<?php
 
function displayuser($s)
{
	$arr = ['77' => 'Arthur', '66' => 'John',  '59' => 'Smith'];
	return $arr[$s];
}
function displayaccount($s)
{
	$arr = ['28' => 'ACCOUNT'];
	return $arr[$s];
}
 
$text = "[userid=77] has created a new task. [userid=59] and [userid=66] is are subscribed. This task is assigned to [accountid=28]";
print "Before: $text\n";
$text = preg_replace_callback('@\[userid=(\d+)]|\[accountid=(\d+)]@', function($m) {
	return !empty($m[1]) ? displayuser($m[1]) : displayaccount($m[2]);
}, $text);
print "After: $text\n";

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