MediaWiki Implementation

Note: Version 1.01 of geohashes.php is currently installed on this wiki, as well as Variables.php.

A MediaWiki extension to allow us to handle Geohashes a little nicer and more automatically. Any questions to the talk page here, although I would appreciate a poke on my talk page also.

Note that the whole algorithm is not fully implemented, because those on IRC said that templates could do the rest.

--Edgemaster 21:39, 23 May 2008 (UTC)

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The Code

Feel free to tidy it up, poke an admin if you feel your changes are worthy to be deployed on this wiki.

<?php
$wgExtensionCredits[$type][] = array(
    'name' => "Geohashing MediaWiki Parser Functions",
    'description' => "Adds {{#md5}} and {{#dow}} handlers",
    'descriptionmsg' => "",
    'version' => "1.01",
    'author' => "Edgemaster (grand.edgemaster@gmail.com)",
    'url' => "http://wiki.xkcd.com/geohashing/MediaWiki_Implementation"
);

$wgExtensionFunctions[] = 'geohashingFunction_Setup';
$wgHooks['LanguageGetMagic'][]       = 'geohashingFunction_Magic';
 
function geohashingFunction_Setup() {
    global $wgParser;
    $wgParser->setFunctionHook( 'md5', 'geohashingMd5Function_Render' );
    $wgParser->setFunctionHook( 'dow', 'geohashingDowFunction_Render' );
}
 
function geohashingFunction_Magic( &$magicWords, $langCode ) {
    $magicWords['md5'] = array( 0, 'md5' );
    $magicWords['dow'] = array( 0, 'dow' );
    return true;
}
 
function geohashingMd5Function_Render( &$parser, $src = '', $half = 0, $decimal = 0) {
    $md5 = md5(trim($src));
    if(!$half) return $md5;
    
    $md5 = substr($md5, ($half-1)*16, 15);
    if(!$decimal) return $md5;
    
    $dec = ('0x'.$md5) / pow(16,15);
    return $dec;
}

function geohashingDowFunction_Render( &$parser, $Y = 0, $m = 0, $d = 0) {
    foreach(array('Y', 'm', 'd') as $var) {
        $$var = intval($$var);
        if($$var < 10) $$var = '0' . $$var;
        if(!intval($$var)) $$var = date($var);
    }
    return trim(@file_get_contents("http://irc.peeron.com/xkcd/map/data/$Y/$m/$d"));
    // file_get_contents returns nothing on http error, we hide the warning from php
}
?>

Changelog

• v1.01 - 1 Jul 2008 Passing all 16 hex-characters of a half-hash causes PHP to misinterpret sign when decimalising, so instead we only pass the first 15... besides, that still gives microscopic accuracy (~100 femtometres). Hence the fifteens shown in lines 30 and 33 above. --Tim P 19:13, 1 July 2008 (UTC)

In-wiki Usage

This extension adds two new parser functions: {{#md5}} and {{#dow}}.

#md5

md5s a string, optionally splitting into halves and decimalising.

{{#md5:string|halve|decimal}}

Parameters:

• string: the string to md5
• halve: (optional) splits the hash into two, as required by The Algorithm. 0 = do not half, 1 = first half, 2 = 2nd half. Defaults to 0.
• decimal: (optional) converts the half to decimal if set. Defaults to 0, requires halve to be set to 1 or 2!

Examples:

• {{#md5:testing testing!}}: f9da4c546dff04d46e1fab3ca0456b42
• {{#md5:2005-05-26-10458.68}}: db9318c2259923d08b672cb305440f97
• {{#md5:2005-05-26-10458.68|0}}: db9318c2259923d08b672cb305440f97
• {{#md5:2005-05-26-10458.68|1}}: db9318c2259923d
• {{#md5:2005-05-26-10458.68|2}}: 8b672cb305440f9
• {{#md5:2005-05-26-10458.68|1|1}}: 0.857713267707
• {{#md5:2005-05-26-10458.68|2|1}}: 0.54454306955928

#dow

Fetches the opening Dow Index for a date from the irc.peeron.com service.

{{#dow:year|month|day}}

Parameters:

• year: 4 digit year
• month: month (1 or 2 digits are acceptable)
• day: day (1 or 2 digits are acceptable)

The only validation done is to check the values are non-null. If any of the 3 are null (or all of the 3), then today's date will be used instead. (Always requires the colon to produce a result)

Examples:

• {{#dow:}}: 44837.75
• {{#dow:2005|05|26}}: 10458.68
• These will fail:
  • (lack of data) {{#dow:1854|05|26}}:
  • (bad syntax) {{#dow}}: {{#dow}}

Variables Extension too plz

Installing

Copy this into a file called $mediwikipath/extensions/Variables/Variables.php:

<?php

if ( !defined( 'MEDIAWIKI' ) ) {
    die( 'This file is a MediaWiki extension, it is not a valid entry point' );
}

$wgExtensionFunctions[] = 'wfSetupVariables';

$wgExtensionCredits['parserhook'][] = array(
	'name' => 'Variables',
	'url' => 'http://www.mediawiki.org/wiki/Extension:VariablesExtension',
	'author' => 'Rob Adams',
	'description' => 'Define page-scoped variables'
);

$wgHooks['LanguageGetMagic'][]       = 'wfVariablesLanguageGetMagic';

class ExtVariables {
    var $mVariables;

    function vardefine( &$parser, $expr = '', $value = '' ) {
	$this->mVariables[$expr] = $value;
	return '';
    }

    function varf( &$parser, $expr = '' ) {
	return $this->mVariables[$expr];
    }
}

function wfSetupVariables() {
    global $wgParser, $wgMessageCache, $wgExtVariables, $wgMessageCache, $wgHooks;

    $wgExtVariables = new ExtVariables;

    $wgParser->setFunctionHook( 'vardefine', array( &$wgExtVariables, 'vardefine' ) );
    $wgParser->setFunctionHook( 'var', array( &$wgExtVariables, 'varf' ) );
}

function wfVariablesLanguageGetMagic( &$magicWords, $langCode = 0 ) {
	require_once( dirname( __FILE__ ) . '/Variables.i18n.php' );
	foreach( efVariablesWords( $langCode ) as $word => $trans )
		$magicWords[$word] = $trans;
	return true;
}

Copy this into a file called $mediwikipath/extensions/Variables/Variables.i18n.php:

<?php

/**
 * Get translated magic words, if available
 *
 * @param string $lang Language code
 * @return array
 */
function efVariablesWords( $lang ) {
	$words = array();

	/**
	 * English
	 */
	$words['en'] = array(
		'var' 		=> array( 0, 'var' ),
		'vardefine' 	=> array( 0, 'vardefine' ),
	);

	# English is used as a fallback, and the English synonyms are
	# used if a translation has not been provided for a given word
	return ( $lang == 'en' || !isset( $words[$lang] ) )
		? $words['en']
		: array_merge( $words['en'], $words[$lang] );
}

Then add

require_once( "$IP/extensions/Variables/Variables.php" );

to the end of LocalSettings.php.