feat(css): add normalize_spacing_only_value function for improved whitespace handling

Introduces a new helper function, `normalize_spacing_only_value`, to enhance the normalization of CSS property values by managing whitespace more effectively. This function replaces the previous inline logic, ensuring consistent handling of spaces, particularly around parentheses. Additionally, updates the test for relative RGB color to account for trailing whitespace, ensuring accurate normalization in various scenarios.

Author: Dwlad90

crates/stylex-css/src/css/common.rs

@@ -485,6 +485,27 @@ fn has_relative_color_call(value: &str, function_name: &str) -> bool {
   })
 }
 
+fn normalize_spacing_only_value(value: &str) -> String {
+  let value = MANY_SPACES.replace_all(value, " ");
+  let mut normalized = String::with_capacity(value.len());
+  let mut previous_char: Option<char> = None;
+  let mut chars = value.chars().peekable();
+
+  while let Some(ch) = chars.next() {
+    if ch == ' ' {
+      match (previous_char, chars.peek()) {
+        (Some('('), _) | (_, Some(')')) => continue,
+        _ => {},
+      }
+    }
+
+    normalized.push(ch);
+    previous_char = Some(ch);
+  }
+
+  normalized
+}
+
 fn is_escaped(value: &[u8], index: usize) -> bool {
   let mut backslash_count = 0;
   let mut cursor = index;
@@ -661,9 +682,7 @@ pub fn normalize_css_property_value(
   detect_unclosed_strings(css_property_value);
 
   if should_normalize_spacing_only {
-    return MANY_SPACES
-      .replace_all(css_property_value, " ")
-      .replace("( ", "(");
+    return normalize_spacing_only_value(css_property_value);
   }
 
   let (parsed_css, errors) = swc_parse_css(css_rule.as_str());

crates/stylex-css/src/css/tests/common_test.rs

@@ -624,7 +624,7 @@ mod normalize_css_property_value_tests {
   #[test]
   fn relative_rgb_color_collapses_whitespace_after_open_paren() {
     let opts = default_options();
-    let result = normalize_css_property_value("color", "rgb(   from red r g b)", &opts);
+    let result = normalize_css_property_value("color", "rgb(   from red r g b   )", &opts);
     assert_eq!(result, "rgb(from red r g b)");
   }