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/*
* Copyright (C) 2012 Typesafe Inc. <http://www.typesafe.com>
*/
package scala.async
import scala.reflect.macros.Context
private[async] final case class AnfTransform[C <: Context](c: C) {
import c.universe._
val utils = TransformUtils[c.type](c)
import utils._
def apply(tree: Tree): List[Tree] = {
val unique = uniqueNames(tree)
// Must prepend the () for issue #31.
anf.transformToList(Block(List(c.literalUnit.tree), unique))
}
private def uniqueNames(tree: Tree): Tree = {
new UniqueNames(tree).transform(tree)
}
/** Assigns unique names to all definitions in a tree, and adjusts references to use the new name.
* Only modifies names that appear more than once in the tree.
*
* This step is needed to allow us to safely merge blocks during the `inline` transform below.
*/
private final class UniqueNames(tree: Tree) extends Transformer {
val repeatedNames: Set[Name] = tree.collect {
case dt: DefTree => dt.symbol.name
}.groupBy(x => x).filter(_._2.size > 1).keySet
/** Stepping outside of the public Macro API to call [[scala.reflect.internal.Symbols.Symbol.name_=]] */
val symtab = c.universe.asInstanceOf[reflect.internal.SymbolTable]
val renamed = collection.mutable.Set[Symbol]()
override def transform(tree: Tree): Tree = {
tree match {
case defTree: DefTree if repeatedNames(defTree.symbol.name) =>
val trans = super.transform(defTree)
val origName = defTree.symbol.name
val sym = defTree.symbol.asInstanceOf[symtab.Symbol]
val fresh = name.fresh(sym.name.toString)
sym.name = defTree.symbol.name match {
case _: TermName => symtab.newTermName(fresh)
case _: TypeName => symtab.newTypeName(fresh)
}
renamed += trans.symbol
val newName = trans.symbol.name
trans match {
case ValDef(mods, name, tpt, rhs) =>
treeCopy.ValDef(trans, mods, newName, tpt, rhs)
case DefDef(mods, name, tparams, vparamss, tpt, rhs) =>
treeCopy.DefDef(trans, mods, newName, tparams, vparamss, tpt, rhs)
case TypeDef(mods, name, tparams, rhs) =>
treeCopy.TypeDef(tree, mods, newName, tparams, transform(rhs))
// If we were to allow local classes / objects, we would need to rename here.
case ClassDef(mods, name, tparams, impl) =>
treeCopy.ClassDef(tree, mods, newName, tparams, transform(impl).asInstanceOf[Template])
case ModuleDef(mods, name, impl) =>
treeCopy.ModuleDef(tree, mods, newName, transform(impl).asInstanceOf[Template])
case x => super.transform(x)
}
case Ident(name) =>
if (renamed(tree.symbol)) treeCopy.Ident(tree, tree.symbol.name)
else tree
case Select(fun, name) =>
if (renamed(tree.symbol)) {
treeCopy.Select(tree, transform(fun), tree.symbol.name)
} else super.transform(tree)
case _ => super.transform(tree)
}
}
}
private object trace {
private var indent = -1
def indentString = " " * indent
def apply[T](prefix: String, args: Any)(t: => T): T = {
indent += 1
def oneLine(s: Any) = s.toString.replaceAll("""\n""", "\\\\n").take(127)
try {
AsyncUtils.trace(s"${indentString}$prefix(${oneLine(args)})")
val result = t
AsyncUtils.trace(s"${indentString}= ${oneLine(result)}")
result
} finally {
indent -= 1
}
}
}
private object inline {
def transformToList(tree: Tree): List[Tree] = trace("inline", tree) {
val stats :+ expr = anf.transformToList(tree)
expr match {
case Apply(fun, args) if isAwait(fun) =>
val valDef = defineVal(name.await, expr, tree.pos)
stats :+ valDef :+ Ident(valDef.name)
case If(cond, thenp, elsep) =>
// if type of if-else is Unit don't introduce assignment,
// but add Unit value to bring it into form expected by async transform
if (expr.tpe =:= definitions.UnitTpe) {
stats :+ expr :+ Literal(Constant(()))
} else {
val varDef = defineVar(name.ifRes, expr.tpe, tree.pos)
def branchWithAssign(orig: Tree) = orig match {
case Block(thenStats, thenExpr) => Block(thenStats, Assign(Ident(varDef.name), thenExpr))
