package dotty.tools
package dotc
package ast
import core._
import util.Positions._, Types._, Contexts._, Constants._, Names._, NameOps._, Flags._
import SymDenotations._, Symbols._, StdNames._, Annotations._, Trees._
import TreeInfo._
import Decorators._
import language.higherKinds
import collection.mutable.ListBuffer
object desugar {
import untpd._
private type VarInfo = (NameTree, Tree)
object Mode extends Enumeration {
val Type, Expr, Pattern = Value
}
def valDef(vdef: ValDef)(implicit ctx: Context): Tree = {
val ValDef(mods, name, tpt, rhs) = vdef
if (!ctx.owner.isClass || (mods is Private)) vdef
else {
val lname = name.toLocalName
val field = vdef.derivedValDef(mods, lname, tpt, rhs)
val getter = vdef.derivedDefDef(mods, name, Nil, Nil, tpt, Ident(lname))
if (!(mods is Mutable)) Thicket(field, getter)
else {
val setterParam = makeSyntheticParameter(tpt = TypeTree(field))
val setter = vdef.derivedDefDef(
mods, name.getterToSetter, Nil, (setterParam :: Nil) :: Nil, EmptyTree, refOfDef(setterParam))
Thicket(field, getter, setter)
}
}
}
def defDef(meth: DefDef, isPrimaryConstructor: Boolean = false): DefDef = {
val DefDef(mods, name, tparams, vparamss, tpt, rhs) = meth
val epbuf = new ListBuffer[ValDef]
def makeEvidenceParam(cxBound: Tree): ValDef = ???
val tparams1 = tparams mapConserve {
case tparam @ TypeDef(mods, name, ttparams, ContextBounds(tbounds, cxbounds)) =>
for (cxbound <- cxbounds) {
val paramFlags: FlagSet = if (isPrimaryConstructor) PrivateLocalParamAccessor else Param
val epname = (nme.EVIDENCE_PARAM_PREFIX.toString + epbuf.length).toTermName
epbuf +=
ValDef(Modifiers(paramFlags | Implicit), epname, cxbound, EmptyTree)
}
tparam.derivedTypeDef(mods, name, ttparams, tbounds)
case tparam =>
tparam
}
epbuf.toList match {
case Nil =>
meth
case evidenceParams =>
val vparamss1 = vparamss.reverse match {
case (vparams @ (vparam :: _)) :: rvparamss if vparam.mods is Implicit =>
((vparams ++ evidenceParams) :: rvparamss).reverse
case _ =>
vparamss :+ evidenceParams
}
meth.derivedDefDef(mods, name, tparams1, vparamss1, tpt, rhs)
}
}
def typeDef(tdef: TypeDef)(implicit ctx: Context): Tree = {
val TypeDef(mods, name, tparams, rhs) = tdef
if (mods is PrivateLocalParamAccessor) {
val tparam = tdef.derivedTypeDef(
tdef.mods &~ PrivateLocal | ExpandedName, tdef.name.expandedName(ctx.owner), tdef.tparams, tdef.rhs)
val alias = tdef.derivedTypeDef(
Modifiers(PrivateLocal | Synthetic), tdef.name, Nil, refOfDef(tparam))
Thicket(tparam :: alias :: Nil)
}
else tdef
}
private val synthetic = Modifiers(Synthetic)
def classDef(cdef: ClassDef)(implicit ctx: Context): Tree = {
val ClassDef(
mods, name, impl @ Template(constr0, parents, self, body)) = cdef
val constr1 = defDef(constr0, isPrimaryConstructor = true)
val tparams = constr1.tparams.map(tparam => tparam.derivedTypeDef(
Modifiers(Param), tparam.name, tparam.tparams, tparam.rhs))
// ensure parameter list is non-empty
val vparamss =
if (constr1.vparamss.isEmpty) {
if (mods is Case)
ctx.error("case class needs to have at least one parameter list", cdef.pos)
ListOfNil
} else
constr1.vparamss.nestedMap(vparam => vparam.derivedValDef(
Modifiers(Param), vparam.name, vparam.tpt, vparam.rhs))
val constr = constr1.derivedDefDef(
