Change config array with regex

replace.php

<?php

$boolean = true;

$array = <<<'EOT'
[
	'db'=>'mydb',
	'user'=>'root',
	'pass'=>'',
	'host'=>'localhost',
	'date'=>$boolean ? 'ja' : 'nee',
];
EOT;

$newVals=['db'=>'testdb'];

echo preg_replace_callback("/'([\w ]+)'=>'([\w ]+)',/",
function($matches) use($newVals) {
	$val = isset($newVals[$matches[1]]) ? $newVals[$matches[1]] : $matches[2];
	return "'$matches[1]'=>'$val'',";
},
$array);