Refactor ScalaTargetType/ScalaTarget

The refactor in this commit is driven by the work in the subsequent
commit for issue scalacenter#659 (creating a Scaladex badge that supplies
concise info on supported Scala versions). The key word there is
'concise' - given the many Scala artifacts that can be published for
a single artifact version (the matrix of Scala language version, the
platform - Scala JS/Native/SBT - and the platform version), achieving
a concise summary requires a lot of grouping.

Grouping by Scala `LanguageVersion` was easy enough, but grouping by
platform & platform version was harder, as there wasn't any existing
class to represent that. Consequently, I introduced the concept of a
'platform edition' (eg 'Scala JS 0.6', or 'Scala Native 0.4'), which
is composed of two values:

* targetType (Scala JS, Scala Native, or SBT)
* platform version (eg the version '0.6' or '1.0' of Scala JS)

...this is like a `ScalaTarget`, but without the Scala Language
version that `ScalaTarget` includes (eg a `ScalaTarget` is
specifically compiled for, eg, _Scala 2.11_ on Scala JS 0.6).

Having introduced the concept of `PlatformEdition`, it made sense to
redefine relevant `ScalaTarget`s in terms of that - to do this meant
moving several ad-hoc methods from the companion objects of
`ScalaTarget` implementations (ie `ScalaJs`, `ScalaNative`,
`SbtPlugin`) to the corresponding `ScalaTargetType` implementations
and making them more widely available, by declaring them in the
`PlatformVersionedTargetType`. This removed duplication of this code:

* producing a String `render` value for platform names
* checking validity of platform versions.

A lot of repetition was removed, and in fact most of the `ScalaTarget`
companion objects were now empty and could be deleted.

Another smaller change was prompted by the upcoming need to identify
a `ScalaTargetType` by name (when the user specifies it as a query
string parameter). To do that, you need a full list of
`ScalaTargetType`s, and then you can also use that list to create an
`Ordering[ScalaTargetType]`

Also tidied up various tests that were creating their own platform
version constants (as I was already moving equivalent constants from
`ScalaTarget` companion objects to `ScalaTargetType` objects)

data/src/main/scala/ch.epfl.scala.index.data/central/CentralMissing.scala

@@ -17,12 +17,15 @@ import ch.epfl.scala.index.data.maven.PomsReader
 import ch.epfl.scala.index.data.project.ArtifactMetaExtractor
 import ch.epfl.scala.index.model.misc.Sha1
 import ch.epfl.scala.index.model.release.{
+  Js,
   MinorBinary,
+  Native,
+  Sbt,
   SbtPlugin,
-  ScalaVersion,
   ScalaJs,
   ScalaJvm,
-  ScalaNative
+  ScalaNative,
+  ScalaVersion
 }
 import de.heikoseeberger.akkahttpjson4s.Json4sSupport._
 import org.joda.time.DateTime
@@ -257,23 +260,18 @@ class CentralMissing(paths: DataPaths)(implicit val system: ActorSystem) {
         .flatten
         .toSet
 
-    val sbt013 = MinorBinary(0, 13)
-    val sbt10 = MinorBinary(1, 0)
-    val scalaJs06 = MinorBinary(0, 6)
-    val native03 = MinorBinary(0, 3)
-
     val allTargets = List(
       ScalaJvm(ScalaVersion.`2.13`),
       ScalaJvm(ScalaVersion.`2.12`),
       ScalaJvm(ScalaVersion.`2.11`),
       ScalaJvm(ScalaVersion.`2.10`),
-      SbtPlugin(ScalaVersion.`2.10`, sbt013),
-      SbtPlugin(ScalaVersion.`2.12`, sbt10),
-      ScalaJs(ScalaVersion.`2.13`, scalaJs06),
-      ScalaJs(ScalaVersion.`2.12`, scalaJs06),
-      ScalaJs(ScalaVersion.`2.11`, scalaJs06),
-      ScalaJs(ScalaVersion.`2.10`, scalaJs06),
-      ScalaNative(ScalaVersion.`2.11`, native03)
+      SbtPlugin(ScalaVersion.`2.10`, Sbt.`0.13`),
+      SbtPlugin(ScalaVersion.`2.12`, Sbt.`1.0`),
+      ScalaJs(ScalaVersion.`2.13`, Js.`0.6`),
+      ScalaJs(ScalaVersion.`2.12`, Js.`0.6`),
+      ScalaJs(ScalaVersion.`2.11`, Js.`0.6`),
+      ScalaJs(ScalaVersion.`2.10`, Js.`0.6`),
+      ScalaNative(ScalaVersion.`2.11`, Native.`0.3`)
     )
 
     val releasesDownloads =

model/src/main/scala/ch.epfl.scala.index.model/Project.scala

@@ -1,14 +1,17 @@
 package ch.epfl.scala.index.model
 
 import ch.epfl.scala.index.model.release.{
+  BinaryVersion,
+  Js,
+  LanguageVersion,
+  Native,
+  Sbt,
   SbtPlugin,
   ScalaJs,
   ScalaJvm,
   ScalaNative
 }
 import misc.{GithubInfo, GithubRepo, Url}
-import ch.epfl.scala.index.model.release.LanguageVersion
-import ch.epfl.scala.index.model.release.BinaryVersion
 
