/* NSC -- new Scala compiler
* Copyright 2005-2010 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package transform
import symtab._
import Flags._
import scala.collection.{ mutable, immutable }
import scala.collection.mutable.ListBuffer
abstract class Mixin extends InfoTransform with ast.TreeDSL {
import global._
import definitions._
import CODE._
/** The name of the phase: */
val phaseName: String = "mixin"
/** The phase might set the following new flags: */
override def phaseNewFlags: Long = lateMODULE | notABSTRACT
/** This map contains a binding (class -> info) if
* the class with this info at phase mixinPhase has been treated for mixin composition
*/
private val treatedClassInfos = collection.mutable.Map[Symbol, Type]()
// --------- helper functions -----------------------------------------------
/** A member of a trait is implemented statically if its implementation after the
* mixin transform is in the static implementation module. To be statically
* implemented, a member must be a method that belonged to the trait's implementation class
* before (e.g. it is not abstract). Not statically implemented are
* - non-private modules: these are implemented directly in the mixin composition class
* (private modules, on the other hand, are implemented statically, but their
* module variable is not. all such private modules are lifted, because
* non-lifted private modules have been eliminated in ExplicitOuter)
* - field accessors and superaccessors, except for lazy value accessors which become initializer
* methods in the impl class (because they can have arbitrary initializers)
*/
private def isImplementedStatically(sym: Symbol) =
sym.owner.isImplClass && sym.isMethod &&
(!sym.isModule || sym.hasFlag(PRIVATE | LIFTED)) &&
(!(sym hasFlag (ACCESSOR | SUPERACCESSOR)) || sym.hasFlag(LAZY))
/** A member of a trait is static only if it belongs only to the
* implementation class, not the interface, and it is implemented
* statically.
*/
private def isStaticOnly(sym: Symbol) =
isImplementedStatically(sym) && sym.isImplOnly
/** A member of a trait is forwarded if it is implemented statically and it
* is also visible in the trait's interface. In that case, a forwarder to
* the member's static implementation will be added to the class that
* inherits the trait.
*/
private def isForwarded(sym: Symbol) =
isImplementedStatically(sym) && !sym.isImplOnly
/** Maps the type of an implementation class to its interface;
* maps all other types to themselves.
*/
private def toInterface(tp: Type): Type =
atPhase(currentRun.mixinPhase)(tp.typeSymbol.toInterface).tpe
/** Maps all parts of this type that refer to implementation classes to
* their corresponding interfaces.
*/
private val toInterfaceMap = new TypeMap {
def apply(tp: Type): Type = mapOver( tp match {
case TypeRef(pre, sym, args) if (sym.isImplClass) =>
typeRef(pre, atPhase(currentRun.mixinPhase)(sym.toInterface), args)
case _ => tp
})
}
/** The implementation class corresponding to a currently compiled interface.
* todo: try to use Symbol.implClass instead?
*/
private def implClass(iface: Symbol): Symbol = {
val impl = iface.implClass
if (impl != NoSymbol) impl else erasure.implClass(iface)
}
/** Returns the symbol that is accessed by a super-accessor in a mixin composition.
*
* @param base The class in which everything is mixed together
* @param member The symbol statically referred to by the superaccessor in the trait
* @param mixinClass The mixin class that produced the superaccessor
*/
private def rebindSuper(base: Symbol, member: Symbol, mixinClass: Symbol): Symbol =
atPhase(currentRun.picklerPhase.next) {
var bcs = base.info.baseClasses.dropWhile(mixinClass !=).tail
var sym: Symbol = NoSymbol
if (settings.debug.value)
log("starting rebindsuper " + base + " " + member + ":" + member.tpe +
" " + mixinClass + " " + base.info.baseClasses + "/" + bcs)
while (!bcs.isEmpty && sym == NoSymbol) {
if (settings.debug.value) {
val other = bcs.head.info.nonPrivateDecl(member.name);
log("rebindsuper " + bcs.head + " " + other + " " + other.tpe +
" " + other.isDeferred)
}
sym = member.matchingSymbol(bcs.head, base.thisType).suchThat(sym => !sym.hasFlag(DEFERRED | BRIDGE))
bcs = bcs.tail
}
assert(sym != NoSymbol, member)
sym
}
// --------- type transformation -----------------------------------------------
def isConcreteAccessor(member: Symbol) =
(member hasFlag ACCESSOR) &&
(!(member hasFlag DEFERRED) || (member hasFlag lateDEFERRED))
/** Is member overridden (either directly or via a bridge) in base class sequence `bcs'? */
def isOverriddenAccessor(member: Symbol, bcs: List[Symbol]): Boolean = atPhase(ownPhase) {
def hasOverridingAccessor(clazz: Symbol) = {
clazz.info.nonPrivateDecl(member.name).alternatives.exists(
sym =>
isConcreteAccessor(sym) &&
!sym.hasFlag(MIXEDIN) &&
matchesType(sym.tpe, member.tpe, true))
}
bcs.head != member.owner &&
(hasOverridingAccessor(bcs.head) || isOverriddenAccessor(member, bcs.tail))
}
/** Add given member to given class, and mark member as mixed-in.
