Introduce genesis widget for dynamically creating widgets

See the "RedefineLet" test for a contrived example of usage

core/modules/widgets/genesis.js

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+/*\
+title: $:/core/modules/widgets/genesis.js
+type: application/javascript
+module-type: widget
+
+Genesis widget for dynamically creating widgets
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+var Widget = require("$:/core/modules/widgets/widget.js").widget;
+
+var GenesisWidget = function(parseTreeNode,options) {
+	this.initialise(parseTreeNode,options);
+};
+
+/*
+Inherit from the base widget class
+*/
+GenesisWidget.prototype = new Widget();
+
+/*
+Render this widget into the DOM
+*/
+GenesisWidget.prototype.render = function(parent,nextSibling) {
+	this.parentDomNode = parent;
+	this.computeAttributes();
+	this.execute();
+	this.renderChildren(parent,nextSibling);
+};
+
+/*
+Compute the internal state of the widget
+*/
+GenesisWidget.prototype.execute = function() {
+	var self = this;
+	// Collect attributes
+	this.genesisType = this.getAttribute("$type","element");
+	this.genesisTag = this.getAttribute("$tag","div");
+	this.genesisNames = this.getAttribute("$names","");
+	this.genesisValues = this.getAttribute("$values","");
+	// Construct parse tree
+	var parseTreeNodes = [{
+		type: this.genesisType,
+		tag: this.genesisTag,
+		attributes: {},
+		orderedAttributes: [],
+		children: this.parseTreeNode.children || []
+	}];
+	// Apply attributes in $names/$values
+	this.attributeNames = [];
+	this.attributeValues = [];
+	if(this.genesisNames && this.genesisValues) {
+		this.attributeNames = this.wiki.filterTiddlers(self.genesisNames,this);
+		this.attributeValues = this.wiki.filterTiddlers(self.genesisValues,this);
+		$tw.utils.each(this.attributeNames,function(varname,index) {
+			$tw.utils.addAttributeToParseTreeNode(parseTreeNodes[0],varname,self.attributeValues[index] || "");
+		});
+	}
+	// Apply explicit attributes
+	$tw.utils.each(this.attributes,function(value,name) {
+		if(name.charAt(0) === "$") {
+			if(name.charAt(1) === "$") {
+				// Double $$ is changed to a single $
+				name = name.substr(1);
+			} else {
+				// Single dollar is ignored
+				return;
+			}
+		}
+		$tw.utils.addAttributeToParseTreeNode(parseTreeNodes[0],name,value);
+	});
+	// Construct the child widgets
+	this.makeChildWidgets(parseTreeNodes);
+};
+
+/*
+Selectively refreshes the widget if needed. Returns true if the widget or any of its children needed re-rendering
+*/
+GenesisWidget.prototype.refresh = function(changedTiddlers) {
+	var changedAttributes = this.computeAttributes(),
+		filterNames = this.getAttribute("$names",""),
+		filterValues = this.getAttribute("$values",""),
+		attributeNames = this.wiki.filterTiddlers(filterNames,this),
+		attributeValues = this.wiki.filterTiddlers(filterValues,this);
+	if($tw.utils.count(changedAttributes) > 0 || !$tw.utils.isArrayEqual(this.attributeNames,attributeNames) || !$tw.utils.isArrayEqual(this.attributeValues,attributeValues)) {
+		this.refreshSelf();
+		return true;
+	} else {
+		return this.refreshChildren(changedTiddlers);
+	}
+};
+
+exports.genesis = GenesisWidget;
+
+})();

editions/test/tiddlers/tests/data/genesis-widget/DollarSigns.tid

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+title: Genesis/DollarSigns
+description: Usage of genesis widget with attributes starting with dollar signs
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
+title: Output
+
+\whitespace trim
+<$genesis $type="let" myvar="Kitten">(<$text text=<<myvar>>/>)</$genesis>
+<$genesis $type="let" $$myvar="Kitten">(<$text text=<<$myvar>>/>)</$genesis>
+_
+title: ExpectedResult
+
+<p>(Kitten)(Kitten)</p>

