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/**
* Copyright (C) 2012 Typesafe Inc. <http://www.typesafe.com>
*/
package scala.async
import language.experimental.macros
import scala.reflect.macros.Context
import scala.collection.mutable.ListBuffer
import scala.concurrent.{ Future, Promise }
import scala.util.control.NonFatal
/*
* @author Philipp Haller
*/
object Async extends AsyncUtils {
def async[T](body: T): Future[T] = macro asyncImpl[T]
def await[T](awaitable: Future[T]): T = ???
def asyncImpl[T: c.WeakTypeTag](c: Context)(body: c.Expr[T]): c.Expr[Future[T]] = {
import c.universe._
import Flag._
val builder = new ExprBuilder[c.type](c)
val awaitMethod = awaitSym(c)
body.tree match {
case Block(stats, expr) =>
val asyncBlockBuilder = new builder.AsyncBlockBuilder(stats, expr, 0, 1000, 1000)
vprintln(s"states of current method (${ asyncBlockBuilder.asyncStates }):")
asyncBlockBuilder.asyncStates foreach vprintln
val handlerExpr = asyncBlockBuilder.mkHandlerExpr()
vprintln(s"GENERATED handler expr:")
vprintln(handlerExpr)
val handlerForLastState: c.Expr[PartialFunction[Int, Unit]] = {
val tree = Apply(Select(Ident("result"), c.universe.newTermName("success")),
List(asyncBlockBuilder.asyncStates.last.body))
builder.mkHandler(asyncBlockBuilder.asyncStates.last.state, c.Expr[Unit](tree))
}
vprintln("GENERATED handler for last state:")
vprintln(handlerForLastState)
val localVarTrees = asyncBlockBuilder.asyncStates.init.flatMap(_.allVarDefs).toList
val unitIdent = Ident(definitions.UnitClass)
val resumeFunTree: c.Tree = DefDef(Modifiers(), newTermName("resume"), List(), List(List()), unitIdent,
Try(Apply(Select(
Apply(Select(handlerExpr.tree, newTermName("orElse")), List(handlerForLastState.tree)),
newTermName("apply")), List(Ident(newTermName("state")))),
List(
CaseDef(
Apply(Select(Select(Select(Ident(newTermName("scala")), newTermName("util")), newTermName("control")), newTermName("NonFatal")), List(Bind(newTermName("t"), Ident(nme.WILDCARD)))),
EmptyTree,
Block(List(
Apply(Select(Ident(newTermName("result")), newTermName("failure")), List(Ident(newTermName("t"))))),
Literal(Constant(()))))), EmptyTree))
val methodBody = reify {
val result = Promise[T]()
var state = 0
/*
def resume(): Unit = {
try {
(handlerExpr.splice orElse handlerForLastState.splice)(state)
} catch {
case NonFatal(t) => result.failure(t)
}
}
resume()
*/
c.Expr(Block(
localVarTrees :+ resumeFunTree,
Apply(Ident(newTermName("resume")), List())
)).splice
result.future
}
//vprintln("ASYNC: Generated method body:")
//vprintln(c.universe.showRaw(methodBody))
//vprintln(c.universe.show(methodBody))
methodBody
case _ =>
// issue error message
reify {
sys.error("expression not supported by async")
}
}
}
}
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