fix: #67 idempotent format issue

Author: xixiaofinland

src/context.rs

@@ -114,6 +114,10 @@ impl Comment {
         self.metadata.has_empty_line_above
     }
 
+    pub fn has_prev_node_else_keyword(&self) -> bool {
+        self.metadata.has_prev_node_else_keyword
+    }
+
     pub fn is_followed_by_bracket_composite_node(&self) -> bool {
         self.metadata.is_followed_by_bracket_composite_node
     }
@@ -163,22 +167,26 @@ pub struct CommentMetadata {
     has_empty_line_above: bool,
     has_empty_line_below: bool,
     has_prev_node: bool,
+    has_prev_node_else_keyword: bool,
     is_followed_by_bracket_composite_node: bool,
 }
 
 impl CommentMetadata {
     pub fn from(node: &Node, comment_type: CommentType) -> Self {
         let prev = node.prev_named_sibling();
-        let next = node.next_named_sibling();
-
         let has_prev_node = prev.is_some();
 
+
+        let prev_unnamed = node.prev_sibling();
+        let has_prev_node_else_keyword = prev_unnamed.map(|n| n.kind() == "else").unwrap_or(false);
+
         let has_leading_content = if let Some(prev_node) = prev {
             node.start_position().row == prev_node.end_position().row
         } else {
             false
         };
 
+        let next = node.next_named_sibling();
         let has_trailing_content = match comment_type {
             CommentType::Line => false,
             CommentType::Block => {
@@ -214,6 +222,7 @@ impl CommentMetadata {
             has_empty_line_above,
             has_empty_line_below,
             has_prev_node,
+            has_prev_node_else_keyword,
             is_followed_by_bracket_composite_node,
         }
     }

src/utility.rs

@@ -357,7 +357,13 @@ pub fn handle_pre_comments<'a>(
             // if it's in group(), then multi-line mode is selected in fits()
             // otherwise, do nothing
             docs.push(b.force_break());
+
             // 1st element heading logic is handled in the preceding node;
+            // except the preceding is an unnamed node like `else`
+            if comment.has_prev_node_else_keyword() {
+                docs.push(b.nl());
+            }
+
             if i != 0 {
                 if comment.has_newline_above() {
                     docs.push(b.empty_new_line());

tests/to-do/twice_format_issue3.in

@@ -0,0 +1,7 @@
+class TestClass {
+  {
+    if (true)
+    // comment 1
+    {}
+   }
+}