From c50695e3c37be6c05707a14183aa23429d2e08f2 Mon Sep 17 00:00:00 2001
From: Sergio Arbeo <serabe@gmail.com>
Date: Fri, 4 Nov 2016 11:02:02 +0100
Subject: [PATCH] [FEATURE beta] Assert expand properties are balanced and not
 nested

In #13693, it is asked to error for an unsupported feature. Though we
don't say that this is not supported, it would be nice if we could let
the user know that what he is trying to do will not work instead of
silently fail.

Fixes #13693

(cherry picked from commit 6f2d615d815fc55b5e2aa2db4a00b538ec3bc41b)
---
 packages/ember-metal/lib/expand_properties.js | 21 +++++++++++++++++++
 .../tests/expand_properties_test.js           | 14 +++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/packages/ember-metal/lib/expand_properties.js b/packages/ember-metal/lib/expand_properties.js
index 626bf31a51a..e7c69cfb679 100644
--- a/packages/ember-metal/lib/expand_properties.js
+++ b/packages/ember-metal/lib/expand_properties.js
@@ -41,6 +41,27 @@ export default function expandProperties(pattern, callback) {
     'Brace expanded properties cannot contain spaces, e.g. "user.{firstName, lastName}" should be "user.{firstName,lastName}"',
     pattern.indexOf(' ') === -1
   );
+  assert(
+    `Brace expanded properties have to be balanced and cannot be nested, pattern: ${pattern}`,
+    ((str) => {
+      let inBrace = 0;
+      let char;
+      for (let i = 0; i < str.length; i++) {
+        char = str.charAt(i);
+
+        if (char === '{') {
+          inBrace++;
+        } else if (char === '}') {
+          inBrace--;
+        }
+
+        if (inBrace > 1 || inBrace < 0) {
+          return false;
+        }
+      }
+
+      return true;
+    })(pattern));
 
   let parts = pattern.split(SPLIT_REGEX);
   let properties = [parts];
diff --git a/packages/ember-metal/tests/expand_properties_test.js b/packages/ember-metal/tests/expand_properties_test.js
index 975831caf34..dea11f2e722 100644
--- a/packages/ember-metal/tests/expand_properties_test.js
+++ b/packages/ember-metal/tests/expand_properties_test.js
@@ -75,6 +75,20 @@ QUnit.test('A property with only brace expansions expands correctly', function()
   deepEqual(expected.sort(), foundProperties.sort());
 });
 
+QUnit.test('Nested brace expansions are not allowed', function() {
+  let nestedBraceProperties = [
+    'a.{b.{c,d}}',
+    'a.{{b}.c}',
+    'a.{b,c}.{d.{e,f}.g',
+    'a.{b.{c}',
+    'a.{b,c}}'
+  ];
+
+  nestedBraceProperties.forEach((invalidProperties) => {
+    expectAssertion(() => expandProperties(invalidProperties, addProperty));
+  }, /Brace expanded properties have to be balanced and cannot be nested/);
+});
+
 QUnit.test('A pattern must be a string', function() {
   expect(1);