 /**
  * Project representation which contains all necessary meta data to
@@ -76,12 +79,11 @@ case class Project(
       id = None,
       scalaVersion = LanguageVersion.sortFamilies(scalaVersion),
       scalaJsVersion =
-        BinaryVersion.sortAndFilter(scalaJsVersion, ScalaJs.isValid).toList,
+        BinaryVersion.sortAndFilter(scalaJsVersion, Js.isValid).toList,
       scalaNativeVersion = BinaryVersion
-        .sortAndFilter(scalaNativeVersion, ScalaNative.isValid)
+        .sortAndFilter(scalaNativeVersion, Native.isValid)
         .toList,
-      sbtVersion =
-        BinaryVersion.sortAndFilter(sbtVersion, SbtPlugin.isValid).toList
+      sbtVersion = BinaryVersion.sortAndFilter(sbtVersion, Sbt.isValid).toList
     )
   }
 

model/src/main/scala/ch.epfl.scala.index.model/release/ScalaTarget.scala

@@ -1,26 +1,94 @@
 package ch.epfl.scala.index.model
 package release
 
-import ch.epfl.scala.index.model.release
 import fastparse.NoWhitespace._
 import fastparse._
 
 object ScalaTargetType {
-  implicit val ordering: Ordering[ScalaTargetType] = Ordering.by {
-    case Jvm => 5
-    case Js => 4
-    case Native => 3
-    case Sbt => 2
-    case Java => 1
-  }
+
+  val All = Seq(Java, Sbt, Native, Js, Jvm)
+
+  implicit val ordering: Ordering[ScalaTargetType] = Ordering.by(All.indexOf(_))
+
 }
 
 sealed trait ScalaTargetType
 case object Jvm extends ScalaTargetType
-case object Js extends ScalaTargetType
-case object Native extends ScalaTargetType
+
+case class PlatformEdition(
+    targetType: PlatformVersionedTargetType,
+    version: BinaryVersion
+) {
+  val isValid: Boolean = targetType.isValid(version)
+  val render: String = s"${targetType.platformId} $version"
+}
+
+case class PlatformAndLanguageVersions(
+    language: LanguageVersion,
+    platform: BinaryVersion
+)
+
+sealed trait PlatformVersionedTargetType extends ScalaTargetType {
+  def encode(platformAndLanguageVersions: PlatformAndLanguageVersions): String
+  val platformId: String
+  val stableBinaryVersions: Set[BinaryVersion]
+  def isValid(version: BinaryVersion): Boolean =
+    stableBinaryVersions.contains(version)
+  def Parser[_: P]: P[ScalaTarget]
+}
+case object Js extends PlatformVersionedTargetType {
+  val platformId = "scala-js"
+  def encode(versions: PlatformAndLanguageVersions) =
+    s"_sjs${versions.platform}_${versions.language}"
+
+  val `0.6`: BinaryVersion = MinorBinary(0, 6)
+  val `1.x`: BinaryVersion = MajorBinary(1)
+
+  val stableBinaryVersions = Set(`0.6`, `1.x`)
+
+  def Parser[_: P]: P[ScalaTarget] =
+    ("_sjs" ~ BinaryVersion.Parser ~ "_" ~ LanguageVersion.Parser).map {
+      case (scalaJsVersion, scalaVersion) =>
+        ScalaJs(scalaVersion, scalaJsVersion)
+    }
+}
+case object Native extends PlatformVersionedTargetType {
+  val platformId = "scala-native"
+  def encode(versions: PlatformAndLanguageVersions) =
+    s"_native${versions.platform}_${versions.language}"
+  val `0.3`: BinaryVersion = MinorBinary(0, 3)
+  val `0.4`: BinaryVersion = MinorBinary(0, 4)
+
+  val stableBinaryVersions = Set(`0.3`, `0.4`)
+
+  def Parser[_: P]: P[ScalaTarget] =
+    ("_native" ~ BinaryVersion.Parser ~ "_" ~ LanguageVersion.Parser).map {
+      case (scalaNativeVersion, scalaVersion) =>
+        ScalaNative(scalaVersion, scalaNativeVersion)
+    }
+}
 case object Java extends ScalaTargetType
-case object Sbt extends ScalaTargetType
+case object Sbt extends PlatformVersionedTargetType {
+  val platformId = "sbt"
+  def encode(versions: PlatformAndLanguageVersions) =
+    s"_${versions.language}_${versions.platform}"
+
+  val `0.13`: BinaryVersion = MinorBinary(0, 13)
+  val `1.0`: BinaryVersion = MinorBinary(1, 0)
+
+  val stableBinaryVersions = Set(`0.13`, `1.0`)
+
+  def Parser[_: P]: P[ScalaTarget] =
+    ("_" ~ LanguageVersion.Parser ~ "_" ~ BinaryVersion.Parser.filter(isValid))
+      .map { case (scalaVersion, sbtVersion) =>
+        SbtPlugin(scalaVersion, sbtVersion)
+      } | ("_" ~ BinaryVersion.Parser.filter(
+      isValid
+    ) ~ "_" ~ LanguageVersion.Parser)
+      .map { case (scalaVersion, sbtVersion) =>
+        SbtPlugin(sbtVersion, scalaVersion)
+      }
+}
 
