root/trunk/plugins/syntaxhl.php

<?php
/* include the geshi stuff */
require_once("syntaxhl_files/geshi.php");

Class syntaxhl extends MvBlog_plugin implements MvBlog_pluginiface {
    /* variables */
    public $name    = "Syntax color highlighter";
    public $author  = "Michiel van Baak";
    public $license = "GPL";
    public $website = "http://www.mvblog.org";
    public $description = "Provides syntax color highlighting inside posts.";

    private $_mvblog;

    /* methods */
    public function __construct(&$mvblog) {
        $this->addHook("text_output", "syntaxhighlight");
        $this->_mvblog =& $mvblog;
    }

    public function activate() {
        /* get data, do whatever is needed on plugin activation */
    }

    public function deactivate() {
    }

    public function syntaxhighlight($text) {
        /* make copy of input because we are going to modify it */
        $pluginoutput = $text;

        /* find all blocks of [code:<language> .... :code] */
        preg_match_all("/\[code:(.*):code\]/Us", $text, $matches);
        foreach ($matches[0] as $codeblock) {
            $data = "";
            /* get the language for the code block */
            preg_match("/\[code:(\w{1,})/", $codeblock, $langmatch);
            $language = $langmatch[1];
            /* remove the special code to identify code blocks */
            $data = str_replace("[code:$language", "", $codeblock);
            $data = str_replace(":code]", "", $data);
            $data = str_replace("<br />", "", html_entity_decode($data));
            /* use geshi to syntax highlight the code */
            $geshi = new Geshi(trim($data), strtolower($language));
            $geshi->enable_classes();
            /* geshi comes with some style tags, so load the inline stylesheets */
            $data =  "<style type=\"text/css\">\n";
            $data .= $geshi->get_stylesheet();
            $data .= "</style>\n";
            /* enable line numbers */
            $geshi->enable_line_numbers(GESHI_NORMAL_LINE_NUMBERS);
            /* the actual highlighting is here */
            $data .= $geshi->parse_code();
            /* replace the original code with the highlighted code */
            $pluginoutput = str_replace($codeblock, $data, $pluginoutput);
        }
        /* return the modified code with highlighting */
        return $pluginoutput;
    }
}
?>