Added new filter operator for adding prefixes and suffixes to titles; these new filter operators are useful in contexts where only a filter expression is allowed and where macro processing isn't allowed. The filters complement the existing remove suffix and prefix filter operators. (So much for the "filter" in filter operator.)

core/modules/filters/addprefix.js

@@ -0,0 +1,28 @@
+/*\
+title: $:/core/modules/filters/addprefix.js
+type: application/javascript
+module-type: filteroperator
+
+Filter operator for adding a prefix to each title in the list. This is
+especially useful in contexts where only a filter expression is allowed
+and macro substitution isn't available.
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/*
+Export our filter function
+*/
+exports.addprefix = function(source,operator,options) {
+	var results = [];
+	source(function(tiddler,title) {
+		results.push(operator.operand + title);
+	});
+	return results;
+};
+
+})();

core/modules/filters/addsuffix.js

@@ -0,0 +1,28 @@
+/*\
+title: $:/core/modules/filters/addsuffix.js
+type: application/javascript
+module-type: filteroperator
+
+Filter operator for adding a suffix to each title in the list. This is
+especially useful in contexts where only a filter expression is allowed
+and macro substitution isn't available.
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/*
+Export our filter function
+*/
+exports.addsuffix = function(source,operator,options) {
+	var results = [];
+	source(function(tiddler,title) {
+		results.push(title + operator.operand);
+	});
+	return results;
+};
+
+})();