How to add line numbers for code blocks in Pelican

Dheepak Krishnamurthy

Updated on

Update : I’ve removed line numbers because it is selected along with the code if someone wants to copy. I’ll post here if I find a better solution.

I’ve found that line numbering with word wrap could only be achieved in Pelican by a certain set of steps. I’ve listed the CSS and the Plugin I’ve used to get that to work.

Add the following lines in your theme.css

/* For use with the code_line-number_word-wrap_switcher_jquery.js Pelican plugin */
code {
    overflow: auto;
    /* This uses `white-space: pre-wrap` to get elements within <pre> tags to wrap. Python, for code chunks within three backticks (```), doesn't wordwrap code lines by default, because they're within <pre> tags, which don't wrap by default. See https://github.com/github/markup/issues/168 , which is specifically about this parsing issue, even though that link's discussion is talking about GitHub. */
    white-space: pre-wrap;       /* css-3 */
    white-space: -moz-pre-wrap;  /* Mozilla, since 1999 */
    white-space: -pre-wrap;      /* Opera 4-6 */
    white-space: -o-pre-wrap;    /* Opera 7 */
    word-wrap: break-word;       /* Internet Explorer 5.5+ */
}

/* Following http://bililite.com/blog/2012/08/05/line-numbering-in-pre-elements/, use CSS to add line numbers to all spans that have the class 'code-line' */

.highlight pre {
    counter-reset: linecounter;
    padding-left: 2em;
}
.highlight pre span.code-line {
    counter-increment: linecounter;
    padding-left: 1em;
    text-indent: -1em;
    display: inline-block;
}
.highlight pre span.code-line:before {
    content: counter(linecounter);
    padding-right: 1em;
    display: inline-block;
    color: grey;
    text-align: right;
}

Then, we turn off the default linenums in codehilite. Also add the following pelican-plugin.

MD_EXTENSIONS = ['fenced_code', 'codehilite(css_class=highlight, linenums=False)', ]

PLUGINS = ['better_codeblock_line_numbering']

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