮娉曞姛鑳姐傛垜浠彲浠ョ洿鎺ュ湪紼嬪簭涓啓鍏ヤ笂榪扮殑琛ㄨ揪寮忓畾涔夛紝鐒跺悗鎴戜滑鐨勭▼搴忓氨鏀寔榪欎簺琛ㄨ揪寮忕殑澶勭悊浜?jiǎn)銆備笉闇瑕佷換浣曢澶栫殑紼嬪簭澶勭悊銆傛墍闇瑕佺殑浠呬粎鏄痠nclude涓浜涘ご鏂囦歡鑰屽凡銆傛槸鐨勶紝浠呬粎鏄痠nclude涓浜涘ご鏂囦歡銆備笉瑕佹媴蹇?jī)闇瑕佸畨瑁呬粈涔堥澶栫殑涓滆タ錛屾垨鑰呴渶瑕侀摼鎺ヤ粈涔堝簱錛屽洜涓篠pirit鐨勫疄鐜板畬鍏ㄦ槸澶存枃浠剁粍鎴愮殑錛屾垜浠笉闇瑕侀摼鎺ヤ換浣曞簱銆傛妸boost鐨勫ご鏂囦歡璺緞鏀懼埌緙栬瘧鏈熶腑錛岀洿鎺ョ紪璇戝氨ok浜?jiǎn)銆傚緢杞誨閥銆?br>
涓嬮潰灝辨槸鎴戠敤Boost Spirit瀹炵幇鐨勫洓鍒欒繍綆楄〃杈懼紡鐨勪唬鐮侊紝鐢變簬鎴戠殑閲嶇偣鏄〃杈懼紡鐨勮В鏋愬拰璁＄畻錛屽洜姝ゆ垜娌℃湁鐗瑰埆澶勭悊浜旇繘鍒跺埌鍗佽繘鍒剁殑杞崲闂銆備絾鏄坊鍔犺搗鏉ユ樉鐒朵笉楹葷儲(chǔ)銆傛垜鍙粰鍑轟簡(jiǎn)涓涓簲榪涘埗鏁存暟閮ㄥ垎鐨勮緭鍑恒傚鏋滆〃杈懼紡鍑洪敊錛屽彲浠ョ洿鎺ョ敤綆ご鎸囧嚭鍝噷鏈夐敊銆傚緢鏂逛究璋冭瘯錛氾級(jí) 鑰屼笖浠ｇ爜閲忔槸鍘熸枃绔犵殑浜斿垎涔嬩竴銆傜紪璇戝悗涔熶粎浠呮槸35KB錛屼篃涓嶆槸寰堣噧鑲跨殑銆?br>
澶у澶氫簡(jiǎn)瑙ｆ爣鍑嗗簱錛屽浜?jiǎn)瑙oost錛孋++鐨勭紪鐮佷篃鏄緢鏈夎叮鍛崇殑銆?br>
#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
#include <iostream>
#include <string>
#include <cmath>
#include <limits>
using namespace boost::spirit;
using namespace boost::spirit::qi;
using namespace boost::spirit::ascii;
using namespace boost::spirit::arg_names;
template <typename Iterator>
struct calculator : grammar<Iterator, double(), space_type>
{
calculator() : calculator::base_type(expression)
{
expression = term[_val = _1]
>> *( ('+' >> term[_val += _1]) | ('-' >> term[_val -= _1]) );
term = factor[_val = _1]
>> *( ('*' >> factor[_val *= _1]) | ('/' >> factor[_val /= _1]) );
factor = double_[_val = _1] | '(' >> expression[_val = _1] >> ')'
| ('-' >> factor[_val = -_1]) | ('+' >> factor[_val = _1]);
}
rule<Iterator, double(), space_type> expression, term, factor, number;
};
// http://www.jb.man.ac.uk/~slowe/cpp/itoa.html
std::string itoa(int value, int base) {
const int MAX_DIGITS = 35;
const char* DIGITS = "0123456789abcdefghijklmnopqrstuvwxyz";
std::string buf;
buf.reserve( MAX_DIGITS ); // Pre-allocate enough space.
if (base < 2 || base > 36) return buf;
int quotient = value;
do {
buf.push_back(DIGITS[ std::abs(quotient % base) ]);
quotient /= base;
} while ( quotient );
if ( value < 0) buf.push_back('-');
std::reverse( buf.begin(), buf.end() );
return buf;
}
int main(int argc, char* argv[])
{
std::cout << "璇瘋緭鍏ヤ竴涓〃杈懼紡錛屽錛?+2.5*(6-25/4)-8.32" << std::endl << std::endl;
std::cout << "鎴栬緭鍏閫鍑恒?/span>" << std::endl << std::endl;
std::cout << "> ";
calculator<std::string::const_iterator> calc;
std::string str;
double result;
while (std::getline(std::cin, str))
{
if (str.empty() || str[0] == 'q' || str[0] == 'Q')
break;
std::string::const_iterator iter = str.begin();
std::string::const_iterator end = str.end();
bool r = phrase_parse(iter, end, calc, result, space);
if (r && iter == end)
{
std::cout << "杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?/span>";
if (result == std::numeric_limits<double>::infinity())
std::cout << "∞";
else if (result == std::numeric_limits<double>::quiet_NaN())
std::cout << "緇撴灉闈炴暟鍊?/span>";
else
{
std::cout << result << std::endl;
std::cout << "鏁存暟閮ㄥ垎杞崲涓?榪涘埗涓猴細(xì)" << itoa(static_cast<int>(result), 5);
}
std::cout << std::endl;
}
else
{
std::cout << "[杈撳叆鐨勮〃杈懼紡閿欒]" << std::endl;
std::cout << str << std::endl;
std::cout << std::string(iter - str.begin(), '-') << "^" << std::endl;
}
std::cout << std::endl << "> ";
}
return 0;
}
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
#include <iostream>
#include <string>
#include <cmath>
#include <limits>
using namespace boost::spirit;
using namespace boost::spirit::qi;
using namespace boost::spirit::ascii;
using namespace boost::spirit::arg_names;
template <typename Iterator>
struct calculator : grammar<Iterator, double(), space_type>
{
calculator() : calculator::base_type(expression)
{
expression = term[_val = _1]
>> *( ('+' >> term[_val += _1]) | ('-' >> term[_val -= _1]) );
term = factor[_val = _1]
>> *( ('*' >> factor[_val *= _1]) | ('/' >> factor[_val /= _1]) );
factor = double_[_val = _1] | '(' >> expression[_val = _1] >> ')'
| ('-' >> factor[_val = -_1]) | ('+' >> factor[_val = _1]);
}
rule<Iterator, double(), space_type> expression, term, factor, number;
};
// http://www.jb.man.ac.uk/~slowe/cpp/itoa.html
std::string itoa(int value, int base) {
const int MAX_DIGITS = 35;
const char* DIGITS = "0123456789abcdefghijklmnopqrstuvwxyz";
std::string buf;
buf.reserve( MAX_DIGITS ); // Pre-allocate enough space.
