Failed to markdown parser function in php using regex - php

Question

Let's write a simple markdown parser function that will take in a single line of markdown and be translated into the appropriate HTML. To keep it simple, we'll support only one feature of markdown in atx syntax: headers.
Headers are designated by (1-6) hashes followed by a space, followed by text. The number of hashes determines the header level of the HTML output.
Examples
# Header will become <h1>Header</h1>
## Header will become <h2>Header</h2>
###### Header will become <h6>Header</h6>
My code :
function markdown_parser ($markdown) {
$regex = '/(?:(#+)(.+?)\n)|(?:(.+?)\n\s*=+\s*\n)/';
$headerText = $markdown."\n";
$headerText = preg_replace_callback(
$regex,
function($matches){
if (!preg_match('/\s/',$matches[2])) {
return "#".$matches[2];
}
if($matches[1] != ""){
$h_num = strlen($matches[1]);
return html_entity_decode("<h$h_num>".trim($matches[2])."</h$h_num>");
}
},
$headerText
);
return $headerText;
}
its not working as failed test case :
Failed asserting that two strings are identical.
Expected: Behind # The Scenes
Actual : Behind <h1>The Scenes</h1>

Answer 1

What i understood is you want to limit your markdown conversion to a range of 1-6 depth for your title.
Give a try to this code :
function markdown_parser ($markdown) {
$regex = '/(?:(#+)(.+?)\n)|(?:(.+?)\n\s*=+\s*\n)/';
$headerText = $markdown."\n";
$headerText = preg_replace_callback(
$regex,
function($matches) use ($markdown){
if (!preg_match('/\s/',$matches[2])) {
return "#".$matches[2];
}
if($matches[1] != ""){
$h_num = strlen($matches[1]);
if (\in_array($h_num, \range(1, 6), true)) {
return html_entity_decode("<h$h_num>" . trim($matches[2]) . "</h$h_num>");
}
return $markdown;
}
},
$headerText
);
return $headerText;
}
I only add a condition to check if your number of hashtag is in range of 1 until 6if (\in_array($h_num, \range(1, 6), true)) {