dotty.tools.dotc.ast.Desugar.scala Maven / Gradle / Ivy
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 Decorators._, transform.SymUtils._
import NameKinds.{UniqueName, EvidenceParamName, DefaultGetterName}
import language.higherKinds
import typer.FrontEnd
import collection.mutable.ListBuffer
import reporting.diagnostic.messages._
import reporting.trace
object desugar {
import untpd._
import DesugarEnums._
/** Info of a variable in a pattern: The named tree and its type */
private type VarInfo = (NameTree, Tree)
/** Names of methods that are added unconditionally to case classes */
def isDesugaredCaseClassMethodName(name: Name)(implicit ctx: Context): Boolean =
name == nme.copy || name.isSelectorName
// ----- DerivedTypeTrees -----------------------------------
class SetterParamTree extends DerivedTypeTree {
def derivedTree(sym: Symbol)(implicit ctx: Context) = tpd.TypeTree(sym.info.resultType)
}
class TypeRefTree extends DerivedTypeTree {
def derivedTree(sym: Symbol)(implicit ctx: Context) = tpd.TypeTree(sym.typeRef)
}
class TermRefTree extends DerivedTypeTree {
def derivedTree(sym: Symbol)(implicit ctx: Context) = tpd.ref(sym)
}
/** A type tree that computes its type from an existing parameter.
* @param suffix String difference between existing parameter (call it `P`) and parameter owning the
* DerivedTypeTree (call it `O`). We have: `O.name == P.name + suffix`.
*/
class DerivedFromParamTree(suffix: String) extends DerivedTypeTree {
/** Make sure that for all enclosing module classes their companion classes
* are completed. Reason: We need the constructor of such companion classes to
* be completed so that OriginalSymbol attachments are pushed to DerivedTypeTrees
* in apply/unapply methods.
*/
override def ensureCompletions(implicit ctx: Context) =
if (!(ctx.owner is Package))
if (ctx.owner.isClass) {
ctx.owner.ensureCompleted()
if (ctx.owner is ModuleClass)
ctx.owner.linkedClass.ensureCompleted()
}
else ensureCompletions(ctx.outer)
/** Return info of original symbol, where all references to siblings of the
* original symbol (i.e. sibling and original symbol have the same owner)
* are rewired to like-named* parameters or accessors in the scope enclosing
* the current scope. The current scope is the scope owned by the defined symbol
* itself, that's why we have to look one scope further out. If the resulting
* type is an alias type, dealias it. This is necessary because the
* accessor of a type parameter is a private type alias that cannot be accessed
* from subclasses.
*
* (*) like-named means:
*
* parameter name == reference name ++ suffix
*/
def derivedTree(sym: Symbol)(implicit ctx: Context) = {
val relocate = new TypeMap {
val originalOwner = sym.owner
def apply(tp: Type) = tp match {
case tp: NamedType if tp.symbol.exists && (tp.symbol.owner eq originalOwner) =>
val defctx = ctx.outersIterator.dropWhile(_.scope eq ctx.scope).next()
var local = defctx.denotNamed(tp.name ++ suffix).suchThat(_.isParamOrAccessor).symbol
if (local.exists) (defctx.owner.thisType select local).dealiasKeepAnnots
else {
def msg =
s"no matching symbol for ${tp.symbol.showLocated} in ${defctx.owner} / ${defctx.effectiveScope.toList}"
ErrorType(msg).assertingErrorsReported(msg)
}
case _ =>
mapOver(tp)
}
}
tpd.TypeTree(relocate(sym.info))
}
}
/** A type definition copied from `tdef` with a rhs typetree derived from it */
def derivedTypeParam(tdef: TypeDef, suffix: String = ""): TypeDef =
cpy.TypeDef(tdef)(
name = tdef.name ++ suffix,
rhs = new DerivedFromParamTree(suffix).withPos(tdef.rhs.pos).watching(tdef)
)
/** A derived type definition watching `sym` */
def derivedTypeParam(sym: TypeSymbol)(implicit ctx: Context): TypeDef =
TypeDef(sym.name, new DerivedFromParamTree("").watching(sym)).withFlags(TypeParam)
/** A value definition copied from `vdef` with a tpt typetree derived from it */
def derivedTermParam(vdef: ValDef) =
cpy.ValDef(vdef)(
tpt = new DerivedFromParamTree("") withPos vdef.tpt.pos watching vdef)
// ----- Desugar methods -------------------------------------------------
/** var x: Int = expr
* ==>
* def x: Int = expr
* def x_=($1: ): Unit = ()
*/
def valDef(vdef: ValDef)(implicit ctx: Context): Tree = {
val ValDef(name, tpt, rhs) = vdef
val mods = vdef.mods
val setterNeeded =
(mods is Mutable) && ctx.owner.isClass && (!(mods is PrivateLocal) || (ctx.owner is Trait))
if (setterNeeded) {
// TODO: copy of vdef as getter needed?
// val getter = ValDef(mods, name, tpt, rhs) withPos vdef.pos?
// right now vdef maps via expandedTree to a thicket which concerns itself.