 /*
 SemanticVersion will only contain the information from the artifactId
@@ -41,45 +109,42 @@ sealed trait ScalaTarget extends Ordered[ScalaTarget] {
     ScalaTarget.ordering.compare(this, that)
 }
 
+sealed trait ScalaTargetWithPlatformBinaryVersion extends ScalaTarget {
+  val platformEdition: PlatformEdition
+  lazy val targetType: PlatformVersionedTargetType = platformEdition.targetType
+
+  lazy val isValid: Boolean = languageVersion.isValid && platformEdition.isValid
+
+  lazy val render = s"${platformEdition.render} ($languageVersion)"
+  lazy val platformAndLanguageVersions: PlatformAndLanguageVersions =
+    PlatformAndLanguageVersions(languageVersion, platformEdition.version)
+  lazy val encode: String = targetType.encode(platformAndLanguageVersions)
+}
+
 case class ScalaJvm(languageVersion: LanguageVersion) extends ScalaTarget {
-  val render = languageVersion.render
+  val render: String = languageVersion.render
   val encode = s"_$languageVersion"
   val targetType: ScalaTargetType = Jvm
   val isValid: Boolean = languageVersion.isValid
 }
 case class ScalaJs(
     languageVersion: LanguageVersion,
     scalaJsVersion: BinaryVersion
-) extends ScalaTarget {
-  val render = s"scala-js $scalaJsVersion (${languageVersion.render})"
-  val encode = s"_sjs${scalaJsVersion}_$languageVersion"
-  val targetType: ScalaTargetType = Js
-  val isValid: Boolean = languageVersion.isValid && ScalaJs.isValid(
-    scalaJsVersion
-  )
+) extends ScalaTargetWithPlatformBinaryVersion {
+  val platformEdition = PlatformEdition(Js, scalaJsVersion)
 }
 case class ScalaNative(
     languageVersion: LanguageVersion,
     scalaNativeVersion: BinaryVersion
-) extends ScalaTarget {
-  val render = s"scala-native $scalaNativeVersion (${languageVersion.render})"
-  val encode = s"_native${scalaNativeVersion}_$languageVersion"
-  val targetType: ScalaTargetType = Native
-  val isValid: Boolean = languageVersion.isValid && ScalaNative.isValid(
-    scalaNativeVersion
-  )
+) extends ScalaTargetWithPlatformBinaryVersion {
+  val platformEdition = PlatformEdition(Native, scalaNativeVersion)
 }
 
 case class SbtPlugin(
     languageVersion: LanguageVersion,
     sbtVersion: BinaryVersion
-) extends ScalaTarget {
-  val render = s"sbt $sbtVersion ($languageVersion)"
-  val encode = s"_${languageVersion}_$sbtVersion"
-  val targetType: ScalaTargetType = Sbt
-  val isValid: Boolean = languageVersion.isValid && SbtPlugin.isValid(
-    sbtVersion
-  )
+) extends ScalaTargetWithPlatformBinaryVersion {
+  val platformEdition = PlatformEdition(Sbt, sbtVersion)
 }
 
 object ScalaJvm {
@@ -102,72 +167,16 @@ object ScalaJvm {
     ("_" ~ LanguageVersion.Parser).map(ScalaJvm.apply)
 }
 
