Wouldn't it be better to have $params = [ ... ]?

with [ ... ] being a Multiline Array?

Or better return Mage::getUrl('*/*/*', [ ... ]);

I think this will be to much work.

Lets keep it simple.

@sreichel i meant to write the params array like this:

$params = [
    '_current'     => true,
    '_use_rewrite' => true,
    '_query'       => $filterState,
    '_escape'      => true,
];

or like this:

return Mage::getUrl('*/*/*', [
    '_current'     => true,
    '_use_rewrite' => true,
    '_query'       => $filterState,
    '_escape'      => true,
]);

i found a rector for similar stuff, but not quite the right thing:
https://getrector.com/rule-detail/inline-array-return-assign-rector

Edit: i asked if there is an extra rule: rectorphp/rector#9747
there isn't one right now

Yeah, to automate it, but atm i dont wont to spent much time for writing rules.

(there should be some project/OM-related rules first e.g. change to getDataById())

btw ... we also have CodeSniffer/Beatifier, cs-fixer with additional ECS rules, but no one covers this