minify selectors

selectors/parser.rs

@@ -17,6 +17,7 @@ use cssparser::{Parser as CssParser, ToCss, Token};
 use precomputed_hash::PrecomputedHash;
 use smallvec::{smallvec, SmallVec};
 use std::borrow::Borrow;
+use std::collections::HashSet;
 use std::fmt::{self, Debug};
 use std::iter::Rev;
 use std::slice;
@@ -540,6 +541,28 @@ impl<'i, Impl: SelectorImpl<'i>> SelectorList<'i, Impl> {
  }
  }
 
+ pub fn minify(&mut self) {
+ self
+ .0
+ .iter()
+ .enumerate()
+ .fold(
+ (HashSet::with_capacity(self.0.len()), Vec::with_capacity(self.0.len())),
+ |(mut seen, mut to_remove), (i, selector)| {
+ if !seen.insert(selector.to_css_string()) {
+ to_remove.push(i);
+ }
+ (seen, to_remove)
+ },
+ )
+ .1
+ .into_iter()
+ .rev()
+ .for_each(|i| {
+ self.0.remove(i);
+ });
+ }
+
  /// Creates a new SelectorList.
  pub fn new(v: SmallVec<[Selector<'i, Impl>; 1]>) -> Self {
  SelectorList(v)

src/lib.rs

@@ -8872,6 +8872,18 @@ mod tests {
 
  #[test]
  fn test_merge_rules() {
+ test(
+ r#"
+ .foo, .bar, .foo {
+ color: red;
+ }
+ "#,
+ indoc! {r#"
+ .foo, .bar {
+ color: red;
+ }
+ "#},
+ );
  test(
  r#"
  .foo {

src/rules/style.rs

@@ -56,6 +56,8 @@ impl<'i, T: Clone> StyleRule<'i, T> {
  context: &mut MinifyContext<'_, 'i>,
  parent_is_unused: bool,
  ) -> Result<bool, MinifyError> {
+ self.selectors.minify();
+
  let mut unused = false;
  if !context.unused_symbols.is_empty() {
  if is_unused(&mut self.selectors.0.iter(), &context.unused_symbols, parent_is_unused) {