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/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package typechecker
import symtab.Flags._
import scala.reflect.internal.util.ListOfNil
/*
* @author Martin Odersky
* @version 1.0
*/
trait Unapplies extends ast.TreeDSL {
self: Analyzer =>
import global._
import definitions._
import CODE.{ CASE => _, _ }
import treeInfo.{ isRepeatedParamType, isByNameParamType }
private def unapplyParamName = nme.x_0
private def caseMods = Modifiers(SYNTHETIC | CASE)
// In the typeCompleter (templateSig) of a case class (resp its module),
// synthetic `copy` (reps `apply`, `unapply`) methods are added. To compute
// their signatures, the corresponding ClassDef is needed. During naming (in
// `enterClassDef`), the case class ClassDef is added as an attachment to the
// moduleClass symbol of the companion module.
class ClassForCaseCompanionAttachment(val caseClass: ClassDef)
/** Returns unapply or unapplySeq if available, without further checks.
*/
def directUnapplyMember(tp: Type): Symbol = (tp member nme.unapply) orElse (tp member nme.unapplySeq)
/** Filters out unapplies with multiple (non-implicit) parameter lists,
* as they cannot be used as extractors
*/
def unapplyMember(tp: Type): Symbol = directUnapplyMember(tp) filter (sym => !hasMultipleNonImplicitParamLists(sym))
object HasUnapply {
def unapply(tp: Type): Option[Symbol] = unapplyMember(tp).toOption
}
private def toIdent(x: DefTree) = Ident(x.name) setPos x.pos.focus
private def classType(cdef: ClassDef, tparams: List[TypeDef]): Tree = {
// SI-7033 Unattributed to avoid forcing `cdef.symbol.info`.
val tycon = Ident(cdef.symbol)
if (tparams.isEmpty) tycon else AppliedTypeTree(tycon, tparams map toIdent)
}
private def constrParamss(cdef: ClassDef): List[List[ValDef]] = {
val ClassDef(_, _, _, Template(_, _, body)) = resetAttrs(cdef.duplicate)
val DefDef(_, _, _, vparamss, _, _) = treeInfo firstConstructor body
vparamss
}
private def constrTparamsInvariant(cdef: ClassDef): List[TypeDef] = {
val ClassDef(_, _, tparams, _) = resetAttrs(cdef.duplicate)
val tparamsInvariant = tparams.map(tparam => copyTypeDef(tparam)(mods = tparam.mods &~ (COVARIANT | CONTRAVARIANT)))
tparamsInvariant
}
/** The return value of an unapply method of a case class C[Ts]
* @param param The name of the parameter of the unapply method, assumed to be of type C[Ts]
* @param caseclazz The case class C[Ts]
*/
private def caseClassUnapplyReturnValue(param: Name, caseclazz: ClassDef) = {
def caseFieldAccessorValue(selector: ValDef): Tree = {
// Selecting by name seems to be the most straight forward way here to
// avoid forcing the symbol of the case class in order to list the accessors.
def selectByName = Ident(param) DOT caseAccessorName(caseclazz.symbol, selector.name)
// But, that gives a misleading error message in neg/t1422.scala, where a case
// class has an illegal private[this] parameter. We can detect this by checking
// the modifiers on the param accessors.
// We just generate a call to that param accessor here, which gives us an inaccessible
// symbol error, as before.
def localAccessor = caseclazz.impl.body find {
case t @ ValOrDefDef(mods, selector.name, _, _) => mods.isPrivateLocal
case _ => false
}
localAccessor.fold(selectByName)(Ident(param) DOT _.symbol)
}
// Working with trees, rather than symbols, to avoid cycles like SI-5082
constrParamss(caseclazz).take(1).flatten match {
case Nil => TRUE
case xs => SOME(xs map caseFieldAccessorValue: _*)
}
}
/** The module corresponding to a case class; overrides toString to show the module's name
*/
def caseModuleDef(cdef: ClassDef): ModuleDef = {
val params = constrParamss(cdef)
def inheritFromFun = !cdef.mods.hasAbstractFlag && cdef.tparams.isEmpty && (params match {
case List(ps) if ps.length <= MaxFunctionArity => true
case _ => false
})
def createFun = {
def primaries = params.head map (_.tpt)
gen.scalaFunctionConstr(primaries, toIdent(cdef), abstractFun = true)
}
def parents = if (inheritFromFun) List(createFun) else Nil
def toString = DefDef(
Modifiers(OVERRIDE | FINAL | SYNTHETIC),
nme.toString_,
Nil,
ListOfNil,
TypeTree(),
Literal(Constant(cdef.name.decode)))
companionModuleDef(cdef, parents, List(toString))
}
def companionModuleDef(cdef: ClassDef, parents: List[Tree] = Nil, body: List[Tree] = Nil): ModuleDef = atPos(cdef.pos.focus) {
