Support nested macro definitions (#7004)

* First commit

* Switched to \end <name> instead of all those repeated backslashes

Thanks @kookma. See https://github.com/Jermolene/TiddlyWiki5/pull/7004#issuecomment-1286429236

* Docs update

core/modules/parsers/wikiparser/rules/macrodef.js

@@ -58,7 +58,7 @@ exports.parse = function() {
 	var reEnd;
 	if(this.match[3]) {
 		// If so, the end of the body is marked with \end
-		reEnd = /(\r?\n\\end[^\S\n\r]*(?:$|\r?\n))/mg;
+		reEnd = new RegExp("(\\r?\\n\\\\end[^\\S\\n\\r]*(?:" + $tw.utils.escapeRegExp(this.match[1]) + ")?(?:$|\\r?\\n))","mg");
 	} else {
 		// Otherwise, the end of the definition is marked by the end of the line
 		reEnd = /($|\r?\n)/mg;

editions/test/tiddlers/tests/data/macros/NestedMacros.tid

@@ -0,0 +1,36 @@
+title: Macros/NestedMacros
+description: Nested Macros
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
+title: Output
+
+\whitespace trim
+
+\define outer()
+\whitespace trim
+
+\define middle()
+\whitespace trim
+
+\define inner()
+\whitespace trim
+
+Jaguar
+
+\end inner
+
+<<inner>>
+
+\end middle
+
+<<middle>>
+
+\end outer
+
+<<outer>>
+
++
+title: ExpectedResult
+
+<p>Jaguar</p>

editions/tw5.com/tiddlers/wikitext/Macro Definitions in WikiText.tid

@@ -1,13 +1,15 @@
 caption: Macro Definitions
 created: 20150220181617000
-modified: 20180820165115455
+modified: 20221022135909352
 tags: WikiText
 title: Macro Definitions in WikiText
 type: text/vnd.tiddlywiki
 
 A [[macro|Macros]] is defined using a `\define` [[pragma|Pragma]]. Like any pragma, this can only appear at the start of a tiddler.
 
-The first line of the definition specifies the macro name and any parameters. Each parameter has a name and, optionally, a default value that is used if no value is supplied on a particular call to the macro. The lines that follow contain the text of the macro text (i.e. the snippet represented by the macro name), until `\end` appears on a line by itself:
+The first line of the definition specifies the macro name and any parameters. Each parameter has a name and, optionally, a default value that is used if no value is supplied on a particular call to the macro.
+
+The lines that follow contain the text of the macro text (i.e. the snippet represented by the macro name), until `\end` appears on a line by itself:
 
 <$codeblock code={{$:/editions/tw5.com/macro-examples/say-hi}}/>
 
@@ -17,6 +19,20 @@ Alternatively, the entire definition can be presented on a single line without a
 \define sayhi(name:"Bugs Bunny") Hi, I'm $name$.
 ```
 
+Macro definitions can be nested by specifying the name of the macro in the `\end` marker. For example:
+
+<<wikitext-example-without-html src:"""\define special-button(caption:"Click me")
+\define actions()
+<$action-sendmessage $message="tm-notify" $param="HelloThere"/>
+\end actions
+<$button actions=<<actions>>>
+$caption$
+</$button>
+\end special-button
+
+<<special-button>>
+""">>
+
 A more formal [[presentation|Macro Definition Syntax]] of this syntax is also available.
 
 !! Accessing variables and parameters