feature(formatter): Add BreakParent IR element

crates/rome_formatter/src/format_element.rs

@@ -735,6 +735,41 @@ pub fn group_elements_with_options(
     format_elements![leading, group, trailing]
 }
 
+/// IR element that forces the parent group to print in expanded mode.
+///
+/// Has no effect if used outside of a group or element that introduce implicit groups (fill element).
+///
+/// ## Examples
+///
+/// ```
+/// use rome_formatter::{Formatted, LineWidth};
+/// use rome_formatter::prelude::*;
+///
+/// let elements = group_elements(format_elements![
+///     token("["),
+///     soft_block_indent(format_elements![
+///         token("'Good morning! How are you today?',"),
+///         soft_line_break_or_space(),
+///         token("2,"),
+///         expand_parent(), // Forces the parent to expand
+///         soft_line_break_or_space(),
+///         token("3"),
+///     ]),
+///     token("]"),
+/// ]);
+///
+/// assert_eq!(
+///     "[\n\t'Good morning! How are you today?',\n\t2,\n\t3\n]",
+///     Formatted::new(elements, PrinterOptions::default()).print().as_code()
+/// );
+/// ```
+///
+/// ## Prettier
+/// Equivalent to Prettier's `break_parent` IR element
+pub const fn expand_parent() -> FormatElement {
+    FormatElement::ExpandParent
+}
+
 /// Creates a group that forces all elements inside it to be printed on a
 /// single line. This behavior can in turn be escaped by introducing an inner
 /// `Group` element that will resume the normal breaking behavior of the printer.
@@ -1083,6 +1118,9 @@ pub enum FormatElement {
     /// See [crate::group_elements] for documentation and examples.
     Group(Group),
 
+    /// Forces the parent group to print in expanded mode.
+    ExpandParent,
+
     /// See [crate::hard_group_elements] for documentation and examples.
     HardGroup(Group),
 
@@ -1196,6 +1234,7 @@ impl Debug for FormatElement {
                 .debug_tuple("Verbatim")
                 .field(&verbatim.element)
                 .finish(),
+            FormatElement::ExpandParent => write!(fmt, "ExpandParent"),
         }
     }
 }
@@ -1585,6 +1624,7 @@ impl FormatElement {
             FormatElement::Comment(content) => content.will_break(),
             FormatElement::Verbatim(verbatim) => verbatim.element.will_break(),
             FormatElement::LineSuffixBoundary => false,
+            FormatElement::ExpandParent => true,
         }
     }
 

crates/rome_formatter/src/printer/mod.rs

@@ -223,8 +223,7 @@ impl<'a> Printer<'a> {
             }
             FormatElement::LineSuffixBoundary => {
                 const HARD_BREAK: &FormatElement = &hard_line_break();
-                // enqueue a line break, this will flush the line suffix
-                queue.enqueue(PrintElementCall::new(HARD_BREAK, args));
+                self.queue_line_suffixes(HARD_BREAK, args, queue);
             }
 
             FormatElement::Comment(content) => {
@@ -241,6 +240,9 @@ impl<'a> Printer<'a> {
 
                 queue.enqueue(PrintElementCall::new(&verbatim.element, args));
             }
+            FormatElement::ExpandParent => {
+                // No-op, only has an effect on `fits`
+            }
         }
     }
 
@@ -603,7 +605,7 @@ fn fits_on_line<'a>(
         pending_indent: printer.state.pending_indent,
         pending_space: printer.state.pending_space,
         line_width: printer.state.line_width,
-        has_line_suffix: printer.state.line_suffixes.is_empty(),
+        has_line_suffix: printer.state.line_suffixes.len() > 0,
     };
 
     let result = loop {
@@ -765,6 +767,11 @@ fn fits_element_on_line<'a, 'rest>(
         FormatElement::Verbatim(verbatim) => {
             queue.enqueue(PrintElementCall::new(&verbatim.element, args))
         }
+        FormatElement::ExpandParent => {
+            if args.mode.is_flat() || args.hard_group {
+                return Fits::No;
+            }
+        }
     }
 
     Fits::Maybe

crates/rome_js_formatter/tests/specs/prettier/js/comments/while.js.snap

@@ -1,6 +1,8 @@
 ---
 source: crates/rome_js_formatter/tests/prettier_tests.rs
+assertion_line: 121
 expression: while.js
+
 ---
 # Input
 ```js