[Regex]Greta不支持“Named Groups”特性

微软研究院出品的Greta（http://research.microsoft.com/projects/greta/）是一款非常优秀的正则表达式模板类库，GRETA的匹配速度比boost(http://www.boost.org)正则表达式库大约快7倍，比ATL7的CATLRegExp快10倍。你可以通过http://research.microsoft.com/projects/greta/regex_perf.html了解他的超快速度。

但是他并不支持“Named Groups”特性，这在dotNet Regex引擎中是提供的。

在Greta花费了半天时间总是试验不出来这个特性后，只好去问了维护这个引擎的微软工程师。下面是来往信件：

发件人: Chris Quirk [mailto:chrisq…(at)microsoft.com]

发送时间: 2004年9月21日 2:59

收件人: Yun Zheng; Ashish Aggarwal

主题: RE: greta gripe:for groupname syntax

Greta doesn’t support named groups; instead, it uses the more standard approach of numbering them.

So you should check your regex to

"^(\\w+):(\\w+)"

Then you access the first group as capture number 1 and the second as capture number 2, as in Perl, etc.

As far as I know, named captures are a peculiarity of the .NET Regex engine.

From: Yun Zheng

Sent: Sunday, September 19, 2004 9:27 PM

To: Ashish Aggarwal; Chris Quirk

Subject: greta gripe:for groupname syntax

Hi!

I'm using greta now.It's very perfect,but I have a question:

In C#,I can do this:

[C#]

Regex r = new Regex("^(?\\w+):(?\\w+)");

Match m = r.Match("Section1:119900");

But, in VC7+greta-2[1].6.4,I run this codes:

std::string strDest("Section1:119900");

regex::rpattern pat("^(?\\w+):(?\\w+)",

regex::NOCASE|regex::GLOBAL|regex::EXTENDED);

regex::match_results::backref_type br

= pat.match( strDest, results );

when run to construct rpattern,I get bad_regexpr( "bad extension sequence" ) exception.

How does Greta support groupname syntax?

Thanks!

Yun Zheng