Implement String to/from ByteArray conversion (KT-24810)

libraries/stdlib/common/src/kotlin/TextH.kt

@@ -82,6 +82,13 @@ expect enum class RegexOption {
     MULTILINE
 }
 
+/**
+ *  The exception thrown when a character encoding or decoding error occurs.
+ */
+@SinceKotlin("1.3")
+@ExperimentalStdlibApi
+public expect open class CharacterCodingException() : Exception
+
 
 // From char.kt
 
@@ -135,6 +142,45 @@ public expect fun CharArray.concatToString(startIndex: Int = 0, endIndex: Int =
 @ExperimentalStdlibApi
 public expect fun String.toCharArray(startIndex: Int = 0, endIndex: Int = this.length): CharArray
 
+/**
+ * Decodes a string from the bytes in UTF-8 encoding in this array or its subrange.
+ *
+ * @param startIndex the beginning (inclusive) of the subrange to decode, 0 by default.
+ * @param endIndex the end (exclusive) of the subrange to decode, size of this array by default.
+ * @param throwOnInvalidSequence specifies whether to throw an exception on malformed byte sequence or replace it by the replacement char `\uFFFD`.
+ *
+ * @throws IndexOutOfBoundsException if [startIndex] is less than zero or [endIndex] is greater than the size of this array.
+ * @throws IllegalArgumentException if [startIndex] is greater than [endIndex].
+ * @throws CharacterCodingException if the byte array contains malformed UTF-8 byte sequence and [throwOnInvalidSequence] is true.
+ */
+@SinceKotlin("1.3")
+@ExperimentalStdlibApi
+public expect fun ByteArray.decodeToString(
+    startIndex: Int = 0,
+    endIndex: Int = this.size,
+    throwOnInvalidSequence: Boolean = false
+): String
+
+/**
+ * Encodes this string or its substring to an array of bytes in UTF-8 encoding.
+ *
+ * @param startIndex the beginning (inclusive) of the substring to encode, 0 by default.
+ * @param endIndex the end (exclusive) of the substring to encode, length of this string by default.
+ * @param throwOnInvalidSequence specifies whether to throw an exception on malformed char sequence or replace.
+ *
+ * @throws IndexOutOfBoundsException if [startIndex] is less than zero or [endIndex] is greater than the length of this string.
+ * @throws IllegalArgumentException if [startIndex] is greater than [endIndex].
+ * @throws CharacterCodingException if this string contains malformed char sequence and [throwOnInvalidSequence] is true.
+ */
+@SinceKotlin("1.3")
+@ExperimentalStdlibApi
+public expect fun String.encodeToByteArray(
+    startIndex: Int = 0,
+    endIndex: Int = this.length,
+    throwOnInvalidSequence: Boolean = false
+): ByteArray
+
+
 internal expect fun String.nativeIndexOf(str: String, fromIndex: Int): Int
 internal expect fun String.nativeLastIndexOf(str: String, fromIndex: Int): Int