Extension:RandomSelection

<?php
/**
 * RandomSelection -- randomly displays one of the given options.
 * Usage: <choose><option>A</option><option>B</option></choose>
 * Optional parameter: <option weight="3"> == 3x weight given
 *
 * @file
 * @ingroup Extensions
 * @version 2.1.5
 * @date 17 January 2010
 * @author Ross McClure <http://www.mediawiki.org/wiki/User:Algorithm>
 * @link http://www.mediawiki.org/wiki/Extension:RandomSelection Documentation
 */
 
if( !defined( 'MEDIAWIKI' ) ) {
	die( "This is not a valid entry point to MediaWiki.\n" );
}
 
$wgHooks['ParserFirstCallInit'][] = 'wfRandomSelection';
 
$wgExtensionCredits['parserhook'][] = array(
	'name' => 'RandomSelection',
	'version' => '2.1.5',
	'author' => 'Ross McClure',
	'description' => 'Displays a random option from the given set.',
	'url' => 'http://www.mediawiki.org/wiki/Extension:RandomSelection',
);
 
function wfRandomSelection( &$parser ) {
	$parser->setHook( 'choose', 'renderChosen' );
	return true;
}
 
function renderChosen( $input, $argv, $parser ) {
	# Prevent caching
	$parser->disableCache();
 
	# Parse the options and calculate total weight
	$len = preg_match_all(
		"/<option(?:(?:\\s[^>]*?)?\\sweight=[\"']?([^\\s>]+))?"
			. "(?:\\s[^>]*)?>([\\s\\S]*?)<\\/option>/",
		$input,
		$out
	);
	$r = 0;
	for( $i = 0; $i < $len; $i++ ) {
		if( strlen( $out[1][$i] ) == 0 ) {
			$out[1][$i] = 1;
		} else {
			$out[1][$i] = intval( $out[1][$i] );
		}
		$r += $out[1][$i];
	}
 
	# Choose an option at random
	if( $r <= 0 ) {
		return '';
	}
	$r = mt_rand( 1, $r );
	for( $i = 0; $i < $len; $i++ ) {
		$r -= $out[1][$i];
		if( $r <= 0 ) {
			$input = $out[2][$i];
			break;
		}
	}
 
	# Parse tags and return
	return $parser->recursiveTagParse( $input );
}