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package mill.discover
import mill.define.{Target, Task}
import mill.discover.Router.EntryPoint
import scala.language.experimental.macros
/**
* Metadata about a build that is extracted & materialized at compile-time,
* letting us use it at run-time without needing to use the heavy weight
* scala-reflect library.
*
* Note that [[Mirror]] allows you to store and inspect metadata of a type
* [[T]] even without a concrete instance of [[T]] itself.
*/
case class Mirror[-T, V](node: (T, List[List[Any]]) => V,
commands: Seq[EntryPoint[V]],
targets: Seq[Mirror.TargetPoint[V, _]],
children: List[(String, Mirror[T, _])],
crossChildren: Option[(V => List[List[Any]], Mirror[T, _])]){
def labelled(obj: T, p: Seq[Mirror.Segment]) = {
val crossValues = p.map{case Mirror.Segment.Cross(vs) => vs case _ => Nil}.toList
targets.map(t => t.labelled(node(obj, crossValues.reverse.map(_.toList)), p.reverse))
}
}
object Mirror{
def renderSelector(selector: Seq[Mirror.Segment]) = {
val Mirror.Segment.Label(head) :: rest = selector.toList
val stringSegments = rest.map{
case Mirror.Segment.Label(s) => "." + s
case Mirror.Segment.Cross(vs) => "[" + vs.mkString(",") + "]"
}
head + stringSegments.mkString
}
sealed trait Segment
object Segment{
case class Label(value: String) extends Segment
case class Cross(value: Seq[Any]) extends Segment
}
def traverse[T, V, R](t: T, hierarchy: Mirror[T, V])
(f: (Mirror[T, _], => Seq[Segment]) => Seq[R]): Seq[R] = {
def rec[C](segmentsRev: List[Segment], h: Mirror[T, C]): Seq[R]= {
val crossValues = segmentsRev.map{case Segment.Cross(vs) => vs case _ => Nil}
val self = f(h, segmentsRev)
self ++
h.children.flatMap{case (label, c) => rec(Segment.Label(label) :: segmentsRev, c)} ++
h.crossChildren.toSeq.flatMap{
case (crossGen, c) =>
crossGen(h.node(t, crossValues.reverse.map(_.toList))).flatMap(cross =>
rec(Segment.Cross(cross) :: segmentsRev, c)
)
}
}
rec(Nil, hierarchy)
}
/**
* A target after being materialized in a concrete build
*/
case class LabelledTarget[V](target: Target[V],
format: upickle.default.ReadWriter[V],
segments: Seq[Segment])
/**
* Represents metadata about a particular target, before the target is
* materialized for a concrete build
*/
case class TargetPoint[T, V](label: String,
format: upickle.default.ReadWriter[V],
run: T => Target[V]) {
def labelled(t: T, segments: Seq[Segment]) = {
LabelledTarget(run(t), format, segments :+ Segment.Label(label))
}
}
def makeTargetPoint[T, V](label: String, func: T => Target[V])
(implicit f1: upickle.default.Reader[V],
f2: upickle.default.Writer[V]) = {
val f = upickle.default.ReadWriter(f2.write, f1.read)
TargetPoint(label, f, func)
}
}
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