# Implode() FR and Patch

- Thread: https://externals.io/message/42119
- Original archive: https://news-web.php.net/php.internals/42119
- Started by Igor Feghali on 2008-12-06T02:21:21+00:00
- Messages: 11
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## #42119 — Igor Feghali — 2008-12-06T02:21:21+00:00

URL: https://externals.io/message/42119#42119

Hello There,

I would like to propose a third argument to `implode()`, named
skip_empty, that will cause empty elements to be ignored when
generating the implode string. By empty I mean everything that
converts to an empty string such as '', false, null, etc.

For example:

<?php
$a = array(1,'',2,null,3,0,4,true,5,false,false);
echo implode(',', $a); // old behavior
echo "\n";
echo implode(',', $a, true); // new feature
echo "\n";
echo $foo;
echo "\n";
?>

Will output:

1,,2,,3,0,4,1,5,,
1,2,3,0,4,1,5

Obviously the new parameter defaults to 'false' for backwards compatibility.

The patch file is attached for evaluation, review, feedback etc.
Please keep in mind that this is my first time playing with PHP source
so expect flaws on my code.

I did a few simple tests (using `time`, if someone has a non buggy
valgrind for OS X please let me know) against 5.3 CVS (named php53 in
examples) and my patched version (named php+ in examples). The PHP
scripts are right below the tests. Looking at the results I would say
there is almost no performance loss.

Before I place a feature request at PHP.net I would love to hear some
feedback here, or even a yes/no for this feature.

Best Regards,
Igor Feghali.

=== TEST 1 ===
$ time ./php53 /tmp/more_small.php
real    0m0.257s
user    0m0.223s
sys     0m0.032s

$ time ./php53 /tmp/more_small.php
real    0m0.258s
user    0m0.224s
sys     0m0.032s

$ time ./php53 /tmp/more_small.php
real    0m0.260s
user    0m0.225s
sys     0m0.032s

$ time ./php+ /tmp/more_small.php
real    0m0.261s
user    0m0.226s
sys     0m0.033s

$ time ./php+ /tmp/more_small.php
real    0m0.258s
user    0m0.224s
sys     0m0.032s

$ time ./php+ /tmp/more_small.php
real    0m0.260s
user    0m0.225s
sys     0m0.033s


=== TEST 2 ===
$ time ./php53 /tmp/less_big.php
real    0m0.328s
user    0m0.205s
sys     0m0.120s

$ time ./php53 /tmp/less_big.php
real    0m0.328s
user    0m0.206s
sys     0m0.120s

$ time ./php53 /tmp/less_big.php
real    0m0.326s
user    0m0.205s
sys     0m0.119s

$ time ./php+ /tmp/less_big.php
real    0m0.330s
user    0m0.206s
sys     0m0.122s

$ time ./php+ /tmp/less_big.php
real    0m0.330s
user    0m0.206s
sys     0m0.121s

$ time ./php+ /tmp/less_big.php
real    0m0.333s
user    0m0.207s
sys     0m0.124s


=== TEST 3 ===
$ time ./php+ /tmp/lots_null.php
real    0m0.263s
user    0m0.229s
sys     0m0.032s

$ time ./php+ /tmp/lots_null.php
real    0m0.261s
user    0m0.227s
sys     0m0.032s

$ time ./php+ /tmp/lots_null.php
real    0m0.260s
user    0m0.226s
sys     0m0.032s

$ time ./php+ /tmp/no_null.php
real    0m0.259s
user    0m0.226s
sys     0m0.032s

$ time ./php+ /tmp/no_null.php
real    0m0.257s
user    0m0.223s
sys     0m0.031s

$ time ./php+ /tmp/no_null.php
real    0m0.264s
user    0m0.229s
sys     0m0.032s

=== SCRIPTS ===
less_big.php
<?php

$str = str_repeat(str_repeat('foo', 1000).',', 11345);
$arr = explode(',', $str);

$out = implode(',', $arr);

lots_null.php
<?php

$str = str_repeat('foo,,', 99999);
$arr = explode(',', $str);

$out = implode(',', $arr);

more_small.php
<?php

$str = str_repeat('foo,bar,', 99999);
$arr = explode(',', $str);

$out = implode(',', $arr);

no_null.php
<?php

$str = str_repeat('foo,,', 99999);
$arr = explode(',', $str);

$out = implode(',', $arr, true);

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## #42121 — Kenan R Sulayman — 2008-12-06T09:41:13+00:00

URL: https://externals.io/message/42119#42121 · In reply to: #42119

Dear Igor,
that's a really great feature!

