From 84a3ebcaa1dd626781d824c3e8c4da225101d806 Mon Sep 17 00:00:00 2001
From: LeanBitLab <245915690+LeanBitLab@users.noreply.github.com>
Date: Wed, 7 Oct 2026 08:10:43 +0000
Subject: [PATCH] Performance: Pre-compile Regex in String.splitOnWhitespace

`StringUtils.splitOnWhitespace()` created a new `Regex("\\s+")` instance
every time it was called. Because it is used in various text processing
and dictionary-filtering paths, pre-compiling this to a single, static
property eliminates unnecessary regex compilation overhead and avoids
useless GC pressure during fast typing/searching.
---
 .jules/bolt.md                                                | 4 ++++
 .../main/java/helium314/keyboard/latin/common/StringUtils.kt  | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/.jules/bolt.md b/.jules/bolt.md
index 5d54a29f7..77119f7cb 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -1,3 +1,7 @@
 ## 2024-05-18 - Language Detector Optimization
 **Learning:** `LanguageDetector.detect` uses `Regex("[^\\p{L}]+")` inside `detectByHeuristics`, creating a new Regex instance on every call. This method is called via `ProofreadHelper` which is likely triggered on user typing or interaction. Pre-compiling the Regex as a top-level constant avoids the overhead of regex compilation for every detection call.
 **Action:** Always check for repeated Regex instantiations in frequently called string processing or detection methods and extract them to top-level or companion object properties.
+
+## 2024-05-18 - StringUtils Whitespace Split Optimization
+**Learning:** `StringUtils.splitOnWhitespace` creates a `Regex("\\s+")` inline every time it is called. Since this is an extension function used across settings and text processing, this causes unnecessary allocations.
+**Action:** Abstract frequent inline regex usages into `private val` properties at the object or file level to avoid repeated regex compilation.
diff --git a/app/src/main/java/helium314/keyboard/latin/common/StringUtils.kt b/app/src/main/java/helium314/keyboard/latin/common/StringUtils.kt
index 51c6edfdd..d0360ff21 100644
--- a/app/src/main/java/helium314/keyboard/latin/common/StringUtils.kt
+++ b/app/src/main/java/helium314/keyboard/latin/common/StringUtils.kt
@@ -291,7 +291,8 @@ fun isEmoji(c: Int): Boolean = StringUtils.mightBeEmoji(c) && isEmoji(StringUtil
 /** returns whether the text is a single emoji */
 fun isEmoji(text: CharSequence): Boolean = mightBeEmoji(text) && text.matches(emoRegex)
 
-fun String.splitOnWhitespace() = split(Regex("\\s+")).filter { it.isNotEmpty() }
+private val WHITESPACE_REGEX = Regex("\\s+")
+fun String.splitOnWhitespace() = split(WHITESPACE_REGEX).filter { it.isNotEmpty() }
 
 // from https://github.com/mathiasbynens/emoji-test-regex-pattern, MIT license
 // matches single emojis only