Add join attribute to list widget (#7694)

* Add join attribute to list widget

* Use new join attribute in HTML saving templates

This simplifies the logic involved in saving tiddlers in JSON format
into TW html files, and should also slightly speed up the saving process
depending on how often that list widget gets refreshed.

* Unit tests for list widget's new join attribute

* Add `<$list-join>` widget

Allows specifying complicated join text more easily than an attribute

core/modules/widgets/list.js

@@ -50,8 +50,8 @@ ListWidget.prototype.render = function(parent,nextSibling) {
 		$tw.modules.applyMethods("storyview",this.storyViews);
 	}
 	this.parentDomNode = parent;
-	this.computeAttributes();
-	this.execute();
+	var changedAttributes = this.computeAttributes();
+	this.execute(changedAttributes);
 	this.renderChildren(parent,nextSibling);
 	// Construct the storyview
 	var StoryView = this.storyViews[this.storyViewName];
@@ -71,7 +71,7 @@ ListWidget.prototype.render = function(parent,nextSibling) {
 /*
 Compute the internal state of the widget
 */
-ListWidget.prototype.execute = function() {
+ListWidget.prototype.execute = function(changedAttributes) {
 	var self = this;
 	// Get our attributes
 	this.template = this.getAttribute("template");
@@ -80,6 +80,10 @@ ListWidget.prototype.execute = function() {
 	this.counterName = this.getAttribute("counter");
 	this.storyViewName = this.getAttribute("storyview");
 	this.historyTitle = this.getAttribute("history");
+	// Create join template only if needed
+	if(this.join === undefined || (changedAttributes && changedAttributes.join)) {
+		this.join = this.makeJoinTemplate();
+	}
 	// Compose the list elements
 	this.list = this.getTiddlerList();
 	var members = [],
@@ -102,6 +106,7 @@ ListWidget.prototype.findExplicitTemplates = function() {
 	var self = this;
 	this.explicitListTemplate = null;
 	this.explicitEmptyTemplate = null;
+	this.explicitJoinTemplate = null;
 	this.hasTemplateInBody = false;
 	var searchChildren = function(childNodes) {
 		$tw.utils.each(childNodes,function(node) {
@@ -109,6 +114,8 @@ ListWidget.prototype.findExplicitTemplates = function() {
 				self.explicitListTemplate = node.children;
 			} else if(node.type === "list-empty") {
 				self.explicitEmptyTemplate = node.children;
+			} else if(node.type === "list-join") {
+				self.explicitJoinTemplate = node.children;
 			} else if(node.type === "element" && node.tag === "p") {
 				searchChildren(node.children);
 			} else {
@@ -152,6 +159,24 @@ ListWidget.prototype.getEmptyMessage = function() {
 	}
 };
 
