From f26df219c0bb236740abf711b7b4de05f8c3fc2f Mon Sep 17 00:00:00 2001
From: AbhaySingh2477 <abhaysingh2477@users.noreply.github.com>
Date: Wed, 24 Jun 2026 14:02:27 +0530
Subject: [PATCH] Fix infinite loop and parsing error on subtraction

---
 CalculatorLexer.js | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/CalculatorLexer.js b/CalculatorLexer.js
index 9ade9b5..3b2e21d 100644
--- a/CalculatorLexer.js
+++ b/CalculatorLexer.js
@@ -32,10 +32,18 @@ CalculatorLexer.prototype.nextToken = function () {
 				return '*';
 			}
 		} else if (this.c === '-') {
-			if (this.isNumber(this.input[this.p + 1])) {
+			var isNegativeSign = false;
+			var i = this.p - 1;
+			while (i >= 0 && /\s/.test(this.input[i])) i--;
+			if (i < 0 || ['(', '+', '-', '*', '/', '=', ','].indexOf(this.input[i]) > -1) {
+				isNegativeSign = true;
+			}
+			
+			if (isNegativeSign && this.isNumber(this.input[this.p + 1])) {
 				// this is a negative number
 				return this.number();
 			} else {
+				this.consume();
 				return '-';
 			}
 		} else if (this.isNumber(this.c)) {