// I don't see a problem with that but if there is one we can avoid it by making a copy here.
val setterParam = makeSyntheticParameter(tpt = (new SetterParamTree).watching(vdef))
// The rhs gets filled in later, when field is generated and getter has parameters (see Memoize miniphase)
val setterRhs = if (vdef.rhs.isEmpty) EmptyTree else unitLiteral
val setter = cpy.DefDef(vdef)(
name = name.setterName,
tparams = Nil,
vparamss = (setterParam :: Nil) :: Nil,
tpt = TypeTree(defn.UnitType),
rhs = setterRhs
).withMods((mods | Accessor) &~ CaseAccessor)
Thicket(vdef, setter)
}
else vdef
}
def makeImplicitParameters(tpts: List[Tree], forPrimaryConstructor: Boolean = false)(implicit ctx: Context) =
for (tpt <- tpts) yield {
val paramFlags: FlagSet = if (forPrimaryConstructor) PrivateLocalParamAccessor else Param
val epname = EvidenceParamName.fresh()
ValDef(epname, tpt, EmptyTree).withFlags(paramFlags | Implicit)
}
/** Expand context bounds to evidence params. E.g.,
*
* def f[T >: L <: H : B](params)
* ==>
* def f[T >: L <: H](params)(implicit evidence$0: B[T])
*
* Expand default arguments to default getters. E.g,
*
* def f[T: B](x: Int = 1)(y: String = x + "m") = ...
* ==>
* def f[T](x: Int)(y: String)(implicit evidence$0: B[T]) = ...
* def f$default$1[T] = 1
* def f$default$2[T](x: Int) = x + "m"
*/
private def defDef(meth: DefDef, isPrimaryConstructor: Boolean = false)(implicit ctx: Context): Tree = {
val DefDef(name, tparams, vparamss, tpt, rhs) = meth
val mods = meth.mods
val epbuf = new ListBuffer[ValDef]
def desugarContextBounds(rhs: Tree): Tree = rhs match {
case ContextBounds(tbounds, cxbounds) =>
epbuf ++= makeImplicitParameters(cxbounds, isPrimaryConstructor)
tbounds
case LambdaTypeTree(tparams, body) =>
cpy.LambdaTypeTree(rhs)(tparams, desugarContextBounds(body))
case _ =>
rhs
}
val tparams1 = tparams mapConserve { tparam =>
cpy.TypeDef(tparam)(rhs = desugarContextBounds(tparam.rhs))
}
val meth1 = addEvidenceParams(cpy.DefDef(meth)(tparams = tparams1), epbuf.toList)
/** The longest prefix of parameter lists in vparamss whose total length does not exceed `n` */
def takeUpTo(vparamss: List[List[ValDef]], n: Int): List[List[ValDef]] = vparamss match {
case vparams :: vparamss1 =>
val len = vparams.length
if (n >= len) vparams :: takeUpTo(vparamss1, n - len) else Nil
case _ =>
Nil
}
def normalizedVparamss = meth1.vparamss map (_ map (vparam =>
cpy.ValDef(vparam)(rhs = EmptyTree)))
def dropContextBound(tparam: TypeDef) = tparam.rhs match {
case ContextBounds(tbounds, _) => cpy.TypeDef(tparam)(rhs = tbounds)
case _ => tparam
}
def defaultGetters(vparamss: List[List[ValDef]], n: Int): List[DefDef] = vparamss match {
case (vparam :: vparams) :: vparamss1 =>
def defaultGetter: DefDef =
DefDef(
name = DefaultGetterName(meth.name, n),
tparams = meth.tparams.map(tparam => dropContextBound(toDefParam(tparam))),
vparamss = takeUpTo(normalizedVparamss.nestedMap(toDefParam), n),
tpt = TypeTree(),
rhs = vparam.rhs
)
.withMods(Modifiers(mods.flags & AccessFlags, mods.privateWithin))
.withFlags(Synthetic)
val rest = defaultGetters(vparams :: vparamss1, n + 1)
if (vparam.rhs.isEmpty) rest else defaultGetter :: rest
case Nil :: vparamss1 =>
defaultGetters(vparamss1, n)
case nil =>
Nil
}
val defGetters = defaultGetters(vparamss, 0)
if (defGetters.isEmpty) meth1
else {
val meth2 = cpy.DefDef(meth1)(vparamss = normalizedVparamss)
.withMods(meth1.mods | DefaultParameterized)
Thicket(meth2 :: defGetters)
}
}
// Add all evidence parameters in `params` as implicit parameters to `meth` */
private def addEvidenceParams(meth: DefDef, params: List[ValDef])(implicit ctx: Context): DefDef =
params match {
case Nil =>
meth
case evidenceParams =>
val vparamss1 = meth.vparamss.reverse match {
case (vparams @ (vparam :: _)) :: rvparamss if vparam.mods is Implicit =>
((evidenceParams ++ vparams) :: rvparamss).reverse
case _ =>
meth.vparamss :+ evidenceParams
}
cpy.DefDef(meth)(vparamss = vparamss1)
}
/** The implicit evidence parameters of `meth`, as generated by `desugar.defDef` */
private def evidenceParams(meth: DefDef)(implicit ctx: Context): List[ValDef] =
meth.vparamss.reverse match {
case (vparams @ (vparam :: _)) :: _ if vparam.mods is Implicit =>
vparams.dropWhile(!_.name.is(EvidenceParamName))
case _ =>
Nil
}
@sharable private val synthetic = Modifiers(Synthetic)
private def toDefParam(tparam: TypeDef): TypeDef =
tparam.withMods(tparam.rawMods & EmptyFlags | Param)
private def toDefParam(vparam: ValDef): ValDef =
vparam.withMods(vparam.rawMods & (Implicit | Erased) | Param)
/** The expansion of a class definition. See inline comments for what is involved */
def classDef(cdef: TypeDef)(implicit ctx: Context): Tree = {
val className = checkNotReservedName(cdef).asTypeName
val impl @ Template(constr0, parents, self, _) = cdef.rhs
val mods = cdef.mods
val companionMods = mods
.withFlags((mods.flags & AccessFlags).toCommonFlags)
.withMods(Nil)
var defaultGetters: List[Tree] = Nil
def decompose(ddef: Tree): DefDef = ddef match {
case meth: DefDef => meth
case Thicket((meth: DefDef) :: defaults) =>
defaultGetters = defaults
meth
}
val constr1 = decompose(defDef(constr0, isPrimaryConstructor = true))
// The original type and value parameters in the constructor already have the flags
// needed to be type members (i.e. param, and possibly also private and local unless
// prefixed by type or val). `tparams` and `vparamss` are the type parameters that
// go in `constr`, the constructor after desugaring.
