package forge
import ammonite.ops.{ls, mkdir}
import forge.util.{Args, PathRef}
import play.api.libs.json.{Format, JsValue, Json}
import scala.annotation.compileTimeOnly
import language.experimental.macros
import reflect.macros.blackbox.Context
import scala.collection.mutable
abstract class Target[T] extends Target.Ops[T]{
/**
* What other Targets does this Target depend on?
*/
val inputs: Seq[Target[_]]
/**
* Evaluate this target
*/
def evaluate(args: Args): T
/**
* Even if this target's inputs did not change, does it need to re-evaluate
* anyway?
*/
def sideHash: Int = 0
@compileTimeOnly("Target#apply() can only be used with a T{...} block")
def apply(): T = ???
}
object Target{
class Target0[T](t: T) extends Target[T]{
lazy val t0 = t
val inputs = Nil
def evaluate(args: Args) = t0
}
class Target1[T](t: => Target[T]) extends Target[T]{
lazy val t0 = t
lazy val inputs = t0.inputs
def evaluate(args: Args) = t0.evaluate(args)
}
implicit def toTarget[T](t: T): Target[T] = new Target0(t)
implicit def apply[T](t: => Target[T]): Target[T] = new Target1(t)
def raw[T](t: T): Target[T] = macro impl[T]
def impl[T: c.WeakTypeTag](c: Context)(t: c.Expr[T]): c.Expr[Target[T]] = {
import c.universe._
val bound = collection.mutable.Buffer.empty[(c.Tree, c.TermName)]
object transformer extends c.universe.Transformer{
override def transform(tree: c.Tree): c.Tree = tree match{
case q"$fun.apply()" if fun.tpe <:< weakTypeOf[Target[_]] =>
val newTerm = TermName(c.freshName())
bound.append((fun, newTerm))
val ident = Ident(newTerm)
ident
case _ => super.transform(tree)
}
}
val transformed = transformer.transform(t.tree)
val (exprs, names) = bound.unzip
val embedded = bound.length match{
case 0 => transformed
case 1 => q"zip(..$exprs).map{ case ${names(0)} => $transformed }"
case n =>
// For some reason, pq"(..$names)" doesn't work...
val pq = n match{
case 2 => pq"(${names(0)}, ${names(1)})"
case 3 => pq"(${names(0)}, ${names(1)}, ${names(2)})"
case 4 => pq"(${names(0)}, ${names(1)}, ${names(2)}, ${names(3)})"
case 5 => pq"(${names(0)}, ${names(1)}, ${names(2)}, ${names(3)}, ${names(4)})"
}
q"zip(..$exprs).map{ case $pq => $transformed }"
}
c.Expr[Target[T]](c.untypecheck(embedded))
}
abstract class Ops[T]{ this: Target[T] =>
def map[V](f: T => V) = new Target.Mapped(this, f)
def filter(f: T => Boolean) = this
def withFilter(f: T => Boolean) = this
def zip[V](other: Target[V]) = new Target.Zipped(this, other)
}
def traverse[T](source: Seq[Target[T]]) = {
new Traverse[T](source)
}
class Traverse[T](val inputs: Seq[Target[T]]) extends Target[Seq[T]]{
def evaluate(args: Args) = {
for (i <- 0 until args.length)
yield args(i).asInstanceOf[T]
}
}
class Mapped[T, V](source: Target[T], f: T => V) extends Target[V]{
def evaluate(args: Args) = f(args(0))
val inputs = List(source)
}
class Zipped[T, V](source1: Target[T],
source2: Target[V]) extends Target[(T, V)]{
def evaluate(args: Args) = (args(0), args(1))
val inputs = List(source1, source2)
}
def path(path: ammonite.ops.Path) = new Path(path)
class Path(path: ammonite.ops.Path) extends Target[PathRef]{
def handle = PathRef(path)
def evaluate(args: Args) = handle
override def sideHash = handle.hashCode()
val inputs = Nil
}
class Subprocess(val inputs: Seq[Target[_]],
command: Args => Seq[String]) extends Target[Subprocess.Result] {
def evaluate(args: Args) = {
mkdir(args.dest)
import ammonite.ops._
implicit val path = ammonite.ops.Path(args.dest, pwd)
val toTarget = () // Shadow the implicit conversion :/
val output = %%(command(args))
assert(output.exitCode == 0)
Subprocess.Result(output, PathRef(args.dest))
}
}
object Subprocess{
case class Result(result: ammonite.ops.CommandResult, dest: PathRef)
object Result{
implicit val tsFormat: Format[Target.Subprocess.Result] = Json.format
}
}
}