constr1.mods, constr1.name, tparams, vparamss, constr1.tpt, constr1.rhs)
val classTypeRef = {
val tycon = Ident(cdef.name)
val tparams = cdef.impl.constr.tparams
if (tparams.isEmpty) tycon else AppliedTypeTree(tycon, tparams map refOfDef)
}
val creatorExpr = New(classTypeRef, vparamss nestedMap refOfDef)
val caseClassMeths =
if (mods is Case) {
val caseParams = vparamss.head.toArray
def syntheticProperty(name: TermName, rhs: Tree) =
DefDef(synthetic, name, Nil, Nil, EmptyTree, rhs)
val isDefinedMeth = syntheticProperty(nme.isDefined, Literal(Constant(true)))
val productArityMeth = syntheticProperty(nme.productArity, Literal(Constant(caseParams.length)))
val productElemMeths = for (i <- 0 until caseParams.length) yield
syntheticProperty(("_" + (i + 1)).toTermName, Select(This(EmptyTypeName), caseParams(i).name))
val copyMeths =
if (mods is Abstract) Nil
else {
val copyFirstParams = vparamss.head.map(vparam =>
vparam.derivedValDef(vparam.mods, vparam.name, vparam.tpt, refOfDef(vparam)))
val copyRestParamss = vparamss.tail.nestedMap(vparam =>
vparam.derivedValDef(vparam.mods, vparam.name, vparam.tpt, EmptyTree))
DefDef(synthetic, nme.copy, tparams, copyFirstParams :: copyRestParamss, EmptyTree, creatorExpr) :: Nil
}
copyMeths ::: isDefinedMeth :: productArityMeth :: productElemMeths.toList
}
else Nil
val caseCompanions =
if (mods is Case) {
val parent =
if (tparams.nonEmpty) ref(defn.AnyRefAlias.typeConstructor)
else (vparamss :\ classTypeRef) ((vparams, restpe) => Function(vparams map (_.tpt), restpe))
val applyMeths =
if (mods is Abstract) Nil
else DefDef(synthetic, nme.apply, tparams, vparamss, EmptyTree, creatorExpr) :: Nil
val unapplyMeth = {
val unapplyParam = makeSyntheticParameter(tpt = classTypeRef)
DefDef(synthetic, nme.unapply, tparams, (unapplyParam :: Nil) :: Nil, EmptyTree, This(EmptyTypeName))
}
moduleDef(
ModuleDef(
Modifiers(Synthetic), name.toTermName,
Template(emptyConstructor, parent :: Nil, EmptyValDef(), applyMeths ::: unapplyMeth :: Nil))
).toList
}
else Nil
val implicitWrappers =
if (mods is Implicit) {
if (ctx.owner is Package)
ctx.error("implicit classes may not be toplevel", cdef.pos)
if (mods is Case)
ctx.error("implicit classes may not case classes", cdef.pos)
DefDef(Modifiers(Synthetic | Implicit), name.toTermName,
tparams, vparamss, EmptyTree, creatorExpr) :: Nil
}
else Nil
val cdef1 = cdef.derivedClassDef(mods, name,
impl.derivedTemplate(constr, parents, self,
constr1.tparams ::: constr1.vparamss.flatten ::: body ::: caseClassMeths))
Thicket(cdef1 :: caseCompanions ::: implicitWrappers)
}
/** Expand to:
* <module> val name: name$ = New(name$)
* <module> final class name$ extends parents { self: name.type => body }
*/
def moduleDef(mdef: ModuleDef)(implicit ctx: Context): Tree = {
val ModuleDef(mods, name, tmpl @ Template(constr, parents, self, body)) = mdef
val clsName = name.moduleClassName
val clsRef = Ident(clsName)
val modul = ValDef(mods | ModuleCreationFlags, name, clsRef, New(clsRef, Nil))
val clsSelf = self.derivedValDef(self.mods, self.name, SingletonTypeTree(Ident(name)), self.rhs)
val clsTmpl = tmpl.derivedTemplate(constr, parents, clsSelf, body)
val cls = ClassDef(mods.toTypeFlags & AccessFlags | ModuleClassCreationFlags, clsName, clsTmpl)