/** Does `tree' look like a reference to AnyVal? Temporary test before we have inline classes */
def isAnyVal(tree: Tree): Boolean = tree match {
case Ident(tpnme.AnyVal) => true
case Select(qual, tpnme.AnyVal) => isScala(qual)
case _ => false
}
def isScala(tree: Tree): Boolean = tree match {
case Ident(nme.scala_) => true
case Select(Ident(nme.ROOTPKG), nme.scala_) => true
case _ => false
}
val isCaseClass = mods.is(Case) && !mods.is(Module)
val isCaseObject = mods.is(Case) && mods.is(Module)
val isImplicit = mods.is(Implicit)
val isEnum = mods.isEnumClass && !mods.is(Module)
def isEnumCase = mods.isEnumCase
val isValueClass = parents.nonEmpty && isAnyVal(parents.head)
// This is not watertight, but `extends AnyVal` will be replaced by `inline` later.
val originalTparams = constr1.tparams
val originalVparamss = constr1.vparamss
lazy val derivedEnumParams = enumClass.typeParams.map(derivedTypeParam)
val impliedTparams =
if (isEnumCase && originalTparams.isEmpty)
derivedEnumParams.map(tdef => tdef.withFlags(tdef.mods.flags | PrivateLocal))
else
originalTparams
val constrTparams = impliedTparams.map(toDefParam)
val constrVparamss =
if (originalVparamss.isEmpty) { // ensure parameter list is non-empty
if (isCaseClass && originalTparams.isEmpty)
ctx.error(CaseClassMissingParamList(cdef), cdef.namePos)
ListOfNil
}
else originalVparamss.nestedMap(toDefParam)
val constr = cpy.DefDef(constr1)(tparams = constrTparams, vparamss = constrVparamss)
val (normalizedBody, enumCases, enumCompanionRef) = {
// Add constructor type parameters and evidence implicit parameters
// to auxiliary constructors; set defaultGetters as a side effect.
def expandConstructor(tree: Tree) = tree match {
case ddef: DefDef if ddef.name.isConstructorName =>
decompose(
defDef(
addEvidenceParams(
cpy.DefDef(ddef)(tparams = constrTparams),
evidenceParams(constr1).map(toDefParam))))
case stat =>
stat
}
// The Identifiers defined by a case
def caseIds(tree: Tree) = tree match {
case tree: MemberDef => Ident(tree.name.toTermName) :: Nil
case PatDef(_, ids, _, _) => ids
}
val stats = impl.body.map(expandConstructor)
if (isEnum) {
val (enumCases, enumStats) = stats.partition(DesugarEnums.isEnumCase)
val enumCompanionRef = new TermRefTree()
val enumImport = Import(enumCompanionRef, enumCases.flatMap(caseIds))
(enumImport :: enumStats, enumCases, enumCompanionRef)
}
else (stats, Nil, EmptyTree)
}
def anyRef = ref(defn.AnyRefAlias.typeRef)
val derivedTparams = constrTparams.map(derivedTypeParam(_))
val derivedVparamss = constrVparamss.nestedMap(derivedTermParam(_))
val arity = constrVparamss.head.length
val classTycon: Tree = new TypeRefTree // watching is set at end of method
def appliedTypeTree(tycon: Tree, args: List[Tree]) =
(if (args.isEmpty) tycon else AppliedTypeTree(tycon, args))
.withPos(cdef.pos.startPos)
def isHK(tparam: Tree): Boolean = tparam match {
case TypeDef(_, LambdaTypeTree(tparams, body)) => true
case TypeDef(_, rhs: DerivedTypeTree) => isHK(rhs.watched)
case _ => false
}
def appliedRef(tycon: Tree, tparams: List[TypeDef] = constrTparams, widenHK: Boolean = false) = {
val targs = for (tparam <- tparams) yield {
val targ = refOfDef(tparam)
def fullyApplied(tparam: Tree): Tree = tparam match {
case TypeDef(_, LambdaTypeTree(tparams, body)) =>
AppliedTypeTree(targ, tparams.map(_ => TypeBoundsTree(EmptyTree, EmptyTree)))
case TypeDef(_, rhs: DerivedTypeTree) =>
fullyApplied(rhs.watched)
case _ =>
targ
}
if (widenHK) fullyApplied(tparam) else targ
}
appliedTypeTree(tycon, targs)
}
// a reference to the class type bound by `cdef`, with type parameters coming from the constructor
val classTypeRef = appliedRef(classTycon)
// a reference to `enumClass`, with type parameters coming from the case constructor
lazy val enumClassTypeRef =
if (enumClass.typeParams.isEmpty)
enumClassRef
else if (originalTparams.isEmpty)
appliedRef(enumClassRef)
else {
ctx.error(i"explicit extends clause needed because both enum case and enum class have type parameters"
, cdef.pos.startPos)
appliedTypeTree(enumClassRef, constrTparams map (_ => anyRef))
}
// new C[Ts](paramss)
lazy val creatorExpr = New(classTypeRef, constrVparamss nestedMap refOfDef)
// Methods to add to a case class C[..](p1: T1, ..., pN: Tn)(moreParams)
// def _1 = this.p1
// ...
