Unify Regex.split behavior in JVM, JS regarding empty match delimiters

Rewrite split implementation for JVM

#KT-21049

libraries/stdlib/jvm/src/kotlin/text/regex/Regex.kt

@@ -187,7 +187,23 @@ internal constructor(private val nativePattern: Pattern) : Serializable {
     @Suppress("ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS")
     public actual fun split(input: CharSequence, limit: Int = 0): List<String> {
         require(limit >= 0, { "Limit must be non-negative, but was $limit." })
-        return nativePattern.split(input, if (limit == 0) -1 else limit).asList()
+
+        val matcher = nativePattern.matcher(input)
+        if (!matcher.find() || limit == 1) return listOf(input.toString())
+
+        val result = ArrayList<String>(if (limit > 0) limit.coerceAtMost(10) else 10)
+        var lastStart = 0
+        val lastSplit = limit - 1 // negative if there's no limit
+
+        do {
+            result.add(input.substring(lastStart, matcher.start()))
+            lastStart = matcher.end()
+            if (lastSplit >= 0 && result.size == lastSplit) break
+        } while (matcher.find())
+
+        result.add(input.substring(lastStart, input.length))
+
+        return result
     }
 
     /** Returns the string representation of this regular expression, namely the [pattern] of this regular expression. */

libraries/stdlib/test/text/RegexTest.kt

@@ -203,6 +203,24 @@ class RegexTest {
 
     }
 
+    @Test fun splitByEmptyMatch() {
+        val input = "test"
+
+        val emptyMatch = "".toRegex()
+
+        assertEquals(input.split(""), input.split(emptyMatch))
+        assertEquals(input.split("", limit = 3), input.split(emptyMatch, limit = 3))
+
+        assertEquals("".split(""), "".split(emptyMatch))
+
+        val emptyMatchBeforeT = "(?=t)".toRegex()
+
+        assertEquals(listOf("", "tes", "t"), input.split(emptyMatchBeforeT))
+        assertEquals(listOf("", "test"), input.split(emptyMatchBeforeT, limit = 2))
+
+        assertEquals(listOf("", "tee"), "tee".split(emptyMatchBeforeT))
+    }
+
 
 
 }