Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:67301
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 209.85.217.171 as permitted sender)
MIME-Version: 1.0
Sender: laruence@gmail.com
In-Reply-To: <CABBJUpdWS_y3z9jdHD2_5_tW9dZb29HFQjuNuotH6Eir9iUE5A@mail.gmail.com>
References: <CABBJUpd40Rnq=Ux5viXeNwkSDO2oUYgT+VznWtU0W-7ZDz5ChA@mail.gmail.com>
 <CABBJUpfZTiVH8AUNpknZC9y7uD4CP20KvuqtpZkVKfSDgRheAQ@mail.gmail.com>
 <CAF+90c94mJED9=6vqRAuZMYNfxt6YtcnEuCrhsy2Beh=uBNG9Q@mail.gmail.com>
 <CABBJUpfDgHHF8FaoC5=V9b70zHTKZKZheeCBQg3DWCPaWKuqkw@mail.gmail.com>
 <CAF+90c-zC7tHtB11Zv07ubHqBjKEj2tLninXA93BB5hjQngzfg@mail.gmail.com>
 <CABBJUpf498q9epxACy=jFhxaxiFXYOSnVsSvk1qq8Bzg0oMjUQ@mail.gmail.com>
 <CAAyV7nEsnMAwZstdFPaKCk-=eEdK-wLrq5JgnOy1-MDn+Ca4aQ@mail.gmail.com> <CABBJUpdWS_y3z9jdHD2_5_tW9dZb29HFQjuNuotH6Eir9iUE5A@mail.gmail.com>
Date: Sat, 4 May 2013 22:31:02 +0800
Message-ID: <CABBJUpd6F_JvLwkTr7AfNYoMufT=7wHkOMf88GMnvK=7Xnzf5g@mail.gmail.com>
Cc: PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=047d7b343360555b3204dbe552d9
Subject: Re: [PHP-DEV] Re: [PROPOSAL]Add second to callback of preg_replace_callback
From: laruence@php.net (Laruence)

--047d7b343360555b3204dbe552d9
Content-Type: text/plain; charset=UTF-8

I made a RFC for this: https://wiki.php.net/rfc/second_arg_to_preg_callback

thanks




On Sat, May 4, 2013 at 10:28 PM, Laruence <laruence@php.net> wrote:

>
>
>
> On Sat, May 4, 2013 at 9:46 PM, Anthony Ferrara <ircmaxell@gmail.com>wrote:
>
>> Laruence,
>>
>> > foreach ($replacements as $regex => $callback) {
>> > >     $str = preg_replace_callback($regex, $callback, $str);
>> > > }
>> > >
>> >
>> >  So if there are 10 regex in the array, you will got 10 DO_FCALL. 10
>> times
>> > arguments accept, 10 times etc...
>> >
>> >  and AS I already said: IT is inefficient. I personally can not accept
>> it.
>> >
>> > thanks
>> >
>> >
>> My initial reaction was that the difference in runtime is going to be so
>> insignificant that it's the very definition of a micro-optimization
>> between
>> the two. And unless you're doing it millions of times in a hot-loop, it's
>> never even going to be realized. I was going to reply to that effect.
>>
>> Then I decided to write a quick test.
>>
>> $count = 100;
>>
>> $start = microtime(true);
>> for ($i = 0; $i < $count; $i++) {
>>     $str = "abc";
>>     $str = preg_replace_callback('/a/', function($a) { return
>> strtoupper($a[0]); }, $str);
>>   $str = preg_replace_callback('/b/', function($a) { return
>> strtoupper($a[0]); }, $str);
>>     $str = preg_replace_callback('/c/', function($a) { return
>> strtoupper($a[0]); }, $str);
>>     $str = preg_replace_callback('/a/', function($a) { return
>> strtolower($a[0]); }, $str);
>>     $str = preg_replace_callback('/b/', function($a) { return
>> strtolower($a[0]); }, $str);
>>     $str = preg_replace_callback('/c/', function($a) { return
>> strtolower($a[0]); }, $str);
>> }
>> echo "Completed in " . (microtime(true) - $start) . " Seconds\n";
>>
>> $start = microtime(true);
>> for ($i = 0; $i < $count; $i++) {
>>     $str = "abc";
>>     $str = preg_replace(array(
>>           '/a/e',
>>             '/b/e',
>>             '/c/e',
>>             '/a/e',
>>             '/b/e',
>>             '/c/e',
>>         ),
>>         array(
>>             'strtoupper(\'$1\')',
>>             'strtoupper(\'$1\')',
>>             'strtoupper(\'$1\')',
>>             'strtolower(\'$1\')',
>>             'strtolower(\'$1\')',
>>             'strtolower(\'$1\')',
>>         ),
>>         $str
>>     );
>> }
>> echo "Completed in " . (microtime(true) - $start) . " Seconds\n";
>>
>> So basically, it's comparing the old behavior (one call to preg_replace)
>> that you want to emulate, with what Nikita is suggesting.
>>
>> I ran it on 3v4l (http://3v4l.org/dRjtU) and the results were quite
>> surprising. I was expecting the first to be slightly slower than the
>> second. But the reality surprised me:
>>
>> Completed in 0.00076389312744141 Seconds Completed in 0.0012428760528564
>> Seconds
>>
>> As it turns out, calling preg_replace_callback() multiple times is almost
>> 50% faster than using a single call to preg_replace().
>>
>> It's likely due to the precompiled nature of closures, vs the compilation
>> happening multiple times at invocation in the preg_replace /e case.
>>
>> But it's still worth noting that switching from the /e style to a more
>> traditional preg_replace_callback implementation will get you a
>> significant
>> boost in performance of that.
>>
>> Now, keep in mind, we're talking 0.000005 seconds saved per "execution"
>> (group of 6 replacements). So it's not likely to matter much or be worth
>> worrying about...
>>
> Hey:
>   thanks for the benchmark, but please don't think it's useless just
> because it's monior
>
>   PHP is a web program language, let's think about a high trafiic site,
> which get 100, 000, 000 pv perday.
>
>   100, 000, 000 * 0.0000005 = 500s perday
>
>   and inefficent not always means performance only,  in this case , you
> need to define various functions for different regexs if you use loop style.
>
>   and do you prefer array_walk or foreach when you try to iteraterly
> process an array?
>
>
> thanks
>
>>
>> My $0.02 at least...
>>
>> Anthony
>>
>
>
>
> --
> Laruence  Xinchen Hui
> http://www.laruence.com/
>



-- 
Laruence  Xinchen Hui
http://www.laruence.com/

--047d7b343360555b3204dbe552d9--