From 4e76780447e013128026ecca5751c69d24320b52 Mon Sep 17 00:00:00 2001
From: Peter Stenger <pete@stenger.io>
Date: Sat, 19 Apr 2025 18:09:25 -0500
Subject: [PATCH 1/2] Allow .0

---
 spec/parser.js    | 2 ++
 src/handlebars.yy | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/spec/parser.js b/spec/parser.js
index 93ad216..82f663f 100644
--- a/spec/parser.js
+++ b/spec/parser.js
@@ -36,6 +36,8 @@ describe('parser', function () {
     equalsAst('{{this/foo}}', '{{ p%foo }}');
     equalsAst('{{this.foo}}', '{{ p%this.foo }}');
     equalsAst('{{this.#foo}}', '{{ p%this.#foo }}');
+    equalsAst('{{this.foo.0}}', '{{ p%this.foo/0 }}');
+    equalsAst('{{this.0}}', '{{ p%this.0 }}');
   });
 
   it('parses mustaches with - in a path', function () {
diff --git a/src/handlebars.yy b/src/handlebars.yy
index ed26c2c..507f2f8 100644
--- a/src/handlebars.yy
+++ b/src/handlebars.yy
@@ -174,6 +174,6 @@ path
   ;
 
 pathSegments
-  : pathSegments sep ID { $1.push({part: yy.id($3), original: $3, separator: $2}); $$ = $1; }
+  : pathSegments sep (ID | NUMBER) { $1.push({part: yy.id($3), original: $3, separator: $2}); $$ = $1; }
   | ID -> [{part: yy.id($1), original: $1}]
   ;

From a5fca87aa8e322b13c6689dbb79b7335e5a0f366 Mon Sep 17 00:00:00 2001
From: Pete Stenger <pete@stenger.io>
Date: Sat, 19 Apr 2025 22:16:40 -0500
Subject: [PATCH 2/2] More comprehensive test case

---
 lib/helpers.js | 6 ++++++
 spec/parser.js | 8 ++++++++
 2 files changed, 14 insertions(+)

diff --git a/lib/helpers.js b/lib/helpers.js
index ef567e2..3e03643 100644
--- a/lib/helpers.js
+++ b/lib/helpers.js
@@ -60,6 +60,12 @@ export function preparePath(data, sexpr, parts, loc) {
   let tail = [];
   let depth = 0;
 
+  // Check if the first path segment is a number, which should throw an error
+  if (parts.length > 0 && !data && !sexpr && 
+      !isNaN(parseFloat(parts[0].part)) && isFinite(parts[0].part)) {
+    throw new Exception('Invalid path: ' + parts.map(p => (p.separator ?? '') + p.part).join(''), { loc });
+  }
+
   for (let i = 0, l = parts.length; i < l; i++) {
     let part = parts[i].part;
     // If we have [] syntax then we do not treat path references as operators,
diff --git a/spec/parser.js b/spec/parser.js
index 82f663f..ff0bfb0 100644
--- a/spec/parser.js
+++ b/spec/parser.js
@@ -36,8 +36,16 @@ describe('parser', function () {
     equalsAst('{{this/foo}}', '{{ p%foo }}');
     equalsAst('{{this.foo}}', '{{ p%this.foo }}');
     equalsAst('{{this.#foo}}', '{{ p%this.#foo }}');
+    equalsAst('{{this.0.foo}}', '{{ p%this.0/foo }}');
     equalsAst('{{this.foo.0}}', '{{ p%this.foo/0 }}');
     equalsAst('{{this.0}}', '{{ p%this.0 }}');
+    shouldThrow(
+      function () {
+        astFor('{{0.foo}}');
+      },
+      Error,
+      /Invalid path: 0.foo/
+    );
   });
 
   it('parses mustaches with - in a path', function () {