+/*
+Compose the template for a join between list items
+*/
+ListWidget.prototype.makeJoinTemplate = function() {
+	var parser,
+		join = this.getAttribute("join","");
+	if(join) {
+		parser = this.wiki.parseText("text/vnd.tiddlywiki",join,{parseAsInline:true})
+		if(parser) {
+			return parser.tree;
+		} else {
+			return [];
+		}
+	} else {
+		return this.explicitJoinTemplate; // May be null, and that's fine
+	}
+};
+
 /*
 Compose the template for a list item
 */
@@ -160,6 +185,7 @@ ListWidget.prototype.makeItemTemplate = function(title,index) {
 	var tiddler = this.wiki.getTiddler(title),
 		isDraft = tiddler && tiddler.hasField("draft.of"),
 		template = this.template,
+		join = this.join,
 		templateTree;
 	if(isDraft && this.editTemplate) {
 		template = this.editTemplate;
@@ -185,12 +211,12 @@ ListWidget.prototype.makeItemTemplate = function(title,index) {
 		}
 	}
 	// Return the list item
-	var parseTreeNode = {type: "listitem", itemTitle: title, variableName: this.variableName, children: templateTree};
+	var parseTreeNode = {type: "listitem", itemTitle: title, variableName: this.variableName, children: templateTree, join: join};
+	parseTreeNode.isLast = index === this.list.length - 1;
 	if(this.counterName) {
 		parseTreeNode.counter = (index + 1).toString();
 		parseTreeNode.counterName = this.counterName;
 		parseTreeNode.isFirst = index === 0;
-		parseTreeNode.isLast = index === this.list.length - 1;
 	}
 	return parseTreeNode;
 };
@@ -206,7 +232,7 @@ ListWidget.prototype.refresh = function(changedTiddlers) {
 		this.storyview.refreshStart(changedTiddlers,changedAttributes);
 	}
 	// Completely refresh if any of our attributes have changed
-	if(changedAttributes.filter || changedAttributes.variable || changedAttributes.counter || changedAttributes.template || changedAttributes.editTemplate || changedAttributes.emptyMessage || changedAttributes.storyview || changedAttributes.history) {
+	if(changedAttributes.filter || changedAttributes.variable || changedAttributes.counter || changedAttributes.template || changedAttributes.editTemplate || changedAttributes.join || changedAttributes.emptyMessage || changedAttributes.storyview || changedAttributes.history) {
 		this.refreshSelf();
 		result = true;
 	} else {
@@ -310,10 +336,29 @@ ListWidget.prototype.handleListChanges = function(changedTiddlers) {
 			}
 		} else {
 			// Cycle through the list, inserting and removing list items as needed
+			var mustRecreateLastItem = false;
+			if(this.join && this.join.length) {
+				if(this.children.length !== this.list.length) {
+						mustRecreateLastItem = true;
+				} else if(prevList[prevList.length-1] !== this.list[this.list.length-1]) {
+						mustRecreateLastItem = true;
+				}
+			}
+			var isLast = false, wasLast = false;
 			for(t=0; t<this.list.length; t++) {
+				isLast = t === this.list.length-1;
 				var index = this.findListItem(t,this.list[t]);
+				wasLast = index === this.children.length-1;
+				if(wasLast && (index !== t || this.children.length !== this.list.length)) {
+					mustRecreateLastItem = !!(this.join && this.join.length);
+				}
 				if(index === undefined) {
 					// The list item must be inserted
+					if(isLast && mustRecreateLastItem && t>0) {
+						// First re-create previosly-last item that will no longer be last
+						this.removeListItem(t-1);
+						this.insertListItem(t-1,this.list[t-1]);
+					}
 					this.insertListItem(t,this.list[t]);
 					hasRefreshed = true;
 				} else {
@@ -322,12 +367,18 @@ ListWidget.prototype.handleListChanges = function(changedTiddlers) {
 						this.removeListItem(n);
 						hasRefreshed = true;
 					}
-					// Refresh the item we're reusing
+					// Refresh the item we're reusing, or recreate if necessary
+					if(mustRecreateLastItem && (isLast || wasLast)) {
+						this.removeListItem(t);
+						this.insertListItem(t,this.list[t]);
+						hasRefreshed = true;
+					} else {
 						var refreshed = this.children[t].refresh(changedTiddlers);
 						hasRefreshed = hasRefreshed || refreshed;
 					}
 				}
 			}
+		}
 		// Remove any left over items
 		for(t=this.children.length-1; t>=this.list.length; t--) {
 			this.removeListItem(t);
@@ -414,8 +465,17 @@ ListItemWidget.prototype.execute = function() {
 		this.setVariable(this.parseTreeNode.counterName + "-first",this.parseTreeNode.isFirst ? "yes" : "no");
 		this.setVariable(this.parseTreeNode.counterName + "-last",this.parseTreeNode.isLast ? "yes" : "no");
 	}
+	// Add join if needed
+	var children = this.parseTreeNode.children,
+		join = this.parseTreeNode.join;
+	if(join && join.length && !this.parseTreeNode.isLast) {
+		children = children.slice(0);
+		$tw.utils.each(join,function(joinNode) {
+			children.push(joinNode);
+		})
+	}
 	// Construct the child widgets
-	this.makeChildWidgets();
+	this.makeChildWidgets(children);
 };
 
 /*
@@ -450,4 +510,14 @@ ListEmptyWidget.prototype.refresh = function() { return false; }
 
 exports["list-empty"] = ListEmptyWidget;
 
+var ListJoinWidget = function(parseTreeNode,options) {
+	// Main initialisation inherited from widget.js
+	this.initialise(parseTreeNode,options);
+};
+ListJoinWidget.prototype = new Widget();
+ListJoinWidget.prototype.render = function() {}
+ListJoinWidget.prototype.refresh = function() { return false; }
+
+exports["list-join"] = ListJoinWidget;
+
 })();

core/templates/html-json-skinny-tiddler.tid

@@ -1,4 +1,3 @@
 title: $:/core/templates/html-json-skinny-tiddler
 
-<$list filter="[<numTiddlers>compare:number:gteq[1]] ~[<counter>!match[1]]">`,`<$text text=<<newline>>/></$list>
 <$jsontiddler tiddler=<<currentTiddler>> exclude="text" escapeUnsafeScriptChars="yes"/>