*/
def addMember(clazz: Symbol, member: Symbol): Symbol = {
if (settings.debug.value) log("new member of " + clazz + ":" + member.defString)
clazz.info.decls enter member
member setFlag MIXEDIN
}
def needsExpandedSetterName(field: Symbol) =
!(field hasFlag LAZY) &&
(if (field.isMethod) (field hasFlag STABLE) else !(field hasFlag MUTABLE))
/** Add getters and setters for all non-module fields of an implementation
* class to its interface unless they are already present. This is done
* only once per class. The mixedin flag is used to remember whether late
* members have been added to an interface.
* - lazy fields don't get a setter.
*/
def addLateInterfaceMembers(clazz: Symbol) {
if ((treatedClassInfos get clazz) != Some(clazz.info)) {
treatedClassInfos(clazz) = clazz.info
assert(phase == currentRun.mixinPhase)
/** Create a new getter. Getters are never private or local. They are
* always accessors and deferred. */
def newGetter(field: Symbol): Symbol = {
// println("creating new getter for "+ field +" : "+ field.info +" at "+ field.locationString+(field hasFlag MUTABLE))
// atPhase(currentRun.erasurePhase){
// println("before erasure: "+ (field.info))
// }
clazz.newMethod(field.pos, nme.getterName(field.name))
.setFlag(field.flags & ~(PRIVATE | LOCAL) | ACCESSOR | lateDEFERRED |
(if (field hasFlag MUTABLE) 0 else STABLE))
.setInfo(MethodType(List(), field.info)) // TODO preserve pre-erasure info?
}
/** Create a new setter. Setters are never private or local. They are
* always accessors and deferred. */
def newSetter(field: Symbol): Symbol = {
//println("creating new setter for "+field+field.locationString+(field hasFlag MUTABLE))
val setterName = nme.getterToSetter(nme.getterName(field.name))
val setter = clazz.newMethod(field.pos, setterName)
.setFlag(field.flags & ~(PRIVATE | LOCAL) | ACCESSOR | lateDEFERRED)
setter.setInfo(MethodType(setter.newSyntheticValueParams(List(field.info)), UnitClass.tpe)) // TODO preserve pre-erasure info?
if (needsExpandedSetterName(field)) {
//println("creating expanded setter from "+field)
setter.name = nme.expandedSetterName(setter.name, clazz)
}
setter
}
clazz.info // make sure info is up to date, so that implClass is set.
val impl = implClass(clazz)
assert(impl != NoSymbol)
for (member <- impl.info.decls.toList) {
if (!member.isMethod && !member.isModule && !member.isModuleVar) {
assert(member.isTerm && !member.isDeferred, member)
if (member.getter(impl) hasFlag PRIVATE) {
member.makeNotPrivate(clazz) // this will also make getter&setter not private
}
val getter = member.getter(clazz)
if (getter == NoSymbol) addMember(clazz, newGetter(member))
if (!member.tpe.isInstanceOf[ConstantType] && !member.hasFlag(LAZY)) {
val setter = member.setter(clazz, needsExpandedSetterName(member))
if (setter == NoSymbol) addMember(clazz, newSetter(member))
}
}
}
if (settings.debug.value) log("new defs of " + clazz + " = " + clazz.info.decls);
}
}
/** Map a lazy, mixedin field accessor to it's trait member accessor */
val initializer = new mutable.HashMap[Symbol, Symbol]
/** Add all members to be mixed in into a (non-trait-) class
* These are:
* for every mixin trait T that is not also inherited by the superclass:
* add late interface members to T and then:
* - if a member M of T is forwarded to the implementation class, add
* a forwarder for M unless one exists already.
* The alias of the forwarder is the static member it forwards to.