Thicket(cls :: valDef(modul).toList)
}
def memberDef(tree: Tree)(implicit ctx: Context): Tree = tree match {
case tree: ValDef => valDef(tree)
case tree: TypeDef => typeDef(tree)
case tree: DefDef => defDef(tree)
case tree: ClassDef => classDef(tree)
case tree: ModuleDef => moduleDef(tree)
}
def apply(tree: Tree, mode: Mode.Value)(implicit ctx: Context): Tree = {
def labelDefAndCall(lname: TermName, rhs: Tree, call: Tree) = {
val ldef = DefDef(Modifiers(Label), lname, Nil, ListOfNil, TypeTree(), rhs)
Block(ldef, call)
}
def derivedValDef(mods: Modifiers, named: NameTree, tpt: Tree, rhs: Tree) =
ValDef(mods, named.name.asTermName, tpt, rhs).withPos(named.pos)
/** Translate infix operation expression left op right
*/
def makeBinop(left: Tree, op: Name, right: Tree): Tree = {
def assignToNamedArg(arg: Tree) = arg match {
case Assign(Ident(name), rhs) => arg.derivedNamedArg(name, rhs)
case _ => arg
}
if (isLeftAssoc(op)) {
val args: List[Tree] = right match {
case Parens(arg) => assignToNamedArg(arg) :: Nil
case Tuple(args) => args mapConserve assignToNamedArg
case _ => right :: Nil
}
Apply(Select(left, op), args)
} else {
val x = ctx.freshName().toTermName
Block(
ValDef(Modifiers(Synthetic), x, TypeTree(), left),
Apply(Select(right, op), Ident(x)))
}
}
/** Make closure corresponding to function params => body */
def makeClosure(params: List[ValDef], body: Tree) =
Block(
DefDef(Modifiers(Synthetic), nme.ANON_FUN, Nil, params :: Nil, EmptyTree, body),
Closure(Nil, Ident(nme.ANON_FUN)))
/** Make closure corresponding to partial function { cases } */
def makeCaseClosure(cases: List[CaseDef]) = {
val param = makeSyntheticParameter()
makeClosure(param :: Nil, Match(Ident(param.name), cases))
}
/** Create tree for for-comprehension <for (enums) do body> or
* <for (enums) yield body> where mapName and flatMapName are chosen
* corresponding to whether this is a for-do or a for-yield.
* The creation performs the following rewrite rules:
*
* 1.
*
* for (P <- G) E ==> G.foreach (P => E)
*
* Here and in the following (P => E) is interpreted as the function (P => E)
* if P is a variable pattern and as the partial function { case P => E } otherwise.
*
* 2.
*
* for (P <- G) yield E ==> G.map (P => E)
*
* 3.
*
* for (P_1 <- G_1; P_2 <- G_2; ...) ...
* ==>
* G_1.flatMap (P_1 => for (P_2 <- G_2; ...) ...)
*
* 4.
*
* for (P <- G; E; ...) ...
* =>
* for (P <- G.filter (P => E); ...) ...
*
* 5. For any N:
*
* for (P_1 <- G; P_2 = E_2; val P_N = E_N; ...)
* ==>
* for (TupleN(P_1, P_2, ... P_N) <-
* for (x_1 @ P_1 <- G) yield {
* val x_2 @ P_2 = E_2
* ...
* val x_N & P_N = E_N
* TupleN(x_1, ..., x_N)
* } ...)
*
* If any of the P_i are variable patterns, the corresponding `x_i @ P_i' is not generated
* and the variable constituting P_i is used instead of x_i
*
* @param mapName The name to be used for maps (either map or foreach)
* @param flatMapName The name to be used for flatMaps (either flatMap or foreach)
* @param enums The enumerators in the for expression
* @param body The body of the for expression
*/
def makeFor(mapName: TermName, flatMapName: TermName, enums: List[Tree], body: Tree): Tree = {
/** Make a function value pat => body.
