{% comment -%}
Fixes the HTML for highlighted code with linenos.

Derived from the workaround provided by Dmitry Hrabrov (DeXP) at
https://github.com/penibelst/jekyll-compress-html/issues/71#issuecomment-188144901

Explanation:

The HTML produced by Rouge with the linenos option matches CSS `code table`.
Jekyll (<= 4.1.1) always wraps the highlighted HTML with `pre`, which is 
unnecessary and non-conforming, and leads to validation error reports.
The fix removes the `pre` tags around `_code` whenever it contains the pattern
`<table class="rouge-table">`. This change avoids validation errors, and
allows the use of [Jekyll layout for compressing HTML](http://jch.penibelst.de),
which relies on `pre` tags not being nested. 

Usage:

{% capture fix_linenos_code %}{% highlight AnyLanguage linenos %}
Some code
{% endhighlight %}{% endcapture %}{% include fix_linenos.html %}{{ fix_linenos_code }}

Caveats:

The above does not work when `Some code` happens to contain the matched string 
`<table class="rouge-table">`.

{%- endcomment %}

{% if fix_linenos_code contains '<table class="rouge-table">' %}
    {% assign fix_linenos_code = fix_linenos_code | replace: "<pre><code", "<code" %}
    {% assign fix_linenos_code = fix_linenos_code | replace: "</code></pre>", "</code>" %}
{% endif %}