Improve grouping of expressions (targets #23).

3 files changed, 20 insertions, 3 deletions

diff --git a/sqlparse/engine/grouping.py b/sqlparse/engine/grouping.py
index 3536a8b..47e77ac 100644
--- a/sqlparse/engine/grouping.py
+++ b/sqlparse/engine/grouping.py
@@ -125,7 +125,7 @@ def group_comparison(tlist):
         return (token.ttype in (T.String.Symbol, T.Name, T.Number,
                                 T.Number.Integer, T.Literal,
                                 T.Literal.Number.Integer)
-                or isinstance(token, (sql.Identifier,))
+                or isinstance(token, (sql.Identifier, sql.Parenthesis))
                 or (token.ttype is T.Keyword
                     and token.value.upper() in ['NULL', ]))
     _group_left_right(tlist, T.Operator.Comparison, None, sql.Comparison,
diff --git a/sqlparse/sql.py b/sqlparse/sql.py
index 3f1e98b..9567aa5 100644
--- a/sqlparse/sql.py
+++ b/sqlparse/sql.py
@@ -546,6 +546,14 @@ class Comparison(TokenList):
     """A comparison used for example in WHERE clauses."""
     __slots__ = ('value', 'ttype', 'tokens')
 
+    @property
+    def left(self):
+        return self.tokens[0]
+
+    @property
+    def right(self):
+        return self.tokens[-1]
+
 
 class Comment(TokenList):
     """A comment."""
diff --git a/tests/test_grouping.py b/tests/test_grouping.py
index fe6aa7d..f4bfb1a 100644
--- a/tests/test_grouping.py
+++ b/tests/test_grouping.py
@@ -262,9 +262,18 @@ def test_comparison_with_keywords():  # issue90
     assert len(p.tokens) == 1
     assert isinstance(p.tokens[0], sql.Comparison)
     assert len(p.tokens[0].tokens) == 5
-    assert p.tokens[0].tokens[0].value == 'foo'
-    assert p.tokens[0].tokens[-1].value == 'NULL'
+    assert p.tokens[0].left.value == 'foo'
+    assert p.tokens[0].right.value == 'NULL'
     # make sure it's case-insensitive
     p = sqlparse.parse('foo = null')[0]
     assert len(p.tokens) == 1
     assert isinstance(p.tokens[0], sql.Comparison)
+
+
+def test_comparison_with_parenthesis():  # issue23
+    p = sqlparse.parse('(3 + 4) = 7')[0]
+    assert len(p.tokens) == 1
+    assert isinstance(p.tokens[0], sql.Comparison)
+    comp = p.tokens[0]
+    assert isinstance(comp.left, sql.Parenthesis)
+    assert comp.right.ttype is T.Number.Integer