// def _N = this.pN
// def copy(p1: T1 = p1: @uncheckedVariance, ...,
// pN: TN = pN: @uncheckedVariance)(moreParams) =
// new C[...](p1, ..., pN)(moreParams)
//
// Note: copy default parameters need @uncheckedVariance; see
// neg/t1843-variances.scala for a test case. The test would give
// two errors without @uncheckedVariance, one of them spurious.
val caseClassMeths = {
def syntheticProperty(name: TermName, rhs: Tree) =
DefDef(name, Nil, Nil, TypeTree(), rhs).withMods(synthetic)
def productElemMeths = {
val caseParams = constrVparamss.head.toArray
for (i <- 0 until arity if nme.selectorName(i) `ne` caseParams(i).name)
yield syntheticProperty(nme.selectorName(i), Select(This(EmptyTypeIdent), caseParams(i).name))
}
def enumTagMeths = if (isEnumCase) enumTagMeth(CaseKind.Class)._1 :: Nil else Nil
def copyMeths = {
def isRepeated(tree: Tree): Boolean = tree match {
case PostfixOp(_, Ident(tpnme.raw.STAR)) => true
case ByNameTypeTree(tree1) => isRepeated(tree1)
case _ => false
}
val hasRepeatedParam = constrVparamss.exists(_.exists {
case ValDef(_, tpt, _) => isRepeated(tpt)
})
if (mods.is(Abstract) || hasRepeatedParam) Nil // cannot have default arguments for repeated parameters, hence copy method is not issued
else {
def copyDefault(vparam: ValDef) =
makeAnnotated("scala.annotation.unchecked.uncheckedVariance", refOfDef(vparam))
val copyFirstParams = derivedVparamss.head.map(vparam =>
cpy.ValDef(vparam)(rhs = copyDefault(vparam)))
val copyRestParamss = derivedVparamss.tail.nestedMap(vparam =>
cpy.ValDef(vparam)(rhs = EmptyTree))
DefDef(nme.copy, derivedTparams, copyFirstParams :: copyRestParamss, TypeTree(), creatorExpr)
.withMods(synthetic) :: Nil
}
}
if (isCaseClass)
copyMeths ::: enumTagMeths ::: productElemMeths.toList
else Nil
}
// Case classes and case objects get Product parents
// Enum cases get an inferred parent if no parents are given
var parents1 = parents
if (isEnumCase && parents.isEmpty)
parents1 = enumClassTypeRef :: Nil
if (isCaseClass | isCaseObject)
parents1 = parents1 :+ scalaDot(str.Product.toTypeName)
if (isEnum)
parents1 = parents1 :+ ref(defn.EnumType)
// The Eq instance for an Enum class. For an enum class
//
// enum class C[T1, ..., Tn]
//
// we generate:
//
// implicit def eqInstance[T1$1, ..., Tn$1, T1$2, ..., Tn$2](implicit
// ev1: Eq[T1$1, T1$2], ..., evn: Eq[Tn$1, Tn$2]])
// : Eq[C[T1$, ..., Tn$1], C[T1$2, ..., Tn$2]] = Eq
//
// Higher-kinded type arguments `Ti` are omitted as evidence parameters.
//
// FIXME: This is too simplistic. Instead of just generating evidence arguments
// for every first-kinded type parameter, we should look instead at the
// actual types occurring in cases and derive parameters from these. E.g. in
//
// enum HK[F[_]] {
// case C1(x: F[Int]) extends HK[F[Int]]
// case C2(y: F[String]) extends HL[F[Int]]
//
// we would need evidence parameters for `F[Int]` and `F[String]`
// We should generate Eq instances with the techniques
// of typeclass derivation once that is available.
def eqInstance = {
val leftParams = constrTparams.map(derivedTypeParam(_, "$1"))
val rightParams = constrTparams.map(derivedTypeParam(_, "$2"))
val subInstances =
for ((param1, param2) <- leftParams `zip` rightParams if !isHK(param1))
yield appliedRef(ref(defn.EqType), List(param1, param2), widenHK = true)
DefDef(
name = nme.eqInstance,
tparams = leftParams ++ rightParams,
vparamss = if (subInstances.isEmpty) Nil else List(makeImplicitParameters(subInstances)),
tpt = appliedTypeTree(ref(defn.EqType),
appliedRef(classTycon, leftParams) :: appliedRef(classTycon, rightParams) :: Nil),
rhs = ref(defn.EqModule.termRef)).withFlags(Synthetic | Implicit)
}
def eqInstances = if (isEnum) eqInstance :: Nil else Nil
// The thicket which is the desugared version of the companion object
// synthetic object C extends parentTpt { defs }
def companionDefs(parentTpt: Tree, defs: List[Tree]) =
moduleDef(
ModuleDef(
className.toTermName, Template(emptyConstructor, parentTpt :: Nil, EmptyValDef, defs))
.withMods(companionMods | Synthetic))
.withPos(cdef.pos).toList
val companionMembers = defaultGetters ::: eqInstances ::: enumCases
// The companion object definitions, if a companion is needed, Nil otherwise.
// companion definitions include:
// 1. If class is a case class case class C[Ts](p1: T1, ..., pN: TN)(moreParams):
// def apply[Ts](p1: T1, ..., pN: TN)(moreParams) = new C[Ts](p1, ..., pN)(moreParams) (unless C is abstract)
// def unapply[Ts]($1: C[Ts]) = $1
// 2. The default getters of the constructor
// The parent of the companion object of a non-parameterized case class
// (T11, ..., T1N) => ... => (TM1, ..., TMN) => C
// For all other classes, the parent is AnyRef.
val companions =
if (isCaseClass) {
// The return type of the `apply` method, and an (empty or singleton) list
// of widening coercions
val (applyResultTpt, widenDefs) =
if (!isEnumCase)
(TypeTree(), Nil)
else if (parents.isEmpty || enumClass.typeParams.isEmpty)
(enumClassTypeRef, Nil)
else
enumApplyResult(cdef, parents, derivedEnumParams, appliedRef(enumClassRef, derivedEnumParams))
val companionParent =
if (constrTparams.nonEmpty ||
constrVparamss.length > 1 ||
mods.is(Abstract) ||
constr.mods.is(Private)) anyRef
else
// todo: also use anyRef if constructor has a dependent method type (or rule that out)!