core/templates/html-json-tiddler.tid

@@ -1,3 +1,3 @@
 title: $:/core/templates/html-json-tiddler
 
-<$list filter="[<counter>!match[1]]">`,`<$text text=<<newline>>/></$list><$jsontiddler tiddler=<<currentTiddler>> escapeUnsafeScriptChars="yes"/>
+<$jsontiddler tiddler=<<currentTiddler>> escapeUnsafeScriptChars="yes"/>

core/templates/store.area.template.html.tid

@@ -6,14 +6,14 @@ title: $:/core/templates/store.area.template.html
     <$list filter="[[storeAreaFormat]is[variable]getvariable[]else[json]match[json]]">
         <!-- New-style JSON store area, with an old-style store area for compatibility with v5.1.x tooling -->
         `<script class="tiddlywiki-tiddler-store" type="application/json">[`
-            <$vars newline={{{ [charcode[10]] }}}>
+            <$let newline={{{ [charcode[10]] }}} join=`,$(newline)$`>
                 <$text text=<<newline>>/>
-                <$list filter=<<saveTiddlerFilter>> counter="counter" template="$:/core/templates/html-json-tiddler"/>
+                <$list filter=<<saveTiddlerFilter>> join=<<join>> template="$:/core/templates/html-json-tiddler"/>
                 <$vars numTiddlers={{{ [subfilter<saveTiddlerFilter>count[]] }}}>
-                    <$list filter={{{ [<skinnySaveTiddlerFilter>] }}} counter="counter" template="$:/core/templates/html-json-skinny-tiddler"/>
+                    <$list filter={{{ [<skinnySaveTiddlerFilter>] }}} join=<<join>> template="$:/core/templates/html-json-skinny-tiddler"/>
                 </$vars>
                 <$text text=<<newline>>/>
-            </$vars>
+            </$let>
         `]</script>`
         `<div id="storeArea" style="display:none;">`
         `</div>`

core/ui/ViewTemplate/subtitle.tid

@@ -4,11 +4,8 @@ tags: $:/tags/ViewTemplate
 \whitespace trim
 <$reveal type="nomatch" stateTitle=<<folded-state>> text="hide" tag="div" retain="yes" animate="yes">
 <div class="tc-subtitle">
-<$list filter="[all[shadows+tiddlers]tag[$:/tags/ViewTemplate/Subtitle]!has[draft.of]]" variable="subtitleTiddler" counter="indexSubtitleTiddler">
-<$list filter="[<indexSubtitleTiddler-first>match[no]]" variable="ignore">
-&nbsp;
-</$list>
-<$transclude tiddler=<<subtitleTiddler>> mode="inline"/>
+<$list filter="[all[shadows+tiddlers]tag[$:/tags/ViewTemplate/Subtitle]!has[draft.of]]" variable="subtitleTiddler">
+<$transclude tiddler=<<subtitleTiddler>> mode="inline"/><$list-join>&nbsp;</$list-join>
 </$list>
 </div>
 </$reveal>

editions/prerelease/tiddlers/Release 5.3.2.tid

@@ -41,6 +41,33 @@ description: Under development
 
 Note that the <<.attr "emptyMessage">> and <<.attr "template">> attributes take precedence if they are present.
 
+!! Joiners for the ListWidget
+
+<<.link-badge-added "https://github.com/Jermolene/TiddlyWiki5/pull/7694">> a <<.attr "join">> attribute to the <<.wid "ListWidget">> widget to insert a short piece of text between list items. This is both easier to use and faster than using the <<.attr "counter">> attribute for the same purpose. So if your list looked like this:
+
+```
+<$list filter=<<filter>> counter="counter" variable="item">
+<$text text=<<item>>/><$list filter="[<counter-last>match[no]]" variable="ignore"><$text text=", "/></$list>
+</$list>
+```
+
+You can replace it with:
+
+```
+<$list filter=<<filter>> variable="item" join=", ">
+<$text text=<<item>>/>
+</$list>
+```
+
+If the joiner text that you need is long and awkward to write in an attribute, you can use the new `<$list-join>` widget. Like `<$list-template>` and `<$list-empty>`, it must be an immediate child of the <<.wid "ListWidget">>:
+
+```
+<$list filter=<<filter>> variable="item">
+<$text text=<<item>>/>
+<$list-join>, and <em>also</em> let's not forget </$list-join>
+</$list>
+```
+
 !! jsonset operator
 
