string_replace_callback_solution.php

<?php

$template =[
	'@name@' => [
		'User name',
		'Anik',
	],
	'@email@' => [
		'Email',
		'my.mail@mail.com'
	],
	'@address@' => [
		'Address',
		[ 
			'Diamond Head', 
			'Honolulu', 
			'Hawaii'
		],
	],
];

$text = "@name@ has an email of: @email@. He lives in @address@";

function replacer($match){
	global $template;
	if(array_key_exists($match[0], $template)){
		$value_on_match = $template[$match[0]];
		if(is_string($value_on_match[1])){
			return $value_on_match[1];
		} elseif(is_array($value_on_match[1])){
			return implode(", ", $value_on_match[1]);
		}
	}
	return $match[0];
}

$pattern = sprintf("~%s~", implode("|", array_keys($template)));
echo preg_replace_callback($pattern, "replacer", $text) . PHP_EOL;