optimizer: address comment.

2016-01-04 10:34:41 +08:00
parent a8baf4fc02
commit fcbd15dae8
1 changed files with 4 additions and 1 deletions
--- a/optimizer/evaluator/evaluator.go
+++ b/optimizer/evaluator/evaluator.go
@ -55,9 +55,12 @@ func Eval(ctx context.Context, expr ast.ExprNode) (interface{}, error) {
 // EvalBool evalueates an expression to a boolean value.
 func EvalBool(ctx context.Context, expr ast.ExprNode) (bool, error) {
 	val, err := Eval(ctx, expr)
-	if err != nil || val == nil {
+	if err != nil {
 		return false, errors.Trace(err)
 	}
+	if val == nil {
+		return false, nil
+	}

 	i, err := types.ToBool(val)
 	if err != nil {