* If pat is a var pattern id: T then this gives (id: T) => body
* Otherwise this gives { case pat => body }
*/
def makeLambda(pat: Tree, body: Tree): Tree = pat match {
case VarPattern(named, tpt) =>
makeClosure(derivedValDef(Modifiers(Param), named, tpt, EmptyTree) :: Nil, body)
case _ =>
makeCaseClosure(CaseDef(pat, EmptyTree, body) :: Nil)
}
/** If `pat` is not yet a `Bind` wrap it in one with a fresh name
*/
def makeBind(pat: Tree): Tree = pat match {
case Bind(_, _) => pat
case _ => Bind(ctx.freshName().toTermName, pat)
}
/** Is pattern `pat` irrefutable when matched against `rhs`?
* We only can do a simple syntactic check here; a more refined check
* is done later prompted by the presence of a "withFilterIfRefutable" call.
*/
def isIrrefutable(pat: Tree, rhs: Tree): Boolean = {
def matchesTuple(pats: List[Tree], rhs: Tree): Boolean = rhs match {
case Tuple(trees) => (pats corresponds trees)(isIrrefutable)
case Parens(rhs1) => matchesTuple(pats, rhs1)
case Block(_, rhs1) => matchesTuple(pats, rhs1)
case If(_, thenp, elsep) => matchesTuple(pats, thenp) && matchesTuple(pats, elsep)
case Match(_, cases) => cases forall (matchesTuple(pats, _))
case CaseDef(_, _, rhs1) => matchesTuple(pats, rhs)
case Throw(_) => true
case _ => false
}
pat match {
case Bind(_, pat1) => isIrrefutable(pat1, rhs)
case Parens(pat1) => isIrrefutable(pat1, rhs)
case Tuple(pats) => matchesTuple(pats, rhs)
case _ => isVarPattern(pat)
}
}
/** Make a pattern filter:
* rhs.withFilterIfRefutable { case pat => true case _ => false }
*/
def makePatFilter(rhs: Tree, pat: Tree): Tree = {
val cases = List(
CaseDef(pat, EmptyTree, Literal(Constant(true))),
CaseDef(Ident(nme.WILDCARD), EmptyTree, Literal(Constant(false))))
Apply(Select(rhs, nme.withFilterIfRefutable), Match(EmptyTree, cases))
}
/** rhs.name with a pattern filter on rhs unless `pat` is irrefutable when
* matched against `rhs`.
*/
def rhsSelect(rhs: Tree, name: TermName, pat: Tree) = {
val rhs1 = if (isIrrefutable(pat, rhs)) rhs else makePatFilter(rhs, pat)
Select(rhs1, name)
}
enums match {
case (enum @ GenFrom(pat, rhs)) :: Nil =>
Apply(rhsSelect(rhs, mapName, pat), makeLambda(pat, body))
case GenFrom(pat, rhs) :: (rest @ (GenFrom(_, _) :: _)) =>
val cont = makeFor(mapName, flatMapName, rest, body)
Apply(rhsSelect(rhs, flatMapName, pat), makeLambda(pat, cont))
case (enum @ GenFrom(pat, rhs)) :: (rest @ GenAlias(_, _) :: _) =>
val (valeqs, rest1) = rest.span(_.isInstanceOf[GenAlias])
val pats = valeqs map { case GenAlias(pat, _) => pat }
val rhss = valeqs map { case GenAlias(_, rhs) => rhs }
val defpat1 = makeBind(pat)
val defpats = pats map makeBind
val pdefs = (defpats, rhss).zipped map (makePatDef(Modifiers(), _, _))
val ids = (defpat1 :: defpats) map { case Bind(name, _) => Ident(name) }
val rhs1 = makeFor(nme.map, nme.flatMap, GenFrom(defpat1, rhs) :: Nil, Block(pdefs, makeTuple(ids)))
val allpats = pat :: pats
val vfrom1 = GenFrom(makeTuple(allpats), rhs1)
makeFor(mapName, flatMapName, vfrom1 :: rest1, body)
case (enum @ GenFrom(pat, rhs)) :: test :: rest =>
val filtered = Apply(rhsSelect(rhs, nme.withFilter, pat), makeLambda(pat, test))
makeFor(mapName, flatMapName, GenFrom(pat, filtered) :: rest, body)
case _ =>
EmptyTree //may happen for erroneous input
}
}
def makeAnnotated(cls: Symbol, tree: Tree) =
Annotated(TypedSplice(tpd.New(cls.typeConstructor)), tree)
/** Returns list of all pattern variables, possibly with their types,
* without duplicates
*/
def getVariables(tree: Tree): List[VarInfo] =
getVars(new ListBuffer[VarInfo], tree).toList
/** In case there is exactly one variable x_1 in pattern
* val/var p = e ==> val/var x_1 = (e: @unchecked) match (case p => (x_1))
*
* in case there are zero or more than one variables in pattern
* val/var p = e ==> private synthetic val t$ = (e: @unchecked) match (case p => (x_1, ..., x_N))
* val/var x_1 = t$._1
* ...
