Best way to do a multi-line regex replace?

Question

I understand that for a long time the |replace filter has supported regex modifiers, but I can't seem to get the syntax right for multiline searches.

For example, here I want to extract the internal markup within a list that's been generated via Markdown, so I can do something with the internals:

{% set html = html|replace('/\\n/', '')|replace('/^(<ul>)(.*)(<\\/ul>)$/', '$2') %}

That works, but I should be able to use a modifier with the second replace so I don't have to use the first one, right?

But none of these work:

{% set html = html|replace('/^(<ul>)(.*)(<\\/ul>)$/m', '$2') %}

{% set html = html|replace('/^(<ul>)(.*)(<\\/ul>)$/\\m', '$2') %}

{% set html = html|replace('/^(<ul>)(.*)(<\\/ul>)$/(?m)', '$2') %}

What am I doing wrong?

Answer 1

I'm on my phone, so I'm not able to test, but it looks to me like your regex is explicitly expecting the string you're testing to start with <ul> and end with </ul>, and despite the multiline flag, any line breaks at the start or end of the string will prevent a match.

Try removing the ^ and $ from the start and end your pattern match to disable explicit start and end of string matching.