(constrVparamss :\ (if (isEnumCase) applyResultTpt else classTypeRef)) (
(vparams, restpe) => Function(vparams map (_.tpt), restpe))
def widenedCreatorExpr =
(creatorExpr /: widenDefs)((rhs, meth) => Apply(Ident(meth.name), rhs :: Nil))
val applyMeths =
if (mods is Abstract) Nil
else
DefDef(nme.apply, derivedTparams, derivedVparamss, applyResultTpt, widenedCreatorExpr)
.withFlags(Synthetic | (constr1.mods.flags & DefaultParameterized)) :: widenDefs
val unapplyMeth = {
val unapplyParam = makeSyntheticParameter(tpt = classTypeRef)
val unapplyRHS = if (arity == 0) Literal(Constant(true)) else Ident(unapplyParam.name)
DefDef(nme.unapply, derivedTparams, (unapplyParam :: Nil) :: Nil, TypeTree(), unapplyRHS)
.withMods(synthetic)
}
companionDefs(companionParent, applyMeths ::: unapplyMeth :: companionMembers)
}
else if (companionMembers.nonEmpty)
companionDefs(anyRef, companionMembers)
else if (isValueClass) {
constr0.vparamss match {
case (_ :: Nil) :: _ => companionDefs(anyRef, Nil)
case _ => Nil // error will be emitted in typer
}
}
else Nil
enumCompanionRef match {
case ref: TermRefTree => // have the enum import watch the companion object
val (modVal: ValDef) :: _ = companions
ref.watching(modVal)
case _ =>
}
// For an implicit class C[Ts](p11: T11, ..., p1N: T1N) ... (pM1: TM1, .., pMN: TMN), the method
// synthetic implicit C[Ts](p11: T11, ..., p1N: T1N) ... (pM1: TM1, ..., pMN: TMN): C[Ts] =
// new C[Ts](p11, ..., p1N) ... (pM1, ..., pMN) =
val implicitWrappers =
if (!isImplicit)
Nil
else if (ctx.owner is Package) {
ctx.error(TopLevelImplicitClass(cdef), cdef.pos)
Nil
}
else if (isCaseClass) {
ctx.error(ImplicitCaseClass(cdef), cdef.pos)
Nil
}
else if (arity != 1) {
ctx.error(ImplicitClassPrimaryConstructorArity(), cdef.pos)
Nil
}
else
// implicit wrapper is typechecked in same scope as constructor, so
// we can reuse the constructor parameters; no derived params are needed.
DefDef(className.toTermName, constrTparams, constrVparamss, classTypeRef, creatorExpr)
.withMods(companionMods | Synthetic | Implicit)
.withPos(cdef.pos) :: Nil
val self1 = {
val selfType = if (self.tpt.isEmpty) classTypeRef else self.tpt
if (self.isEmpty) self
else cpy.ValDef(self)(tpt = selfType).withMods(self.mods | SelfName)
}
val cdef1 = addEnumFlags {
val originalTparamsIt = impliedTparams.toIterator
val originalVparamsIt = originalVparamss.toIterator.flatten
val tparamAccessors = derivedTparams.map(_.withMods(originalTparamsIt.next().mods))
val caseAccessor = if (isCaseClass) CaseAccessor else EmptyFlags
val vparamAccessors = derivedVparamss match {
case first :: rest =>
first.map(_.withMods(originalVparamsIt.next().mods | caseAccessor)) ++
rest.flatten.map(_.withMods(originalVparamsIt.next().mods))
case _ =>
Nil
}
cpy.TypeDef(cdef)(
name = className,
rhs = cpy.Template(impl)(constr, parents1, self1,
tparamAccessors ::: vparamAccessors ::: normalizedBody ::: caseClassMeths))
}
// install the watch on classTycon
classTycon match {
case tycon: DerivedTypeTree => tycon.watching(cdef1)
case _ =>
}
flatTree(cdef1 :: companions ::: implicitWrappers)
}
val AccessOrSynthetic = AccessFlags | Synthetic
/** Expand
*
* object name extends parents { self => body }
*
* to:
* val name: name$ = New(name$)
* final class name$ extends parents { self: name.type => body }
*/
def moduleDef(mdef: ModuleDef)(implicit ctx: Context): Tree = {
val moduleName = checkNotReservedName(mdef).asTermName
val impl = mdef.impl
val mods = mdef.mods
def isEnumCase = mods.isEnumCase
if (mods is Package)
PackageDef(Ident(moduleName), cpy.ModuleDef(mdef)(nme.PACKAGE, impl).withMods(mods &~ Package) :: Nil)
else if (isEnumCase)
expandEnumModule(moduleName, impl, mods, mdef.pos)
else {
val clsName = moduleName.moduleClassName
val clsRef = Ident(clsName)
val modul = ValDef(moduleName, clsRef, New(clsRef, Nil))
.withMods(mods.toTermFlags & RetainedModuleValFlags | ModuleValCreationFlags)
.withPos(mdef.pos.startPos)
val ValDef(selfName, selfTpt, _) = impl.self
val selfMods = impl.self.mods
if (!selfTpt.isEmpty) ctx.error(ObjectMayNotHaveSelfType(mdef), impl.self.pos)
val clsSelf = ValDef(selfName, SingletonTypeTree(Ident(moduleName)), impl.self.rhs)
.withMods(selfMods)
.withPos(impl.self.pos orElse impl.pos.startPos)
val clsTmpl = cpy.Template(impl)(self = clsSelf, body = impl.body)
val cls = TypeDef(clsName, clsTmpl)
.withMods(mods.toTypeFlags & RetainedModuleClassFlags | ModuleClassCreationFlags)
Thicket(modul, classDef(cls).withPos(mdef.pos))
}
}
/** The name of `mdef`, after checking that it does not redefine a Scala core class.
