feat(css): parse scss interpolation expressions

crates/biome_css_formatter/src/generated.rs

@@ -7979,6 +7979,44 @@ impl IntoFormat<CssFormatContext> for biome_css_syntax::ScssIncludeAtRule {
         )
     }
 }
+impl FormatRule<biome_css_syntax::ScssInterpolation>
+    for crate::scss::auxiliary::interpolation::FormatScssInterpolation
+{
+    type Context = CssFormatContext;
+    #[inline(always)]
+    fn fmt(
+        &self,
+        node: &biome_css_syntax::ScssInterpolation,
+        f: &mut CssFormatter,
+    ) -> FormatResult<()> {
+        FormatNodeRule::<biome_css_syntax::ScssInterpolation>::fmt(self, node, f)
+    }
+}
+impl AsFormat<CssFormatContext> for biome_css_syntax::ScssInterpolation {
+    type Format<'a> = FormatRefWithRule<
+        'a,
+        biome_css_syntax::ScssInterpolation,
+        crate::scss::auxiliary::interpolation::FormatScssInterpolation,
+    >;
+    fn format(&self) -> Self::Format<'_> {
+        FormatRefWithRule::new(
+            self,
+            crate::scss::auxiliary::interpolation::FormatScssInterpolation::default(),
+        )
+    }
+}
+impl IntoFormat<CssFormatContext> for biome_css_syntax::ScssInterpolation {
+    type Format = FormatOwnedWithRule<
+        biome_css_syntax::ScssInterpolation,
+        crate::scss::auxiliary::interpolation::FormatScssInterpolation,
+    >;
+    fn into_format(self) -> Self::Format {
+        FormatOwnedWithRule::new(
+            self,
+            crate::scss::auxiliary::interpolation::FormatScssInterpolation::default(),
+        )
+    }
+}
 impl FormatRule<biome_css_syntax::ScssKeywordArgument>
     for crate::scss::auxiliary::keyword_argument::FormatScssKeywordArgument
 {

crates/biome_css_formatter/src/scss/any/expression.rs

@@ -11,6 +11,7 @@ impl FormatRule<AnyScssExpression> for FormatAnyScssExpression {
             AnyScssExpression::AnyCssValue(node) => node.format().fmt(f),
             AnyScssExpression::ScssBinaryExpression(node) => node.format().fmt(f),
             AnyScssExpression::ScssExpression(node) => node.format().fmt(f),
+            AnyScssExpression::ScssInterpolation(node) => node.format().fmt(f),
             AnyScssExpression::ScssListExpression(node) => node.format().fmt(f),
             AnyScssExpression::ScssMapExpression(node) => node.format().fmt(f),
             AnyScssExpression::ScssParenthesizedExpression(node) => node.format().fmt(f),

crates/biome_css_formatter/src/scss/any/expression_item.rs

@@ -13,6 +13,7 @@ impl FormatRule<AnyScssExpressionItem> for FormatAnyScssExpressionItem {
             AnyScssExpressionItem::CssGenericDelimiter(node) => node.format().fmt(f),
             AnyScssExpressionItem::ScssArbitraryArgument(node) => node.format().fmt(f),
             AnyScssExpressionItem::ScssBinaryExpression(node) => node.format().fmt(f),
+            AnyScssExpressionItem::ScssInterpolation(node) => node.format().fmt(f),
             AnyScssExpressionItem::ScssKeywordArgument(node) => node.format().fmt(f),
             AnyScssExpressionItem::ScssListExpression(node) => node.format().fmt(f),
             AnyScssExpressionItem::ScssMapExpression(node) => node.format().fmt(f),

crates/biome_css_formatter/src/scss/auxiliary/interpolation.rs

@@ -0,0 +1,26 @@
+use crate::prelude::*;
+use biome_css_syntax::{ScssInterpolation, ScssInterpolationFields};
+use biome_formatter::{format_args, write};
+
+#[derive(Debug, Clone, Default)]
+pub(crate) struct FormatScssInterpolation;
+impl FormatNodeRule<ScssInterpolation> for FormatScssInterpolation {
+    fn fmt_fields(&self, node: &ScssInterpolation, f: &mut CssFormatter) -> FormatResult<()> {
+        let ScssInterpolationFields {
+            hash_token,
+            l_curly_token,
+            value,
+            r_curly_token,
+        } = node.as_fields();
+
+        write!(
+            f,
+            [group(&format_args![
+                hash_token.format(),
+                l_curly_token.format(),
+                value.format(),
+                r_curly_token.format()
+            ])]
+        )
+    }
+}

crates/biome_css_formatter/src/scss/auxiliary/mod.rs

@@ -10,6 +10,7 @@ pub(crate) mod extend_optional_modifier;
 pub(crate) mod forward_as_clause;
 pub(crate) mod hide_clause;
 pub(crate) mod include_argument_list;
+pub(crate) mod interpolation;
 pub(crate) mod keyword_argument;
 pub(crate) mod list_expression;
 pub(crate) mod list_expression_element;

crates/biome_css_formatter/tests/specs/css/scss/expression/interpolation.scss

@@ -0,0 +1,6 @@
+$direct:#{$name};
+$binary:#{1+2};
+$nested:#{($a+1)*2};
+$call:#{map-get($map,
+key)};
+$list:#{1,2,3};

crates/biome_css_formatter/tests/specs/css/scss/expression/interpolation.scss.snap