* - for every abstract accessor in T, add a field and an implementation for that accessor
* - for every super accessor in T, add an implementation of that accessor
* - for every module in T, add a module
*/
def addMixedinMembers(clazz: Symbol, unit : CompilationUnit) {
def cloneBeforeErasure(iface: Symbol, clazz: Symbol, imember: Symbol): Symbol = {
val newSym = atPhase(currentRun.erasurePhase){
val res = imember.cloneSymbol(clazz)
// since we used the member (imember) from the interface that represents the trait that's being mixed in,
// have to instantiate the interface type params (that may occur in imember's info) as they are seen from the class
// we can't use the member that we get from the implementation class, as it's a clone that was made after erasure,
// and thus it does not know its info at the beginning of erasure anymore
// optimize: no need if iface has no typeparams
if(iface.typeParams nonEmpty) res.setInfo(clazz.thisType.baseType(iface).memberInfo(imember))
res
} // clone before erasure got rid of type info we'll need to generate a javaSig
// now we'll have the type info at (the beginning of) erasure in our history,
newSym.updateInfo(imember.info.cloneInfo(newSym)) // and now newSym has the info that's been transformed to fit this period (no need for asSeenFrom as phase.erasedTypes)
newSym // TODO: verify we need the updateInfo and document why
}
if (!(clazz hasFlag JAVA) && (treatedClassInfos get clazz) != Some(clazz.info)) {
treatedClassInfos(clazz) = clazz.info
assert(!clazz.isTrait, clazz)
assert(!clazz.info.parents.isEmpty, clazz)
// first complete the superclass with mixed in members
addMixedinMembers(clazz.superClass,unit)
//Console.println("adding members of " + clazz.info.baseClasses.tail.takeWhile(superclazz !=) + " to " + clazz);//DEBUG
/** Mix in members of implementation class mixinClass into class clazz */
def mixinImplClassMembers(impl: Symbol, iface: Symbol) {
assert (impl.isImplClass)
for (member <- impl.info.decls.toList) {
if (isForwarded(member)) {
val imember = member.overriddenSymbol(iface)
// atPhase(currentRun.erasurePhase){
// println(""+(clazz, iface, clazz.typeParams, iface.typeParams, imember, clazz.thisType.baseType(iface), clazz.thisType.baseType(iface).memberInfo(imember), imember.info substSym(iface.typeParams, clazz.typeParams) ))
// }
// Console.println("mixin member "+member+":"+member.tpe+member.locationString+" "+imember+" "+imember.overridingSymbol(clazz)+" to "+clazz+" with scope "+clazz.info.decls)//DEBUG
if (imember.overridingSymbol(clazz) == NoSymbol &&
clazz.info.findMember(member.name, 0, lateDEFERRED, false).alternatives.contains(imember)) {
val member1 = addMember(
clazz,
cloneBeforeErasure(iface, clazz, imember) setPos clazz.pos resetFlag (DEFERRED | lateDEFERRED))
member1.asInstanceOf[TermSymbol] setAlias member;
}
}
}
}
/** Mix in members of trait mixinClass into class clazz. Also,
* for each lazy field in mixinClass, add a link from its mixed in member to its
* initializer method inside the implclass.
*/
def mixinTraitMembers(mixinClass: Symbol) {
// For all members of a trait's interface do:
for (member <- mixinClass.info.decls.toList) {
if (isConcreteAccessor(member)) {
if (isOverriddenAccessor(member, clazz.info.baseClasses)) {
if (settings.debug.value) println("!!! is overridden val: "+member)
} else {
// mixin field accessors
val member1 = addMember(
clazz,
cloneBeforeErasure(mixinClass, clazz, member) //member.cloneSymbol(clazz)
setPos clazz.pos
resetFlag (DEFERRED | lateDEFERRED))
// println("mixing in: "+ (member, member.info, member1.info))
// atPhase(currentRun.erasurePhase){
// println("before erasure: "+ (member.info, member1.info))
// }
if (member.hasFlag(LAZY)) {
var init = implClass(mixinClass).info.decl(member.name)
assert(init != NoSymbol, "Could not find initializer for " + member.name)
initializer(member1) = init
}
if (!member.isSetter)
member.tpe match {
case MethodType(Nil, ConstantType(_)) =>
// member is a constant; only getter is needed
;
case MethodType(Nil, TypeRef(_, UnitClass, _)) =>
// member is a value of type unit. No field needed
;
case _ => // otherwise mixin a field as well
// atPhase: the private field is moved to the implementation class by erasure,
// so it can no longer be found in the member's owner (the trait)
val accessed = atPhase(currentRun.picklerPhase)(member.accessed)
val sym = atPhase(currentRun.erasurePhase){ // #3857, need to retain info before erasure when cloning (since cloning only carries over the current entry in the type history)
clazz.newValue(member.pos, nme.getterToLocal(member.name)).setInfo(member.tpe.resultType) // so we have a type history entry before erasure
}
sym.updateInfo(member.tpe.resultType) // info at current phase
addMember(clazz,
sym
setFlag (LOCAL | PRIVATE | member.getFlag(MUTABLE | LAZY))
setFlag (if (!member.hasFlag(STABLE)) MUTABLE else 0)
setAnnotations accessed.annotations)
}
}
} else if (member hasFlag SUPERACCESSOR) { // mixin super accessors
val member1 = addMember(clazz, member.cloneSymbol(clazz)) setPos clazz.pos
assert(member1.alias != NoSymbol, member1)
val alias1 = rebindSuper(clazz, member.alias, mixinClass)
member1.asInstanceOf[TermSymbol] setAlias alias1
} else if (member.isMethod && member.isModule && !(member hasFlag (LIFTED | BRIDGE))) {
// mixin objects: todo what happens with abstract objects?
addMember(clazz, member.cloneSymbol(clazz))
.setPos(clazz.pos)
.resetFlag(DEFERRED | lateDEFERRED)
}
}
}
for (mc <- clazz.mixinClasses)
if (mc hasFlag lateINTERFACE) {
// @SEAN: adding trait tracking so we don't have to recompile transitive closures
unit.depends += mc
addLateInterfaceMembers(mc)
mixinTraitMembers(mc)
mixinImplClassMembers(implClass(mc), mc)
}
}
}
/** The info transform for this phase does the following:
* - The parents of every class are mapped from implementation class to interface
* - Implementation classes become modules that inherit nothing
* and that define all.
