⚡ Bolt: [performance improvement] Pre-compile regex in StringUtils.splitOnWhitespace

.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.

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