Endpoint metadata ADT and specs

core/src/main/scala/io/finch/Endpoint.scala

@@ -69,6 +69,8 @@ trait Endpoint[A] { self =>
    */
   def apply(input: Input): Endpoint.Result[A]
 
+  def meta: Endpoint.Meta
+
   /**
    * Maps this endpoint to the given function `A => B`.
    */
@@ -91,6 +93,7 @@ trait Endpoint[A] { self =>
 
       final override def item = self.item
       final override def toString: String = self.toString
+      final override def meta: Endpoint.Meta = self.meta
   }
 
   /**
@@ -114,6 +117,7 @@ trait Endpoint[A] { self =>
 
       override def item = self.item
       final override def toString: String = self.toString
+      final override def meta: Endpoint.Meta = self.meta
     }
 
   /**
@@ -141,6 +145,7 @@ trait Endpoint[A] { self =>
 
       override def item = self.item
       final override def toString: String = self.toString
+      final override def meta: Endpoint.Meta = self.meta
    }
 
   /**
@@ -187,6 +192,7 @@ trait Endpoint[A] { self =>
 
       override def item = self.item
       final override def toString: String = self.toString
+      final override def meta: Endpoint.Meta = self.meta
     }
 
   /**
@@ -202,6 +208,7 @@ trait Endpoint[A] { self =>
 
       override def item = items.MultipleItems
       final override def toString: String = s"${other.toString} :: ${self.toString}"
+      final override def meta: Endpoint.Meta = EndpointMetadata.Product(other.meta, self.meta)
     }
 
   /**
@@ -220,6 +227,7 @@ trait Endpoint[A] { self =>
 
     override def item = items.MultipleItems
     final override def toString: String = s"(${self.toString} :+: ${other.toString})"
+    final override def meta: Endpoint.Meta = EndpointMetadata.Coproduct(other.meta, self.meta)
   }
 
   /**
@@ -349,6 +357,7 @@ trait Endpoint[A] { self =>
 
       override def item = self.item
       override final def toString: String = self.toString
+      override final def meta: Endpoint.Meta = self.meta
     }
 
   /**
@@ -357,6 +366,7 @@ trait Endpoint[A] { self =>
   final def withToString(ts: => String): Endpoint[A] = new Endpoint[A] {
     final def apply(input: Input): Endpoint.Result[A] = self(input)
     final override def toString: String = ts
+    final override def meta: Endpoint.Meta = self.meta
   }
 
   private[this] def withOutput[B](fn: Output[A] => Output[B]): Endpoint[B] =
@@ -370,11 +380,14 @@ object Endpoint {
 
   type Result[A] = EndpointResult[A]
 
+  type Meta = EndpointMetadata
+
   /**
    * Creates an empty [[Endpoint]] (an endpoint that never matches) for a given type.
    */
   def empty[A]: Endpoint[A] = new Endpoint[A] {
     final def apply(input: Input): Result[A] = EndpointResult.Skipped
+    final def meta: Endpoint.Meta = EndpointMetadata.Empty
   }
 
   /**
@@ -383,6 +396,8 @@ object Endpoint {
   def const[A](a: A): Endpoint[A] = new Endpoint[A] {
     final def apply(input: Input): Result[A] =
       EndpointResult.Matched(input, Rerunnable.const(Output.payload(a)))
+
+    final def meta: Endpoint.Meta = EndpointMetadata.Const
   }
 
   /**
@@ -400,6 +415,8 @@ object Endpoint {
   def lift[A](a: => A): Endpoint[A] = new Endpoint[A] {
     final def apply(input: Input): Result[A] =
       EndpointResult.Matched(input, Rerunnable(Output.payload(a)))
+
+    final def meta: Endpoint.Meta = EndpointMetadata.Const
   }
 
   /**
@@ -408,6 +425,8 @@ object Endpoint {
   def liftAsync[A](fa: => Future[A]): Endpoint[A] = new Endpoint[A] {
     final def apply(input: Input): Result[A] =
       EndpointResult.Matched(input, Rerunnable.fromFuture(fa).map(a => Output.payload(a)))
+
+    final def meta: Endpoint.Meta = EndpointMetadata.Const
   }
 
   /**
@@ -422,6 +441,8 @@ object Endpoint {
   def liftOutput[A](oa: => Output[A]): Endpoint[A] = new Endpoint[A] {
     final def apply(input: Input): Result[A] =
       EndpointResult.Matched(input, Rerunnable(oa))
+
+    final def meta: Endpoint.Meta = EndpointMetadata.Const
   }
 