*
* @param sym ...
* @param tp ...
* @return ...
*/
override def transformInfo(sym: Symbol, tp: Type): Type = tp match {
case ClassInfoType(parents, decls, clazz) =>
var parents1 = parents
var decls1 = decls
if (!clazz.isPackageClass) {
atPhase(phase.next)(clazz.owner.info)
if (clazz.isImplClass) {
clazz setFlag lateMODULE
var sourceModule = clazz.owner.info.decls.lookup(sym.name.toTermName)
if (sourceModule != NoSymbol) {
sourceModule setPos sym.pos
sourceModule.flags = MODULE | FINAL
} else {
sourceModule = clazz.owner.newModule(
sym.pos, sym.name.toTermName, sym.asInstanceOf[ClassSymbol])
clazz.owner.info.decls enter sourceModule
}
sourceModule setInfo sym.tpe
assert(clazz.sourceModule != NoSymbol)//debug
parents1 = List()
decls1 = new Scope(decls.toList filter isImplementedStatically)
} else if (!parents.isEmpty) {
parents1 = parents.head :: (parents.tail map toInterface)
}
}
//decls1 = atPhase(phase.next)(new Scope(decls1.toList))//debug
if ((parents1 eq parents) && (decls1 eq decls)) tp
else ClassInfoType(parents1, decls1, clazz)
case MethodType(params, restp) =>
toInterfaceMap(
if (isImplementedStatically(sym)) {
val ownerParam = sym.newSyntheticValueParam(toInterface(sym.owner.typeOfThis))
MethodType(ownerParam :: params, restp)
} else
tp)
case _ =>
tp
}
import scala.collection._
/** Return a map of single-use fields to the lazy value that uses them during initialization.
* Each field has to be private and defined in the enclosing class, and there must
* be exactly one lazy value using it.
*
* Such fields will be nulled after the initializer has memoized the lazy value.
*/
def singleUseFields(templ: Template): collection.Map[Symbol, List[Symbol]] = {
val usedIn = new mutable.HashMap[Symbol, List[Symbol]] {
override def default(key: Symbol) = Nil
}
object SingleUseTraverser extends Traverser {
override def traverse(tree: Tree) {
tree match {
case Assign(lhs, rhs) => traverse(rhs) // assignments don't count
case _ =>
if (tree.hasSymbol && tree.symbol != NoSymbol) {
val sym = tree.symbol
if ((sym.hasFlag(ACCESSOR) || (sym.isTerm && !sym.isMethod))
&& sym.hasFlag(PRIVATE)
&& !(currentOwner.isGetter && currentOwner.accessed == sym) // getter
&& !definitions.isValueClass(sym.tpe.resultType.typeSymbol)
&& sym.owner == templ.symbol.owner
&& !sym.hasFlag(LAZY)
&& !tree.isDef) {
log("added use in: " + currentOwner + " -- " + tree)
usedIn(sym) ::= currentOwner
}
}
super.traverse(tree)
}
}
}
SingleUseTraverser(templ)
log("usedIn: " + usedIn)
usedIn filter { pair =>
val member = pair._2.head
(member.isValue
&& member.hasFlag(LAZY)
&& pair._2.tail.isEmpty) }
}
// --------- term transformation -----------------------------------------------
protected def newTransformer(unit: CompilationUnit): Transformer =
new MixinTransformer(unit)
class MixinTransformer(unit : CompilationUnit) extends Transformer {
/** Within a static implementation method: the parameter referring to the
* current object undefined everywhere else.
*/
private var self: Symbol = _
/** The rootContext used for typing */
private val rootContext =
erasure.NoContext.make(EmptyTree, RootClass, new Scope)
/** The typer */
private var localTyper: erasure.Typer = _
private def typedPos(pos: Position)(tree: Tree) = localTyper typed { atPos(pos)(tree) }
/** Map lazy values to the fields they should null after initialization. */
private var lazyValNullables: mutable.MultiMap[Symbol, Symbol] = _
import scala.collection._
/** Map a field symbol to a unique integer denoting its position in the class layout.
* For each class, fields defined by the class come after inherited fields. Mixed-in
* fields count as fields defined by the class itself.
*/
private val fieldOffset: mutable.Map[Symbol, Int] = new mutable.HashMap[Symbol, Int]
/** The first transform; called in a pre-order traversal at phase mixin
* (that is, every node is processed before its children).
