Add suffix and parameter to trim operator (#4811)

* Add suffix and parameter to trim operator

Fixes #4809

* Unit tests for new trim operator parameters

* Mention trim operator in 5.1.23 release notes

* Address review comments

* Move regex escaping into utils.js trim functions

This way the trimPrefix and trimSuffix functions from utils.js are safe
to call without regex-escaping their parameters, which should make them
easier to use from other parts of the Javascript code.

editions/prerelease/tiddlers/Release 5.1.23.tid

@@ -62,6 +62,7 @@ type: text/vnd.tiddlywiki
 * [[Extended|https://github.com/Jermolene/TiddlyWiki5/pull/4741]] [[WidgetMessage: tm-import-tiddlers]] to override the title $:/Import and to better control whether the import tiddler is opened automatically
 * [[Extended|https://github.com/Jermolene/TiddlyWiki5/pull/4740]] the EditWidget to pass all attributes through to the sub-widget
 * [[Extended|https://github.com/Jermolene/TiddlyWiki5/commit/bd2cf5c46498222a32ebda92da3ae50bde33decb]] the internal `<$element>` widget to add a hook so that plugins can intercept DOM node creation
+* [[Extended|https://github.com/Jermolene/TiddlyWiki5/pull/4811]] the [[trim Operator]] to optionally trim off a prefixing or suffixing string from input tiddler titles
 
 ! Bug Fixes
 

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

@@ -467,6 +467,18 @@ function runTests(wiki) {
 		// Ensure that join correctly handles empty strings in source
 		expect(wiki.filterTiddlers("[[]] Paul +[join[-]]").join(",")).toBe("-Paul");
 		expect(wiki.filterTiddlers("[[ John ]] [[Paul ]] [[ George]] Ringo +[trim[]join[-]]").join(",")).toBe("John-Paul-George-Ringo");
+		expect(wiki.filterTiddlers("[[ abc ]] [[def ]] [[ ghi]] +[trim[]]").join(",")).toBe("abc,def,ghi");
+		expect(wiki.filterTiddlers("[[ abc ]] [[def ]] [[ ghi]] +[trim:prefix[]]").join(",")).toBe("abc ,def ,ghi");
+		expect(wiki.filterTiddlers("[[ abc ]] [[def ]] [[ ghi]] +[trim:suffix[]]").join(",")).toBe(" abc,def, ghi");
+		expect(wiki.filterTiddlers("[[ abacus ]] [[ baobab ]] +[trim[ab]]").join(",")).toBe(" abacus , baobab ");
+		expect(wiki.filterTiddlers("[[ abacus ]] [[ baobab ]] +[trim[a]]").join(",")).toBe(" abacus , baobab ");
+		expect(wiki.filterTiddlers("abacus baobab +[trim[a]]").join(",")).toBe("bacus,baobab");
+		expect(wiki.filterTiddlers("abacus baobab +[trim[ab]]").join(",")).toBe("acus,baob");
+		expect(wiki.filterTiddlers("abacus baobab +[trim:prefix[ab]]").join(",")).toBe("acus,baobab");
+		expect(wiki.filterTiddlers("abacus baobab +[trim:suffix[ab]]").join(",")).toBe("abacus,baob");
+		// Trim doesn't hiccup on regexp special characters
+		expect(wiki.filterTiddlers("[[.*abacus.*]] [[.+baobab.+]] +[trim[.*]]").join(",")).toBe("abacus,.+baobab.+");
+		expect(wiki.filterTiddlers("[[.*abacus.*]] [[.+baobab.+]] +[trim[.+]]").join(",")).toBe(".*abacus.*,baobab");
 	});
 
 	it("should handle the mathematics operators", function() {

editions/tw5.com/tiddlers/filters/examples/trim Operator (Examples).tid

@@ -5,3 +5,11 @@ title: trim Operator (Examples)
 type: text/vnd.tiddlywiki
 
 <<.operator-example 1 "[[ a b ]trim[]addprefix[-]addsuffix[-]]">>
+
+<<.operator-example 2 "[[ abc ]] [[def ]] [[ ghi]] +[trim[]addprefix[-]addsuffix[-]]">>
+<<.operator-example 3 "[[ abc ]] [[def ]] [[ ghi]] +[trim:prefix[]addprefix[-]addsuffix[-]]">>
+<<.operator-example 4 "[[ abc ]] [[def ]] [[ ghi]] +[trim:suffix[]addprefix[-]addsuffix[-]]">>
+
+<<.operator-example 5 "abacus baobab +[trim[ab]]">>
+<<.operator-example 6 "abacus baobab +[trim:prefix[ab]]">>
+<<.operator-example 7 "abacus baobab +[trim:suffix[ab]]">>

editions/tw5.com/tiddlers/filters/removeprefix.tid

@@ -12,4 +12,6 @@ op-output: those input titles that start with <<.place S>>, but with those chara
 
 <<.s-matching-is-case-sensitive>>
 
+<<.tip " This filters out input titles that do not start with S. For removing S without filtering out input titles that don't start with S, see [[trim|trim Operator]].">>
+
 <<.operator-examples "removeprefix">>

editions/tw5.com/tiddlers/filters/removesuffix.tid

@@ -12,4 +12,6 @@ op-output: those input titles that end with <<.place S>>, but with those charact
 
 <<.s-matching-is-case-sensitive>>
 
+<<.tip " This filters out input titles that do not end with S. For removing S without filtering out input titles that don't end with S, see [[trim|trim Operator]].">>
+
 <<.operator-examples "removesuffix">>

editions/tw5.com/tiddlers/filters/trim Operator.tid

@@ -1,13 +1,16 @@
 caption: trim
 created: 20190613153740241
 modified: 20190613153820282
+op-purpose: returns each item in the list with whitespace, or a given character string, trimmed from the start and/or end
 op-input: a [[selection of titles|Title Selection]]
-op-output: the input titles with whitespace trimmed from the start and end
-op-purpose: returns each item in the list with whitespace trimmed from the start and end
+op-parameter: <<.from-version "5.1.23">> a string of characters
+op-parameter-name: S
+op-output: the input titles with <<.place S>>, or whitespace if <<.place S>> is not specified, trimmed from the start and/or end
 tags: [[Filter Operators]]
 title: trim Operator
 type: text/vnd.tiddlywiki
 
 <<.from-version "5.1.20">>
+<<.from-version "5.1.23">>The <<.op trim>> filter allows a parameter specifying a string to trim.
 
 <<.operator-examples "trim">>