* If it does redefine, issue an error and return a mangled name instead of the original one.
*/
def checkNotReservedName(mdef: MemberDef)(implicit ctx: Context): Name = {
val name = mdef.name
if (ctx.owner == defn.ScalaPackageClass && defn.reservedScalaClassNames.contains(name.toTypeName)) {
def kind = if (name.isTypeName) "class" else "object"
ctx.error(em"illegal redefinition of standard $kind $name", mdef.pos)
name.errorName
}
else name
}
/** val p1, ..., pN: T = E
* ==>
* makePatDef[[val p1: T1 = E]]; ...; makePatDef[[val pN: TN = E]]
*
* case e1, ..., eN
* ==>
* expandSimpleEnumCase([case e1]); ...; expandSimpleEnumCase([case eN])
*/
def patDef(pdef: PatDef)(implicit ctx: Context): Tree = flatTree {
val PatDef(mods, pats, tpt, rhs) = pdef
if (mods.isEnumCase)
pats map {
case id: Ident =>
expandSimpleEnumCase(id.name.asTermName, mods,
Position(pdef.pos.start, id.pos.end, id.pos.start))
}
else {
val pats1 = if (tpt.isEmpty) pats else pats map (Typed(_, tpt))
pats1 map (makePatDef(pdef, mods, _, rhs))
}
}
/** If `pat` is a variable pattern,
*
* val/var/lazy val p = e
*
* Otherwise, in case there is exactly one variable x_1 in pattern
* val/var/lazy val p = e ==> val/var/lazy val x_1 = (e: @unchecked) match (case p => (x_1))
*
* in case there are zero or more than one variables in pattern
* val/var/lazy p = e ==> private[this] synthetic [lazy] val t$ = (e: @unchecked) match (case p => (x_1, ..., x_N))
* val/var/def x_1 = t$._1
* ...
* val/var/def x_N = t$._N
* If the original pattern variable carries a type annotation, so does the corresponding
* ValDef or DefDef.
*/
def makePatDef(original: Tree, mods: Modifiers, pat: Tree, rhs: Tree)(implicit ctx: Context): Tree = pat match {
case IdPattern(named, tpt) =>
derivedValDef(original, named, tpt, rhs, mods)
case _ =>
val rhsUnchecked = makeAnnotated("scala.unchecked", rhs)
val vars = getVariables(pat)
val isMatchingTuple: Tree => Boolean = {
case Tuple(es) => es.length == vars.length
case _ => false
}
val ids = for ((named, _) <- vars) yield Ident(named.name)
val caseDef = CaseDef(pat, EmptyTree, makeTuple(ids))
val matchExpr =
if (forallResults(rhs, isMatchingTuple)) rhs
else Match(rhsUnchecked, caseDef :: Nil)
vars match {
case Nil =>
matchExpr
case (named, tpt) :: Nil =>
derivedValDef(original, named, tpt, matchExpr, mods)
case _ =>
val tmpName = UniqueName.fresh()
val patMods =
mods & Lazy | Synthetic | (if (ctx.owner.isClass) PrivateLocal else EmptyFlags)
val firstDef =
ValDef(tmpName, TypeTree(), matchExpr)
.withPos(pat.pos.union(rhs.pos)).withMods(patMods)
def selector(n: Int) = Select(Ident(tmpName), nme.selectorName(n))
val restDefs =
for (((named, tpt), n) <- vars.zipWithIndex)
yield
if (mods is Lazy) derivedDefDef(original, named, tpt, selector(n), mods &~ Lazy)
else derivedValDef(original, named, tpt, selector(n), mods)
flatTree(firstDef :: restDefs)
}
}
/** Expand variable identifier x to x @ _ */
def patternVar(tree: Tree)(implicit ctx: Context) = {
val Ident(name) = tree
Bind(name, Ident(nme.WILDCARD)).withPos(tree.pos)
}
def defTree(tree: Tree)(implicit ctx: Context): Tree = tree match {
case tree: ValDef => valDef(tree)
case tree: TypeDef => if (tree.isClassDef) classDef(tree) else tree
case tree: DefDef =>
if (tree.name.isConstructorName) tree // was already handled by enclosing classDef
else defDef(tree)
case tree: ModuleDef => moduleDef(tree)
case tree: PatDef => patDef(tree)
}
/** { stats; }
* ==>
* { stats; () }
*/
def block(tree: Block)(implicit ctx: Context): Block = tree.expr match {
case EmptyTree =>
cpy.Block(tree)(tree.stats,
unitLiteral withPos (if (tree.stats.isEmpty) tree.pos else tree.pos.endPos))
case _ =>
tree
}
/** Translate infix operation expression
*
* l op r ==> l.op(r) if op is left-associative
* ==> r.op(l) if op is right-associative
*/
def binop(left: Tree, op: Ident, right: Tree)(implicit ctx: Context): Apply = {
def assignToNamedArg(arg: Tree) = arg match {
case Assign(Ident(name), rhs) => cpy.NamedArg(arg)(name, rhs)
case _ => arg
}
def makeOp(fn: Tree, arg: Tree, selectPos: Position) = {
val args: List[Tree] = arg match {
case Parens(arg) => assignToNamedArg(arg) :: Nil
case Tuple(args) => args.mapConserve(assignToNamedArg)
case _ => arg :: Nil
}
Apply(Select(fn, op.name).withPos(selectPos), args)
}
if (isLeftAssoc(op.name))
makeOp(left, right, Position(left.pos.start, op.pos.end, op.pos.start))
else
makeOp(right, left, Position(op.pos.start, right.pos.end))
}
/** Make closure corresponding to function.