A question: hasn't the new one got a better performance ?

Thanks,
--
(c) Kenan Sulayman
Freelance Designer and Programmer

Life's Live Poetry
http://MyJurnal.tk/

---

## #42122 — Igor Feghali — 2008-12-06T10:25:47+00:00

URL: https://externals.io/message/42119#42122 · In reply to: #42121

Hello Kenan,

Thank you for your feedback.


> A question: hasn't the new one got a better performance ?

According to my tests I would say they perform are equal. Please let
me know if you did any deeper tests.

PS: on string.c where one read :

implstr.len--;

should be:

implstr.len -= Z_STRLEN_P(delim);

Best Regards,
Igor Feghali.

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## #42123 — Kenan R Sulayman — 2008-12-06T10:35:31+00:00

URL: https://externals.io/message/42119#42123 · In reply to: #42122

Dear Igor,
in local tests, here on my server, the performance was,
every time I did it, at least 0.02 Second up to 0.1 Second faster than the
origin.

I'd appreciate, if this feature got included into the next build.

Thanks,
--
(c) Kenan Sulayman
Freelance Designer and Programmer

Life's Live Poetry
http://MyJurnal.tk/

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## #42124 — Kenan R Sulayman — 2008-12-06T10:37:21+00:00

URL: https://externals.io/message/42119#42124 · In reply to: #42123

I'd appreciate it*

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## #42125 — Igor Feghali — 2008-12-06T14:00:09+00:00

URL: https://externals.io/message/42119#42125 · In reply to: #42119

Please see attached a new patch that fixes the problem with delimiters
bigger than one char (that's what happens when you code after
midnight). Also, as suggested by Hannes, skip_empty is now being
parsed as zend boolean (b) instead of zval (Z).

Regards,
Igor Feghali.

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## #42129 — Lars Strojny — 2008-12-06T23:07:46+00:00

URL: https://externals.io/message/42119#42129 · In reply to: #42119

Hi Igor,

thanks for the patch, I think it is an idea worth considering. Except
that the proposed solution with executing `array_filter()` might be
enough. You ran into a situation where this became a bottleneck in your
code?

Am Samstag, den 06.12.2008, 00:21 -0200 schrieb Igor Feghali:
> Hello There,
> 
> I would like to propose a third argument to `implode()`, named
> skip_empty, that will cause empty elements to be ignored when
> generating the implode string. By empty I mean everything that
> converts to an empty string such as '', false, null, etc.

For consistency, if we decide to introduce that for `implode()`, we should
do it for `explode()` too.

php -r "var_dump(explode(',', 'foo,,bla'));"
array(3) {
  [0]=>
  string(3) "foo"
  [1]=>
  string(0) ""
  [2]=>
  string(3) "bla"
}

and

php -r "var_dump(explode(',', 'foo,,bla', true));"
array(2) {
  [0]=>
  string(3) "foo"
  [1]=>
  string(3) "bla"
}

Anyway, would you mind writing a proper RFC for the addition?

cu, Lars
-- 
   Jabber: lars@strojny.net
   Weblog: http://usrportage.de

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## #42130 — Igor Feghali — 2008-12-07T00:38:25+00:00

URL: https://externals.io/message/42119#42130 · In reply to: #42129

> enough. You ran into a situation where this became a bottleneck in your
> code?

nope. I just think its something too "simple", too "obvious" and too
"frequent" so it deserves the love of php internals. Having to call
 `array_filter()` and yet a callback function just to check the emptiness
of an element is too much of a hassle and a waste of both - running
and development time.

> For consistency, if we decide to introduce that for `implode()`, we should
> do it for `explode()` too.

