# User:Paxed/ReplaceCharsBlock
Contents

1 ReplaceCharsBlock extension

1.1 Tips

2 TODO
3 Code for ReplaceCharsBlock.php

ReplaceCharsBlock extension
Adds a 

<replacecharsblock> -tag, which allows replacing (or translating, using php:strtr) characters and strings in the block with other characters or strings. Replacements are defined first, and the block of text to be replaced after an empty line.
Replacement format is replace_from=replace_to, one per line.

<replacecharsblock>
b=foo

abcb
</replacecharsblock>

afoocfoo

default as a replacement: used for any characters that don't have explicitly defined replacement. $1 in the replacement will be substituted with the character which is being replaced.
newline as a replacement: each newline character will be replaced with this.
Longer replacement strings will be replaced first, then shorter ones.
Replacements are case sensitive.
For example:

<div class="ttyscreen">{{lightgray|
<replacecharsblock>
k=[[kobold|{{red|k}}]]
k̂=[[kobold shaman|{{brightblue|k}}]]
f=[[cat|{{white|f}}]]
@={{white|@}}
bar=[[foo|{{yellow|foo}}]]
newline=<br/>
|=|
-=-
 =&nbsp;

-------  -------  -------  -------
|......  |.BAR..  |......  |kkkk̂k.
|.....|  |.bar.|  |.....|  |kkkkk|
|..k..|  |.....|  |..f..|  |kkfkk|
|.kfk.|  |..kk.|  |.kkk.|  |k...k|
|.k@k.|  |..@fk|  |..@..|  |kk@kk|
|.....|  |..kk.|  |.....|  |kkkkk|
-.-----  -.-----  -.-----  -.-----
</replacecharsblock>
}}</div>

-------&nbsp;&nbsp;-------&nbsp;&nbsp;-------&nbsp;&nbsp;-------|......&nbsp;&nbsp;|.BAR..&nbsp;&nbsp;|......&nbsp;&nbsp;|kkkkk.|.....|&nbsp;&nbsp;|.foo.|&nbsp;&nbsp;|.....|&nbsp;&nbsp;|kkkkk||..k..|&nbsp;&nbsp;|.....|&nbsp;&nbsp;|..f..|&nbsp;&nbsp;|kkfkk||.kfk.|&nbsp;&nbsp;|..kk.|&nbsp;&nbsp;|.kkk.|&nbsp;&nbsp;|k...k||.k@k.|&nbsp;&nbsp;|..@fk|&nbsp;&nbsp;|..@..|&nbsp;&nbsp;|kk@kk||.....|&nbsp;&nbsp;|..kk.|&nbsp;&nbsp;|.....|&nbsp;&nbsp;|kkkkk|-.-----&nbsp;&nbsp;-.-----&nbsp;&nbsp;-.-----&nbsp;&nbsp;-.-----

Predefined replacement rulesets can be used with <replacecharsblock rules="ttymap">, which would load rules from {{ttymap}}. The lines after the first empty line in the ruleset template are ignored. Additional rules can be defined as normal.

Tips
Instead of using default={{lightgray|$1}}, it's more efficient to wrap the whole block in a {{lightgray}} template, as shown above.
The rules |=|, -=- and &nbsp;=&nbsp; are useful for preventing | and - from being parsed as wiki markup, and to prevent consecutive spaces from collapsing.  (These rules probably should be included automatically by default, but they currently aren't.)
TODO
Allow multiple replacement definitions for same char; use the replacements in the order they're defined, looping.
Maybe also in random order, though that'll invalidate cache.
Exceptions? (eg. maybe one 'k' is different from all the other 'k' chars) Format, how to define?

Code for ReplaceCharsBlock.php
<?php
/**
 * ReplaceCharsBlock -- replace chars in a block with strings.
 *
 */

if( !defined( 'MEDIAWIKI' ) ) {
        die( "This is not a valid entry point to MediaWiki.\n" );
}

$wgHooks['ParserFirstCallInit'][] = 'wfReplaceCharsBlock';

$wgExtensionCredits['parserhook'][] = array(
        'name' => 'ReplaceCharsBlock',
        'version' =&gt; '0.5',
        'author' =&gt; array(
                '[http://nethackwiki.com/wiki/User:Paxed Pasi Kallinen]',
                '[http://nethackwiki.com/wiki/User:Ilmari_Karonen Ilmari Karonen]',
        ),
        'url' =&gt; 'http://nethackwiki.com/wiki/User:Paxed/ReplaceCharsBlock',
        'description' =&gt; 'Replace characters in a block of text with strings.',
);

function wfReplaceCharsBlock( &amp;$parser ) {
        $parser-&gt;setHook( 'replacecharsblock', 'renderCharReplacement' );
        return true;
}

function replaceCharsBlockGetPageContent ($name) {
    $id = Title::newFromText($name, NS_TEMPLATE)-&gt;getArticleId();
    if ($id == null) return "";
    $article = Article::newFromId($id);
    if ($article == null) return "";

    $rev = $article-&gt;getRevision();
    $content = $rev-&gt;getContent(Revision::RAW);
    $text = ContentHandler::getContentText($content);
    return $text;
}

function renderCharReplacement( $input, $argv, $parser, $frame ) {
        /*$parser-&gt;disableCache();*/

        list($defs, $text) = array_pad(preg_split('/\n\s*\n/', $input, 2), 2, null);
        if (!isset($text) || is_null($text)) {
                $text = $defs;
                $defs = "";
        }

        if (isset($argv['rules'])) {
            list( $ruledefs, $ruledoc ) = preg_split( '/\n\s*\n/', replaceCharsBlockGetPageContent($argv['rules']), 2 );
            $defs = $ruledefs . $defs;
        }

        $reps = array();
        $default = false;

        $defs = explode( "\n", $defs );
        foreach ( $defs as $i =&gt; $line ) {
                if ( !preg_match( '/\S/u', $line ) ) {
                        continue;
                }
                if ( !preg_match( '/^(\X+?)=(.+)$/u', $line, $match ) ) {
                        return "<strong class="error">Replacecharsblock error on line $i: invalid definition " . htmlspecialchars( $line ) . "</strong>";
                }
                // wfDebug( __METHOD__ . ": mapping $match[1] to $match[2]\n" );
                if ( $match[1] === 'default' ) {
                        $default = $match[2];
                } else if ( $match[1] === 'newline' ) {
                    $reps["\n"] = $match[2];
                } else {
                        $reps[ $match[1] ] = $match[2];
                }
        }

        if ( $default !== false ) {
                preg_match_all( '/(?&gt;[^\\pM\\pC]\\pM*)/u', $text, $chars );
                $chars = array_diff( array_unique( $chars[0] ), array_keys( $reps ) );
                foreach ( $chars as $char ) {
                        $reps[$char] = str_replace( '$1', $char, $default );
                        // wfDebug( __METHOD__ . ": adding default map from $char to $reps[$char]\n" );
                }
        }

        $text = strtr( $text, $reps );
        return $parser-&gt;recursiveTagParse( $text, $frame );
}

</replacecharsblock></replacecharsblock>