Merge pull request #303 from sideeffffect/apply-helper

VirtusLab · May 31, 2024 · c78ba30 · c78ba30
2 parents d3f3a3b + 6eab7df
commit c78ba30
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Showing 5 changed files with 67 additions and 12 deletions.
diff --git a/core/shared/src/main/scala-3/org/virtuslab/yaml/YamlCodecCrossCompat.scala b/core/shared/src/main/scala-3/org/virtuslab/yaml/YamlCodecCrossCompat.scala
@@ -3,13 +3,11 @@ package org.virtuslab.yaml
 import scala.deriving.Mirror
 
 private[yaml] trait YamlCodecCompanionCrossCompat {
+
+  def make[A](implicit decoder: YamlDecoder[A], encoder: YamlEncoder[A]): YamlCodec[A]
+
   inline def derived[T](using m: Mirror.Of[T]): YamlCodec[T] =
-    new YamlCodec[T]:
-      val decoder = YamlDecoder.derived[T]
-      val encoder = YamlEncoder.derived[T]
-
-      def construct(node: Node)(using
-          settings: LoadSettings = LoadSettings.empty
-      ): Either[ConstructError, T] = decoder.construct(node)
-      def asNode(obj: T): Node = encoder.asNode(obj)
+    val decoder = YamlDecoder.derived[T]
+    val encoder = YamlEncoder.derived[T]
+    make(decoder, encoder)
 }
diff --git a/core/shared/src/main/scala/org/virtuslab/yaml/YamlCodec.scala b/core/shared/src/main/scala/org/virtuslab/yaml/YamlCodec.scala
@@ -3,6 +3,28 @@ package org.virtuslab.yaml
 /**
  * A type class that provides both-way conversion between [[Node]] and [[T]]
  */
-trait YamlCodec[T] extends YamlDecoder[T] with YamlEncoder[T]
+trait YamlCodec[T] extends YamlDecoder[T] with YamlEncoder[T] { self =>
 
-object YamlCodec extends YamlCodecCompanionCrossCompat
+  def mapInvariant[T1](f: T => T1)(g: T1 => T): YamlCodec[T1] =
+    YamlCodec.make(self.map(f), self.mapContra(g))
+
+  def mapInvariantError[T1](f: T => Either[ConstructError, T1])(g: T1 => T): YamlCodec[T1] =
+    YamlCodec.make(self.flatMap(f), self.mapContra(g))
+}
+
+object YamlCodec extends YamlCodecCompanionCrossCompat {
+
+  def apply[T](implicit self: YamlCodec[T]): YamlCodec[T] = self
+
+  def make[A](implicit decoder: YamlDecoder[A], encoder: YamlEncoder[A]): YamlCodec[A] =
+    new YamlCodec[A] {
+
+      override def construct(node: Node)(implicit
+          settings: LoadSettings
+      ): Either[ConstructError, A] =
+        decoder.construct(node)
+
+      override def asNode(obj: A): Node =
+        encoder.asNode(obj)
+    }
+}
diff --git a/core/shared/src/main/scala/org/virtuslab/yaml/YamlDecoder.scala b/core/shared/src/main/scala/org/virtuslab/yaml/YamlDecoder.scala
@@ -32,9 +32,23 @@ trait YamlDecoder[T] { self =>
     ): Either[ConstructError, T1] =
       self.construct(node).map(f)
   }
+
+  final def flatMap[T1](f: T => Either[ConstructError, T1]): YamlDecoder[T1] = new YamlDecoder[T1] {
+    override def construct(node: Node)(implicit
+        settings: LoadSettings
+    ): Either[ConstructError, T1] =
+      self.construct(node).flatMap(f)
+  }
 }
 
 object YamlDecoder extends YamlDecoderCompanionCrossCompat {
+
+  def apply[T](implicit self: YamlDecoder[T]): YamlDecoder[T] = self
+
+  def from[T](pf: PartialFunction[Node, Either[ConstructError, T]])(implicit
+      classTag: ClassTag[T]
+  ): YamlDecoder[T] = apply[T](pf)
+
   def apply[T](
       pf: PartialFunction[Node, Either[ConstructError, T]]
   )(implicit classTag: ClassTag[T]): YamlDecoder[T] =
@@ -147,7 +161,7 @@ object YamlDecoder extends YamlDecoderCompanionCrossCompat {
     }
   }
 
-  implicit def forOption[T](implicit c: YamlDecoder[T]): YamlDecoder[Option[T]] = YamlDecoder {
+  implicit def forOption[T](implicit c: YamlDecoder[T]): YamlDecoder[Option[T]] = YamlDecoder.from {
     node =>
       if (node.tag == Tag.nullTag) Right(None)
       else c.construct(node).map(Option(_))

diff --git a/core/shared/src/main/scala/org/virtuslab/yaml/YamlEncoder.scala b/core/shared/src/main/scala/org/virtuslab/yaml/YamlEncoder.scala
@@ -3,11 +3,18 @@ package org.virtuslab.yaml
 /**
  * A type class that provides a conversion from a given type [[T]] into [[Node]]
  */
-trait YamlEncoder[T] {
+trait YamlEncoder[T] { self =>
   def asNode(obj: T): Node
+
+  final def mapContra[T1](f: T1 => T): YamlEncoder[T1] = new YamlEncoder[T1] {
+    override def asNode(obj: T1): Node = self.asNode(f(obj))
+  }
 }
 
 object YamlEncoder extends YamlEncoderCrossCompanionCompat {
+
+  def apply[T](implicit self: YamlEncoder[T]): YamlEncoder[T] = self
+
   implicit def forByte: YamlEncoder[Byte]       = v => Node.ScalarNode(v.toString)
   implicit def forChar: YamlEncoder[Char]       = v => Node.ScalarNode(v.toString)
   implicit def forShort: YamlEncoder[Short]     = v => Node.ScalarNode(v.toString)

diff --git a/core/shared/src/test/scala-3/org/virtuslab/yaml/decoder/DecoderSuite.scala b/core/shared/src/test/scala-3/org/virtuslab/yaml/decoder/DecoderSuite.scala
@@ -191,6 +191,20 @@ class DecoderSuite extends munit.FunSuite:
     assertEquals(yaml.as[Spec], Right(expectedSpec))
   }
 
+  test("codec mapping") {
+    case class Capital(value: String)
+
+    object Capital:
+      given YamlCodec[Capital] =
+        YamlCodec.make[String].mapInvariant(s => Capital(s.toUpperCase))(_.value.toUpperCase)
+
+    assertEquals(
+      "- hello\n- world\n".as[List[Capital]],
+      Right(List(Capital("HELLO"), Capital("WORLD")))
+    )
+    assertEquals(List(Capital("hello"), Capital("world")).asYaml, "- HELLO\n- WORLD\n")
+  }
+
   test("alias for scalar node") {
     val yaml =
       s"""|- &a 5