editions/test/tiddlers/tests/data/genesis-widget/MultipleAttributes.tid

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+title: Genesis/MultipleAttributes
+description: Usage of genesis widget with multiple attributes
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
+title: Output
+
+\whitespace trim
+<$genesis $type="let" $names="myvar other" $values="Kitten Donkey" myvar="Shark">(<$text text=<<myvar>>/>|<$text text=<<other>>/>)</$genesis>
+<$genesis $type="let" $names="$myvar $other" $values="Kitten Donkey" $$myvar="Shark">(<$text text=<<$myvar>>/>|<$text text=<<$other>>/>)</$genesis>
+_
+title: ExpectedResult
+
+<p>(Shark|Donkey)(Shark|Donkey)</p>

editions/test/tiddlers/tests/data/genesis-widget/RedefineLet.tid

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+title: Genesis/RedefineLet
+description: Using the genesis widget to override the let widget
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
+title: Output
+
+\whitespace trim
+\function <$let>
+\whitespace trim
+<$setmultiplevariables $names="[enlist<paramNames>]" $values="[enlist<paramValues>addprefix[--]addsuffix[--]]">
+<$slot $name="ts-body"/>
+</$setmultiplevariables>
+\end
+<$let
+	one="Elephant"
+	$two="Kangaroo"
+	$$three="Giraffe"
+>
+(<$text text=<<one>>/>)
+(<$text text=<<$two>>/>)
+(<$text text=<<$$three>>/>)
+</$let>
+_
+title: Definition
+
+\whitespace trim
+_
+title: ExpectedResult
+
+<p>(--Elephant--)
+(--Kangaroo--)
+(--Giraffe--)</p>

editions/test/tiddlers/tests/data/genesis-widget/Simple.tid

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+title: Genesis/Simple
+description: Simple usage of genesis widget
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
+title: Output
+
+\whitespace trim
+<$genesis $tag="div">Mouse</$genesis>
+<$genesis $tag="div" class="tc-thing" label="Squeak">Mouse</$genesis>
+_
+title: ExpectedResult
+
+<p><div>Mouse</div><div class="tc-thing" label="Squeak">Mouse</div></p>

editions/tw5.com/tiddlers/widgets/GenesisWidget.tid

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+caption: genesis
+created: 20220502144738010
+modified: 20220502144738010
+tags: Widgets
+title: GenesisWidget
+type: text/vnd.tiddlywiki
+
+! Introduction
+
+<<.from-version "5.2.3">> The genesis widget allows the dynamic construction of widgets, where the name and attributes of the widget can be dynamically determined, and do not need to be known in advance.
+
+! Content and Attributes
+
+The content of the `<$genesis>` widget is used as the content of the dynamically created widget.
+
+|!Attribute |!Description |
+|$type |The type of widget to create |
+|$tag |The HTML tag to be used for "element" widgets |
+|$names |An optional filter evaluating to the names of a list of variables to be applied to the widget |
+|$values |An optional filter evaluating to the values corresponding to the list of names specified in `$names` |
+|//{other attributes starting with $}// |Other attributes starting with a single dollar sign are reserved for future use |
+|//{attributes starting with $$}// |Attributes starting with two dollar signs are appplied as attributes to the output widget, but with the attribute name changed to use a single dollar sign |
+|//{attributes not starting with $}// |Any other attributes that do not start with a dollar are applied as attributes to the output widget |
+
+Note that attributes explicitly specified take precedence over attributes with the same name specified in the `$names` filter.
+
+! Examples
+
+<$macrocall $name='wikitext-example-without-html' 
+src='<$set name="myTiddler" value="HelloThere">
+  <$set name="myVariable" tiddler=<<myTiddler>> field={{$:/docs/anyField!!field}}>
+    <$text text=<<myVariable>>/>
+  </$set>
+</$set>'/>