From 245bf503e2a948ac98170516d11df632e85a948b Mon Sep 17 00:00:00 2001
From: bendn <bend.n@outlook.com>
Date: Sun, 25 May 2025 02:01:04 +0700
Subject: [PATCH] increase perf of charsearcher for single ascii characters

---
 library/core/src/str/iter.rs    |  2 +-
 library/core/src/str/pattern.rs | 32 +++++++++++++++++++++++++++++++-
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/library/core/src/str/iter.rs b/library/core/src/str/iter.rs
index 425c4eaee28ee..49c581f352eb3 100644
--- a/library/core/src/str/iter.rs
+++ b/library/core/src/str/iter.rs
@@ -656,7 +656,7 @@ impl<'a, P: Pattern> SplitInternal<'a, P> {
         None
     }
 
-    #[inline]
+    #[inline(always)]
     fn next(&mut self) -> Option<&'a str> {
         if self.finished {
             return None;
diff --git a/library/core/src/str/pattern.rs b/library/core/src/str/pattern.rs
index bcbbb11c83b2f..e8189a2187b63 100644
--- a/library/core/src/str/pattern.rs
+++ b/library/core/src/str/pattern.rs
@@ -429,8 +429,23 @@ unsafe impl<'a> Searcher<'a> for CharSearcher<'a> {
             SearchStep::Done
         }
     }
-    #[inline]
+    #[inline(always)]
     fn next_match(&mut self) -> Option<(usize, usize)> {
+        if self.utf8_size == 1 {
+            return match self
+                .haystack
+                .as_bytes()
+                .get(self.finger..self.finger_back)?
+                .iter()
+                .position(|x| *x == self.utf8_encoded[0])
+            {
+                Some(x) => {
+                    self.finger += x + 1;
+                    Some((self.finger - 1, self.finger))
+                }
+                None => None,
+            };
+        }
         loop {
             // get the haystack after the last character found
             let bytes = self.haystack.as_bytes().get(self.finger..self.finger_back)?;
@@ -498,6 +513,21 @@ unsafe impl<'a> ReverseSearcher<'a> for CharSearcher<'a> {
     }
     #[inline]
     fn next_match_back(&mut self) -> Option<(usize, usize)> {
+        if self.utf8_size == 1 {
+            return match self
+                .haystack
+                .get(self.finger..self.finger_back)?
+                .as_bytes()
+                .iter()
+                .rposition(|&x| x == self.utf8_encoded[0])
+            {
+                Some(x) => {
+                    self.finger_back = self.finger + x;
+                    Some((self.finger_back, self.finger_back + 1))
+                }
+                None => None,
+            };
+        }
         let haystack = self.haystack.as_bytes();
         loop {
             // get the haystack up to but not including the last character searched