From 806f0d900c9e39da7b6ea88f7bf7ab5f138d87cc Mon Sep 17 00:00:00 2001
From: Nicolas Dandrimont <nicolas.dandrimont@crans.org>
Date: Mon, 8 Apr 2013 00:17:42 +0200
Subject: [PATCH] Throw an error on unbalanced expressions

---
 hy/lex/states.py      |  3 +++
 tests/lex/test_lex.py | 15 +++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/hy/lex/states.py b/hy/lex/states.py
index 72caba6..52d6fa3 100644
--- a/hy/lex/states.py
+++ b/hy/lex/states.py
@@ -161,6 +161,9 @@ class ListeyThing(State):
         if char == self.end_char:
             return Idle
 
+        if char in ")]}":
+            raise LexException("Unexpected closing character: `%s'" % (char))
+
         if char in WHITESPACE:
             self.commit()
             return
diff --git a/tests/lex/test_lex.py b/tests/lex/test_lex.py
index d3b3706..45922b9 100644
--- a/tests/lex/test_lex.py
+++ b/tests/lex/test_lex.py
@@ -44,6 +44,21 @@ def test_lex_exception():
         pass
 
 
+def test_unbalanced_exception():
+    """Ensure the tokenization fails on unbalanced expressions"""
+    try:
+        tokenize("(bar))")
+        assert True is False
+    except LexException:
+        pass
+
+    try:
+        tokenize("(baz [quux]])")
+        assert True is False
+    except LexException:
+        pass
+
+
 def test_lex_expression_symbols():
     """ Make sure that expressions produce symbols """
     objs = tokenize("(foo bar)")