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package scala.async.internal
trait AsyncTransform {
self: AsyncMacro =>
import c.universe._
import c.internal._
import decorators._
val asyncBase: AsyncBase
def asyncTransform[T](execContext: Tree)
(resultType: WeakTypeTag[T]): Tree = {
// We annotate the type of the whole expression as `T @uncheckedBounds` so as not to introduce
// warnings about non-conformant LUBs. See SI-7694
// This implicit propagates the annotated type in the type tag.
implicit val uncheckedBoundsResultTag: WeakTypeTag[T] = c.WeakTypeTag[T](uncheckedBounds(resultType.tpe))
reportUnsupportedAwaits(body)
// Transform to A-normal form:
// - no await calls in qualifiers or arguments,
// - if/match only used in statement position.
val anfTree0: Block = anfTransform(body, c.internal.enclosingOwner)
val anfTree = futureSystemOps.postAnfTransform(anfTree0)
cleanupContainsAwaitAttachments(anfTree)
containsAwait = containsAwaitCached(anfTree)
val applyDefDefDummyBody: DefDef = {
val applyVParamss = List(List(ValDef(Modifiers(Flag.PARAM), name.tr, TypeTree(futureSystemOps.tryType[Any]), EmptyTree)))
DefDef(NoMods, name.apply, Nil, applyVParamss, TypeTree(definitions.UnitTpe), literalUnit)
}
// Create `ClassDef` of state machine with empty method bodies for `resume` and `apply`.
val stateMachine: ClassDef = {
val body: List[Tree] = {
val stateVar = ValDef(Modifiers(Flag.MUTABLE | Flag.PRIVATE | Flag.LOCAL), name.state, TypeTree(definitions.IntTpe), Literal(Constant(StateAssigner.Initial)))
val resultAndAccessors = mkMutableField(futureSystemOps.promType[T](uncheckedBoundsResultTag), name.result, futureSystemOps.createProm[T](uncheckedBoundsResultTag).tree)
val execContextValDef = ValDef(NoMods, name.execContext, TypeTree(), execContext)
val apply0DefDef: DefDef = {
// We extend () => Unit so we can pass this class as the by-name argument to `Future.apply`.
// See SI-1247 for the the optimization that avoids creation.
DefDef(NoMods, name.apply, Nil, Nil, TypeTree(definitions.UnitTpe), Apply(Ident(name.apply), literalNull :: Nil))
}
List(emptyConstructor, stateVar) ++ resultAndAccessors ++ List(execContextValDef) ++ List(applyDefDefDummyBody, apply0DefDef)
}
val customParents = futureSystemOps.stateMachineClassParents
val tycon = if (customParents.exists(!_.typeSymbol.asClass.isTrait)) {
// prefer extending a class to reduce the class file size of the state machine.
symbolOf[scala.runtime.AbstractFunction1[Any, Any]]
} else {
// ... unless a custom future system already extends some class
symbolOf[scala.Function1[Any, Any]]
}
val tryToUnit = appliedType(tycon, futureSystemOps.tryType[Any], typeOf[Unit])
val template = Template((futureSystemOps.stateMachineClassParents ::: List(tryToUnit, typeOf[() => Unit])).map(TypeTree(_)), emptyValDef, body)
val t = ClassDef(NoMods, name.stateMachineT, Nil, template)
typecheckClassDef(t)
}
val stateMachineClass = stateMachine.symbol
val asyncBlock: AsyncBlock = {
val symLookup = new SymLookup(stateMachineClass, applyDefDefDummyBody.vparamss.head.head.symbol)
buildAsyncBlock(anfTree, symLookup)
}
logDiagnostics(anfTree, asyncBlock.asyncStates.map(_.toString))
val liftedFields: List[Tree] = liftables(asyncBlock.asyncStates)
// live variables analysis
// the result map indicates in which states a given field should be nulled out
val assignsOf = fieldsToNullOut(asyncBlock.asyncStates, liftedFields)
for ((state, flds) <- assignsOf) {
val assigns = flds.map { fld =>
val fieldSym = fld.symbol
val assign = Assign(gen.mkAttributedStableRef(thisType(fieldSym.owner), fieldSym), mkZero(fieldSym.info))
asyncBase.nullOut(c.universe)(c.Expr[String](Literal(Constant(fieldSym.name.toString))), c.Expr[Any](Ident(fieldSym))).tree match {
case Literal(Constant(value: Unit)) => assign
case x => Block(x :: Nil, assign)
}
}
val asyncState = asyncBlock.asyncStates.find(_.state == state).get
asyncState.stats = assigns ++ asyncState.stats
}
def startStateMachine: Tree = {
val stateMachineSpliced: Tree = spliceMethodBodies(
liftedFields,
stateMachine,
atMacroPos(asyncBlock.onCompleteHandler[T])
)
def selectStateMachine(selection: TermName) = Select(Ident(name.stateMachine), selection)
Block(List[Tree](
stateMachineSpliced,
ValDef(NoMods, name.stateMachine, TypeTree(), Apply(Select(New(Ident(stateMachine.symbol)), nme.CONSTRUCTOR), Nil)),
futureSystemOps.spawn(Apply(selectStateMachine(name.apply), Nil), selectStateMachine(name.execContext))
),
futureSystemOps.promiseToFuture(c.Expr[futureSystem.Prom[T]](selectStateMachine(name.result))).tree)
}
val isSimple = asyncBlock.asyncStates.size == 1
val result = if (isSimple)
futureSystemOps.spawn(body, execContext) // generate lean code for the simple case of `async { 1 + 1 }`
else
startStateMachine
cleanupContainsAwaitAttachments(result)
}
def logDiagnostics(anfTree: Tree, states: Seq[String]) {
def location = try {
macroPos.source.path
} catch {
case _: UnsupportedOperationException =>
macroPos.toString
}
AsyncUtils.vprintln(s"In file '$location':")
AsyncUtils.vprintln(s"${c.macroApplication}")
AsyncUtils.vprintln(s"ANF transform expands to:\n $anfTree")
states foreach (s => AsyncUtils.vprintln(s))
}
/**
* Build final `ClassDef` tree of state machine class.
