Path: csiph.com!usenet.pasdenom.info!aioe.org!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: =?UTF-8?B?Sm9zaHVhIENyYW5tZXIg8J+Qpw==?= <Pidgeot18@verizon.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: regex tidy
Date: Fri, 23 May 2014 15:05:41 -0500
Organization: A noiseless patient Spider
Lines: 24
Message-ID: <llo9mp$ej7$1@dont-email.me>
References: <375vn9th0bc1faa04eg136be53hbvfjq4v@4ax.com> <o9GdnRy5BZPqP-LOnZ2dnUVZ7vGdnZ2d@giganews.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Injection-Date: Fri, 23 May 2014 20:05:46 +0000 (UTC)
Injection-Info: mx05.eternal-september.org; posting-host="8b6ddcc38ecbed2f71b30fabadb8aa0b"; logging-data="14951"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX18ZpNtqczKyORuZMOxfVOH8ZkMpKb7YJa0="
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:30.0) Gecko/20100101 Thunderbird/30.0
In-Reply-To: <o9GdnRy5BZPqP-LOnZ2dnUVZ7vGdnZ2d@giganews.com>
Cancel-Lock: sha1:1nwl4vqybqV/JmMQSId2sjCZ/jI=
Xref: csiph.com comp.lang.java.programmer:28552

On 5/23/2014 2:33 PM, Leif Roar Moldskred wrote:
> Roedy Green <see_website@mindprod.com.invalid> wrote:
>>
>> What would a Java regex tidier do?
>>
>
> Evil.
>
> Regular expressions should be written to as closely as
> possible mirror a mental or conceptual model of the
> inputs it will match, and not to be as short or compact
> as possible.
>
> For instance, to match dates on the pattern "YY-MM-dd"
> your regular expression should be "\\d{2}-\\d{2}-\\d{2}"
> and not "((^|-)\\d{2}){3}"

Those two regexes aren't actually equivalent. The latter matches 
-00-00-00, for example. I assume you meant "\\d{2}(?:-\\d{2}){2}"?


-- 
Beware of bugs in the above code; I have only proved it correct, not 
tried it. -- Donald E. Knuth