XML in plaintext, what to do with it?

[porton]

I want to extend XHTML with tags like

<pre syntax:format="python">
# Some Python code
def f():
    pass
</pre>

The text in <pre> tag should be "enriched" with <span> HTML tags with classes, to highlight the syntax of the text inside <pre>.

What my code should do if the processed <pre> tag already contains some XML tags? Example:

<pre syntax:format="python">
# Some Python code
def f():
    <em>pass</em>
</pre>

The variants I thought of:

1. first remove the tags (like <em> in the above example)
2. leave the content of the <pre> tag as is (just remove syntax:format argument)
3. terminate my pipeline processing with an error

Edited August 13, 2018 by porton

[justsomeguy]

A pre tag means the contents are pre-formatted, so the correct behavior is to print out any tags that appear in the pre block instead of rendering them.

[porton]

@justsomeguy You confuse between pre-formatted and plain text. <pre> in HTML can contain any formatting tags (<em>, <strong>, etc.)

I decide to raise an exception in this case, because other ways do not work for me.

[justsomeguy]

It looks like that's correct, several tags are allowed in a pre block.