   /**
@@ -431,6 +452,8 @@ object Endpoint {
   def liftOutputAsync[A](foa: => Future[Output[A]]): Endpoint[A] = new Endpoint[A] {
     final def apply(input: Input): Result[A] =
       EndpointResult.Matched(input, Rerunnable.fromFuture(foa))
+
+    final def meta: Endpoint.Meta = EndpointMetadata.Const
   }
 
   /**

core/src/main/scala/io/finch/EndpointMetadata.scala

@@ -0,0 +1,43 @@
+package io.finch
+
+sealed trait Segment
+
+object Segment {
+
+  case class Part(name: String) extends Segment
+
+  case object Wildcard extends Segment
+
+  case object Empty extends Segment
+
+}
+
+sealed trait EndpointMetadata
+
+object EndpointMetadata {
+
+  case class Method(method: com.twitter.finagle.http.Method, a: EndpointMetadata) extends EndpointMetadata
+
+  case class Path(segment: io.finch.Segment) extends EndpointMetadata
+
+  case class Parameter(name: String) extends EndpointMetadata
+
+  case class Parameters(name: String) extends EndpointMetadata
+
+  case class Header(name: String) extends EndpointMetadata
+
+  case class Cookie(name: String) extends EndpointMetadata
+
+  case object Body extends EndpointMetadata
+
+  case class Multipart(name: String) extends EndpointMetadata
+
+  case class Coproduct(a: EndpointMetadata, b: EndpointMetadata) extends EndpointMetadata
+
+  case class Product(a: EndpointMetadata, b: EndpointMetadata) extends EndpointMetadata
+
+  case object Const extends EndpointMetadata
+
+  case object Empty extends EndpointMetadata
+
+}

core/src/main/scala/io/finch/Endpoints.scala

@@ -23,6 +23,8 @@ trait Endpoints extends Bodies
       EndpointResult.Matched(input.copy(route = Nil), Rs.OutputHNil)
 
     final override def toString: String = "*"
+
+    final def meta: Endpoint.Meta = EndpointMetadata.Path(Segment.Wildcard)
   }
 
   /**
@@ -33,6 +35,8 @@ trait Endpoints extends Bodies
       EndpointResult.Matched(input, Rs.OutputHNil)
 
     final override def toString: String = ""
+
+    final def meta: Endpoint.Meta = EndpointMetadata.Path(Segment.Empty)
   }
 
   /**
@@ -43,5 +47,7 @@ trait Endpoints extends Bodies
       EndpointResult.Matched(input, Rs.payload(input.request))
 
     final override def toString: String = "root"
+
+    final def meta: Endpoint.Meta = EndpointMetadata.Const
   }
 }

core/src/main/scala/io/finch/endpoint/body.scala

@@ -28,6 +28,8 @@ private abstract class FullBody[A] extends Endpoint[A] {
     }
 
   final override def item: RequestItem = items.BodyItem
+
+  final def meta: Endpoint.Meta = EndpointMetadata.Body
 }
 
 private object FullBody {
@@ -153,5 +155,6 @@ private[finch] trait Bodies {
 
     final override def item: RequestItem = items.BodyItem
     final override def toString: String = "asyncBody"
+    final def meta: Endpoint.Meta = EndpointMetadata.Body
   }
 }

core/src/main/scala/io/finch/endpoint/cookie.scala

@@ -17,6 +17,7 @@ private abstract class Cookie[A](name: String) extends Endpoint[A] {
 
   final override def item: items.RequestItem = items.CookieItem(name)
   final override def toString: String = s"cookie($name)"
+  final def meta: Endpoint.Meta = EndpointMetadata.Cookie(name)
 }
 
 private object Cookie {

core/src/main/scala/io/finch/endpoint/header.scala

@@ -25,6 +25,7 @@ private abstract class Header[F[_], A](name: String, d: DecodeEntity[A], tag: Cl
 
   final override def item: RequestItem = items.HeaderItem(name)
   final override def toString: String = s"header($name)"
+  final def meta: Endpoint.Meta = EndpointMetadata.Header(name)
 }
 
 private object Header {

core/src/main/scala/io/finch/endpoint/multipart.scala

@@ -34,6 +34,7 @@ private abstract class Multipart[A, B](name: String) extends Endpoint[B] {
 
   final override def item: RequestItem = ParamItem(name)
   final override def toString: String = name
+  final def meta: Endpoint.Meta = EndpointMetadata.Multipart(name)
 }
 
 private object Multipart {

core/src/main/scala/io/finch/endpoint/param.scala

@@ -26,7 +26,7 @@ private abstract class Param[F[_], A](name: String, d: DecodeEntity[A], tag: Cla
 
   final override def item: items.RequestItem = items.ParamItem(name)
   final override def toString: String = s"param($name)"
-
+  final def meta: Endpoint.Meta = EndpointMetadata.Parameter(name)
 
