ConfGet: turn getKey into tail-recursive

scalameta · Jun 6, 2021 · 9f3c857 · 9f3c857
1 parent 1460cad
commit 9f3c857
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Showing 2 changed files with 29 additions and 29 deletions.
diff --git a/metaconfig-core/shared/src/main/scala/metaconfig/Conf.scala b/metaconfig-core/shared/src/main/scala/metaconfig/Conf.scala
@@ -107,7 +107,7 @@ object Conf {
     ): Configured[Option[T]] =
       ConfGet
         .getKey(this, path +: extraNames)
-        .map(value => ev.read(value).map(Some(_)))
+        .map(ev.read(_).map(Some(_)))
         .getOrElse(Configured.Ok(None))
   }
   object Obj {
@@ -118,10 +118,9 @@ object Conf {
   def getEx[A](state: A, conf: Conf, path: Seq[String])(
       implicit ev: ConfDecoderEx[A]
   ): Configured[A] =
-    ConfGet.getKey(conf, path) match {
-      case None => Configured.Ok(state)
-      case Some(subconf) => ev.read(Some(state), subconf)
-    }
+    ConfGet
+      .getKey(conf, path)
+      .fold(Configured.ok(state))(ev.read(Some(state), _))
 
   def getSettingEx[A](state: A, conf: Conf, setting: Setting)(
       implicit ev: ConfDecoderEx[A]

diff --git a/metaconfig-core/shared/src/main/scala/metaconfig/internal/ConfGet.scala b/metaconfig-core/shared/src/main/scala/metaconfig/internal/ConfGet.scala
@@ -1,46 +1,47 @@
 package metaconfig.internal
 
+import scala.annotation.tailrec
 import scala.collection.mutable
 import metaconfig.Conf
 import metaconfig.ConfDecoder
 import metaconfig.ConfError
 import metaconfig.Configured
 
 object ConfGet {
-  def getKey(obj: Conf, keys: Seq[String]): Option[Conf] =
+  def getKey(conf: Conf, keys: Seq[String]): Option[Conf] =
     if (keys.isEmpty) None
-    else {
-      obj match {
-        case obj @ Conf.Obj(_) =>
-          obj.values
-            .collectFirst { case (key, value) if key == keys.head => value }
-            .orElse(getKey(obj, keys.tail))
+    else
+      conf match {
+        case obj: Conf.Obj => getKey(obj, keys)
         case _ => None
       }
-    }
+
+  @tailrec
+  private def getKey(obj: Conf.Obj, keys: Seq[String]): Option[Conf] =
+    if (keys.isEmpty) None
+    else
+      obj.values.collectFirst { case (key, value) if key == keys.head => value } match {
+        case x: Some[_] => x
+        case _ => getKey(obj, keys.tail)
+      }
 
   def getOrElse[T](conf: Conf, default: T, path: String, extraNames: String*)(
       implicit ev: ConfDecoder[T]
-  ): Configured[T] = {
-    getKey(conf, path +: extraNames) match {
-      case Some(value) => ev.read(value)
-      case None => Configured.Ok(default)
-    }
-  }
+  ): Configured[T] =
+    getKey(conf, path +: extraNames).fold(Configured.ok(default))(ev.read)
 
   def get[T](conf: Conf, path: String, extraNames: String*)(
       implicit ev: ConfDecoder[T]
   ): Configured[T] = {
-    getKey(conf, path +: extraNames) match {
-      case Some(value) => ev.read(value)
-      case None =>
-        conf match {
-          case obj @ Conf.Obj(_) => ConfError.missingField(obj, path).notOk
-          case _ =>
-            ConfError
-              .typeMismatch(s"Conf.Obj with field $path", conf, path)
-              .notOk
-        }
+    conf match {
+      case obj: Conf.Obj =>
+        getKey(obj, path +: extraNames)
+          .map(ev.read)
+          .getOrElse(ConfError.missingField(obj, path).notOk)
+      case _ =>
+        ConfError
+          .typeMismatch(s"Conf.Obj with field $path", conf, path)
+          .notOk
     }
   }