Wordpress: Highlight PHP Code

WordPress: Highlight PHP Code

by Jens on Nov.22, 2009, under PHP, Programmierung, Technik

Ich werde mal versuchen einige meiner Einträge auf Englisch zu verfassen – um in der Übung zu bleiben.

I like to write about programming, and since I am using WordPress and writing plugins for it, PHP is the language of choice when it comes to blog-related development.

I wanted to put my PHP-Code into my entries and I wanted it to look nice, which means mono-spaced font and syntax highlighting. The first one was fairly easy to archieve by just changing the CSS. Whenever I put code into my blog, I write it between <pre> and </pre>, so I just had to change the CSS for the pre-element:

 pre {
    height: auto;
    overflow: auto;
    color: #EEE;
    padding: 5px;
    margin: 10px;
    scroll: auto;
    font-family: Courier New, monospace;
    font-weight: bold;
    white-space: pre;
    font-size: 9pt;
    line-height: 10pt;
}

The highlighting however must be done on the server side by PHP, so I had to write another (in fact two) filter-function:


<?php

function highlightCode($content) {
    if (false === strpos($content, '<pre>')) {
        return $content;
    }

    $content = preg_replace_callback(
        '|\<pre\>(.*?)\</pre\>|is',
        'highlightCodeCallback',
        $content
    );

    return $content;
}

function highlightCodeCallback($matches) {
    if (false === strpos($matches[0], '<?php')) {
        return $matches[0];
    }

    $code = $matches[0];
    $code = preg_replace(
        '|\<code\>\s*\</code\>|is',
        '/*§§BR§§*/', $code
    );
    $code = strip_tags($code);
    // Wordpress adds the space when saving
    $code = str_replace('<?php', '<?php', $code);
    $code = highlight_string($code, true);
    $code = str_replace('/*§§BR§§*/', "\n\n", $code);
    $code = htmlspecialchars_decode($code);
    $code = str_replace('<?php', '<?php', $code);

    return '<pre>'. $code .'</pre>';
}

Is it just ?