* What transform does:
* - For every non-trait class, add all mixed in members to the class info.
* - For every trait, add all late interface members to the class info
* - For every static implementation method:
* - remove override flag
* - create a new method definition that also has a `self' parameter
* (which comes first) Iuli: this position is assumed by tail call elimination
* on a different receiver. Storing a new 'this' assumes it is located at
* index 0 in the local variable table. See 'STORE_THIS' and GenJVM/GenMSIL.
* - Map implementation class types in type-apply's to their interfaces
* - Remove all fields in implementation classes
*/
private def preTransform(tree: Tree): Tree = {
val sym = tree.symbol
tree match {
case Template(parents, self, body) =>
localTyper = erasure.newTyper(rootContext.make(tree, currentOwner))
atPhase(phase.next)(currentOwner.owner.info)//todo: needed?
if (!currentOwner.isTrait) addMixedinMembers(currentOwner,unit)
else if (currentOwner hasFlag lateINTERFACE) addLateInterfaceMembers(currentOwner)
tree
case DefDef(mods, name, tparams, List(vparams), tpt, rhs) =>
if (currentOwner.isImplClass) {
if (isImplementedStatically(sym)) {
sym setFlag notOVERRIDE
self = sym.newValue(sym.pos, nme.SELF)
.setFlag(PARAM)
.setInfo(toInterface(currentOwner.typeOfThis));
val selfdef = ValDef(self) setType NoType
treeCopy.DefDef(tree, mods, name, tparams, List(selfdef :: vparams), tpt, rhs)
} else {
EmptyTree
}
} else {
if (currentOwner.isTrait && sym.isSetter && !atPhase(currentRun.picklerPhase)(sym.isDeferred)) {
sym.addAnnotation(AnnotationInfo(TraitSetterAnnotationClass.tpe, List(), List()))
}
tree
}
case Apply(tapp @ TypeApply(fn, List(arg)), List()) =>
if (arg.tpe.typeSymbol.isImplClass) {
val ifacetpe = toInterface(arg.tpe)
arg.tpe = ifacetpe
tapp.tpe = MethodType(List(), ifacetpe)
tree.tpe = ifacetpe
}
tree
case ValDef(_, _, _, _) if currentOwner.isImplClass =>
EmptyTree
case _ =>
tree
}
}
/** Create an identifier which references self parameter.
*
* @param pos ...
*/
private def selfRef(pos: Position) =
gen.mkAttributedIdent(self) setPos pos
/** Replace a super reference by this or the self parameter, depending
* on whether we are in an implementation class or not.
* Leave all other trees unchanged */
private def transformSuper(qual: Tree) =
if (!qual.isInstanceOf[Super]) qual
else if (currentOwner.enclClass.isImplClass) selfRef(qual.pos)
else gen.mkAttributedThis(currentOwner.enclClass)
/** Create a static reference to given symbol <code>sym</code> of the
* form <code>M.sym</code> where M is the symbol's implementation module.
*/
private def staticRef(sym: Symbol): Tree = {
sym.owner.info //todo: needed?
sym.owner.owner.info //todo: needed?
if (sym.owner.sourceModule == NoSymbol) {
assert(false, "" + sym + " in " + sym.owner + " in " + sym.owner.owner +
" " + sym.owner.owner.info.decls.toList)//debug
}
REF(sym.owner.sourceModule) DOT sym
}
/** Add all new definitions to a non-trait class
* These fall into the following categories:
* - for a trait interface:
* - abstract accessors for all fields in the implementation class
* - for a non-trait class:
* - A field for every in a mixin class
* - Setters and getters for such fields
* - getters for mixed in lazy fields are completed
* - module variables and module creators for every module in a mixin class
* (except if module is lifted -- in this case the module variable
* is local to some function, and the creator method is static.)
* - A super accessor for every super accessor in a mixin class
* - Forwarders for all methods that are implemented statically
* All superaccessors are completed with right-hand sides (@see completeSuperAccessor)
* @param clazz The class to which definitions are added
*/
private def addNewDefs(clazz: Symbol, stats: List[Tree]): List[Tree] = {
val newDefs = new ListBuffer[Tree]
/** Attribute given tree and anchor at given position */
def attributedDef(pos: Position, tree: Tree): Tree = {
if (settings.debug.value) log("add new def to " + clazz + ": " + tree)
typedPos(pos)(tree)
}
/** The position of given symbol, or, if this is undefined,
* the position of the current class. */
def position(sym: Symbol) =
if (sym.pos == NoPosition) clazz.pos else sym.pos
/** Add tree at given position as new definition */
def addDef(pos: Position, tree: Tree) {
newDefs += attributedDef(pos, tree)
}
/** Add new method definition.
