How to keep empty values in filtered array?

[Finesse]

What

I've found that Filter removes an empty value from the input array after you apply any filter on it:

$filter = new Filter();
$filter->all()->trim();
$result = $filter->filter([
    'one' => ' 1 ',
    'zero' => ' 0 ',
    'space' => ' ',
    'null' => null,
    'false' => false
]);
var_dump($result);
/*
[
    'one' => '1'
]
*/

In this case I don't want to remove empty values (especially the ' 0 ' value), I just want to trim them. If I wanted to remove empty values I would call:

$filter
    ->all()
    ->trim()
    ->callback(function ($value) { return $value === '' ? null : $value; })
    ->removeNull();

What is expected

All the array keys are preserved:

$filter = new Filter();
$filter->all()->trim();
$result = $filter->filter([
    'one' => ' 1 ',
    'zero' => ' 0 ',
    'space' => ' ',
    'null' => null,
    'false' => false
]);
var_dump($result);
/*
[
    'one' => '1',
    'zero' => '0',
    'space' => '',
    'null' => '', // or null
    'false' => ''
]
*/

[Finesse]

Here is my solution:

$input = [
    'one' => ' 1 ',
    'zero' => ' 0 ',
    'space' => ' ',
    'null' => null,
    'false' => false
];
$filter = new Filter();
$filter->values(array_keys($input))->trim();
$result = $filter->filter($input);
var_dump($result);
/*
[
    'one' => '1',
    'zero' => '0',
    'space' => '',
    'null' => null,
    'false' => ''
]
*/

I think this is a dirty hack.

So we should use all() with cautiousness.

[rick-nu]

Thank you for your report @FinesseRus, I will look into this soon, as this shouldn't be happening of course :)

[Finesse]

@RickvdStaaij I don't claim it's a bug, just asking (maybe I understand the Filter behaviour incorrectly). Thank you for the quick response!

I think removing null values and empty strings is more or less acceptable, but removing '0' and false values is not wanted.