Support for saving result lists in a variable

Extend let filter run prefix to store list of results, and add varlist operator for accessing variables as a list.

We already had partial support for variables returning a list of values in order for functions to work, now we extend it so that any variable can be used to store a list

We should extend the set widget so that it returns a result list that can be accessed with the varlist operator

core/modules/filterrunprefixes/let.js

@@ -25,7 +25,7 @@ exports.let = function(operationSubFunction,options) {
 			var inputSource = widget.wiki.makeTiddlerIterator(results.toArray());
 			// Assign the result of the subfunction to the variable
 			var variables = {};
-			variables[name] = operationSubFunction(inputSource,widget)[0] || "";
+			variables[name] = operationSubFunction(inputSource,widget);
 			// Clear the results
 			results.clear();
 			// Return the variables

core/modules/filters/varlist.js

@@ -0,0 +1,30 @@
+/*\
+title: $:/core/modules/filters/varlist.js
+type: application/javascript
+module-type: filteroperator
+
+Retrieve the value of a variable as a list
+
+[all[shadows+tiddlers]]
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/*
+Export our filter function
+*/
+exports.varlist = function(source,operator,options) {
+	// Check for common optimisations
+	var variableInfo = options.widget.getVariableInfo(operator.operand);
+	if(variableInfo) {
+		return options.wiki.makeTiddlerIterator(variableInfo.resultList);
+	} else {
+		return [];
+	}
+};
+
+})();

core/modules/widgets/widget.js

@@ -83,7 +83,7 @@ Widget.prototype.execute = function() {
 /*
 Set the value of a context variable
 name: name of the variable
-value: value of the variable
+value: value of the variable, can be a string or an array
 params: array of {name:, default:} for each parameter
 isMacroDefinition: true if the variable is set via a \define macro pragma (and hence should have variable substitution performed)
 options includes:
@@ -93,8 +93,10 @@ options includes:
 */
 Widget.prototype.setVariable = function(name,value,params,isMacroDefinition,options) {
 	options = options || {};
+	var valueIsArray = $tw.utils.isArray(value);
 	this.variables[name] = {
-		value: value,
+		value: valueIsArray ? (value[0] || "") : value,
+		resultList: valueIsArray ? value : [value],
 		params: params,
 		isMacroDefinition: !!isMacroDefinition,
 		isFunctionDefinition: !!options.isFunctionDefinition,
@@ -164,6 +166,9 @@ Widget.prototype.getVariableInfo = function(name,options) {
 			resultList = this.wiki.filterTiddlers(value,this.makeFakeWidgetWithVariables(variables),options.source);
 			value = resultList[0] || "";
 		} else {
+			if(variable.resultList) {
+				resultList = variable.resultList;
+			}
 			params = variable.params;
 		}
 		return {
@@ -313,7 +318,7 @@ Widget.prototype.getStateQualifier = function(name) {
 };
 
 /*
-Make a fake widget with specified variables, suitable for variable lookup in filters
+Make a fake widget with specified variables, suitable for variable lookup in filters. Each variable can be a string or an array of strings
 */
 Widget.prototype.makeFakeWidgetWithVariables = function(variables) {
 	var self = this,
@@ -321,7 +326,12 @@ Widget.prototype.makeFakeWidgetWithVariables = function(variables) {
 	return {
 		getVariable: function(name,opts) {
 			if($tw.utils.hop(variables,name)) {
-				return variables[name];
+				var value = variables[name];
+				if($tw.utils.isArray(value)) {
+					return value[0];
+				} else {
+					return value;
+				}
 			} else {
 				opts = opts || {};
 				opts.variables = variables;
@@ -330,9 +340,18 @@ Widget.prototype.makeFakeWidgetWithVariables = function(variables) {
 		},
 		getVariableInfo: function(name,opts) {
 			if($tw.utils.hop(variables,name)) {
+				var value = variables[name];
+				if($tw.utils.isArray(value)) {
 					return {
-					text: variables[name]
+						text: value[0],
+						resultList: value
 					};
+				} else {
+					return {
+						text: value,
+						resultList: [value]
+					};
+				}
 			} else {
 				opts = opts || {};
 				opts.variables = $tw.utils.extend({},variables,opts.variables);

editions/test/tiddlers/tests/data/let-filter-prefix/ResultList.tid

@@ -0,0 +1,12 @@
+title: LetFilterRunPrefix/ResultList
+description: Using the "let" filter run prefix to store result lists, not just single values
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
+title: Output
+
+<$text text={{{ :let:varname[all[tiddlers]] [varlist[varname]sort[]join[,]] }}}/>
++
+title: ExpectedResult
+
+<p>$:/core,ExpectedResult,Output</p>