* val/var x_N = t$._N
* If the original pattern variable carries a type annotation, so does the corresponding
* ValDef.
*/
def makePatDef(mods: Modifiers, pat: Tree, rhs: Tree): Tree = pat match {
case VarPattern(named, tpt) =>
derivedValDef(mods, named, tpt, rhs)
case _ =>
val rhsUnchecked = makeAnnotated(defn.UncheckedAnnot, rhs)
val vars = getVariables(pat)
val ids = for ((named, _) <- vars) yield Ident(named.name)
val caseDef = CaseDef(pat, EmptyTree, makeTuple(ids))
val matchExpr = Match(rhsUnchecked, caseDef :: Nil)
vars match {
case (named, tpt) :: Nil =>
derivedValDef(mods, named, tpt, matchExpr)
case _ =>
val tmpName = ctx.freshName().toTermName
val patMods = Modifiers(PrivateLocal | Synthetic | (mods.flags & Lazy))
val firstDef = ValDef(patMods, tmpName, TypeTree(), matchExpr)
def selector(n: Int) = Select(Ident(tmpName), ("_" + n).toTermName)
val restDefs =
for (((named, tpt), n) <- vars.zipWithIndex)
yield derivedValDef(mods, named, tpt, selector(n))
Thicket(firstDef :: restDefs)
}
}
def isPatternVar(id: Ident) =
mode == Mode.Pattern && isVarPattern(id) && id.name != nme.WILDCARD
// begin desugar
val tree1 = tree match { // todo: move general tree desugaring to typer, and keep only untyped trees here?
case id @ Ident(_) if isPatternVar(id) =>
Bind(id.name, Ident(nme.WILDCARD))
case Typed(id @ Ident(_), tpt) if isPatternVar(id) =>
Bind(id.name, Typed(Ident(nme.WILDCARD), tpt)).withPos(id.pos)
case New(templ: Template) =>
val x = tpnme.ANON_CLASS
val clsDef = ClassDef(Modifiers(Final), x, templ)
Block(clsDef, New(Ident(x), Nil))
case Assign(Apply(fn, args), rhs) =>
Apply(Select(fn, nme.update), args :+ rhs)
case If(cond, thenp, EmptyTree) =>
If(cond, thenp, unitLiteral)
case Match(EmptyTree, cases) =>
makeCaseClosure(cases)
case tree: MemberDef =>
memberDef(tree)
case SymbolLit(str) =>
New(ref(defn.SymbolClass.typeConstructor), (Literal(Constant(str)) :: Nil) :: Nil)
case InterpolatedString(id, strs, elems) =>
Apply(Select(Apply(Ident(nme.StringContext), strs), id), elems)
case Function(args, body) =>
if (mode == Mode.Type) // FunctionN[args: _*, body]
AppliedTypeTree(
ref(defn.FunctionClass(args.length).typeConstructor),
args :+ body)
else
makeClosure(args.asInstanceOf[List[ValDef]], body)
case InfixOp(l, op, r) =>
mode match {
case Mode.Expr => // l.op(r), or val x = r; l.op(x), plus handle named args specially
makeBinop(l, op, r)
case Mode.Pattern => // op(l, r)
Apply(Ident(op), l :: r :: Nil)
case Mode.Type => // op[l, r]
AppliedTypeTree(Ident(op), l :: r :: Nil)
}
case PostfixOp(t, op) =>
if (mode == Mode.Type && op == nme.raw.STAR)
AppliedTypeTree(ref(defn.RepeatedParamType), t)
