Strip inline comments before parsing simple case mappings

Keep comments out of the final UnicodeData field so empty titlecase mappings retain their defaults. Check comment invariance across every parser and Unicode version.

Assisted-By: GPT-6

Author: JLHwung

scripts/parse-simple-case-mapping.mjs

@@ -23,7 +23,7 @@ const parseSimpleCaseMapping = async (version) => {
 	}
 	const lines = source.split('\n');
 	for (const line of lines) {
-		const lineTrimmed = line.trim();
+		const lineTrimmed = line.split('#')[0].trim();
 		if (lineTrimmed === '' || lineTrimmed.startsWith('#')) {
 			continue;
 		}

tests/line-endings.mjs

@@ -17,6 +17,20 @@ for (const file of fs.readdirSync(new URL('../scripts/', import.meta.url))) {
 
 const formats = [
 	['CRLF', (source) => source.replace(/\r?\n/g, '\r\n')],
+	[
+		'inline comments',
+		(source) =>
+			source
+				.split('\n')
+				.map((line) => {
+					if (line.trim().startsWith('#') || !line.includes(';')) return line;
+					return (
+						line.split('#')[0].trimEnd() +
+						'# explanatory comment; with field delimiters'
+					);
+				})
+				.join('\n'),
+	],
 	[
 		'whitespace-only lines and indented comments',
 		(source) =>

tests/parser-formats.mjs

@@ -15,6 +15,28 @@ import {
 } from '../scripts/parse-blocks-scripts-properties.mjs';
 import utils from '../scripts/utils.mjs';
 
+test('Simple case mappings ignore comments after empty and explicit titlecase fields', async (t) => {
+	t.mock.method(utils, 'readDataFile', () =>
+		[
+			'  # A comment; with field delimiters',
+			'0000;<control>;Cc;0;BN;;;;;N;;;;;# no case mappings; still a comment',
+			'0041;LATIN CAPITAL LETTER A;Lu;0;L;;;;;N;;;;0061;# lowercase only',
+			'0061;LATIN SMALL LETTER A;Ll;0;L;;;;;N;;;0041;;# null titlecase defaults to uppercase',
+			'01C6;LATIN SMALL LETTER DZ WITH CARON;Ll;0;L;<compat> 0064 017E;;;;N;;;01C4;;01C5# explicit titlecase; # extra comment marker',
+		].join('\n'),
+	);
+	for (const version of ['4.0.0', '18.0.0']) {
+		const map = await parseSimpleCaseMapping(version);
+		t.assert.equal(map.Uppercase.get(0x61), 0x41);
+		t.assert.equal(map.Lowercase.get(0x41), 0x61);
+		t.assert.equal(map.Titlecase.get(0x61), 0x41);
+		t.assert.equal(map.Titlecase.get(0x1c6), 0x1c5);
+		for (const mappings of Object.values(map)) {
+			t.assert.ok(!mappings.has(0));
+		}
+	}
+});
+
 test('Script_Extensions accepts whitespace runs for singletons and ranges', async (t) => {
 	const read = utils.readDataFile;
 	let source;