Making a simple templating engine in PHP - php

Question

I need to write a simple PHP function to replace text between {{ }} characters with their respective data.
Example:
String: "and with strange aeons even {{noun}} may {{verb}}"
$data = ['noun' => 'bird', 'verb' => 'fly'];
Result:
"and with strange aeons even bird may fly"
I have it almost working with the following code based on preg_replace_callback
function compile($str,$data){
foreach ($data as $k => $v) {
$pattern = '/\b(?<!\-)(' . $k . ')\b(?!-)/i';
$str = preg_replace_callback($pattern, function($m) use($v){
return $v;
}, $str);
}
return $str;
}
But I cant seem to account for the {{ }}.
The result looks like this:
"and with strange aeons even {{bird}} may {{fly}}"
How can I adjust the regex and/or code to account for the double curly brackets?
Also, before anyone asks why I'm trying to do this manually rather than use PHP itself or the Smarty plugin -- its too narrow a use case to install a plugin and I cannot use PHP itself because the input string is coming in as raw text from a database. I need to compile that raw text with data stored in a PHP array.

Answer 1

Since you're looping anyway, keep it simple:
foreach ($data as $k => $v) {
$str = str_ireplace('{{'.$k.'}}', $v, $str);
}
You can add a space before {{ and after }} if needed.

Answer 2

You can use
$str = "and with strange aeons even {{noun}} may {{verb}}";
$data = ['noun' => 'bird', 'verb' => 'fly'];
$pattern = '/{{(' . implode('|', array_keys($data)) . ')}}/i';
echo preg_replace_callback($pattern, function($m) use($data){
return $data[strtolower($m[1])];
}, $str);
// => and with strange aeons even bird may fly
See the PHP demo.
The $pattern will look like /{{(noun|verb)}}/i, and will match noun or verb inside double braces while capturing the word itself. The replacement will be the corresponding key value of the $data array. Turning the Group 1 value to lower case with strtolower($m[1]) is required since the keys in the $data array are all lowercase, and the $pattern can match uppercase variants, too.

Answer 3

Make use of strtr() and call it a day:
$string = 'and with strange aeons even {{noun}} may {{verb}}';
$data = ['{{noun}}' => 'bird', '{{verb}}' => 'fly'];
echo strtr( $string, $data );
produces:
and with strange aeons even bird may fly
strtr() is nice because it won't mess up the string in the event of:
$data = ['{{noun}}' => 'bi{{verb}}rd', '{{verb}}' => 'fly'];