*
* @param sym The method
* @param rhs A function that maps formal parameters to the method's
* right-hand side
*/
def addDefDef(sym: Symbol, rhs: List[Symbol] => Tree) {
addDef(position(sym), DefDef(sym, rhs(sym.paramss.head)))
}
/** Add `newdefs' to `stats', removing any abstract method definitions
* in <code>stats</code> that are matched by some symbol defined in
* <code>newDefs</code>.
*/
def add(stats: List[Tree], newDefs: List[Tree]) = {
val newSyms = newDefs map (_.symbol)
def isNotDuplicate(tree: Tree) = tree match {
case DefDef(_, _, _, _, _, _) =>
val sym = tree.symbol
!(sym.isDeferred &&
(newSyms exists (nsym => nsym.name == sym.name && (nsym.tpe matches sym.tpe))))
case _ =>
true
}
if (newDefs.isEmpty) stats
else newDefs ::: stats.filter(isNotDuplicate)
}
/** If `stat' is a superaccessor, complete it by adding a right-hand side.
* Note: superaccessors are always abstract until this point.
* The method to call in a superaccessor is stored in the accessor symbol's alias field.
* The rhs is:
* super.A(xs) where A is the super accessor's alias and xs are its formal parameters.
* This rhs is typed and then mixin transformed.
*/
def completeSuperAccessor(stat: Tree) = stat match {
case DefDef(mods, name, tparams, List(vparams), tpt, EmptyTree)
if (stat.symbol hasFlag SUPERACCESSOR) =>
val rhs0 = (Super(clazz, nme.EMPTY.toTypeName) DOT stat.symbol.alias)(vparams map (v => Ident(v.symbol)): _*)
val rhs1 = localTyper.typed(atPos(stat.pos)(rhs0), stat.symbol.tpe.resultType)
val rhs2 = atPhase(currentRun.mixinPhase)(transform(rhs1))
if (settings.debug.value)
log("complete super acc " + stat.symbol + stat.symbol.locationString +
" " + rhs1 + " " + stat.symbol.alias + stat.symbol.alias.locationString +
"/" + stat.symbol.alias.owner.hasFlag(lateINTERFACE))//debug
treeCopy.DefDef(stat, mods, name, tparams, List(vparams), tpt, rhs2)
case _ =>
stat
}
import lazyVals._
/** Return the bitmap field for 'offset', create one if not inheriting it already. */
def bitmapFor(clazz: Symbol, offset: Int): Symbol = {
var sym = clazz.info.member(nme.bitmapName(offset / FLAGS_PER_WORD))
assert(!sym.hasFlag(OVERLOADED))
if (sym == NoSymbol) {
sym = clazz.newVariable(clazz.pos, nme.bitmapName(offset / FLAGS_PER_WORD))
.setInfo(IntClass.tpe)
.setFlag(PROTECTED)
atPhase(currentRun.typerPhase) {
sym addAnnotation AnnotationInfo(VolatileAttr.tpe, Nil, Nil)
}
clazz.info.decls.enter(sym)
addDef(clazz.pos, VAL(sym) === ZERO)
}
sym
}
/** Return an (untyped) tree of the form 'Clazz.this.bmp = Clazz.this.bmp | mask'. */
def mkSetFlag(clazz: Symbol, offset: Int): Tree = {
val bmp = bitmapFor(clazz, offset)
val mask = LIT(1 << (offset % FLAGS_PER_WORD))
def x = This(clazz) DOT bmp
x === (x INT_| mask)
}
/** Return an (untyped) tree of the form 'clazz.this.bitmapSym & mask (==|!=) 0', the
* precise comparison operator depending on the value of 'equalToZero'.
*/
def mkTest(clazz: Symbol, mask: Tree, bitmapSym: Symbol, equalToZero: Boolean): Tree = {
def lhs = (This(clazz) DOT bitmapSym) INT_& mask
if (equalToZero) lhs INT_== ZERO
else lhs INT_!= ZERO
}
/** return a 'lazified' version of rhs. It uses double-checked locking to ensure
* initialization is performed at most once. Private fields used only in this
* initializer are subsequently set to null.
*
* @param clazz The class symbol
* @param init The tree which initializes the field ( f = <rhs> )
* @param fieldSym The symbol of this lazy field
* @param offset The offset of this field in the flags bitmap
*
* The result will be a tree of the form
* {
* if ((bitmap$n & MASK) == 0) {
* synchronized(this) {
* if ((bitmap$n & MASK) == 0) {
* init // l$ = <rhs>
* bitmap$n = bimap$n | MASK
* }
* }
* this.f1 = null
* ... this.fn = null
* }
* l$
* }
* where bitmap$n is an int value acting as a bitmap of initialized values. It is
* the 'n' is (offset / 32), the MASK is (1 << (offset % 32)).
