[Regex]Greta不支持“Named Groups”特性

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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。<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

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: <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><chsdate w:st="on" isrocdate="False" islunardate="False" day="21" month="9" year="2004">2004<span lang="EN-US" style="FONT-FAMILY: 宋体; mso-ascii-font-family: Arial; mso-hansi-font-family: 'Times New Roman'"><span lang="EN-US">年</span></span>9<span lang="EN-US" style="FONT-FAMILY: 宋体; mso-ascii-font-family: Arial; mso-hansi-font-family: 'Times New Roman'"><span lang="EN-US">月</span></span>21<span lang="EN-US" style="FONT-FAMILY: 宋体; mso-ascii-font-family: Arial; mso-hansi-font-family: 'Times New Roman'"><span lang="EN-US">日</span></span></chsdate> 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.

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From: Yun Zheng
Sent: Sunday, September 19, 2004 <time w:st="on" minute="27" hour="21">9:27 PM</time>
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

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