ModuleDef(
Modifiers(cdef.mods.flags & AccessFlags | SYNTHETIC, cdef.mods.privateWithin),
cdef.name.toTermName,
gen.mkTemplate(parents, noSelfType, NoMods, Nil, body, cdef.impl.pos.focus))
}
/** The apply method corresponding to a case class
*/
def factoryMeth(mods: Modifiers, name: TermName, cdef: ClassDef): DefDef = {
val tparams = constrTparamsInvariant(cdef)
val cparamss = constrParamss(cdef)
def classtpe = classType(cdef, tparams)
atPos(cdef.pos.focus)(
DefDef(mods, name, tparams, cparamss, classtpe,
New(classtpe, mmap(cparamss)(gen.paramToArg)))
)
}
/** The apply method corresponding to a case class
*/
def caseModuleApplyMeth(cdef: ClassDef): DefDef = factoryMeth(caseMods, nme.apply, cdef)
/** The unapply method corresponding to a case class
*/
def caseModuleUnapplyMeth(cdef: ClassDef): DefDef = {
val tparams = constrTparamsInvariant(cdef)
val method = constrParamss(cdef) match {
case xs :: _ if xs.nonEmpty && isRepeatedParamType(xs.last.tpt) => nme.unapplySeq
case _ => nme.unapply
}
val cparams = List(ValDef(Modifiers(PARAM | SYNTHETIC), unapplyParamName, classType(cdef, tparams), EmptyTree))
val resultType = if (!settings.isScala212) TypeTree() else { // fix for SI-6541 under -Xsource:2.12
def repeatedToSeq(tp: Tree) = tp match {
case AppliedTypeTree(Select(_, tpnme.REPEATED_PARAM_CLASS_NAME), tps) => AppliedTypeTree(gen.rootScalaDot(tpnme.Seq), tps)
case _ => tp
}
constrParamss(cdef) match {
case Nil | Nil :: _ =>
gen.rootScalaDot(tpnme.Boolean)
case params :: _ =>
val constrParamTypes = params.map(param => repeatedToSeq(param.tpt))
AppliedTypeTree(gen.rootScalaDot(tpnme.Option), List(treeBuilder.makeTupleType(constrParamTypes)))
}
}
val ifNull = if (constrParamss(cdef).head.isEmpty) FALSE else REF(NoneModule)
val body = nullSafe({ case Ident(x) => caseClassUnapplyReturnValue(x, cdef) }, ifNull)(Ident(unapplyParamName))
atPos(cdef.pos.focus)(
DefDef(caseMods, method, tparams, List(cparams), resultType, body)
)
}
/**
* Generates copy methods for case classes. Copy only has defaults on the first
* parameter list, as of SI-5009.
*
* The parameter types of the copy method need to be exactly the same as the parameter
* types of the primary constructor. Just copying the TypeTree is not enough: a type `C`
* might refer to something else *inside* the class (i.e. as parameter type of `copy`)
* than *outside* the class (i.e. in the class parameter list).
*
* One such example is t0054.scala:
* class A {
* case class B(x: C) extends A { def copy(x: C = x) = ... }
* class C {} ^ ^
* } (1) (2)
*
* The reference (1) to C is `A.this.C`. The reference (2) is `B.this.C` - not the same.
*
* This is fixed with a hack currently. `Unapplies.caseClassCopyMeth`, which creates the
* copy method, uses empty `TypeTree()` nodes for parameter types.
*
* In `Namers.enterDefDef`, the copy method gets a special type completer (`enterCopyMethod`).
* Before computing the body type of `copy`, the class parameter types are assigned the copy
* method parameters.
*
* This attachment class stores the copy method parameter ValDefs as an attachment in the
* ClassDef of the case class.
*/
def caseClassCopyMeth(cdef: ClassDef): Option[DefDef] = {
def isDisallowed(vd: ValDef) = isRepeatedParamType(vd.tpt) || isByNameParamType(vd.tpt)
val classParamss = constrParamss(cdef)
if (cdef.symbol.hasAbstractFlag || mexists(classParamss)(isDisallowed)) None
else {
def makeCopyParam(vd: ValDef, putDefault: Boolean) = {
val rhs = if (putDefault) toIdent(vd) else EmptyTree
val flags = PARAM | (vd.mods.flags & IMPLICIT) | (if (putDefault) DEFAULTPARAM else 0)
// empty tpt: see comment above
val tpt = atPos(vd.pos.focus)(TypeTree() setOriginal vd.tpt)
treeCopy.ValDef(vd, Modifiers(flags), vd.name, tpt, rhs)
}
val tparams = constrTparamsInvariant(cdef)
val paramss = classParamss match {
case Nil => Nil
case ps :: pss =>
ps.map(makeCopyParam(_, putDefault = true)) :: mmap(pss)(makeCopyParam(_, putDefault = false))
}
val classTpe = classType(cdef, tparams)
val argss = mmap(paramss)(toIdent)
val body: Tree = New(classTpe, argss)
val copyDefDef = atPos(cdef.pos.focus)(
DefDef(Modifiers(SYNTHETIC), nme.copy, tparams, paramss, TypeTree(), body)
)
Some(copyDefDef)
}
}
}
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