From 7f3269fb025051c3eb2794b15e785b85b0ce37f3 Mon Sep 17 00:00:00 2001
From: Jonne Ransijn <jonne@yyny.dev>
Date: Sun, 27 Oct 2024 14:03:16 +0100
Subject: [PATCH] AK: Add ASCII fast path for `Utf8View::contains`

This also makes `Utf8View::trim` significantly faster, since most
strings start and end with ASCII.
---
 AK/Utf8View.cpp | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/AK/Utf8View.cpp b/AK/Utf8View.cpp
index 151b5918c46..edc50e62bae 100644
--- a/AK/Utf8View.cpp
+++ b/AK/Utf8View.cpp
@@ -104,10 +104,19 @@ bool Utf8View::starts_with(Utf8View const& start) const
 
 bool Utf8View::contains(u32 needle) const
 {
-    for (u32 code_point : *this) {
-        if (code_point == needle)
-            return true;
+    if (needle <= 0x7f) {
+        // OPTIMIZATION: Fast path for ASCII
+        for (u8 code_point : as_string()) {
+            if (code_point == needle)
+                return true;
+        }
+    } else {
+        for (u32 code_point : *this) {
+            if (code_point == needle)
+                return true;
+        }
     }
+
     return false;
 }