Use regex for case-insensitive String.replace

KT-41799

libraries/stdlib/jvm/src/kotlin/text/StringsJVM.kt

@@ -77,27 +77,36 @@ public actual fun String.replace(oldChar: Char, newChar: Char, ignoreCase: Boole
  */
 @Suppress("ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS")
 public actual fun String.replace(oldValue: String, newValue: String, ignoreCase: Boolean = false): String {
-    // prefer case-insensitive platform implementation
-    if (!ignoreCase) return (this as java.lang.String).replace(oldValue, newValue)
+    if (ignoreCase) {
+        val matcher = Pattern.compile(oldValue, Pattern.LITERAL or Pattern.CASE_INSENSITIVE).matcher(this)
+        if (!matcher.find()) return this
+        val stringBuilder = StringBuilder()
+        var i = 0
+        do {
+            stringBuilder.append(this, i, matcher.start()).append(newValue)
+            i = matcher.end()
+        } while (matcher.find())
+        return stringBuilder.append(this, i, length).toString()
+    } else {
+        var occurrenceIndex: Int = indexOf(oldValue, 0, ignoreCase)
+        // FAST PATH: no match
+        if (occurrenceIndex < 0) return this
 
-    var occurrenceIndex: Int = indexOf(oldValue, 0, ignoreCase)
-    // FAST PATH: no match
-    if (occurrenceIndex < 0) return this
+        val oldValueLength = oldValue.length
+        val searchStep = oldValueLength.coerceAtLeast(1)
+        val newLengthHint = length - oldValueLength + newValue.length
+        if (newLengthHint < 0) throw OutOfMemoryError()
+        val stringBuilder = StringBuilder(newLengthHint)
 
-    val oldValueLength = oldValue.length
-    val searchStep = oldValueLength.coerceAtLeast(1)
-    val newLengthHint = length - oldValueLength + newValue.length
-    if (newLengthHint < 0) throw OutOfMemoryError()
-    val stringBuilder = StringBuilder(newLengthHint)
-
-    var i = 0
-    do {
-        stringBuilder.append(this, i, occurrenceIndex).append(newValue)
-        i = occurrenceIndex + oldValueLength
-        if (occurrenceIndex >= length) break
-        occurrenceIndex = indexOf(oldValue, occurrenceIndex + searchStep, ignoreCase)
-    } while (occurrenceIndex > 0)
-    return stringBuilder.append(this, i, length).toString()
+        var i = 0
+        do {
+            stringBuilder.append(this, i, occurrenceIndex).append(newValue)
+            i = occurrenceIndex + oldValueLength
+            if (occurrenceIndex >= length) break
+            occurrenceIndex = indexOf(oldValue, occurrenceIndex + searchStep, ignoreCase)
+        } while (occurrenceIndex > 0)
+        return stringBuilder.append(this, i, length).toString()
+    }
 }
 
 /**

libraries/stdlib/test/text/StringTest.kt

@@ -895,6 +895,7 @@ class StringTest {
         assertEquals("/b/", input.replace("ab", "/", ignoreCase = true))
 
         assertEquals("-a-b-b-A-b-", input.replace("", "-"))
+        assertEquals("-a-b-b-A-b-", input.replace("", "-", ignoreCase = true))
     }
 
     @Test fun replaceFirst() {