case _ => Assign(Ident(varDef.name), orig)
}
val ifWithAssign = If(cond, branchWithAssign(thenp), branchWithAssign(elsep))
stats :+ varDef :+ ifWithAssign :+ Ident(varDef.name)
}
case Match(scrut, cases) =>
// if type of match is Unit don't introduce assignment,
// but add Unit value to bring it into form expected by async transform
if (expr.tpe =:= definitions.UnitTpe) {
stats :+ expr :+ Literal(Constant(()))
}
else {
val varDef = defineVar(name.matchRes, expr.tpe, tree.pos)
val casesWithAssign = cases map {
case cd@CaseDef(pat, guard, Block(caseStats, caseExpr)) =>
attachCopy(cd)(CaseDef(pat, guard, Block(caseStats, Assign(Ident(varDef.name), caseExpr))))
case cd@CaseDef(pat, guard, body) =>
attachCopy(cd)(CaseDef(pat, guard, Assign(Ident(varDef.name), body)))
}
val matchWithAssign = attachCopy(tree)(Match(scrut, casesWithAssign))
stats :+ varDef :+ matchWithAssign :+ Ident(varDef.name)
}
case _ =>
stats :+ expr
}
}
def transformToList(trees: List[Tree]): List[Tree] = trees match {
case fst :: rest => transformToList(fst) ++ transformToList(rest)
case Nil => Nil
}
def transformToBlock(tree: Tree): Block = transformToList(tree) match {
case stats :+ expr => Block(stats, expr)
}
private def defineVar(prefix: String, tp: Type, pos: Position): ValDef = {
val vd = ValDef(Modifiers(Flag.MUTABLE), name.fresh(prefix), TypeTree(tp), defaultValue(tp))
vd.setPos(pos)
vd
}
private def defineVal(prefix: String, lhs: Tree, pos: Position): ValDef = {
val vd = ValDef(NoMods, name.fresh(prefix), TypeTree(), lhs)
vd.setPos(pos)
vd
}
}
private object anf {
private[AnfTransform] def transformToList(tree: Tree): List[Tree] = trace("anf", tree) {
def containsAwait = tree exists isAwait
tree match {
case Select(qual, sel) if containsAwait =>
val stats :+ expr = inline.transformToList(qual)
stats :+ attachCopy(tree)(Select(expr, sel).setSymbol(tree.symbol))
case Apply(fun, args) if containsAwait =>
// we an assume that no await call appears in a by-name argument position,
// this has already been checked.
val funStats :+ simpleFun = inline.transformToList(fun)
val argLists = args map inline.transformToList
val allArgStats = argLists flatMap (_.init)
val simpleArgs = argLists map (_.last)
funStats ++ allArgStats :+ attachCopy(tree)(Apply(simpleFun, simpleArgs).setSymbol(tree.symbol))
case Block(stats, expr) if containsAwait =>
inline.transformToList(stats :+ expr)
case ValDef(mods, name, tpt, rhs) if containsAwait =>
if (rhs exists isAwait) {
val stats :+ expr = inline.transformToList(rhs)
stats :+ attachCopy(tree)(ValDef(mods, name, tpt, expr).setSymbol(tree.symbol))
} else List(tree)
case Assign(lhs, rhs) if containsAwait =>
val stats :+ expr = inline.transformToList(rhs)
stats :+ attachCopy(tree)(Assign(lhs, expr))
case If(cond, thenp, elsep) if containsAwait =>
val stats :+ expr = inline.transformToList(cond)
val thenBlock = inline.transformToBlock(thenp)
val elseBlock = inline.transformToBlock(elsep)
stats :+
c.typeCheck(attachCopy(tree)(If(expr, thenBlock, elseBlock)))
case Match(scrut, cases) if containsAwait =>
val scrutStats :+ scrutExpr = inline.transformToList(scrut)
val caseDefs = cases map {
case CaseDef(pat, guard, body) =>
val block = inline.transformToBlock(body)
attachCopy(tree)(CaseDef(pat, guard, block))
}
scrutStats :+ c.typeCheck(attachCopy(tree)(Match(scrutExpr, caseDefs)))
case LabelDef(name, params, rhs) if containsAwait =>
List(LabelDef(name, params, Block(inline.transformToList(rhs), Literal(Constant(())))).setSymbol(tree.symbol))
case TypeApply(fun, targs) if containsAwait =>
val funStats :+ simpleFun = inline.transformToList(fun)
funStats :+ attachCopy(tree)(TypeApply(simpleFun, targs).setSymbol(tree.symbol))
case _ =>
List(tree)
}
}
}
}
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