From ee1bb3da03c42144080c2b44317aa5835eef2c22 Mon Sep 17 00:00:00 2001
From: qsliu <qsliu2017@outlook.com>
Date: Sat, 9 Mar 2024 22:21:25 +0800
Subject: [PATCH] minify selectors

---
 selectors/parser.rs | 23 +++++++++++++++++++++++
 src/lib.rs          | 12 ++++++++++++
 src/rules/style.rs  |  2 ++
 3 files changed, 37 insertions(+)

diff --git a/selectors/parser.rs b/selectors/parser.rs
index 25b1445b..2ed1627a 100644
--- a/selectors/parser.rs
+++ b/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)
diff --git a/src/lib.rs b/src/lib.rs
index 8c70f8ad..1c61205c 100644
--- a/src/lib.rs
+++ b/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 {
diff --git a/src/rules/style.rs b/src/rules/style.rs
index 63d8ed7d..e10397e5 100644
--- a/src/rules/style.rs
+++ b/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) {