feat: inline comments on inherit

CHANGELOG.md

@@ -36,6 +36,16 @@ Types of changes
   +  assert stdenv.isDarwin -> libXaw != null; # fails to link otherwise
   +
   ```
+- Inline comments support for `if-then-else` expressions:
+  ```diff
+                  if y ? ${a}
+  -                then v x.${a} y.${a}
+  -                # both have attr, use merge func
+  -                else x.${a}
+  -              # only x has attr
+  +                then v x.${a} y.${a} # both have attr, use merge func
+  +                else x.${a} # only x has attr
+  ```
 
 ### Changed
 

src/alejandra_engine/src/children2.rs

@@ -1,10 +1,12 @@
 use std::collections::LinkedList;
 
+#[derive(Debug)]
 pub(crate) enum Trivia {
     Comment(String),
     Newlines(usize),
 }
 
+#[derive(Debug)]
 pub(crate) struct Child {
     pub element: rnix::SyntaxElement,
 
@@ -28,16 +30,26 @@ pub(crate) fn new(
         let mut inline_comment = None;
         let mut trivialities = LinkedList::new();
 
+        let mut skip_next_newline = false;
         children.drain_trivia(|element| match element {
             crate::children::Trivia::Comment(text) => {
-                if trivialities.is_empty() && text.starts_with('#') {
+                if inline_comment.is_none()
+                    && trivialities.is_empty()
+                    && text.starts_with('#')
+                {
                     inline_comment = Some(text);
+                    skip_next_newline = true;
                 } else {
                     trivialities.push_back(Trivia::Comment(text));
                 }
             }
             crate::children::Trivia::Whitespace(text) => {
-                let newlines = crate::utils::count_newlines(&text);
+                let mut newlines = crate::utils::count_newlines(&text);
+
+                if skip_next_newline && newlines > 0 {
+                    newlines -= 1;
+                    skip_next_newline = false;
+                }
 
                 if newlines > 0 {
                     trivialities.push_back(Trivia::Newlines(newlines))

src/alejandra_engine/src/rules/inherit.rs

@@ -4,45 +4,83 @@ pub(crate) fn rule(
 ) -> std::collections::LinkedList<crate::builder::Step> {
     let mut steps = std::collections::LinkedList::new();
 
-    let mut children = crate::children::Children::new(build_ctx, node);
+    let children: Vec<crate::children2::Child> =
+        crate::children2::new(build_ctx, node).collect();
 
-    let vertical = children.has_comments()
-        || children.has_newlines()
-        || build_ctx.vertical;
+    let vertical = build_ctx.vertical
+        || children
+            .iter()
+            .any(|child| child.has_inline_comment || child.has_trivialities);
+
+    let children_count = children.len() - 1;
+    let mut children = children.into_iter();
 
     // inherit
-    let child = children.get_next().unwrap();
-    steps.push_back(crate::builder::Step::Format(child));
+    let child = children.next().unwrap();
+    steps.push_back(crate::builder::Step::Format(child.element));
     if vertical {
         steps.push_back(crate::builder::Step::Indent);
     }
 
-    loop {
-        // /**/
-        children.drain_trivia(|element| match element {
-            crate::children::Trivia::Comment(text) => {
-                steps.push_back(crate::builder::Step::NewLine);
-                steps.push_back(crate::builder::Step::Pad);
-                steps.push_back(crate::builder::Step::Comment(text));
-            }
-            crate::children::Trivia::Whitespace(_) => {}
-        });
+    if let Some(text) = child.inline_comment {
+        steps.push_back(crate::builder::Step::Whitespace);
+        steps.push_back(crate::builder::Step::Comment(text));
+        steps.push_back(crate::builder::Step::NewLine);
+        steps.push_back(crate::builder::Step::Pad);
+    } else if vertical {
+        steps.push_back(crate::builder::Step::NewLine);
+        steps.push_back(crate::builder::Step::Pad);
+    }
 
-        if let Some(child) = children.get_next() {
-            // expr
-            if vertical {
+    for trivia in child.trivialities {
+        match trivia {
+            crate::children2::Trivia::Comment(text) => {
+                steps.push_back(crate::builder::Step::Comment(text));
                 steps.push_back(crate::builder::Step::NewLine);
                 steps.push_back(crate::builder::Step::Pad);
-                steps.push_back(crate::builder::Step::FormatWider(child));
-            } else {
-                if let rnix::SyntaxKind::TOKEN_SEMICOLON = child.kind() {
-                } else {
-                    steps.push_back(crate::builder::Step::Whitespace);
+            }
+            crate::children2::Trivia::Newlines(_) => {}
+        }
+    }
+
+    for (index, child) in children.into_iter().enumerate() {
+        let not_last_child = index + 1 < children_count;
+
+        if vertical {
+            steps.push_back(crate::builder::Step::FormatWider(child.element));
+
+            if let Some(text) = child.inline_comment {
+                steps.push_back(crate::builder::Step::Whitespace);
+                steps.push_back(crate::builder::Step::Comment(text));
+                steps.push_back(crate::builder::Step::NewLine);
+                steps.push_back(crate::builder::Step::Pad);
+            } else if (not_last_child && !child.has_trivialities)
+                || matches!(
+                    child.trivialities.front(),
+                    Some(crate::children2::Trivia::Comment(_))
+                )
+            {
+                steps.push_back(crate::builder::Step::NewLine);
+                steps.push_back(crate::builder::Step::Pad);
+            }
+
+            for trivia in child.trivialities {
+                match trivia {
+                    crate::children2::Trivia::Comment(text) => {
+                        steps.push_back(crate::builder::Step::Comment(text));
+                    }
+                    crate::children2::Trivia::Newlines(_) => {}
+                }
+                if not_last_child {
+                    steps.push_back(crate::builder::Step::NewLine);
+                    steps.push_back(crate::builder::Step::Pad);
                 }
-                steps.push_back(crate::builder::Step::Format(child));
             }
         } else {
-            break;
+            if not_last_child {
+                steps.push_back(crate::builder::Step::Whitespace);
+            }
+            steps.push_back(crate::builder::Step::Format(child.element));
         }
     }
 

src/alejandra_engine/tests/cases/inherit/in

@@ -11,4 +11,19 @@
   { inherit /*a*/ b       d /*e*/ ; }
   { inherit /*a*/ b /*c*/ d       ; }
   { inherit /*a*/ b /*c*/ d /*e*/ ; }
+  {
+    inherit # test
+      a # test
+
+      b # test
+      c # test
+      d # test
+
+      e
+      f
+
+      g
+      h
+      ;
+  }
 ]

src/alejandra_engine/tests/cases/inherit/out

@@ -86,4 +86,18 @@
        */
       ;
   }
+  {
+    inherit # test
+      a # test
+      
+      b # test
+      c # test
+      d # test
+      
+      e
+      f
+      g
+      h
+      ;
+  }
 ]