@@ -0,0 +1,42 @@
+---
+source: crates/biome_formatter_test/src/snapshot_builder.rs
+assertion_line: 212
+info: css/scss/expression/interpolation.scss
+---
+
+# Input
+
+```scss
+$direct:#{$name};
+$binary:#{1+2};
+$nested:#{($a+1)*2};
+$call:#{map-get($map,
+key)};
+$list:#{1,2,3};
+
+```
+
+
+=============================
+
+# Outputs
+
+## Output 1
+
+-----
+Indent style: Tab
+Indent width: 2
+Line ending: LF
+Line width: 80
+Quote style: Double Quotes
+Trailing newline: true
+-----
+
+```scss
+$direct: #{$name};
+$binary: #{1 + 2};
+$nested: #{($a + 1) * 2};
+$call: #{map-get($map, key)};
+$list: #{1, 2, 3};
+
+```

crates/biome_css_parser/src/lexer/tests.rs

@@ -2,9 +2,9 @@
 #![expect(unused_mut, unused_variables)]
 
 use super::{CssLexer, TextSize};
+use biome_css_syntax::CssSyntaxKind::EOF;
 use crate::lexer::CssLexContext;
 use crate::CssParserOptions;
-use biome_css_syntax::CssSyntaxKind::EOF;
 use biome_parser::lexer::Lexer;
 use quickcheck_macros::quickcheck;
 use std::sync::mpsc::channel;

crates/biome_css_parser/src/syntax/scss/expression/interpolation.rs

@@ -0,0 +1,41 @@
+use crate::parser::CssParser;
+use biome_css_syntax::CssSyntaxKind::SCSS_INTERPOLATION;
+use biome_css_syntax::{CssSyntaxKind, T};
+use biome_parser::prelude::ParsedSyntax::{Absent, Present};
+use biome_parser::prelude::*;
+use biome_parser::{TokenSet, token_set};
+
+use super::list::parse_scss_inner_expression_until;
+use crate::syntax::scss::expected_scss_expression;
+
+const SCSS_INTERPOLATION_END_TOKEN_SET: TokenSet<CssSyntaxKind> = token_set![T!['}'], T![;]];
+
+/// Parses a standalone SCSS interpolation expression such as `#{$value}`.
+///
+/// Example:
+/// ```scss
+/// $value: #{$name};
+/// ```
+///
+/// Docs: https://sass-lang.com/documentation/interpolation/
+#[inline]
+pub(super) fn parse_scss_interpolation(p: &mut CssParser) -> ParsedSyntax {
+    if !is_at_scss_interpolation(p) {
+        return Absent;
+    }
+
+    let m = p.start();
+
+    p.bump(T![#]);
+    p.bump(T!['{']);
+    parse_scss_inner_expression_until(p, SCSS_INTERPOLATION_END_TOKEN_SET)
+        .or_add_diagnostic(p, expected_scss_expression);
+    p.expect(T!['}']);
+
+    Present(m.complete(p, SCSS_INTERPOLATION))
+}
+
+#[inline]
+pub(super) fn is_at_scss_interpolation(p: &mut CssParser) -> bool {
+    p.at(T![#]) && p.nth_at(1, T!['{'])
+}

crates/biome_css_parser/src/syntax/scss/expression/mod.rs

@@ -1,3 +1,4 @@
+mod interpolation;
 mod list;
 mod map;
 mod precedence;

crates/biome_css_parser/src/syntax/scss/expression/primary.rs

@@ -6,6 +6,7 @@ use biome_css_syntax::T;
 use biome_parser::Parser;
 use biome_parser::prelude::ParsedSyntax;
 
+use super::interpolation::{is_at_scss_interpolation, parse_scss_interpolation};
 use super::map::parse_scss_parenthesized_or_map_expression;
 
 /// Parses SCSS primaries such as parenthesized values, maps, `!important`, and
@@ -19,7 +20,9 @@ use super::map::parse_scss_parenthesized_or_map_expression;
 /// Docs: https://sass-lang.com/documentation/at-rules/function
 #[inline]
 pub(super) fn parse_scss_primary_expression(p: &mut CssParser) -> ParsedSyntax {
-    if p.at(T!['(']) {
+    if is_at_scss_interpolation(p) {
+        parse_scss_interpolation(p)
+    } else if p.at(T!['(']) {
         parse_scss_parenthesized_or_map_expression(p)
     } else if is_at_declaration_important(p) {
         parse_declaration_important(p)

crates/biome_css_parser/tests/css_test_suite/error/scss/expression/interpolation.scss

@@ -0,0 +1,3 @@
+$unclosed: #{$name;
+$empty: #{};
+$missing-rhs: #{1 + };