Merge pull request #135 from geirolz/add-decoder-or-method

Add decoder Or method
geirolz · Sep 21, 2023 · c30c83c · c30c83c
2 parents 064b74d + 13a3e40
commit c30c83c
Show file tree

Hide file tree

Showing 4 changed files with 35 additions and 20 deletions.
diff --git a/core/src/main/scala/cats/xml/codec/Decoder.scala b/core/src/main/scala/cats/xml/codec/Decoder.scala
@@ -40,6 +40,12 @@ trait Decoder[T] {
 
   def flatMap[U](f: T => Decoder[U]): Decoder[U] =
     Decoder.of(ns => decodeCursorResult(ns).andThen(t => f(t).decodeCursorResult(ns)))
+
+  def or(other: Decoder[? <: T]): Decoder[T] =
+    this.attempt.flatMap {
+      case Left(_)  => other.widen[T]
+      case Right(t) => Decoder.pure(t)
+    }
 }
 
 object Decoder extends DecoderInstances with DecoderSyntax {
@@ -66,27 +72,14 @@ object Decoder extends DecoderInstances with DecoderSyntax {
   def const[T](r: => Decoder.Result[T]): Decoder[T] =
     Decoder.of(_ => r)
 
-  def oneOf[T <: Any](
+  def oneOf[T](
     d: Decoder[? <: T],
     d1: Decoder[? <: T],
     dn: Decoder[? <: T]*
-  ): Decoder[? <: T] =
-    Decoder.instance(xml => {
-      NonEmptyList
-        .of(d, (d1 +: dn)*)
-        .foldLeft[Decoder.Result[T]](
-          DecoderFailure.Custom("Cannot decode the value.").invalidNel[T]
-        )((err, decoder) => {
-          err match {
-            case v @ Validated.Valid(_) => v
-            case Validated.Invalid(errors1) =>
-              decoder.decode(xml) match {
-                case v @ Validated.Valid(_)     => v
-                case Validated.Invalid(errors2) => errors2.concatNel(errors1).invalid[T]
-              }
-          }
-        })
-    })
+  ): Decoder[T] =
+    (List(d, d1)  ++ dn.toList)
+      .map(_.widen[T])
+      .reduceLeft(_ or _)
 
   def fromCursor[U](
     f: NodeCursor => FreeCursor[Xml, U]

diff --git a/core/src/test/scala/cats/xml/codec/decoderSuite.scala b/core/src/test/scala/cats/xml/codec/decoderSuite.scala
@@ -184,6 +184,28 @@ class DecoderSuite extends munit.FunSuite {
       expected = DecoderFailure.Custom("ERROR 1").invalidNel
     )
   }
+
+  test("Decoder.or - fail or success") {
+
+    val decoderStr1: Decoder[String] = Decoder.failure(DecoderFailure.Custom("ERROR"))
+    val decoderStr2: Decoder[String] = Decoder.decodeString
+
+    assertEquals(
+      obtained = decoderStr1.or(decoderStr2).decode(Xml.ofString("test")),
+      expected = Valid("test")
+    )
+  }
+
+  test("Decoder.or - success or fail") {
+
+    val decoderStr1: Decoder[String] = Decoder.decodeString
+    val decoderStr2: Decoder[String] = Decoder.failure(DecoderFailure.Custom("ERROR"))
+
+    assertEquals(
+      obtained = decoderStr1.or(decoderStr2).decode(Xml.ofString("test")),
+      expected = Valid("test")
+    )
+  }
 }
 
 class DecoderInstancesSuite extends munit.DisciplineSuite {

diff --git a/core/src/test/scala/cats/xml/testing/VeryLongNumericString.scala b/core/src/test/scala/cats/xml/testing/VeryLongNumericString.scala
@@ -2,7 +2,7 @@ package cats.xml.testing
 
 import org.scalacheck.{Arbitrary, Gen}
 
-case class VeryLongNumericString private (str: String) extends AnyVal
+case class VeryLongNumericString(str: String) extends AnyVal
 object VeryLongNumericString {
 
   private[VeryLongNumericString] def apply(str: String): VeryLongNumericString =

diff --git a/core/src/test/scala/cats/xml/testing/XmlValidName.scala b/core/src/test/scala/cats/xml/testing/XmlValidName.scala
@@ -3,7 +3,7 @@ package cats.xml.testing
 import cats.xml.Xml
 import org.scalacheck.{Arbitrary, Gen}
 
-case class XmlValidName private (value: String) extends AnyVal
+case class XmlValidName(value: String) extends AnyVal
 object XmlValidName {
 
   private def apply(value: String): XmlValidName =