In PHP is there a better way to do dynamic templating - php

Question

I'm creating module for an application which will have simple custom templating with tags that will be replaced with data from a database. The field names will be different in each instance of this module. I want to know if there is a better way to do this.
The code below is what I've come up with, But I believe there must be a better way. I struggled with preg_split and preg_match_all and just hit my limit so I did it the dumb person way.
<?php
$customTemplate = "
<div>
<<This>>
<<that>>
</div>
";
function process_template ($template, $begin = '<<', $end = '>>') {
$begin_exploded = explode($begin, $template);
if (is_array($begin_exploded)) {
foreach ($begin_exploded as $key1 => $value1) {
$end_exploded = explode($end, $value1);
if (is_array($end_exploded)) {
foreach ($end_exploded as $key2 => $value2) {
$tag = $begin.$value2.$end;
$variable = trim($value2);
$find_it = strpos($template,$tag);
if ($find_it !== false) {
//str_replace ($tag, $MyClass->get($variable), $template );
$template = str_replace ($tag, $variable, $template);
}
}
}
}
}
return $template;
}
echo(process_template($customTemplate));
/* Will Echo
<div>
This
that
</div>
*/
?>
In the future I will connect $MyClass->get() to replace the tag with the proper data. And the custom template will be built by the user.

Answer 1

Rather than preg_split or preg_match I would rather use preg_replace_callback, since you are doing replacements, and the replacement value is derived from what looks like will end up being a method in another class.
function process_template($template, $begin = '<<', $end = '>>') {
// get $MyClass in the function scope somehow. Maybe pass it as another parameter?
return preg_replace_callback("/$begin(\w+)$end/", function($var) use ($MyClass) {
return $MyClass->get($var[1]);
}, $template);
}
Here's an example to play with: https://3v4l.org/N1p03
I assume this is just for fun/learning. If I really needed to use a template for something I would rather start with composer require "twig/twig:^2.0" instead. In fact, if you're interested in learning more about how it works you could go check out a well-established system like twig or blade does it. (Better than I've done it in this answer.)

Answer 2

There are tons templating engines around, but sometimes... just add complexity and dependencies for a maybe simple thing. This a modified sample of what I used for make some javascript corrections. This works for your template.
function process_template($html,$b='<<',$e='>>'){
$replace=['this'=>'<input name="this" />','that'=>'<input name="that" />'];
if(preg_match_all('/('.$b.')(.*?)('.$e.')/is',$html,$matches,PREG_SET_ORDER|PREG_OFFSET_CAPTURE)){
$t='';$o=0;
foreach($matches as $m){
//for reference $m[1][0] contains $b, $m[2][0] contains $e
$t.=substr($html,$o,$m[0][1]-$o);
$t.=$replace[$m[2][0]];
$o=$m[3][1]+strlen($m[3][0]);
}
$t.=substr($html,$o);
$html=$t;
}
return $html;
}
$html="
<div>
<<this>>
<<that>>
</div>
";
$new=process_template($html);
echo $new;
For demo purpose I put the array $replace that handling the substitutions. You replace those with your function that will handle the replacement.
Here is a working snippet: https://3v4l.org/MBnbR
I like this function because you have control of what to replace and what to put back on the final result. By the way by using the PREG_OFFSET_CAPTURE also return on the matches the position where the regexp groups happens. Those are on the $m[x][1]. The captured text will be on $m[x][0].