Merge pull request #708 from LeanBitLab/bolt-optimize-is-regex-pattern-15896792960406868180

⚡ Bolt: Optimize regex pattern detection in DictionaryFacilitatorImpl

Author: LeanBitLab

.jules/bolt.md

@@ -24,3 +24,6 @@
 ## 2024-05-18 - Optimize Diacritic Stripping in Suggest
 **Learning:** In `Suggest.isSameIgnoringAccents`, `val DIACRITIC_REGEX = "\\p{M}+".toRegex()` was being used in combination with `Normalizer.normalize` and `replace` to strip accents. This created string allocations via `Normalizer.normalize` and `Regex.replace` even for plain ASCII strings that lack accents, which is a hot path during typing and suggestion processing.
 **Action:** Replace `Regex.replace` with a manual character loop that avoids `Normalizer.normalize` entirely for pure ASCII strings and strips `Character.NON_SPACING_MARK` without regex allocation when normalizing.
+## 2024-05-18 - Optimize Regex pattern detection in DictionaryFacilitatorImpl
+**Learning:** `DictionaryFacilitatorImpl.isRegexPattern` used chained `String.contains()` and `String.startsWith()` calls, which internally execute full loops over the string (or delegate to regex). Replacing these chained calls with a single manual O(N) iteration reduces overhead and prevents repeatedly traversing the string.
+**Action:** Replace chained string detection methods (`contains`, `startsWith`, `endsWith`) with a single manual loop over the string's indices when checking multiple characters in performance hot paths.

app/src/main/java/helium314/keyboard/latin/DictionaryFacilitatorImpl.kt

@@ -1235,15 +1235,22 @@ private class DictionaryGroup(
     private var compiledBlacklistPatterns: List<Regex> = emptyList()
 
     private fun isRegexPattern(pattern: String): Boolean {
-        return pattern.contains(".*")
-            || pattern.contains(".+")
-            || pattern.startsWith("^")
-            || pattern.endsWith("$")
-            || pattern.contains("[")
-            || pattern.contains("(")
-            || pattern.contains("\\")
-            || pattern.contains("|")
-            || pattern.contains("{")
+        if (pattern.isEmpty()) return false
+        val len = pattern.length
+
+        // ⚡ Bolt: Optimize regex pattern detection
+        // Replaced chained String.contains() and startsWith() calls with a single
+        // manual character iteration loop to reduce method overhead and execution time.
+        if (pattern[0] == '^' || pattern[len - 1] == '$') return true
+        for (i in 0 until len) {
+            val c = pattern[i]
+            if (c == '[' || c == '(' || c == '\\' || c == '|' || c == '{') return true
+            if (c == '.' && i + 1 < len) {
+                val next = pattern[i + 1]
+                if (next == '*' || next == '+') return true
+            }
+        }
+        return false
     }
 
     private fun rebuildCompiledPatterns() {