consolidate layout and preview checks

crates/ruff_python_formatter/src/expression/expr_lambda.rs

@@ -137,12 +137,16 @@ impl FormatNodeRule<ExprLambda> for FormatExprLambda {
             write!(f, [dangling_comments(dangling)])?;
         }
 
-        FormatBody {
-            body,
-            dangling,
-            layout: self.layout,
+        if !preview {
+            return body.format().fmt(f);
+        }
+
+        let fmt_body = FormatBody { body, dangling };
+
+        match self.layout {
+            ExprLambdaLayout::Assignment => fits_expanded(&fmt_body).fmt(f),
+            ExprLambdaLayout::Default => fmt_body.fmt(f),
         }
-        .fmt(f)
     }
 }
 
@@ -203,26 +207,16 @@ impl NeedsParentheses for ExprLambda {
 struct FormatBody<'a> {
     body: &'a Expr,
     dangling: &'a [SourceComment],
-    layout: ExprLambdaLayout,
 }
 
 impl Format<PyFormatContext<'_>> for FormatBody<'_> {
     fn fmt(&self, f: &mut PyFormatter) -> FormatResult<()> {
-        let FormatBody {
-            dangling,
-            body,
-            layout,
-        } = self;
-
-        if !is_parenthesize_lambda_bodies_enabled(f.context()) {
-            return body.format().fmt(f);
-        }
+        let FormatBody { dangling, body } = self;
 
         let body = *body;
         let comments = f.context().comments().clone();
         let body_comments = comments.leading_dangling_trailing(body);
 
-        let fmt_body = format_with(|f: &mut PyFormatter| {
         if !dangling.is_empty() {
             // Can't use partition_point because there can be additional end of line comments
             // after the initial set. All of these comments are dangling, for example:
@@ -411,11 +405,5 @@ impl Format<PyFormatContext<'_>> for FormatBody<'_> {
         else {
             parenthesize_if_expands(&body.format().with_options(Parentheses::Never)).fmt(f)
         }
-        });
-
-        match layout {
-            ExprLambdaLayout::Assignment => fits_expanded(&fmt_body).fmt(f),
-            ExprLambdaLayout::Default => fmt_body.fmt(f),
-        }
     }
 }