How do I prevent Kramdown from getting confused by a C++ include? - jekyll

Question

I have written this plugin:
module Jekyll
module Tags
class Prism < Liquid::Block
def initialize(tag_name, text, tokens)
#arg = text.strip
super
end
def render(context)
output = super(context)
"<pre><code class=\"language-#{#arg}\">#{output}</code></pre>"
end
end
end
end
Liquid::Template.register_tag('prism', Jekyll::Tags::Prism)
This is how I use it:
{% prism cpp %}
#include <iostream>
// Hello World
int main()
{
cout << "hello world" << endl;
int a = 10;
}
{% endprism %}
Now, the problem is, that I mostly use C++ Code on my website. When I now generate this markdown with Jekyll, then all text after {% endprism %} would still be within the <pre> Tag, because Kramdown is getting confused by <iostream> If I escape it, (\<iostream\>), then my plugin works as expected, but my Javascript Highlighter is getting confused.
How can I solve this situation without enabling Jekyll's highlighter?

Answer 1

I think your trying to use fenced code block used in GitHub Flavored Markdown.
Why don't you use the Jekyll code highlighting works pefectly out of the box for cpp ? A base css for highlight is available here
Try :
{% highlight cpp %}
#include <iostream>
// Hello World
int main()
{
cout << "hello world" << endl;
int a = 10;
}
{% endhighlight %}

Answer 2

There is a function in the CGI Module, that allows for escaping HTML much like htmlspecialchars from PHP. I changed the liquid plugin to this and it works:
require 'cgi'
module Jekyll
module Tags
class Prism < Liquid::Block
def initialize(tag_name, text, tokens)
#arg = text.strip
super
end
def render(context)
output = super(context)
output = CGI.escapeHTML(output);
"<pre><code class=\"language-#{#arg}\">#{output}</code></pre>"
end
end
end
end
Liquid::Template.register_tag('prism', Jekyll::Tags::Prism)
It escapes all <> to html special chars. Therefore Kramdown does not get confused and prism.js is still able to highlight the code correctly.