* params => body
* ==>
* def $anonfun(params) = body
* Closure($anonfun)
*/
def makeClosure(params: List[ValDef], body: Tree, tpt: Tree = TypeTree(), isImplicit: Boolean)(implicit ctx: Context) =
Block(
DefDef(nme.ANON_FUN, Nil, params :: Nil, tpt, body).withMods(synthetic | Artifact),
Closure(Nil, Ident(nme.ANON_FUN), if (isImplicit) ImplicitEmptyTree else EmptyTree))
/** If `nparams` == 1, expand partial function
*
* { cases }
* ==>
* x$1 => (x$1 @unchecked) match { cases }
*
* If `nparams` != 1, expand instead to
*
* (x$1, ..., x$n) => (x$0, ..., x${n-1} @unchecked) match { cases }
*/
def makeCaseLambda(cases: List[CaseDef], nparams: Int = 1, unchecked: Boolean = true)(implicit ctx: Context) = {
val params = (1 to nparams).toList.map(makeSyntheticParameter(_))
val selector = makeTuple(params.map(p => Ident(p.name)))
if (unchecked)
Function(params, Match(Annotated(selector, New(ref(defn.UncheckedAnnotType))), cases))
else
Function(params, Match(selector, cases))
}
/** Map n-ary function `(p1, ..., pn) => body` where n != 1 to unary function as follows:
*
* x$1 => {
* def p1 = x$1._1
* ...
* def pn = x$1._n
* body
* }
*/
def makeTupledFunction(params: List[ValDef], body: Tree)(implicit ctx: Context): Tree = {
val param = makeSyntheticParameter()
def selector(n: Int) = Select(refOfDef(param), nme.selectorName(n))
val vdefs =
params.zipWithIndex.map{
case (param, idx) =>
DefDef(param.name, Nil, Nil, TypeTree(), selector(idx)).withPos(param.pos)
}
Function(param :: Nil, Block(vdefs, body))
}
def makeImplicitFunction(formals: List[Type], body: Tree)(implicit ctx: Context): Tree = {
val params = makeImplicitParameters(formals.map(TypeTree))
new FunctionWithMods(params, body, Modifiers(Implicit))
}
/** Add annotation to tree:
* tree @fullName
*
* The annotation is usually represented as a TypeTree referring to the class
* with the given name `fullName`. However, if the annotation matches a file name
* that is still to be entered, the annotation is represented as a cascade of `Selects`
* following `fullName`. This is necessary so that we avoid reading an annotation from
* the classpath that is also compiled from source.
*/
def makeAnnotated(fullName: String, tree: Tree)(implicit ctx: Context) = {
val parts = fullName.split('.')
val ttree = ctx.typerPhase match {
case phase: FrontEnd if phase.stillToBeEntered(parts.last) =>
val prefix =
((Ident(nme.ROOTPKG): Tree) /: parts.init)((qual, name) =>
Select(qual, name.toTermName))
Select(prefix, parts.last.toTypeName)
case _ =>
TypeTree(ctx.requiredClass(fullName).typeRef)
}
Annotated(tree, untpd.New(ttree, Nil))
}
private def derivedValDef(original: Tree, named: NameTree, tpt: Tree, rhs: Tree, mods: Modifiers)(implicit ctx: Context) = {
val vdef = ValDef(named.name.asTermName, tpt, rhs)
.withMods(mods)
.withPos(original.pos.withPoint(named.pos.start))
val mayNeedSetter = valDef(vdef)
mayNeedSetter
}
private def derivedDefDef(original: Tree, named: NameTree, tpt: Tree, rhs: Tree, mods: Modifiers) =
DefDef(named.name.asTermName, Nil, Nil, tpt, rhs)
.withMods(mods)
.withPos(original.pos.withPoint(named.pos.start))
/** Main desugaring method */
def apply(tree: Tree)(implicit ctx: Context): Tree = {
/** { label def lname(): Unit = rhs; call }
*/
def labelDefAndCall(lname: TermName, rhs: Tree, call: Tree) = {
val ldef = DefDef(lname, Nil, ListOfNil, TypeTree(defn.UnitType), rhs).withFlags(Label | Synthetic)
Block(ldef, call)
}
/** Create tree for for-comprehension `` or
* `` 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 = trace(i"make for ${ForYield(enums, body)}", show = true) {
/** 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 IdPattern(named, tpt) =>
Function(derivedValDef(pat, named, tpt, EmptyTree, Modifiers(Param)) :: Nil, body)
case _ =>
makeCaseLambda(CaseDef(pat, EmptyTree, body) :: Nil)
}
/** If `pat` is not an Identifier, a Typed(Ident, _), or a Bind, wrap
* it in a Bind with a fresh name. Return the transformed pattern, and the identifier
* that refers to the bound variable for the pattern.
