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package scala.async.internal
trait AsyncTransform {
self: AsyncMacro =>
import global._
def asyncTransform[T](body: Tree, execContext: Tree, cpsFallbackEnabled: Boolean)
(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 propatages the annotated type in the type tag.
implicit val uncheckedBoundsResultTag: WeakTypeTag[T] = WeakTypeTag[T](rootMirror, FixedMirrorTypeCreator(rootMirror, uncheckedBounds(resultType.tpe)))
reportUnsupportedAwaits(body, report = !cpsFallbackEnabled)
// Transform to A-normal form:
// - no await calls in qualifiers or arguments,
// - if/match only used in statement position.
val anfTree: Block = anfTransform(body)
val resumeFunTreeDummyBody = DefDef(Modifiers(), name.resume, Nil, List(Nil), Ident(definitions.UnitClass), Literal(Constant(())))
val applyDefDefDummyBody: DefDef = {
val applyVParamss = List(List(ValDef(Modifiers(Flag.PARAM), name.tr, TypeTree(defn.TryAnyType), EmptyTree)))
DefDef(NoMods, name.apply, Nil, applyVParamss, TypeTree(definitions.UnitTpe), Literal(Constant(())))
}
val stateMachineType = applied("scala.async.StateMachine", List(futureSystemOps.promType[T](uncheckedBoundsResultTag), futureSystemOps.execContextType))
val stateMachine: ClassDef = {
val body: List[Tree] = {
val stateVar = ValDef(Modifiers(Flag.MUTABLE | Flag.PRIVATE | Flag.LOCAL), name.state, TypeTree(definitions.IntTpe), Literal(Constant(0)))
val result = ValDef(NoMods, name.result, TypeTree(futureSystemOps.promType[T](uncheckedBoundsResultTag)), 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 creatio
DefDef(NoMods, name.apply, Nil, Nil, TypeTree(definitions.UnitTpe), Apply(Ident(name.resume), Nil))
}
List(emptyConstructor, stateVar, result, execContextValDef) ++ List(resumeFunTreeDummyBody, applyDefDefDummyBody, apply0DefDef)
}
val template = {
Template(List(stateMachineType), emptyValDef, body)
}
val t = ClassDef(NoMods, name.stateMachineT, Nil, template)
callSiteTyper.typedPos(macroPos)(Block(t :: Nil, Literal(Constant(()))))
t
}
val asyncBlock: AsyncBlock = {
val symLookup = new SymLookup(stateMachine.symbol, applyDefDefDummyBody.vparamss.head.head.symbol)
buildAsyncBlock(anfTree, symLookup)
}
logDiagnostics(anfTree, asyncBlock.asyncStates.map(_.toString))
def startStateMachine: Tree = {
val stateMachineSpliced: Tree = spliceMethodBodies(
liftables(asyncBlock.asyncStates),
stateMachine,
atMacroPos(asyncBlock.onCompleteHandler[T]),
atMacroPos(asyncBlock.resumeFunTree[T].rhs)
)
def selectStateMachine(selection: TermName) = Select(Ident(name.stateMachine), selection)
Block(List[Tree](
stateMachineSpliced,
ValDef(NoMods, name.stateMachine, stateMachineType, Apply(Select(New(Ident(stateMachine.symbol)), nme.CONSTRUCTOR), Nil)),
futureSystemOps.spawn(Apply(selectStateMachine(name.apply), Nil), selectStateMachine(name.execContext))
),
futureSystemOps.promiseToFuture(Expr[futureSystem.Prom[T]](selectStateMachine(name.result))).tree)
}
val isSimple = asyncBlock.asyncStates.size == 1
if (isSimple)
futureSystemOps.spawn(body, execContext) // generate lean code for the simple case of `async { 1 + 1 }`
else
startStateMachine
}
def logDiagnostics(anfTree: Tree, states: Seq[String]) {
def location = try {
macroPos.source.path
} catch {
case _: UnsupportedOperationException =>
macroPos.toString
}
AsyncUtils.vprintln(s"In file '$location':")
AsyncUtils.vprintln(s"${macroApplication}")
AsyncUtils.vprintln(s"ANF transform expands to:\n $anfTree")
states foreach (s => AsyncUtils.vprintln(s))
}
def spliceMethodBodies(liftables: List[Tree], tree: Tree, applyBody: Tree,
resumeBody: Tree): Tree = {
val liftedSyms = liftables.map(_.symbol).toSet
val stateMachineClass = tree.symbol
liftedSyms.foreach {
sym =>
if (sym != null) {
sym.owner = stateMachineClass
if (sym.isModule)
sym.moduleClass.owner = 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 be only be run on the RHS of `def foo`.
class UseFields extends MacroTypingTransformer {
override def transform(tree: Tree): Tree = tree match {
case _ if currentOwner == stateMachineClass =>
super.transform(tree)
case ValDef(_, _, _, rhs) if liftedSyms(tree.symbol) =>
atOwner(currentOwner) {
val fieldSym = tree.symbol
val set = Assign(gen.mkAttributedStableRef(fieldSym.owner.thisType, fieldSym), transform(rhs))
changeOwner(set, tree.symbol, currentOwner)
localTyper.typedPos(tree.pos)(set)
}
case _: DefTree if liftedSyms(tree.symbol) =>
EmptyTree
case Ident(name) if liftedSyms(tree.symbol) =>
val fieldSym = tree.symbol
atPos(tree.pos) {
gen.mkAttributedStableRef(fieldSym.owner.thisType, fieldSym).setType(tree.tpe)
}
case _ =>
super.transform(tree)
}
}
val liftablesUseFields = liftables.map {
case vd: ValDef => vd
case x =>
val useField = new UseFields()
//.substituteSymbols(fromSyms, toSyms)
useField.atOwner(stateMachineClass)(useField.transform(x))
}
tree.children.foreach {
t =>
new ChangeOwnerAndModuleClassTraverser(callSiteTyper.context.owner, tree.symbol).traverse(t)
}
val treeSubst = tree
def fixup(dd: DefDef, body: Tree, ctx: analyzer.Context): Tree = {
val spliceeAnfFixedOwnerSyms = body
val useField = new UseFields()
val newRhs = useField.atOwner(dd.symbol)(useField.transform(spliceeAnfFixedOwnerSyms))
val typer = global.analyzer.newTyper(ctx.make(dd, dd.symbol))
treeCopy.DefDef(dd, dd.mods, dd.name, dd.tparams, dd.vparamss, dd.tpt, typer.typed(newRhs))
}
liftablesUseFields.foreach(t => if (t.symbol != null) stateMachineClass.info.decls.enter(t.symbol))
val result0 = transformAt(treeSubst) {
case t@Template(parents, self, stats) =>
(ctx: analyzer.Context) => {
treeCopy.Template(t, parents, self, liftablesUseFields ++ stats)
}
}
val result = transformAt(result0) {
case dd@DefDef(_, name.apply, _, List(List(_)), _, _) if dd.symbol.owner == stateMachineClass =>
(ctx: analyzer.Context) =>
val typedTree = fixup(dd, changeOwner(applyBody, callSiteTyper.context.owner, dd.symbol), ctx)
typedTree
case dd@DefDef(_, name.resume, _, _, _, _) if dd.symbol.owner == stateMachineClass =>
(ctx: analyzer.Context) =>
val changed = changeOwner(resumeBody, callSiteTyper.context.owner, dd.symbol)
val res = fixup(dd, changed, ctx)
res
}
result
}
}
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