Format filter to create formatted date strings (#4785)

* asdate filter to create formatted date strings

* Added format filter operator

core/language/en-GB/Misc.multids

@@ -27,6 +27,7 @@ Error/EditConflict: File changed on server
 Error/Filter: Filter error
 Error/FilterSyntax: Syntax error in filter expression
 Error/IsFilterOperator: Filter Error: Unknown operand for the 'is' filter operator
+Error/FormatFilterOperator: Filter Error: Unknown suffix for the 'format' filter operator
 Error/LoadingPluginLibrary: Error loading plugin library
 Error/NetworkErrorAlert: `<h2>''Network Error''</h2>It looks like the connection to the server has been lost. This may indicate a problem with your network connection. Please attempt to restore network connectivity before continuing.<br><br>''Any unsaved changes will be automatically synchronised when connectivity is restored''.`
 Error/RecursiveTransclusion: Recursive transclusion error in transclude widget

core/modules/filters/format.js

@@ -0,0 +1,46 @@
+/*\
+title: $:/core/modules/filters/format.js
+type: application/javascript
+module-type: filteroperator
+Filter operator for formatting strings
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+var formatFilterOperators;
+
+function getFormatFilterOperators() {
+	if(!formatFilterOperators) {
+		formatFilterOperators = {};
+		$tw.modules.applyMethods("formatfilteroperator",formatFilterOperators);
+	}
+	return formatFilterOperators;
+}
+
+/*
+Export our filter function
+*/
+exports.format = function(source,operator,options) {
+	// Dispatch to the correct formatfilteroperator
+	var formatFilterOperators = getFormatFilterOperators();
+	if(operator.suffix) {
+		var formatFilterOperator = formatFilterOperators[operator.suffix];
+		if(formatFilterOperator) {
+			return formatFilterOperator(source,operator.operand,options);
+		} else {
+			return [$tw.language.getString("Error/FormatFilterOperator")];
+		}
+	} else {
+		// Return all unchanged if the suffix is missing
+		var results = [];
+		source(function(tiddler,title) {
+			results.push(title);
+		});
+		return results;
+	}
+};
+
+})();

core/modules/filters/format/date.js

@@ -0,0 +1,26 @@
+/*\
+title: $:/core/modules/filters/format/date.js
+type: application/javascript
+module-type: formatfilteroperator
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/*
+Export our filter function
+*/
+exports.date = function(source,operand,options) {
+	var results = [];	
+	source(function(tiddler,title) {
+		var value = $tw.utils.parseDate(title);
+		if(value && $tw.utils.isDate(value) && value.toString() !== "Invalid Date") {
+			results.push($tw.utils.formatDateString(value,operand || "YYYY MM DD 0hh:0mm"));
+		}
+	});	
+	return results;
+};
+
+})();

core/modules/filters/format/relativedate.js

@@ -0,0 +1,26 @@
+/*\
+title: $:/core/modules/filters/format/relativedate.js
+type: application/javascript
+module-type: formatfilteroperator
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/*
+Export our filter function
+*/
+exports.relativedate = function(source,operand,options) {
+	var results = [];	
+	source(function(tiddler,title) {
+		var value = $tw.utils.parseDate(title);
+		if(value && $tw.utils.isDate(value) && value.toString() !== "Invalid Date") {
+			results.push($tw.utils.getRelativeDate((new Date()) - (new Date(value))).description);
+		}
+	});	
+	return results;
+};
+
+})();