Leading, Dangling, and Trailing comments formatting (#4785)

crates/ruff_python_formatter/src/context.rs

@@ -8,6 +8,7 @@ pub struct PyFormatContext<'a> {
     options: SimpleFormatOptions,
     contents: &'a str,
     comments: Comments<'a>,
+    node_level: NodeLevel,
 }
 
 impl<'a> PyFormatContext<'a> {
@@ -20,6 +21,7 @@ impl<'a> PyFormatContext<'a> {
             options,
             contents,
             comments,
+            node_level: NodeLevel::TopLevel,
         }
     }
 
@@ -33,6 +35,15 @@ impl<'a> PyFormatContext<'a> {
         Locator::new(self.contents)
     }
 
+    #[allow(unused)]
+    pub(crate) fn set_node_level(&mut self, level: NodeLevel) {
+        self.node_level = level;
+    }
+
+    pub(crate) fn node_level(&self) -> NodeLevel {
+        self.node_level
+    }
+
     #[allow(unused)]
     pub(crate) fn comments(&self) -> &Comments<'a> {
         &self.comments
@@ -56,7 +67,24 @@ impl Debug for PyFormatContext<'_> {
         f.debug_struct("PyFormatContext")
             .field("options", &self.options)
             .field("comments", &self.comments.debug(self.source_code()))
+            .field("node_level", &self.node_level)
             .field("source", &self.contents)
             .finish()
     }
 }
+
+/// What's the enclosing level of the outer node.
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Default)]
+pub(crate) enum NodeLevel {
+    /// Formatting statements on the module level.
+    #[default]
+    TopLevel,
+
+    /// Formatting nodes that are enclosed by a statement.
+    #[allow(unused)]
+    Statement,
+
+    /// Formatting nodes that are enclosed in a parenthesized expression.
+    #[allow(unused)]
+    Parenthesized,
+}