Pico Anchors

PicoAnchors.php

<?php

# Create file 'PicoAnchors.php' in pico plugin folder and paste content

class PicoAnchors extends AbstractPicoPlugin {

	public function onContentParsed(&$content) {
        while ($this->getNextLink($content, $match)) {
            $linkName = $match['name'][0];
            $endingTagOffset = $match['endingtag'][1] + $this->lastOffset;
            $matchContent = $match[0][0];
            
            $link = "<a class=\"anchor\" href=\"#".$linkName."\">$linkName</a>";
            
            $this->lastOffset += $match[0][1] + strlen($matchContent);
            $content = substr_replace($content, $link, $endingTagOffset, 0);
        }
    }
    
    private const REGEX = '/\<(.{1,5}).*id="(?<name>\S+)".*(?<endingtag>\<\/\1\>)/';
    private $lastOffset = 0;
    private function getNextLink($text, &$outMatch) {
        $outMatch = null;
        if (!preg_match($this::REGEX, substr($text, $this->lastOffset), $match, PREG_OFFSET_CAPTURE)) {
            return false;
        }
        $outMatch = $match;
        return true;
    }
}