if (base < 2 || base > 36) return buf;
int quotient = value;
do {
buf.push_back(DIGITS[ std::abs(quotient % base) ]);
quotient /= base;
} while ( quotient );
if ( value < 0) buf.push_back('-');
std::reverse( buf.begin(), buf.end() );
return buf;
}
int main(int argc, char* argv[])
{
std::cout << "璇瘋緭鍏ヤ竴涓〃杈懼紡錛屽錛?+2.5*(6-25/4)-8.32" << std::endl << std::endl;
std::cout << "鎴栬緭鍏閫鍑恒?/span>" << std::endl << std::endl;
std::cout << "> ";
calculator<std::string::const_iterator> calc;
std::string str;
double result;
while (std::getline(std::cin, str))
{
if (str.empty() || str[0] == 'q' || str[0] == 'Q')
break;
std::string::const_iterator iter = str.begin();
std::string::const_iterator end = str.end();
bool r = phrase_parse(iter, end, calc, result, space);
if (r && iter == end)
{
std::cout << "杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?/span>";
if (result == std::numeric_limits<double>::infinity())
std::cout << "∞";
else if (result == std::numeric_limits<double>::quiet_NaN())
std::cout << "緇撴灉闈炴暟鍊?/span>";
else
{
std::cout << result << std::endl;
std::cout << "鏁存暟閮ㄥ垎杞崲涓?榪涘埗涓猴細(xì)" << itoa(static_cast<int>(result), 5);
}
std::cout << std::endl;
}
else
{
std::cout << "[杈撳叆鐨勮〃杈懼紡閿欒]" << std::endl;
std::cout << str << std::endl;
std::cout << std::string(iter - str.begin(), '-') << "^" << std::endl;
}
std::cout << std::endl << "> ";
}
return 0;
}
榪愯緇撴灉濡備笅錛?br>
璇瘋緭鍏ヤ竴涓〃杈懼紡錛屽錛?/span>3+2.5*(6-25/4)-8.32
鎴栬緭鍏閫鍑恒?br>
> 3+2.5*(6-25/4)-8.32
杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?/span>-5.945
鏁存暟閮ㄥ垎杞崲涓?榪涘埗涓猴細(xì)-10
> -6
杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?/span>-6
鏁存暟閮ㄥ垎杞崲涓?榪涘埗涓猴細(xì)-11
> 6
杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?/span>6
鏁存暟閮ㄥ垎杞崲涓?榪涘埗涓猴細(xì)11
> 1/0
杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?#8734;
> 23 + 4 ((5)-3* 6) + (-1)
[杈撳叆鐨勮〃杈懼紡閿欒]
23 + 4 ((5)-3* 6) + (-1)
-------^
> 23 + 4 ( ( 5-3*6) +1)
[杈撳叆鐨勮〃杈懼紡閿欒]
23 + 4 ( ( 5-3*6) +1)
-------^
> 23 + 4 + ( -5 *3)
杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?/span>12
鏁存暟閮ㄥ垎杞崲涓?榪涘埗涓猴細(xì)22
>
鎴栬緭鍏閫鍑恒?br>
> 3+2.5*(6-25/4)-8.32
杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?/span>-5.945
鏁存暟閮ㄥ垎杞崲涓?榪涘埗涓猴細(xì)-10
> -6
杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?/span>-6
鏁存暟閮ㄥ垎杞崲涓?榪涘埗涓猴細(xì)-11
> 6
杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?/span>6
鏁存暟閮ㄥ垎杞崲涓?榪涘埗涓猴細(xì)11
> 1/0
杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?#8734;
> 23 + 4 ((5)-3* 6) + (-1)
[杈撳叆鐨勮〃杈懼紡閿欒]
23 + 4 ((5)-3* 6) + (-1)
-------^
> 23 + 4 ( ( 5-3*6) +1)
[杈撳叆鐨勮〃杈懼紡閿欒]
23 + 4 ( ( 5-3*6) +1)
-------^
> 23 + 4 + ( -5 *3)
杈撳叆璇硶姝ｇ‘錛岃〃杈懼紡鐨勫間負(fù)錛?/span>12
鏁存暟閮ㄥ垎杞崲涓?榪涘埗涓猴細(xì)22
>
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