 <<.link-badge-added "https://github.com/Jermolene/TiddlyWiki5/pull/7742">> [[jsonset Operator]] for setting values within JSON objects

editions/test/tiddlers/tests/data/list-widget/WithJoinTemplate.tid

@@ -0,0 +1,30 @@
+title: ListWidget/WithJoinTemplate
+description: List widget with join template and $list-empty
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
++
+title: Output
+
+\whitespace trim
+
+\procedure test(filter)
+<$list filter=<<filter>>>
+	Item:<<currentTiddler>>
+
+	<$list-empty>
+		None!
+	</$list-empty>
+
+	<$list-join>,</$list-join>
+</$list>
+\end
+
+<<test "1 2 3">>
+
+<<test "">>
+
++
+title: ExpectedResult
+
+<p>Item:1,Item:2,Item:3</p><p>None!</p>

editions/test/tiddlers/tests/data/list-widget/WithJoinTemplateInBlockMode.tid

@@ -0,0 +1,32 @@
+title: ListWidget/WithJoinTemplateInBlockMode
+description: List widget with join template and $list-empty in block mode
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
++
+title: Output
+
+\whitespace trim
+
+\procedure test(filter)
+<$list filter=<<filter>>>
+
+	Item:<<currentTiddler>>
+
+	<$list-empty>
+		None!
+	</$list-empty>
+
+	<$list-join><br></$list-join>
+</$list>
+\end
+
+<<test "1 2 3">>
+
+<<test "">>
+
++
+title: ExpectedResult
+comment: I wish there was a good way to get rid of these extraneous paragraph elements
+
+<p>Item:1</p><p></p><p></p><br><p>Item:2</p><p></p><p></p><br><p>Item:3</p><p></p><p></p>None!

editions/test/tiddlers/tests/test-widget.js

@@ -527,6 +527,45 @@ describe("Widget module", function() {
 		expect(wrapper.children[0].children[15].sequenceNumber).toBe(53);
 	});
 
+	var testListJoin = function(oldList, newList) {
+		return function() {
+			var wiki = new $tw.Wiki();
+			// Add some tiddlers
+			wiki.addTiddler({title: "Numbers", text: "", list: oldList});
+			var text = "<$list filter='[list[Numbers]]' variable='item' join=', '><<item>></$list>";
+			var widgetNode = createWidgetNode(parseText(text,wiki),wiki);
+			// Render the widget node to the DOM
+			var wrapper = renderWidgetNode(widgetNode);
+			// Test the rendering
+			expect(wrapper.innerHTML).toBe("<p>" + oldList.split(' ').join(', ') + "</p>");
+			// Change the list and ensure new rendering is still right
+			wiki.addTiddler({title: "Numbers", text: "", list: newList});
+			refreshWidgetNode(widgetNode,wrapper,["Numbers"]);
+			expect(wrapper.innerHTML).toBe("<p>" + newList.split(' ').join(', ') + "</p>");
+		}
+	}
+
+	it("the list widget with join should update correctly when empty list gets one item", testListJoin("", "1"));
+	it("the list widget with join should update correctly when empty list gets two items", testListJoin("", "1 2"));
+	it("the list widget with join should update correctly when single-item list is appended to", testListJoin("1", "1 2"));
+	it("the list widget with join should update correctly when single-item list is prepended to", testListJoin("1", "2 1"));
+	it("the list widget with join should update correctly when list is appended", testListJoin("1 2 3 4", "1 2 3 4 5"));
+	it("the list widget with join should update correctly when last item is removed", testListJoin("1 2 3 4", "1 2 3"));
+	it("the list widget with join should update correctly when first item is inserted", testListJoin("1 2 3 4", "0 1 2 3 4"));
+	it("the list widget with join should update correctly when first item is removed", testListJoin("1 2 3 4", "2 3 4"));
+	it("the list widget with join should update correctly when first two items are swapped", testListJoin("1 2 3 4", "2 1 3 4"));
+	it("the list widget with join should update correctly when last two items are swapped", testListJoin("1 2 3 4", "1 2 4 3"));
+	it("the list widget with join should update correctly when last item is moved to the front", testListJoin("1 2 3 4", "4 1 2 3"));
+	it("the list widget with join should update correctly when last item is moved to the middle", testListJoin("1 2 3 4", "1 4 2 3"));
+	it("the list widget with join should update correctly when first item is moved to the back", testListJoin("1 2 3 4", "2 3 4 1"));
+	it("the list widget with join should update correctly when middle item is moved to the back", testListJoin("1 2 3 4", "1 3 4 2"));
+	it("the list widget with join should update correctly when the last item disappears at the same time as other edits 1", testListJoin("1 3 4", "1 2 3"));
+	it("the list widget with join should update correctly when the last item disappears at the same time as other edits 2", testListJoin("1 3 4", "1 3 2"));
+	it("the list widget with join should update correctly when the last item disappears at the same time as other edits 3", testListJoin("1 3 4", "2 1 3"));
+	it("the list widget with join should update correctly when the last item disappears at the same time as other edits 4", testListJoin("1 3 4", "2 3 1"));
+	it("the list widget with join should update correctly when the last item disappears at the same time as other edits 5", testListJoin("1 3 4", "3 1 2"));
+	it("the list widget with join should update correctly when the last item disappears at the same time as other edits 6", testListJoin("1 3 4", "3 2 1"));
+
 	var testCounterLast = function(oldList, newList) {
 		return function() {
 			var wiki = new $tw.Wiki();

