Properly handling unbalanced braces in type name, added some tests

Author: Enmk

clickhouse/types/type_parser.cpp

@@ -139,7 +139,12 @@ bool TypeParser::Parse(TypeAst* type) {
                 type_ = &type_->elements.back();
                 break;
             case Token::EOS:
+            {
+                // Ubalanced braces, brackets, etc is an error.
+                if (open_elements_.size() != 1)
+                    return false;
                 return true;
+            }
             case Token::Invalid:
                 return false;
         }

ut/columns_ut.cpp

@@ -261,9 +261,24 @@ TEST(ColumnsCase, LowCardinalityString_Save) {
 }
 
 TEST(ColumnsCase, CreateSimpleAggregateFunction) {
-    auto col = CreateColumnByType("SimpleAggregateFunction(funt, Int32");
+    auto col = CreateColumnByType("SimpleAggregateFunction(funt, Int32)");
 
     ASSERT_EQ("Int32", col->Type()->GetName());
     ASSERT_EQ(Type::Int32, col->Type()->GetCode());
     ASSERT_NE(nullptr, col->As<ColumnInt32>());
 }
+
+
+TEST(CreateColumnByType, UnmatchedBrackets) {
+    // When type string has unmatched brackets, CreateColumnByType must return nullptr.
+    ASSERT_EQ(nullptr, CreateColumnByType("FixedString(10"));
+    ASSERT_EQ(nullptr, CreateColumnByType("Nullable(FixedString(10000"));
+    ASSERT_EQ(nullptr, CreateColumnByType("Nullable(FixedString(10000)"));
+    ASSERT_EQ(nullptr, CreateColumnByType("LowCardinality(Nullable(FixedString(10000"));
+    ASSERT_EQ(nullptr, CreateColumnByType("LowCardinality(Nullable(FixedString(10000)"));
+    ASSERT_EQ(nullptr, CreateColumnByType("LowCardinality(Nullable(FixedString(10000))"));
+    ASSERT_EQ(nullptr, CreateColumnByType("Array(LowCardinality(Nullable(FixedString(10000"));
+    ASSERT_EQ(nullptr, CreateColumnByType("Array(LowCardinality(Nullable(FixedString(10000)"));
+    ASSERT_EQ(nullptr, CreateColumnByType("Array(LowCardinality(Nullable(FixedString(10000))"));
+    ASSERT_EQ(nullptr, CreateColumnByType("Array(LowCardinality(Nullable(FixedString(10000)))"));
+}