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author | Jon Pretty <jon.pretty@propensive.com> | 2017-11-10 15:23:38 +0000 |
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committer | GitHub <noreply@github.com> | 2017-11-10 15:23:38 +0000 |
commit | 9c90d3f393d18ef0f8f27751a8328913dad7ad25 (patch) | |
tree | 345f7f8a497f5fc12e2aaad9cf9e8119e0059d62 | |
parent | 657d2fb2c16b75c790bf3c3a63d1f830a42893db (diff) | |
parent | 2ae9a65ed0b773f77b5cd8d8c134a125bbaccf5d (diff) | |
download | magnolia-9c90d3f393d18ef0f8f27751a8328913dad7ad25.tar.gz magnolia-9c90d3f393d18ef0f8f27751a8328913dad7ad25.tar.bz2 magnolia-9c90d3f393d18ef0f8f27751a8328913dad7ad25.zip |
Merge pull request #27 from propensive/allow-type-constructor-in-supertrait
Allow type constructor in supertrait
-rw-r--r-- | build.sbt | 5 | ||||
-rw-r--r-- | core/src/main/scala/magnolia.scala | 23 | ||||
-rw-r--r-- | examples/src/main/scala/show.scala | 28 | ||||
-rw-r--r-- | tests/src/main/scala/tests.scala | 4 |
4 files changed, 43 insertions, 17 deletions
@@ -77,7 +77,10 @@ lazy val publishSettings = Seq( import java.io.File -lazy val unmanagedSettings = unmanagedBase := (scalaVersion.value.split("\\.").map(_.toInt).to[List] match { +lazy val unmanagedSettings = unmanagedBase := (scalaVersion.value + .split("\\.") + .map(_.toInt) + .to[List] match { case List(2, 12, _) => baseDirectory.value / "lib" / "2.12" case List(2, 11, _) => baseDirectory.value / "lib" / "2.11" }) diff --git a/core/src/main/scala/magnolia.scala b/core/src/main/scala/magnolia.scala index 293d0f1..9aa5d5f 100644 --- a/core/src/main/scala/magnolia.scala +++ b/core/src/main/scala/magnolia.scala @@ -71,8 +71,21 @@ object Magnolia { val magnoliaObj = q"$magnoliaPkg.Magnolia" val arrayCls = tq"_root_.scala.Array" - val typeConstructor: c.Type = - c.prefix.tree.tpe.member(TypeName("Typeclass")).asType.toType.typeConstructor + val prefixType = c.prefix.tree.tpe + + val typeDefs = prefixType.baseClasses.flatMap { cls => + cls.asType.toType.decls.filter(_.isType).find(_.name.toString == "Typeclass").map { tpe => + tpe.asType.toType.asSeenFrom(prefixType, cls) + } + } + + val typeConstructorOpt = + typeDefs.headOption.map(_.typeConstructor) + + val typeConstructor = typeConstructorOpt.getOrElse { + c.abort(c.enclosingPosition, + "magnolia: the derivation object does not define the Typeclass type constructor") + } def findType(key: Type): Option[TermName] = recursionStack(c.enclosingPosition).frames.find(_.genericType == key).map(_.termName(c)) @@ -258,9 +271,9 @@ object Magnolia { $paramsVal, ($fnVal: Param[$typeConstructor, $genericType] => Any) => new $genericType(..${caseParams.zipWithIndex.map { - case (typeclass, idx) => - q"$fnVal($paramsVal($idx)).asInstanceOf[${typeclass.paramType}]" - } }) + case (typeclass, idx) => + q"$fnVal($paramsVal($idx)).asInstanceOf[${typeclass.paramType}]" + }}) )) }""" ) diff --git a/examples/src/main/scala/show.scala b/examples/src/main/scala/show.scala index e9e74b1..e101c11 100644 --- a/examples/src/main/scala/show.scala +++ b/examples/src/main/scala/show.scala @@ -9,43 +9,51 @@ import scala.language.experimental.macros * be something other than a string. */ trait Show[Out, T] { def show(value: T): Out } -/** companion object to [[Show]] */ -object Show { +trait GenericShow[Out] { /** the type constructor for new [[Show]] instances * * The first parameter is fixed as `String`, and the second parameter varies generically. */ - type Typeclass[T] = Show[String, T] + type Typeclass[T] = Show[Out, T] + + def join(typeName: String, strings: Seq[String]): Out /** creates a new [[Show]] instance by labelling and joining (with `mkString`) the result of * showing each parameter, and prefixing it with the class name */ - def combine[T](ctx: CaseClass[Typeclass, T]): Show[String, T] = new Show[String, T] { + def combine[T](ctx: CaseClass[Typeclass, T]): Show[Out, T] = new Show[Out, T] { def show(value: T) = { val paramStrings = ctx.parameters.map { param => s"${param.label}=${param.typeclass.show(param.dereference(value))}" } - paramStrings.mkString(s"${ctx.typeName.split("\\.").last}(", ",", ")") + join(ctx.typeName.split("\\.").last, paramStrings) } } /** choose which typeclass to use based on the subtype of the sealed trait */ - def dispatch[T](ctx: SealedTrait[Typeclass, T]): Show[String, T] = new Show[String, T] { - def show(value: T): String = ctx.dispatch(value) { sub => + def dispatch[T](ctx: SealedTrait[Typeclass, T]): Show[Out, T] = new Show[Out, T] { + def show(value: T): Out = ctx.dispatch(value) { sub => sub.typeclass.show(sub.cast(value)) } } + /** bind the Magnolia macro to this derivation object */ + implicit def gen[T]: Show[Out, T] = macro Magnolia.gen[T] +} + +/** companion object to [[Show]] */ +object Show extends GenericShow[String] { + /** show typeclass for strings */ implicit val string: Show[String, String] = new Show[String, String] { def show(s: String): String = s } + def join(typeName: String, params: Seq[String]): String = + params.mkString(s"$typeName(", ",", ")") + /** show typeclass for integers */ implicit val int: Show[String, Int] = new Show[String, Int] { def show(s: Int): String = s.toString } - - /** bind the Magnolia macro to this derivation object */ - implicit def gen[T]: Show[String, T] = macro Magnolia.gen[T] } diff --git a/tests/src/main/scala/tests.scala b/tests/src/main/scala/tests.scala index 10eb465..5142861 100644 --- a/tests/src/main/scala/tests.scala +++ b/tests/src/main/scala/tests.scala @@ -55,7 +55,9 @@ object Tests extends TestApp { test("local implicit beats Magnolia") { import magnolia.examples._ - implicit val showPerson: Show[String, Person] = new Show[String, Person] { def show(p: Person) = "nobody" } + implicit val showPerson: Show[String, Person] = new Show[String, Person] { + def show(p: Person) = "nobody" + } implicitly[Show[String, Address]].show(Address("Home", Person("John Smith", 44))) }.assert(_ == "Address(line1=Home,occupant=nobody)") |