else {
assert(mode == Mode.Expr)
if (op == nme.WILDCARD) tree // desugar later by eta expansion
else Select(t, op)
}
case PrefixOp(op, t) =>
if (mode == Mode.Type && op == nme.ARROWkw)
AppliedTypeTree(ref(defn.ByNameParamClass.typeConstructor), t)
else
Select(t, nme.UNARY_PREFIX ++ op)
case Parens(t) =>
t
case Tuple(ts) =>
def PairTypeTree(l: Tree, r: Tree) =
AppliedTypeTree(ref(defn.PairClass.typeConstructor), l :: r :: Nil)
if (mode == Mode.Type) ts.reduceRight(PairTypeTree)
else if (ts.isEmpty) unitLiteral
else ts.reduceRight(Pair(_, _))
case WhileDo(cond, body) =>
// { <label> def while$(): Unit = if (cond) { body; while$() } ; while$() }
val call = Apply(Ident(nme.WHILE_PREFIX), Nil)
val rhs = If(cond, Block(body, call), unitLiteral)
labelDefAndCall(nme.WHILE_PREFIX, rhs, call)
case DoWhile(body, cond) =>
// { label def doWhile$(): Unit = { body; if (cond) doWhile$() } ; doWhile$() }
val call = Apply(Ident(nme.DO_WHILE_PREFIX), Nil)
val rhs = Block(body, If(cond, call, unitLiteral))
labelDefAndCall(nme.DO_WHILE_PREFIX, rhs, call)
case ForDo(enums, body) =>
makeFor(nme.foreach, nme.foreach, enums, body) orElse tree
case ForYield(enums, body) =>
makeFor(nme.map, nme.flatMap, enums, body) orElse tree
case PatDef(mods, pats, tpt, rhs) =>
val pats1 = if (tpt.isEmpty) pats else pats map (Typed(_, tpt))
Thicket(pats1 map (makePatDef(mods, _, rhs)))
case _ =>
tree
}
tree1 match {
case tree1: NameTree => tree1.withName(tree1.name.encode)
case _ => tree1
}
}.withPos(tree.pos)
/** If tree is a variable pattern, return its name and type, otherwise return None.
*/
private object VarPattern {
def unapply(tree: Tree): Option[VarInfo] = tree match {
case id: Ident => Some(id, TypeTree())
case Typed(id: Ident, tpt) => Some((id, tpt))
case _ => None
}
}
/** Traverse pattern and collect all variable names with their types in buffer.
* Works for expanded as well as unexpanded patterns
*
*/
private object getVars extends TreeAccumulator[ListBuffer[VarInfo]] {
override def apply(buf: ListBuffer[VarInfo], tree: Tree): ListBuffer[VarInfo] = {
def seenName(name: Name) = buf exists (_._1.name == name)
def add(named: NameTree, t: Tree): ListBuffer[VarInfo] =
if (seenName(named.name)) buf else buf += ((named, t))
tree match {
case Bind(nme.WILDCARD, _) =>
foldOver(buf, tree)
case tree @ Bind(_, Typed(tree1, tpt)) if !mayBeTypePat(tpt) =>
apply(add(tree, tpt), tree1)
case tree @ Bind(_, tree1) =>
apply(add(tree, TypeTree()), tree1)
case Typed(id: Ident, t) if isVarPattern(id) =>
add(id, t)
case id: Ident if isVarPattern(id) =>
add(id, TypeTree())
case _ =>
foldOver(buf, tree)
}
}
}
}
