python vs. grep

[Kam-Hung Soh]

On Tue, 13 May 2008 00:03:08 +1000, Ricardo Aráoz <ricaraoz at gmail.com>  
wrote:

> Ville Vainio wrote:
>> On May 8, 8:11 pm, Ricardo Aráoz <ricar... at gmail.com> wrote:
>>
>>> All these examples assume your regular expression will not span  
>>> multiple
>>> lines, but this can easily be the case. How would you process the file
>>> with regular expressions that span multiple lines?
>>  re.findall/ finditer, as I said earlier.
>>
>
> Hi, sorry took so long to answer. Too much work.
>
> findall/finditer do not address the issue, they merely find ALL the  
> matches in a STRING. But if you keep reading the files a line at a time  
> (as most examples given in this thread do) then you are STILL in trouble  
> when a regular expression spans multiple lines.
> The easy/simple (too easy/simple?) way I see out of it is to read THE  
> WHOLE file into memory and don't worry. But what if the file is too  
> heavy? So I was wondering if there is any other way out of it. Does grep  
> read the whole file into memory? Does it ONLY process a line at a time?
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>

Standard grep can only match a line at a time.  Are you thinking about  
"sed", which has a sliding window?

See http://www.gnu.org/software/sed/manual/sed.html, Section 4.13

-- 
Kam-Hung Soh <a href="http://kamhungsoh.com/blog">Software Salariman</a>