C ++ 11 regex行尾不匹配

I can't get the $ (dollar-sign) to work as documented in C++11 regular expressions. This is with ECMAScript syntax (the default).

我不能让$(美元符号)像C ++ 11正则表达式中记录的那样工作。这是ECMAScript语法(默认)。

Example (regex.cc):

#include <iostream>
#include <regex>

int main() {
    if ( std::regex_search("one\ntwo", std::regex{"one$"}) ) {
        std::cout << "Should match, doesn't." << std::endl;
    }

    if ( std::regex_search("one\ntwo", std::regex{"two$"}
                         , std::regex_constants::match_not_eol) ) {
        std::cout << "Shouldn't match, does." << std::endl;
    }

    return 0;
}

Expected output: Should match, doesn't.

预期输出:应该匹配,不匹配。

Actual output: Shouldn't match, does.

实际输出:不应该匹配,确实如此。

From http://www.cplusplus.com/reference/regex/ECMAScript/:

$ - End of line - Either it is the end of the target sequence, or precedes a line terminator.

$ - 行结束 - 它是目标序列的末尾,或者在行终止符之前。

From http://www.cplusplus.com/reference/regex/regex_search/:

match_not_eol - Not End-Of-Line - The last character is not considered an end of line ("$" does not match).

match_not_eol - Not End-Of-Line - 最后一个字符不被视为行尾(“$”不匹配)。

Tested with Clang 3.3 and 3.4 on FreeBSD 10:

在FreeBSD 10上使用Clang 3.3和3.4进行测试:

clang++ -std=c++11 -stdlib=libc++ -o regex regex.cc && ./regex

What am I missing?

我错过了什么?

1 个解决方案

#1

Looks like you stumbled on LWG issue 2343

看起来你偶然发现LWG问题2343

To quote,

If Multiline is true, $ matches just before LineTerminator.

如果Multiline为true,则$恰好在LineTerminator之前匹配。

If Multiline is false, $ does not match just before LineTerminator.

如果Multiline为false,则$恰好在LineTerminator之前。

[,,,]

Multiline of the existing implementations are as follows:

现有实现的多行如下:

Multiline=false:

libstdc++ r206594

libc++ r199174

Multiline=true:

Visual Studio Express 2013

Visual Studio Express 2013

boost 1.55

Note: using the current SVN version of libc++, your first test IS actually matched, so looks like this LWG issue is going to be resolved in Multiline's favor

注意:使用当前的SVN版本的libc ++,你的第一个测试IS实际上是匹配的,所以看起来这个LWG问题将在Multiline中得到解决

The second issue (match_not_eol ignored) looks like a fairly straightforward implementation bug. Boost.regex doesn't match that test case.

第二个问题(match_not_eol被忽略)看起来像一个相当简单的实现错误。 Boost.regex与该测试用例不匹配。

#1