 }
 
@@ -75,6 +75,7 @@ private abstract class Params[F[_], A](name: String, d: DecodeEntity[A], tag: Cl
   }
   final override def item: items.RequestItem = items.ParamItem(name)
   final override def toString: String = s"params($name)"
+  final def meta: Endpoint.Meta = EndpointMetadata.Parameters(name)
 }
 
 private object Params {

core/src/main/scala/io/finch/endpoint/path.scala

@@ -14,6 +14,7 @@ private class MatchPath(s: String) extends Endpoint[HNil] {
   }
 
   final override def toString: String = s
+  final def meta: Endpoint.Meta = EndpointMetadata.Path(Segment.Part(s))
 }
 
 private class ExtractPath[A](implicit d: DecodePath[A], ct: ClassTag[A]) extends Endpoint[A] {
@@ -28,6 +29,9 @@ private class ExtractPath[A](implicit d: DecodePath[A], ct: ClassTag[A]) extends
   }
 
   final override def toString: String = s":${ct.runtimeClass.getSimpleName.toLowerCase}"
+
+  final def meta: Endpoint.Meta =
+    EndpointMetadata.Path(Segment.Part(ct.runtimeClass.getSimpleName.toLowerCase))
 }
 
 private class ExtractPaths[A](implicit d: DecodePath[A], ct: ClassTag[A]) extends Endpoint[Seq[A]] {
@@ -38,6 +42,9 @@ private class ExtractPaths[A](implicit d: DecodePath[A], ct: ClassTag[A]) extend
     )
 
   final override def toString: String = s":${ct.runtimeClass.getSimpleName.toLowerCase}*"
+
+  final def meta: Endpoint.Meta =
+    EndpointMetadata.Path(Segment.Part(s"${ct.runtimeClass.getSimpleName.toLowerCase}*"))
 }
 
 private[finch] trait Paths {

core/src/main/scala/io/finch/syntax/EndpointMapper.scala

@@ -15,4 +15,6 @@ class EndpointMapper[A](m: Method, e: Endpoint[A]) extends Endpoint[A] { self =>
     else EndpointResult.Skipped
 
   final override def toString: String = s"${ m.toString.toUpperCase } /${ e.toString }"
+
+  final def meta: Endpoint.Meta = EndpointMetadata.Method(m, e.meta)
 }

core/src/test/scala/io/finch/EndpointMetadataSpec.scala

@@ -0,0 +1,33 @@
+package io.finch
+
+import io.finch.syntax.EndpointMapper
+
+class EndpointMetadataSpec extends FinchSpec {
+
+  behavior of "EndpointMetadata"
+
+  private def interpreter(ms: EndpointMetadata): Endpoint[_] = ms match {
+    case EndpointMetadata.Method(m, meta) => new EndpointMapper(m, interpreter(meta))
+    case EndpointMetadata.Path(s) => s match {
+      case Segment.Part(part) => path(part)
+      case Segment.Wildcard => *
+      case Segment.Empty => /
+    }
+    case EndpointMetadata.Multipart(name) => multipartAttribute(name)
+    case EndpointMetadata.Cookie(name) => cookie(name)
+    case EndpointMetadata.Parameter(name) => param(name)
+    case EndpointMetadata.Parameters(name) => params(name)
+    case EndpointMetadata.Header(name) => header(name)
+    case EndpointMetadata.Body => stringBody
+    case EndpointMetadata.Empty => Endpoint.empty[String]
+    case EndpointMetadata.Const => Endpoint.const("foo")
+    case EndpointMetadata.Coproduct(a, b) => interpreter(b) :+: interpreter(a)
+    case EndpointMetadata.Product(a, b) => interpreter(a) :: interpreter(b)
+  }
+
+  it should "do a round-trip" in {
+    check { l: EndpointMetadata =>
+      interpreter(l).meta === l
+    }
+  }
+}