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

@@ -84,6 +84,7 @@ The action of the list widget depends on the results of the filter combined with
 |limit |<<.from-version "5.3.2">> Optional numeric limit for the number of results that are returned. Negative values will return the results from the end of the list |
 |template |The title of a template tiddler for transcluding each tiddler in the list. When no template is specified, the body of the ListWidget serves as the item template. With no body, a simple link to the tiddler is returned. |
 |editTemplate |An alternative template to use for [[DraftTiddlers|DraftMechanism]] in edit mode |
+|join |<<.from-version "5.3.2">> Text to include between each list item |
 |variable |The name for a [[variable|Variables]] in which the title of each listed tiddler is stored. Defaults to ''currentTiddler'' |
 |counter |<<.from-version "5.2.0">> Optional name for a [[variable|Variables]] in which the 1-based numeric index of each listed tiddler is stored (see below) |
 |emptyMessage |Message to be displayed when the list is empty |
@@ -120,10 +121,29 @@ Displays as:
 </$list>
 <<<
 
-Note that using the `counter` attribute can reduce performance when working with list items that dynamically reorder or update themselves. The best advice is only to use it when it is really necessary: to obtain a numeric index, or to detect the first or last entries in the list.
+Note that using the `counter` attribute can reduce performance when working with list items that dynamically reorder or update themselves. The best advice is only to use it when it is really necessary: to obtain a numeric index, or to detect the first or last entries in the list. Note that if you are only using it to insert something (like a comma) between list items, the `join` attribute performs much better and you should use it instead of `counter`.
 
 Setting `counter="transclusion"` is a handy way to make child elements for each list element be identified as unique. A common use case are multiple [[tag macros|tag Macro]] for the same tag generated by a list widget. Refer to [[tag macro examples|tag Macro (Examples)]] for more details.
 
+!! `join` attribute
+
+<<.from-version "5.3.2">> The optional `join` attribute allow you to insert some [[WikiText]] between each list item without needing to use the `counter` attribute, which can become quite slow if the list is updated frequently.
+
+<<.from-version "5.3.2">> If the widget `<$list-join>` is found as an immediate child of the <<.wid "ListWidget">> widget then the content of that widget is used as the "join" template, included between two list items. Note that the <<.attr "join">> attribute takes precedence if it is present.
+
+For example:
+
+
+```
+<$list filter="[tag[About]sort[title]]" join=", " variable="item"><<item>></$list>
+```
+
+Displays as:
+
+<<<
+<$list filter="[tag[About]sort[title]]" join=", " variable="item"><<item>></$list>
+<<<
+
 !! Edit mode
 
 The `<$list>` widget can optionally render draft tiddlers through a different template to handle editing, see DraftMechanism.

plugins/tiddlywiki/tiddlyweb/html-json-skinny-tiddler.tid

@@ -1,4 +1,3 @@
 title: $:/core/templates/html-json-skinny-tiddler
 
-<$list filter="[<numTiddlers>compare:number:gteq[1]] ~[<counter>!match[1]]">`,`<$text text=<<newline>>/></$list>
 <$jsontiddler tiddler=<<currentTiddler>> exclude="text" escapeUnsafeScriptChars="yes" $revision=<<changecount>> $bag="default" $_is_skinny=""/>

plugins/tiddlywiki/tiddlyweb/html-json-tiddler.tid

@@ -1,4 +1,3 @@
 title: $:/core/templates/html-json-tiddler
 
-<$list filter="[<counter>!match[1]]">`,`<$text text=<<newline>>/></$list>
-<$jsontiddler tiddler=<<currentTiddler>> escapeUnsafeScriptChars="yes" $revision=<<changecount>> $bag="default">/>
+<$jsontiddler tiddler=<<currentTiddler>> escapeUnsafeScriptChars="yes" $revision=<<changecount>> $bag="default"/>