*
* @param liftables trees of definitions that are lifted to fields of the state machine class
* @param tree `ClassDef` tree of the state machine class
* @param applyBody tree of onComplete handler (`apply` method)
* @return transformed `ClassDef` tree of the state machine class
*/
def spliceMethodBodies(liftables: List[Tree], tree: ClassDef, applyBody: Tree): Tree = {
val liftedSyms = liftables.map(_.symbol).toSet
val stateMachineClass = tree.symbol
liftedSyms.foreach {
sym =>
if (sym != null) {
sym.setOwner(stateMachineClass)
if (sym.isModule)
sym.asModule.moduleClass.setOwner(stateMachineClass)
}
}
// Replace the ValDefs in the splicee with Assigns to the corresponding lifted
// fields. Similarly, replace references to them with references to the field.
//
// This transform will only be run on the RHS of `def foo`.
val useFields: (Tree, TypingTransformApi) => Tree = (tree, api) => tree match {
case _ if api.currentOwner == stateMachineClass =>
api.default(tree)
case ValDef(_, _, _, rhs) if liftedSyms(tree.symbol) =>
api.atOwner(api.currentOwner) {
val fieldSym = tree.symbol
if (fieldSym.asTerm.isLazy) Literal(Constant(()))
else {
val lhs = atPos(tree.pos) {
gen.mkAttributedStableRef(thisType(fieldSym.owner.asClass), fieldSym)
}
treeCopy.Assign(tree, lhs, api.recur(rhs)).setType(definitions.UnitTpe).changeOwner(fieldSym, api.currentOwner)
}
}
case _: DefTree if liftedSyms(tree.symbol) =>
EmptyTree
case Ident(name) if liftedSyms(tree.symbol) =>
val fieldSym = tree.symbol
atPos(tree.pos) {
gen.mkAttributedStableRef(thisType(fieldSym.owner.asClass), fieldSym).setType(tree.tpe)
}
case _ =>
api.default(tree)
}
val liftablesUseFields = liftables.map {
case vd: ValDef if !vd.symbol.asTerm.isLazy => vd
case x => typingTransform(x, stateMachineClass)(useFields)
}
tree.children.foreach(_.changeOwner(enclosingOwner, tree.symbol))
val treeSubst = tree
/* Fixes up DefDef: use lifted fields in `body` */
def fixup(dd: DefDef, body: Tree, api: TypingTransformApi): Tree = {
val spliceeAnfFixedOwnerSyms = body
val newRhs = typingTransform(spliceeAnfFixedOwnerSyms, dd.symbol)(useFields)
val newRhsTyped = api.atOwner(dd, dd.symbol)(api.typecheck(newRhs))
treeCopy.DefDef(dd, dd.mods, dd.name, dd.tparams, dd.vparamss, dd.tpt, newRhsTyped)
}
liftablesUseFields.foreach(t => if (t.symbol != null) stateMachineClass.info.decls.enter(t.symbol))
val result0 = transformAt(treeSubst) {
case t@Template(parents, self, stats) =>
(api: TypingTransformApi) => {
treeCopy.Template(t, parents, self, liftablesUseFields ++ stats)
}
}
val result = transformAt(result0) {
case dd@DefDef(_, name.apply, _, List(List(_)), _, _) if dd.symbol.owner == stateMachineClass =>
(api: TypingTransformApi) =>
val typedTree = fixup(dd, applyBody.changeOwner(enclosingOwner, dd.symbol), api)
typedTree
}
result
}
def typecheckClassDef(cd: ClassDef): ClassDef = {
val Block(cd1 :: Nil, _) = typingTransform(atPos(macroPos)(Block(cd :: Nil, Literal(Constant(())))))(
(tree, api) =>
api.typecheck(tree)
)
cd1.asInstanceOf[ClassDef]
}
}
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