From 21ce4218217de6e87c231fa14f3848baf3679532 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Iv=C3=A1n=20Ovejero?= <ivov.src@gmail.com>
Date: Mon, 2 Dec 2024 18:03:25 +0100
Subject: [PATCH] fix: Handle backslashes before opening curly braces

---
 src/ExpressionSplitter.ts       | 21 +++++++++++++++------
 test/ExpressionSplitter.test.ts | 20 ++++++++++++++++++++
 2 files changed, 35 insertions(+), 6 deletions(-)
 create mode 100644 test/ExpressionSplitter.test.ts

diff --git a/src/ExpressionSplitter.ts b/src/ExpressionSplitter.ts
index 3e94bfb..aac0a74 100644
--- a/src/ExpressionSplitter.ts
+++ b/src/ExpressionSplitter.ts
@@ -13,13 +13,17 @@ export interface ExpressionCode {
 
 export type ExpressionChunk = ExpressionCode | ExpressionText;
 
-const OPEN_BRACKET = /(?<escape>\\|)(?<brackets>\{\{)/;
-const CLOSE_BRACKET = /(?<escape>\\|)(?<brackets>\}\})/;
+const OPEN_BRACKET = /(?<brackets>\{\{)/;
+const CLOSE_BRACKET = /(?<brackets>\}\})/;
 
 export const escapeCode = (text: string): string => {
 	return text.replace('\\}}', '}}');
 };
 
+const normalizeBackslashes = (text: string): string => {
+	return text.replace(/\\\\/g, '\\');
+};
+
 export const splitExpression = (expression: string): ExpressionChunk[] => {
 	const chunks: ExpressionChunk[] = [];
 	let searchingFor: 'open' | 'close' = 'open';
@@ -51,16 +55,21 @@ export const splitExpression = (expression: string): ExpressionChunk[] => {
 			}
 			break;
 		}
-		if (res.groups.escape) {
-			buffer += expr.slice(0, res.index + 3);
-			index += res.index + 3;
+
+		const beforeMatch = expr.slice(0, res.index);
+		const backslashCount = beforeMatch.match(/\\*$/)?.[0]?.length ?? 0;
+		const isEscaped = backslashCount % 2 === 1;
+
+		if (isEscaped) {
+			buffer += expr.slice(0, res.index + '{{'.length);
+			index += res.index + '{{'.length;
 		} else {
 			buffer += expr.slice(0, res.index);
 
 			if (searchingFor === 'open') {
 				chunks.push({
 					type: 'text',
-					text: buffer,
+					text: normalizeBackslashes(buffer),
 				});
 				searchingFor = 'close';
 				activeRegex = CLOSE_BRACKET;
diff --git a/test/ExpressionSplitter.test.ts b/test/ExpressionSplitter.test.ts
new file mode 100644
index 0000000..65853ae
--- /dev/null
+++ b/test/ExpressionSplitter.test.ts
@@ -0,0 +1,20 @@
+import { splitExpression } from '../src/ExpressionSplitter';
+
+describe('splitExpression', () => {
+	test('should handle escaping backslashes before double opening curly braces', () => {
+		const expr = 'C:\\\\Users\\\\Administrator\\\\Desktop\\\\abc\\\\{{ $json.files[0].fileName }}';
+		const result = splitExpression(expr);
+
+		expect(result).toEqual([
+			{
+				type: 'text',
+				text: 'C:\\Users\\Administrator\\Desktop\\abc\\',
+			},
+			{
+				type: 'code',
+				text: ' $json.files[0].fileName ',
+				hasClosingBrackets: true,
+			},
+		]);
+	});
+});