-object ScalaJs {
-  val `0.6`: BinaryVersion = MinorBinary(0, 6)
-  val `1.x`: BinaryVersion = MajorBinary(1)
-
-  private val stableBinaryVersions = Set(`0.6`, `1.x`)
-
-  def isValid(version: BinaryVersion): Boolean =
-    stableBinaryVersions.contains(version)
-
-  def Parser[_: P]: P[ScalaTarget] =
-    ("_sjs" ~ BinaryVersion.Parser ~ "_" ~ LanguageVersion.Parser).map {
-      case (scalaJsVersion, scalaVersion) =>
-        ScalaJs(scalaVersion, scalaJsVersion)
-    }
-}
-
-object ScalaNative {
-  val `0.3`: BinaryVersion = MinorBinary(0, 3)
-  val `0.4`: BinaryVersion = MinorBinary(0, 4)
-
-  private val stableBinaryVersions = Set(`0.3`, `0.4`)
-
-  def isValid(version: BinaryVersion): Boolean =
-    stableBinaryVersions.contains(version)
-
-  def Parser[_: P]: P[ScalaTarget] =
-    ("_native" ~ BinaryVersion.Parser ~ "_" ~ LanguageVersion.Parser).map {
-      case (scalaNativeVersion, scalaVersion) =>
-        ScalaNative(scalaVersion, scalaNativeVersion)
-    }
-}
-
-object SbtPlugin {
-  val `0.13`: BinaryVersion = MinorBinary(0, 13)
-  val `1.0`: BinaryVersion = MinorBinary(1, 0)
-
-  private val stableBinaryVersions = Set(`0.13`, `1.0`)
-
-  def isValid(version: BinaryVersion): Boolean = {
-    stableBinaryVersions.contains(version)
-  }
-
-  def Parser[_: P]: P[ScalaTarget] =
-    ("_" ~ LanguageVersion.Parser ~ "_" ~ BinaryVersion.Parser.filter(isValid))
-      .map { case (scalaVersion, sbtVersion) =>
-        SbtPlugin(scalaVersion, sbtVersion)
-      } | ("_" ~ BinaryVersion.Parser.filter(
-      isValid
-    ) ~ "_" ~ LanguageVersion.Parser)
-      .map { case (scalaVersion, sbtVersion) =>
-        SbtPlugin(sbtVersion, scalaVersion)
-      }
-}
-
 object ScalaTarget extends Parsers {
   // Scala > Js > Native > Sbt
   implicit val ordering: Ordering[ScalaTarget] =
     Ordering.by[
       ScalaTarget,
       (ScalaTargetType, Option[BinaryVersion], LanguageVersion)
     ] {
-      case ScalaJvm(version) => (Jvm, None, version)
-      case ScalaJs(version, jsVersion) => (Js, Some(jsVersion), version)
-      case ScalaNative(version, nativeVersion) =>
-        (Native, Some(nativeVersion), version)
-      case SbtPlugin(version, sbtVersion) => (Sbt, Some(sbtVersion), version)
+      case st: ScalaTargetWithPlatformBinaryVersion =>
+        (st.targetType, Some(st.platformEdition.version), st.languageVersion)
+      case st: ScalaTarget => (st.targetType, None, st.languageVersion)
     }
 
   def parse(code: String): Option[ScalaTarget] = {
@@ -178,5 +187,5 @@ object ScalaTarget extends Parsers {
     Parser ~ End
 
   def Parser[_: P]: P[ScalaTarget] =
-    ScalaJs.Parser | ScalaNative.Parser | SbtPlugin.Parser | ScalaJvm.Parser
+    Js.Parser | Native.Parser | Sbt.Parser | ScalaJvm.Parser
 }

model/src/test/scala/ch.epfl.scala.index.model/ArtifactTests.scala

@@ -9,10 +9,7 @@ class ArtifactTests extends FunSpec with Matchers {
       Artifact.parse("cats-core_sjs0.6_2.11") should contain(
         Artifact(
           "cats-core",
-          ScalaJs(
-            languageVersion = ScalaVersion.`2.11`,
-            scalaJsVersion = MinorBinary(0, 6)
-          )
+          ScalaJs(ScalaVersion.`2.11`, Js.`0.6`)
         )
       )
     }
@@ -21,10 +18,7 @@ class ArtifactTests extends FunSpec with Matchers {
       Artifact.parse("cats-core_native0.1_2.11") should contain(
         Artifact(
           "cats-core",
-          ScalaNative(
-            languageVersion = ScalaVersion.`2.11`,
-            scalaNativeVersion = MinorBinary(0, 1)
-          )
+          ScalaNative(ScalaVersion.`2.11`, MinorBinary(0, 1))
         )
       )
     }
@@ -51,15 +45,12 @@ class ArtifactTests extends FunSpec with Matchers {
       Artifact.parse("sbt-microsites_2.12_1.0") should contain(
         Artifact(
           "sbt-microsites",
-          SbtPlugin(
-            languageVersion = ScalaVersion.`2.12`,
-            sbtVersion = MinorBinary(1, 0)
-          )
+          SbtPlugin(ScalaVersion.`2.12`, Sbt.`1.0`)
         )
       )
     }
 
-    it("does not parse unconventionnal") {
+    it("does not parse unconventional") {
       Artifact.parse("sparrow") shouldBe empty
     }