Extension:LoopFunctions
From MediaWiki.org
 Release status: beta |
|
|---|---|
| Implementation | Parser functions |
| Description | provides limited looping functionality in wikitext |
| Author(s) | Carl Fürstenberg |
| Version | 1.0.3 (Dec 17, 2006) |
| MediaWiki | 1.7+ |
| Download | see below |
This extension will enable limited looping functionality in the wikitext, where a variable ($n$ by default) is replaced by the current iteration number of the loop. The variable can be used in a plain text or link. Also the result of the whole loop can be put in an expression, e.g. to compute a factorial. However, the loop body is evaluated before replacing the variable, so e.g. a computation inside the loop body, depending on the value of the variable, is not possible.
Per standard the number of iterations is limited to 100 iterations per session.
Contents |
[edit] Functions
[edit] #for
{{ #for: n | text }}
{{ #for: n | text | replacement parameter }}
where n is the count of iteration and the text is the text to be repeated. If, after expansion of templates, parser functions, and variables, the text contains the text $n$ or what is defined by the third parameter, that will be replaced by the current iteration, starting with 1.
[edit] Examples
calling the template {{ foo: |n=4 | list1=a | list2=b | list3=c | list4=d }} using the template foo, containing: {{ #for: {{{n}}} | {{{list$n$}}}<br/> }} will result in the text
a<br/>b<br/>c<br/>d<br/>
- Sum of squares 1^2 through 5^2: {{#expr:{{#for:5|+$n$*$n$}}}} gives 55.
- Factorial 6 (6!): {{#expr:1{{#for:6|*$n$}}}} gives 720.
Compare, using m:Template:for (talk, backlinks, edit) and m:Template:plus square (talk, backlinks, edit): {{#expr:{{for|call=plus square|pv=1|1|2|3|4|5}}}} gives 55.
For a list of squares it seems that we can only use "for", not "#for".
[edit] Limitation
In the loop body, templates, parser functions, and variables are expanded before replacing the index variable by its values.
Examples:
Parameter of a parser function depending on the index variable:
- {{#for:3|{{lc:Ab$n$}} }} gives ab1ab2ab3; the result is in this case the same as when the repetition was done first, and then the evaluation of each item.
- {{#for:3|{{uc:Ab$n$}} }} gives AB$N$AB$N$AB$N$; the result is in this case not the same, because $n$ is changed to $N$, and therefore not treated as index variable.
- Applying #expr to an expression containing the index variable does not work: expansion of #expr in e.g. {{#expr:2*$n$}} gives the text "Expression error: Unrecognised punctuation character "$"", so this text will be repeated.
Template name depending on the index variable:
- {{#for:3|{{a$n$}} }} gives:
- if the template with the literal name Template:a$n$ does not exist: Template:a1 Template:a2 Template:a3 (the loop body is evaluated as Template:a$n$, after which the loop function repeats that, substituting $n$).
- if the template with the literal name Template:a$n$ does exist: the result of {{a$n$}}{{a$n$}}{{a$n$}}, i.e., the content is repeated unchanged.
[edit] Limitation in combination with m:VariablesExtension
Within the loop a variable can be assigned a value depending on the loop variable, and the value of this variable can be retrieved.
However, it seems that within the loop the variable cannot be assigned a new value depending on its own current value. Instead the value on entering the loop is taken.
[edit] #foreach
{{ #foreach: mask | text }}
{{ #foreach: mask | text | replacement parameter }}
The mask is a string in the format prefix$n$suffix where $n$ can be changed via the replacement parameter. The function #foreach, called inside a template, will produce the text for $n$ = 1, 2, 3,... as long as prefix$n$suffix is a template parameter defined in the template call. If the text contains the text $n$ or what is defined by the third parameter, that will be replaced by the current value of $n$.
It seems that the whole call of #foreach is ignored if the loop body contains a template call or a parser function call, or if the loop body does not contain {{{$n$}}}.
[edit] Examples
Calling the template {{ foo | foo2_bar=a | foo1_bar=b | a=12 | 6 |foo4_bar=c }} using the template foo, containing: {{ #foreach: foo$n$_bar | foo$n$_bar = {{{foo$n$_bar}}}<br/> }} will result in the expanded wikitext
foo1_bar = b<br/>foo2_bar = a<br/>
and hence the output
foo1_bar = b
foo2_bar = a
Since foo3_bar is not defined, foo4_bar is not listed either; neither are a and 1, the parameter names which exist but do not match the pattern.
