feat(rome_js_formatter): Format Arrow Chains

crates/rome_formatter/src/builders.rs

@@ -1231,28 +1231,53 @@ pub fn group<Context>(content: &impl Format<Context>) -> Group<Context> {
     Group {
         content: Argument::new(content),
         group_id: None,
+        should_expand: false,
     }
 }
 
 #[derive(Copy, Clone)]
 pub struct Group<'a, Context> {
     content: Argument<'a, Context>,
     group_id: Option<GroupId>,
+    should_expand: bool,
 }
 
 impl<Context> Group<'_, Context> {
     pub fn with_group_id(mut self, group_id: Option<GroupId>) -> Self {
         self.group_id = group_id;
         self
     }
+
+    /// Setting the value to `true` forces the group and its enclosing group to expand regardless if it otherwise would fit on the
+    /// line or contains any hard line breaks.
+    ///
+    /// The formatter writes a [FormatElement::ExpandParent], forcing any enclosing group to expand, if `should_expand` is `true``.
+    /// It also omits the enclosing [FormatElement::Group] because the group would be forced to expand anyway.
+    /// The [FormatElement:Group] only gets written if the `group id` specified with [Group::with_group_id] isn't [None]
+    /// because other IR elements may reference the group with that group id and the printer may panic
+    /// if no group with the given id is present in the document.
+    pub fn should_expand(mut self, should_expand: bool) -> Self {
+        self.should_expand = should_expand;
+        self
+    }
 }
 
 impl<Context> Format<Context> for Group<'_, Context> {
     fn fmt(&self, f: &mut Formatter<Context>) -> FormatResult<()> {
+        if self.group_id.is_none() && self.should_expand {
+            write!(f, [expand_parent()])?;
+            return f.write_fmt(Arguments::from(&self.content));
+        }
+
         let mut buffer = GroupBuffer::new(f);
+
         buffer.write_fmt(Arguments::from(&self.content))?;
-        let content = buffer.into_vec();
 
+        if self.should_expand {
+            write!(buffer, [expand_parent()])?;
+        }
+
+        let content = buffer.into_vec();
         if content.is_empty() && self.group_id.is_none() {
             return Ok(());
         }
@@ -1269,6 +1294,7 @@ impl<Context> std::fmt::Debug for Group<'_, Context> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.debug_struct("GroupElements")
             .field("group_id", &self.group_id)
+            .field("should_expand", &self.should_expand)
             .field("content", &"{{content}}")
             .finish()
     }

crates/rome_js_formatter/src/js/auxiliary/initializer_clause.rs

@@ -1,11 +1,28 @@
 use crate::prelude::*;
 
-use rome_formatter::write;
+use crate::utils::{with_assignment_layout, AssignmentLikeLayout};
+use rome_formatter::{write, FormatRuleWithOptions};
 use rome_js_syntax::JsInitializerClause;
 use rome_js_syntax::JsInitializerClauseFields;
 
 #[derive(Debug, Clone, Default)]
-pub struct FormatJsInitializerClause;
+pub struct FormatJsInitializerClause {
+    assignment_layout: Option<AssignmentLikeLayout>,
+}
+
+#[derive(Default, Debug)]
+pub struct FormatJsInitializerClauseOptions {
+    pub(crate) assignment_layout: Option<AssignmentLikeLayout>,
+}
+
+impl FormatRuleWithOptions<JsInitializerClause> for FormatJsInitializerClause {
+    type Options = FormatJsInitializerClauseOptions;
+
+    fn with_options(mut self, options: Self::Options) -> Self {
+        self.assignment_layout = options.assignment_layout;
+        self
+    }
+}
 
 impl FormatNodeRule<JsInitializerClause> for FormatJsInitializerClause {
     fn fmt_fields(&self, node: &JsInitializerClause, f: &mut JsFormatter) -> FormatResult<()> {
@@ -14,6 +31,13 @@ impl FormatNodeRule<JsInitializerClause> for FormatJsInitializerClause {
             expression,
         } = node.as_fields();
 
-        write![f, [eq_token.format(), space(), expression.format()]]
+        write![
+            f,
+            [
+                eq_token.format(),
+                space(),
+                with_assignment_layout(&expression?, self.assignment_layout)
+            ]
+        ]
     }
 }