Implement ByteString factory accepting UBytes (#390)

* Implement ByteString factory accepting UBytes

Fixes #389

Author: fzhinkin

bytestring/api/kotlinx-io-bytestring.api

@@ -75,7 +75,9 @@ public final class kotlinx/io/bytestring/ByteStringJvmExtKt {
 }
 
 public final class kotlinx/io/bytestring/ByteStringKt {
+	public static final fun ByteString ()Lkotlinx/io/bytestring/ByteString;
 	public static final fun ByteString ([B)Lkotlinx/io/bytestring/ByteString;
+	public static final fun ByteString-GBYM_sE ([B)Lkotlinx/io/bytestring/ByteString;
 	public static final fun contentEquals (Lkotlinx/io/bytestring/ByteString;[B)Z
 	public static final fun decodeToString (Lkotlinx/io/bytestring/ByteString;)Ljava/lang/String;
 	public static final fun encodeToByteString (Ljava/lang/String;)Lkotlinx/io/bytestring/ByteString;

bytestring/api/kotlinx-io-bytestring.klib.api

@@ -80,5 +80,7 @@ final fun (kotlinx.io.bytestring/ByteStringBuilder).kotlinx.io.bytestring/append
 final fun (kotlinx.io.bytestring/ByteStringBuilder).kotlinx.io.bytestring/append(kotlin/UByte) // kotlinx.io.bytestring/append|append@kotlinx.io.bytestring.ByteStringBuilder(kotlin.UByte){}[0]
 final fun (kotlinx.io.bytestring/ByteStringBuilder).kotlinx.io.bytestring/append(kotlinx.io.bytestring/ByteString) // kotlinx.io.bytestring/append|append@kotlinx.io.bytestring.ByteStringBuilder(kotlinx.io.bytestring.ByteString){}[0]
 final fun <#A: kotlin.text/Appendable> (kotlin.io.encoding/Base64).kotlinx.io.bytestring/encodeToAppendable(kotlinx.io.bytestring/ByteString, #A, kotlin/Int = ..., kotlin/Int = ...): #A // kotlinx.io.bytestring/encodeToAppendable|encodeToAppendable@kotlin.io.encoding.Base64(kotlinx.io.bytestring.ByteString;0:0;kotlin.Int;kotlin.Int){0§<kotlin.text.Appendable>}[0]
+final fun kotlinx.io.bytestring/ByteString(): kotlinx.io.bytestring/ByteString // kotlinx.io.bytestring/ByteString|ByteString(){}[0]
 final fun kotlinx.io.bytestring/ByteString(kotlin/ByteArray...): kotlinx.io.bytestring/ByteString // kotlinx.io.bytestring/ByteString|ByteString(kotlin.ByteArray...){}[0]
+final fun kotlinx.io.bytestring/ByteString(kotlin/UByteArray...): kotlinx.io.bytestring/ByteString // kotlinx.io.bytestring/ByteString|ByteString(kotlin.UByteArray...){}[0]
 final inline fun kotlinx.io.bytestring/buildByteString(kotlin/Int = ..., kotlin/Function1<kotlinx.io.bytestring/ByteStringBuilder, kotlin/Unit>): kotlinx.io.bytestring/ByteString // kotlinx.io.bytestring/buildByteString|buildByteString(kotlin.Int;kotlin.Function1<kotlinx.io.bytestring.ByteStringBuilder,kotlin.Unit>){}[0]

bytestring/common/src/ByteString.kt

@@ -21,6 +21,7 @@
 
 package kotlinx.io.bytestring
 
+import kotlin.js.JsName
 import kotlin.math.max
 import kotlin.math.min
 
@@ -37,6 +38,26 @@ public fun ByteString(vararg bytes: Byte): ByteString = if (bytes.isEmpty()) {
     ByteString.wrap(bytes)
 }
 
+/**
+ * Wraps given [bytes] into a byte string.
+ *
+ * Internally, [bytes] will be stored as [ByteArray], and accesses to individual
+ * [ByteString]'s bytes will return a signed [Byte] as if someone call `bytes[i].toByte()`.
+ *
+ * @param bytes a sequence of bytes to be wrapped.
+ *
+ * @sample kotlinx.io.bytestring.samples.ByteStringSamples.constructionFromUBytesSample
+ */
+@OptIn(ExperimentalUnsignedTypes::class)
+public fun ByteString(vararg bytes: UByte): ByteString = if (bytes.isEmpty()) {
+    ByteString.EMPTY
+} else {
+    ByteString.wrap(bytes.asByteArray())
+}
+
+@JsName("EmptyByteString")
+public fun ByteString(): ByteString = ByteString.EMPTY
+
 /**
  * An immutable wrapper around a byte sequence providing [String] like functionality.
  *

bytestring/common/test/ByteStringTest.kt

@@ -410,4 +410,14 @@ class ByteStringTest {
         assertFalse(ByteString(1, 2, 3, 4, 5).contentEquals(byteArrayOf(1, 2, 3, 4, 5, 6)))
         assertFalse(ByteString(1, 2, 3, 4, 5, 6).contentEquals(byteArrayOf(1, 2, 3, 4, 5)))
     }
+
+    @OptIn(ExperimentalUnsignedTypes::class)
+    @Test
+    fun fromUBytes() {
+        val str = ByteString(0xDEu, 0xADu, 0xC0u, 0xDEu)
+        assertContentEquals(
+            byteArrayOf(0xDE.toByte(), 0xAD.toByte(), 0xC0u.toByte(), 0xDEu.toByte()),
+            str.toByteArray()
+        )
+    }
 }

bytestring/common/test/samples/samples.kt

@@ -199,6 +199,14 @@ class ByteStringSamples {
         assertEquals(3, byteStringFromBytes.size)
     }
 
+    @OptIn(ExperimentalUnsignedTypes::class)
+    @Test
+    fun constructionFromUBytesSample() {
+        val byteStringFromBytes = ByteString(0xCAu, 0xFEu)
+        assertFalse(byteStringFromBytes.isEmpty())
+        assertEquals(2, byteStringFromBytes.size)
+    }
+
     @Test
     fun encodeAndDecodeUtf8String() {
         val helloAsByteString = "hello".encodeToByteString()