feat: serialize AST node back to wikitext string

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

@@ -57,4 +57,8 @@ exports.parse = function() {
 	}];
 };
 
+exports.serialize = function(tree) {
+	return "\n```" + tree.attributes.language.value + "\n" + tree.attributes.code.value + "\n```\n";
+}
+
 })();

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

@@ -31,4 +31,8 @@ exports.parse = function() {
 	return [{type: "element", tag: "hr"}];
 };
 
+exports.serialize = function() {
+	return "\n---\n";
+}
+
 })();

core/modules/utils/parsetree.js

@@ -123,4 +123,32 @@ exports.getParseTreeText = function getParseTreeText(tree) {
 	return output.join("");
 };
 
+/*
+Utility to get the (similarly but not 1:1 equal) original wikitext of a parse tree node or array of nodes
+*/
+exports.serializeParseTree = function serializeParseTree(tree, tiddlerType) {
+	var output = [];
+	if($tw.utils.isArray(tree)) {
+		$tw.utils.each(tree,function(node) {
+			output.push(serializeParseTree(node));
+		});
+	} else {
+		if(tree.type === "text") {
+			output.push(tree.text);
+		} else {
+			var Parser = $tw.wiki.getParser(tiddlerType);
+			var Rule = Parser.prototype.blockRuleClasses[tree.rule] ||
+				Parser.prototype.inlineRuleClasses[tree.rule] ||
+				Parser.prototype.pragmaRuleClasses[tree.rule];
+			if(Rule && Rule.prototype.serialize) {
+				output.push(Rule.prototype.serialize(tree));
+			}
+		}
+		if(tree.children) {
+			return serializeParseTree(tree.children);
+		}
+	}
+	return output.join("");
+};
+
 })();

core/modules/wiki.js

@@ -1035,6 +1035,18 @@ Options include:
 exports.parseText = function(type,text,options) {
 	text = text || "";
 	options = options || {};
+	var Parser = this.getParser(type,options)
+	// Return the parser instance
+	return new Parser(type,text,{
+		parseAsInline: options.parseAsInline,
+		wiki: this,
+		_canonical_uri: options._canonical_uri,
+		configTrimWhiteSpace: options.configTrimWhiteSpace
+	});
+};
+
+exports.getParser = function(type,options) {
+	options = $tw.utils.extend({},options);
 	// Select a parser
 	var Parser = $tw.Wiki.parsers[type];
 	if(!Parser && $tw.utils.getFileExtensionInfo(type)) {
@@ -1046,13 +1058,7 @@ exports.parseText = function(type,text,options) {
 	if(!Parser) {
 		return null;
 	}
-	// Return the parser instance
-	return new Parser(type,text,{
-		parseAsInline: options.parseAsInline,
-		wiki: this,
-		_canonical_uri: options._canonical_uri,
-		configTrimWhiteSpace: options.configTrimWhiteSpace
-	});
+	return Parser;
 };
 
 /*