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Implements Lua functions mw.text.decode, mw.text.encode in a module.
:<code><nowiki>{{#invoke:decodeEncode|decode|s=Source&amp;nbsp;text&amp;copy;}}</nowiki></code> &rarr; <code><nowiki>Source&nbsp;text&copy;</nowiki></code>

See List of XML and HTML character entity references.

== Decode ({{mono|1=&amp;copy;}} &rarr; ©) <span class="anchor" id="Decode"></span>==
{{hatnote|See {{slink||Known issues}} for possible THIN SPACE, epsilon issues}}
:Decodes Named Entities ''from'' entity name ''into'' a regular (unicode) character:
:<code>&amp;copy;</code> &rarr; <code>&copy;</code>
:<code>&amp;gt;</code> &rarr; <code>></code>

All well-defined named entities are decoded ([https://html.spec.whatwg.org/multipage/named-characters.html#named-character-references HTML Named character references], formally: as defined in the [https://www.php.net/get_html_translation_table PHP table]).

:A regular, rendered sentence:
::"At 100 °F, & with a "burning" sun above, we , we ⁄walked⁄."

:In code:
::"<code>At 100&amp;nbsp;&amp;deg;F, &amp; with a &amp;quot;burning&amp;quot; sun above, we &amp;frasl;walked&amp;frasl;.</code>" -- wikitext

:Processing:
:<code><nowiki>{{#invoke:decodeEncode|decode|s=At 100&nbsp;&deg;F, &amp; with a &quot;burning&quot; sun above, we &frasl;walked&frasl;.}}</nowiki></code> &rarr;
::<code>{{#invoke:decodeEncode|decode|s=At 100&nbsp;&deg;F, &amp; with a &quot;burning&quot; sun above, we &frasl;walked&frasl;.}}</code> -- In code: straight characters, no named entities.

:Renders, again:
::"At 100 °F, & with a "burning" sun above, we ⁄walked⁄."

===Decode a reduced set only===
By setting {{para|subset_only|true}}, only these five entity names are decoded: '&amp;lt;', '&amp;gt;', '&amp;amp;', '&amp;quot;', '&amp;nbsp;' (that is, into '&lt;', '&gt;', '&amp;', '&quot;', '&nbsp;').

:'''Note''': There is a difference with the relevant Lua parameter. (This only concerns your task if you also work directly with the Lua mw.text.decode function). Lua documentation defines parameter {{para|decodeNamedEntities}}, having this effect: when ''omitted or false'', only the reduced set of entities is recognized and decoded. This use of 'false' is ''inverted'' in using {{para|subset_only}}: {{para|decodeNamedEntities|false}} =  {{para|subset_only|true}}.

:Also, this module ignores the "omitted" logic: {{para|subset_only}} should be set explicitly to 'true' to be effective.

== Encode (© &rarr; {{mono|1=&amp;copy;}}) <span class="anchor" id="Encode"></span>==
:Function <code>encode</code> encodes some entity-named characters into that name (for example: <code>&</code> &rarr; <code>&amp;amp;</code>).

Regular sentence:
:"At >100 °F, & with a "burning" sun above, we walked. ©"

In code:
:"<code><nowiki>At >100 °F, & with a "burning" sun above, we walked. ©</nowiki></code>"

Encode:
:<code><nowiki>{{#invoke:decodeEncode|encode|s=At >100 °F, & with a "burning" sun above, we walked. ©|charset=&<>{{!}}°"'&©}}</nowiki></code>

:&rarr;

:<code><nowiki>At &amp;gt;100 &amp;#176;F, &amp;amp; with a &amp;quot;burning&amp;quot; sun above, we walked. &amp;#169;</nowiki></code><!-- used Special:ExpandTemplate -->

:Renders as:

:"At &gt;100 &#176;F, &amp; with a &quot;burning&quot; sun above, we walked. &#169;"
===character set to encode===

Per Lua documentation, only a small set of characters is processed. The characterset can be set (expanded) by using {{para|charset}}.

:Example: {{para|charset|<nowiki><>" \'&</nowiki>}} (the default), {{para|charset|<nowiki><>°"'&©{{!}}</nowiki>}}; characters not in the default will be replaced by their decimal entity: <code>©</code> &rarr; <code>&amp;#169;</code> <small>(hexadecimal number, not decimal nor named &amp;copy;)</small>

==Known issues <span class="anchor" id="Template"></span>==
* 13 Sep 2021: NOTE: The encode function with user-supplied charset is now used productively  in {{tl|R/superscript}} and {{tl|R/ref}}. Before implementing breaking changes here, these templates need to be adjusted accordingly!

* 26 Sep 2021:  
:Note: Possible bug: Decoding <code>&amp;ThinSpace;</code> works, but <code>&amp;thinsp;</code> doesn't.
:Resolved in code.

*  4 Feb 2023: 
{{tracked|T328840}}
:See {{slink|Module_talk:DecodeEncode|Bug_report:_bad_decoding_of_U+03B5_ε_(epsilon)}}
:Resolved in code.

==See also==

* mw.text.decode
* mw.text.encode
* :Module:Urldecode

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