*/
def mkLazyDef(clazz: Symbol, lzyVal: Symbol, init: List[Tree], retVal: Tree, offset: Int): Tree = {
def nullify(sym: Symbol): Tree = {
val sym1 = if (sym.hasFlag(ACCESSOR)) sym.accessed else sym
Select(This(clazz), sym1) === LIT(null)
}
val bitmapSym = bitmapFor(clazz, offset)
val mask = LIT(1 << (offset % FLAGS_PER_WORD))
def cond = mkTest(clazz, mask, bitmapSym, true)
val nulls = (lazyValNullables(lzyVal).toList sortBy (_.id) map nullify)
def syncBody = init ::: List(mkSetFlag(clazz, offset), UNIT)
log("nulling fields inside " + lzyVal + ": " + nulls)
val result = gen.mkDoubleCheckedLocking(clazz, cond, syncBody, nulls)
typedPos(init.head.pos)(BLOCK(result, retVal))
}
def mkCheckedAccessor(clazz: Symbol, retVal: Tree, offset: Int, pos: Position): Tree = {
val bitmapSym = bitmapFor(clazz, offset)
val mask = LIT(1 << (offset % FLAGS_PER_WORD))
val msg = "Uninitialized field: " + unit.source + ": " + pos.line
val result =
IF (mkTest(clazz, mask, bitmapSym, false)) .
THEN (retVal) .
ELSE (THROW(UninitializedErrorClass, LIT(msg)))
typedPos(pos)(BLOCK(result, retVal))
}
/** Complete lazy field accessors. Applies only to classes, for it's own (non inherited) lazy fields.
* If 'checkinit' is enabled, getters that check for the initialized bit are generated, and
* the class constructor is changed to set the initialized bits.
*/
def addCheckedGetters(clazz: Symbol, stats: List[Tree]): List[Tree] = {
// TODO: not used?
def findLazyAssignment(stats: List[Tree]): Tree = (
for (s @ Assign(lhs, _) <- stats ; if lhs.symbol hasFlag LAZY) yield s
) head // if there's no assignment then it's a bug and we crash
val stats1 = for (stat <- stats; sym = stat.symbol) yield stat match {
case DefDef(mods, name, tp, vp, tpt, rhs)
if sym.hasFlag(LAZY) && rhs != EmptyTree && !clazz.isImplClass =>
assert(fieldOffset.isDefinedAt(sym))
val rhs1 = if (sym.tpe.resultType.typeSymbol == UnitClass)
mkLazyDef(clazz, sym, List(rhs), UNIT, fieldOffset(sym))
else {
val Block(stats, res) = rhs
mkLazyDef(clazz, sym, stats, Select(This(clazz), res.symbol), fieldOffset(sym))
}
treeCopy.DefDef(stat, mods, name, tp, vp, tpt, rhs1)
case DefDef(mods, name, tp, vp, tpt, rhs)
if needsInitFlag(sym) && rhs != EmptyTree && !clazz.isImplClass && !clazz.isTrait =>
assert(fieldOffset.isDefinedAt(sym))
val rhs1 = (mkCheckedAccessor(clazz, _: Tree, fieldOffset(sym), stat.pos))(
if (sym.tpe.resultType.typeSymbol == UnitClass) UNIT else rhs
)
treeCopy.DefDef(stat, mods, name, tp, vp, tpt, rhs1)
case DefDef(mods, name, tp, vp, tpt, rhs) if sym.isConstructor =>
treeCopy.DefDef(stat, mods, name, tp, vp, tpt, addInitBits(clazz, rhs))
case _ => stat
}
stats1
}
/** Does this field require an initialized bit? */
def needsInitFlag(sym: Symbol) = {
val res = (settings.checkInit.value
&& sym.isGetter
&& !sym.isInitializedToDefault
&& !sym.hasFlag(PARAMACCESSOR | SPECIALIZED)
&& !sym.accessed.hasFlag(PRESUPER)
&& !sym.isOuterAccessor)
// if (settings.debug.value) {
// log("needsInitFlag(" + sym.fullName + "): " + res)
// log("\tsym.isGetter: " + sym.isGetter)
// log("\t!isInitializedToDefault: " + !sym.isInitializedToDefault + sym.hasFlag(DEFAULTINIT) + sym.hasFlag(ACCESSOR) + sym.isTerm)
// log("\t!sym.hasFlag(PARAMACCESSOR): " + !sym.hasFlag(PARAMACCESSOR))
// //println("\t!sym.accessed.hasFlag(PRESUPER): " + !sym.accessed.hasFlag(PRESUPER))
// log("\t!sym.isOuterAccessor: " + !sym.isOuterAccessor)
// }
res
}
/** Adds statements to set the 'init' bit for each field initialized
* in the body of a constructor.