*/
def makeIdPat(pat: Tree): (Tree, Ident) = pat match {
case Bind(name, _) => (pat, Ident(name))
case id: Ident if isVarPattern(id) && id.name != nme.WILDCARD => (id, id)
case Typed(id: Ident, _) if isVarPattern(id) && id.name != nme.WILDCARD => (pat, id)
case _ =>
val name = UniqueName.fresh()
(Bind(name, pat), Ident(name))
}
/** Make a pattern filter:
* rhs.withFilter { case pat => true case _ => false }
*
* On handling irrefutable patterns:
* The idea is to wait until the pattern matcher sees a call
*
* xs withFilter { cases }
*
* where cases can be proven to be refutable i.e. cases would be
* equivalent to { case _ => true }
*
* In that case, compile to
*
* xs withFilter alwaysTrue
*
* where `alwaysTrue` is a predefined function value:
*
* val alwaysTrue: Any => Boolean = true
*
* In the libraries operations can take advantage of alwaysTrue to shortcircuit the
* withFilter call.
*
* def withFilter(f: Elem => Boolean) =
* if (f eq alwaysTrue) this // or rather identity filter monadic applied to this
* else real withFilter
*/
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.withFilter), makeCaseLambda(cases))
}
/** Is pattern `pat` irrefutable when matched against `rhs`?
* We only can do a simple syntactic check here; a more refined check
* is done later in the pattern matcher (see discussion in @makePatFilter).
*/
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, rhs1)
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)
}
}
def isIrrefutableGenFrom(gen: GenFrom): Boolean =
gen.isInstanceOf[IrrefutableGenFrom] ||
IdPattern.unapply(gen.pat).isDefined ||
isIrrefutable(gen.pat, gen.expr)
/** rhs.name with a pattern filter on rhs unless `pat` is irrefutable when
* matched against `rhs`.
*/
def rhsSelect(gen: GenFrom, name: TermName) = {
val rhs = if (isIrrefutableGenFrom(gen)) gen.expr else makePatFilter(gen.expr, gen.pat)
Select(rhs, name)
}
enums match {
case (gen: GenFrom) :: Nil =>
Apply(rhsSelect(gen, mapName), makeLambda(gen.pat, body))
case (gen: GenFrom) :: (rest @ (GenFrom(_, _) :: _)) =>
val cont = makeFor(mapName, flatMapName, rest, body)
Apply(rhsSelect(gen, flatMapName), makeLambda(gen.pat, cont))
case (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 (defpat0, id0) = makeIdPat(pat)
val (defpats, ids) = (pats map makeIdPat).unzip
val pdefs = (valeqs, defpats, rhss).zipped.map(makePatDef(_, Modifiers(), _, _))
val rhs1 = makeFor(nme.map, nme.flatMap, GenFrom(defpat0, rhs) :: Nil, Block(pdefs, makeTuple(id0 :: ids)))
val allpats = pat :: pats
val vfrom1 = new IrrefutableGenFrom(makeTuple(allpats), rhs1)
makeFor(mapName, flatMapName, vfrom1 :: rest1, body)
case (gen: GenFrom) :: test :: rest =>
val filtered = Apply(rhsSelect(gen, nme.withFilter), makeLambda(gen.pat, test))
val genFrom =
if (isIrrefutableGenFrom(gen)) new IrrefutableGenFrom(gen.pat, filtered)
else GenFrom(gen.pat, filtered)
makeFor(mapName, flatMapName, genFrom :: rest, body)
case _ =>
EmptyTree //may happen for erroneous input
}
}
// begin desugar
// Special case for `Parens` desugaring: unlike all the desugarings below,
// its output is not a new tree but an existing one whose position should
// be preserved, so we shouldn't call `withPos` on it.
tree match {
case Parens(t) =>
return t
case _ =>
}
val desugared = tree match {
case SymbolLit(str) =>
Literal(Constant(scala.Symbol(str)))
case Quote(expr) =>
if (expr.isType)
TypeApply(ref(defn.QuotedType_applyR), List(expr))
else
Apply(ref(defn.QuotedExpr_applyR), expr)
case InterpolatedString(id, segments) =>
val strs = segments map {
case ts: Thicket => ts.trees.head
case t => t
}
val elems = segments flatMap {
case ts: Thicket => ts.trees.tail
case t => Nil
} map {
case Block(Nil, expr) => expr // important for interpolated string as patterns, see i1773.scala
case t => t
}
// This is a deliberate departure from scalac, where StringContext is not rooted (See #4732)
Apply(Select(Apply(scalaDot(nme.StringContext), strs), id), elems)
case InfixOp(l, op, r) =>
if (ctx.mode is Mode.Type)
AppliedTypeTree(op, l :: r :: Nil) // op[l, r]
else {
assert(ctx.mode is Mode.Pattern) // expressions are handled separately by `binop`
Apply(op, l :: r :: Nil) // op(l, r)
}
case PostfixOp(t, op) =>
if ((ctx.mode is Mode.Type) && !op.isBackquoted && op.name == tpnme.raw.STAR) {
val seqType = if (ctx.compilationUnit.isJava) defn.ArrayType else defn.SeqType
Annotated(
AppliedTypeTree(ref(seqType), t),
New(ref(defn.RepeatedAnnotType), Nil :: Nil))
} else {
assert(ctx.mode.isExpr || ctx.reporter.hasErrors || ctx.mode.is(Mode.Interactive), ctx.mode)
Select(t, op.name)
}
case PrefixOp(op, t) =>
val nspace = if (ctx.mode.is(Mode.Type)) tpnme else nme
Select(t, nspace.UNARY_PREFIX ++ op.name)
case Tuple(ts) =>
val arity = ts.length
def tupleTypeRef = defn.TupleType(arity)
if (arity > Definitions.MaxTupleArity) {
ctx.error(TupleTooLong(ts), tree.pos)
unitLiteral
} else if (arity == 1) ts.head
else if (ctx.mode is Mode.Type) AppliedTypeTree(ref(tupleTypeRef), ts)
else if (arity == 0) unitLiteral
else Apply(ref(tupleTypeRef.classSymbol.companionModule.termRef), ts)
case WhileDo(cond, body) =>
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