Add tests, improve parsing of nested expressions

pkg/ql/ast_parser.go

@@ -193,17 +193,18 @@ checkToken:
 		list = append(list, String{Value: t.literal})
 		goto next
 	case PARENTHESIS_OPEN:
+		depth := p.level
 		p.level++
-		dpth := p.level
 		if sub, err := p.parseExpr(p.nextToken()); err != nil {
 			return nil, err
 		} else {
 			list = append(list, sub)
 		}
+
 		// Allow parent level to continue parsing.
 		// Example: ((A) AND (B))
 		// +1 since PARENTHESIS_CLOSE decrease level
-		if p.level > 0 && (p.level+1) != dpth {
+		if (p.level + 1) != depth {
 			p.nextToken()
 			goto next
 		}

pkg/ql/ast_parser_test.go

@@ -183,6 +183,39 @@ func TestAstParser_Parser(t *testing.T) {
 				Null{},
 			},
 		},
+		{
+			parser: NewParser().ParseExpression,
+			in:     `((foo1) AND (foo2))`,
+			tree: ASTNodes{
+				ASTNodes{Ident{Value: "foo1"}},
+				Operator{"AND"},
+				ASTNodes{Ident{Value: "foo2"}},
+			},
+		},
+		{
+			parser: NewParser().ParseExpression,
+			in:     `((foo1) AND (foo2) AND foo3)`,
+			tree: ASTNodes{
+				ASTNodes{Ident{Value: "foo1"}},
+				Operator{"AND"},
+				ASTNodes{Ident{Value: "foo2"}},
+				Operator{"AND"},
+				Ident{Value: "foo3"},
+			},
+		},
+		{
+			parser: NewParser().ParseExpression,
+			in:     `((foo1) AND (foo2)) AND foo3`,
+			tree: ASTNodes{
+				ASTNodes{
+					ASTNodes{Ident{Value: "foo1"}},
+					Operator{"AND"},
+					ASTNodes{Ident{Value: "foo2"}},
+				},
+				Operator{"AND"},
+				Ident{Value: "foo3"},
+			},
+		},
 	}
 
 	for i, test := range tests {