Introduce Common readln() and readlnOrNull() top-level functions #KT-48456

libraries/stdlib/jvm/src/kotlin/io/Console.kt

@@ -149,7 +149,7 @@ public actual inline fun println() {
  * The input is decoded using the system default Charset. A [CharacterCodingException] is thrown if input is malformed.
  */
 @SinceKotlin("1.6")
-public fun readln(): String = readlnOrNull() ?: throw ReadAfterEOFException("EOF has already been reached")
+public actual fun readln(): String = readlnOrNull() ?: throw ReadAfterEOFException("EOF has already been reached")
 
 /**
  * Reads a line of input from the standard input stream and returns it,
@@ -160,9 +160,7 @@ public fun readln(): String = readlnOrNull() ?: throw ReadAfterEOFException("EOF
  * The input is decoded using the system default Charset. A [CharacterCodingException] is thrown if input is malformed.
  */
 @SinceKotlin("1.6")
-public fun readlnOrNull(): String? = readLine()
-
-private class ReadAfterEOFException(message: String?) : RuntimeException(message)
+public actual fun readlnOrNull(): String? = readLine()
 
 /**
  * Reads a line of input from the standard input stream.

libraries/stdlib/jvm/test/io/Console.kt

@@ -48,6 +48,20 @@ class ConsoleTest {
         testReadLine("first${linuxLineSeparator}second", listOf("first", "second"))
     }
 
+    @Test
+    fun shouldReadMultipleEmptyLines() {
+        testReadLine(
+            "first${linuxLineSeparator}second${linuxLineSeparator}${linuxLineSeparator}${linuxLineSeparator}",
+            listOf("first", "second", "", "")
+        )
+    }
+
+    @Test
+    fun shouldReadAloneCarriageReturn() {
+        val result = readLines("\r", Charsets.UTF_8)
+        assertEquals(listOf("\r"), result)
+    }
+
     @Test
     fun shouldReadConsecutiveEmptyLines() {
         testReadLine("$linuxLineSeparator$linuxLineSeparator", listOf("", ""))