Example without prefix or suffix:
The call {{showpars | abc | de | w=fgh | ijk }} of Template:Showpars containing {{ #foreach: $n$ | $n$ = {{{$n$}}}<br/> }} gives:
1 = abc
2 = de
3 = ijk
Content of a template that links to the pages given by the values of the unnamed parameters:
{{#foreach:$n$|[[{{{$n$}}}]]<nowiki> </nowiki>}}
[edit] Installation
Copy the following text to extensions/LoopFunctions/LoopFunctions.php and extensions/LoopFunctions/LoopFunctions.i18n.php. Then, include it from LocalSettings.php:
require_once ( 'extensions/LoopFunctions/LoopFunctions.php' );
<?php /** * Some functions to enable limited looping functionallity, * will also replace the text '$n$' or given parameter in the given text to the current loop count plus one. * * @package MediaWiki * @subpackage Extensions * * @link http://www.mediawiki.org/wiki/Extension:LoopFunctions Documentation * * @author Carl Fürstenberg (AzaToth) <azatoth@gmail.com> * @copyright Copyright © 2006 Carl Fürstenberg * @license http://www.gnu.org/copyleft/gpl.html GNU General Public License 2.0 or later */ if ( !defined( 'MEDIAWIKI' ) ) { die( 'This file is a MediaWiki extension, it is not a valid entry point' ); } require_once('LoopFunctions.i18n.php'); $wgExtensionFunctions[] = 'wfSetupLoopFunctions'; $wgExtensionCredits['parserhook'][] = array( 'version' => '1.0.3', 'description' => 'Provides limited looping functionallity in the wikitext', 'name' => 'LoopFunctions', 'url' => 'http://www.mediawiki.org/wiki/Extension:LoopFunctions', 'author' => 'Carl Fürstenberg (AzaToth)' ); $wgHooks['LanguageGetMagic'][] = 'wfLoopFunctionsLanguageGetMagic'; class ExtLoopFunctions { public static $mMaxLoopCount = 100; // Maximum number of loops allowed per session private static $mCurrentLoopCount = 0; // number of executed loops this session public function forHook(&$parser, $nbr_of_loops = 1 , $text = '' , $param = '$n$' ) { $return = ''; $text = trim($text); $param = trim($param); for($i = 0 ; $i < abs ( intval( $nbr_of_loops ) ) ; ++$i ) { if( ++self :: $mCurrentLoopCount > self :: $mMaxLoopCount ) { return wfMsg( 'loopfunc_max_loops' ); } $return .= strtr( $text , array( $param => $i + 1 ) ); } return $parser->replaceVariables( $return , current($parser->mArgStack) , true); } public function foreachHook(&$parser, $mask = '' , $text = '' , $param = '$n$' ) { $variables = current( $parser->mArgStack ); $param = trim( $param ); $text= trim( $text ); list ( $prefix , $suffix ) = $param == '' ? array( $mask , '' ) : explode ( $param , $mask , 2 ); for($i = 0; array_key_exists( $prefix . ( $i + 1 ) . $suffix , $variables ) ; ++$i ) { if( ++self :: $mCurrentLoopCount > self :: $mMaxLoopCount ) { return wfMsg( 'loopfunc_max_loops' ); } $return .= strtr( $text , array( $param => $i + 1 ) ); } return $parser->replaceVariables( $return , $variables , true); } } function wfSetupLoopFunctions() { global $wgParser, $wgExtLoopFunctions, $wgLoopFunctionsMessages, $wgMessageCache; $wgExtLoopFunctions = new ExtLoopFunctions(); $wgParser->setFunctionHook( 'for', array( &$wgExtLoopFunctions, 'forHook' ) ); $wgParser->setFunctionHook( 'foreach', array( &$wgExtLoopFunctions, 'foreachHook' ) ); foreach( $wgLoopFunctionsMessages as $key => $value ) { $wgMessageCache->addMessages( $value, $key ); } } function wfLoopFunctionsLanguageGetMagic( &$magicWords, $langCode ) { global $wgLoopFunctionsMagic; if(!in_array($langCode,$wgLoopFunctionsMagic)) $langCode = 'en'; $magicWords = array_merge($magicWords, $wgLoopFunctionsMagic[$langCode]); return true; }
<?php if ( !defined( 'MEDIAWIKI' ) ) { die( 'This file is a MediaWiki extension, it is not a valid entry point' ); } $wgLoopFunctionsMessages = array(); $wgLoopFunctionsMagic = array(); $wgLoopFunctionsMessages['cs'] = array( 'loopfunc_max_loops' => "Byl přesažen maximální povolený počet smyček", ); $wgLoopFunctionsMessages['en'] = array( 'loopfunc_max_loops' => "Maximum number of allowed loops reached", ); $wgLoopFunctionsMagic['en'] = array( 'for' => array( 0, 'for' ), 'foreach' => array( 0, 'foreach' ), );