Actually that's already on my plans but I was waiting some feedback on
 `implode()` first.

> Anyway, would you mind writing a proper RFC for the addition?

Absolutely. I would appreciate some directions on that though. Can I
just follow the template of, say http://wiki.php.net/rfc/traits ?

Regards,
Igor Feghali.

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## #42131 — Lars Strojny — 2008-12-07T00:52:45+00:00

URL: https://externals.io/message/42119#42131 · In reply to: #42130

Hi Igor,

Am Samstag, den 06.12.2008, 22:38 -0200 schrieb Igor Feghali:
> 
[...]
> nope. I just think its something too "simple", too "obvious" and too
> "frequent" so it deserves the love of php internals. Having to call
> `array_filter()` and yet a callback function just to check the emptiness
> of an element is too much of a hassle and a waste of both - running
> and development time.

Alright, than I would appreciate a few real world use cases.

[... Same for explode ...]
> Actually that's already on my plans but I was waiting some feedback on
> `implode()` first.

Cool!

> > […]
> 
> Absolutely. I would appreciate some directions on that though. Can I
> just follow the template of, say http://wiki.php.net/rfc/traits ?


I guess you meant "Absolutely not" ;-)
The procedure: register a wiki account and start using the "template"
from the traits proposal. We are pretty liberal with adding/removing
chapters, so adjust it as much as you need it to make your point clear.

cu, Lars
-- 
   Jabber: lars@strojny.net
   Weblog: http://usrportage.de

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## #42132 — Igor Feghali — 2008-12-07T01:35:38+00:00

URL: https://externals.io/message/42119#42132 · In reply to: #42131

> Alright, than I would appreciate a few real world use cases.

Ok one immediate use case I can think of:

http://pear.php.net/package/Numbers_Words

In brazilian portuguese we write numbers like that:

1023 => mil e vinte e tres
123 => cento e vinte e tres
23 => vinte e tres
20 => vinte

So we can have an array that binds '3' to 'tres', '2' as a dozen to
'vinte', zero to false or empty string, etc. Parse the numbers from
left to right adding each word as an array element. In the end we can
just implode everything using the delimiter ' e '. Using actual
implode for the number 1023 would result as 'mil e e vinte e tres'
instead of just 'mil e vinte e tres'.

Using array_filter before every `implode()` would add a big visual
overhead. I don't want to get into deeper details but translating
numbers to pt_br words is a lot more complex. We actually have to
parse, evaluate and `implode()` every "chunk" of three numbers first,
then add all the chunks to a new array and finally `implode()`
everything together because there are different rules for inter-chunks
"relationship" and intra-chunks relationship.

I am not saying the use of array_filter *is* a bottleneck. But I am
sure there are a *lot* of heavy applications out there that runs a lot
happier with any bit of performance gain. Also less code means happier
programmers. Example:

function myfunc($var) {
// logic to test if var is not null, not false, not empty string etc.
}

// NOTE: leaving the callback function empty is not desired. 0 and 0.0
should not be skipped in the implode array !
array_filter($arr, 'myfunc');
implode('foo', $arr);

against:

implode('foo', $arr, true);

Again this is just one single example. I had to deal with this
situation a *lot* of times before.

> I guess you meant "Absolutely not" ;-)

Absolutely (now I think its used correctly...)

> The procedure: register a wiki account and start using the "template"
> from the traits proposal. We are pretty liberal with adding/removing
> chapters, so adjust it as much as you need it to make your point clear.

Right.

Best Regards,
Igor Feghali.

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## #42144 — Christian Schneider — 2008-12-08T13:01:16+00:00

URL: https://externals.io/message/42119#42144 · In reply to: #42132

Igor Feghali wrote:
> // NOTE: leaving the callback function empty is not desired. 0 and 0.0
> should not be skipped in the implode array !
> array_filter($arr, 'myfunc');
> implode('foo', $arr);
> 
> against:
> 
> implode('foo', $arr, true);

implode('foo', array_filter($arr, 'myfunc'));

Simple enough and generic.
Not worth adding IMHO.

- Chris