*/
def addInitBits(clazz: Symbol, rhs: Tree): Tree = {
new Transformer {
override def transformStats(stats: List[Tree], exprOwner: Symbol) = {
val stats1 = stats flatMap { stat => stat match {
case Assign(lhs @ Select(This(_), _), rhs) =>
val sym = clazz.info.decl(nme.getterName(lhs.symbol.name))
.suchThat(_.isGetter)
if (rhs == EmptyTree)
List()
else if (sym != NoSymbol && needsInitFlag(sym) && fieldOffset.isDefinedAt(sym)) {
log("adding checked getter for: " + sym + " " + Flags.flagsToString(lhs.symbol.flags))
List(stat, localTyper.typed(mkSetFlag(clazz, fieldOffset(sym))))
} else {
List(stat)
}
case Apply(setter @ Select(Ident(self), _), List(EmptyTree)) if setter.symbol.isSetter =>
// remove initialization for default values
List()
case _ => List(stat)
}
}
super.transformStats(stats1, exprOwner)
}
}.transform(rhs)
}
/** Return the number of bits used by superclass fields.
* This number is a conservative approximation of what is actually used:
* - fields initialized to the default value don't get a checked initializer
* but there is no way to recover this information from types alone.
*/
def usedBits(clazz: Symbol): Int = {
def isField(sym: Symbol) =
sym.hasFlag(PRIVATE) && sym.isTerm && !sym.isMethod
def needsBitmapField(sc: Type, field: Symbol) =
!sc.typeSymbol.isTrait &&
field.owner != clazz &&
(settings.checkInit.value && isField(field) ||
field.hasFlag(LAZY))
// parents != baseClasses.map(_.tpe): bug #1535
val fields = for {
sc <- clazz.info.baseClasses.map(_.tpe)
field <- sc.decls.iterator.toList
if needsBitmapField(sc, field)
} yield field
if (settings.debug.value) log("Found inherited fields in " + clazz + " : " + fields)
fields.length
}
/** Fill the map from fields to offset numbers.
* Instead of field symbols, the map keeps their getter symbols. This makes
* code generation easier later.
*/
def buildFieldPositions(clazz: Symbol) {
var fields = usedBits(clazz)
for (f <- clazz.info.decls.iterator if needsInitFlag(f) || f.hasFlag(LAZY)) {
if (settings.debug.value) log(f.fullName + " -> " + fields)
fieldOffset(f) = fields
fields += 1
}
}
buildFieldPositions(clazz)
// begin addNewDefs
var stats1 = addCheckedGetters(clazz, stats)
// for all symbols `sym' in the class definition, which are mixed in:
for (sym <- clazz.info.decls.toList) {
if (sym hasFlag MIXEDIN) {
if (clazz hasFlag lateINTERFACE) {
// if current class is a trait interface, add an abstract method for accessor `sym'
addDefDef(sym, vparamss => EmptyTree)
} else if (!clazz.isTrait) {
// if class is not a trait add accessor definitions
if ((sym hasFlag ACCESSOR) &&
(!(sym hasFlag DEFERRED) || (sym hasFlag lateDEFERRED))) {
// add accessor definitions
addDefDef(sym, vparams => {
val accessedRef = sym.tpe match {
case MethodType(List(), ConstantType(c)) => Literal(c)
case _ =>
// if it is a mixed-in lazy value, complete the accessor
if (sym.hasFlag(LAZY) && sym.isGetter) {
val rhs1 =
if (sym.tpe.resultType.typeSymbol == UnitClass)
mkLazyDef(clazz, sym, List(Apply(staticRef(initializer(sym)), List(gen.mkAttributedThis(clazz)))), UNIT, fieldOffset(sym))
else {
val assign = atPos(sym.pos) {
Assign(Select(This(sym.accessed.owner), sym.accessed) /*gen.mkAttributedRef(sym.accessed)*/ ,
Apply(staticRef(initializer(sym)), gen.mkAttributedThis(clazz) :: Nil))
}
mkLazyDef(clazz, sym, List(assign), Select(This(clazz), sym.accessed), fieldOffset(sym))
}
rhs1
} else if (sym.getter(sym.owner).tpe.resultType.typeSymbol == UnitClass) {
UNIT
} else {
Select(This(clazz), sym.accessed)
}
}
if (sym.isSetter) {
val isOverriddenSetter =
nme.isTraitSetterName(sym.name) && {
sym.allOverriddenSymbols match {
case other :: _ =>
isOverriddenAccessor(other.getter(other.owner), clazz.info.baseClasses)
case _ =>
false
}
}
if (isOverriddenSetter) UNIT
else accessedRef match {
case Literal(_) => accessedRef
case _ =>
val init = Assign(accessedRef, Ident(vparams.head))
if (settings.checkInit.value && needsInitFlag(sym.getter(clazz))) {
Block(List(init, mkSetFlag(clazz, fieldOffset(sym.getter(clazz)))), UNIT)
} else
init
}
} else if (!sym.hasFlag(LAZY) && needsInitFlag(sym)) {
mkCheckedAccessor(clazz, accessedRef, fieldOffset(sym), sym.pos)
} else
gen.mkCheckInit(accessedRef)
})
} else if (!sym.isMethod) {
// add fields
addDef(position(sym), ValDef(sym))
} else if (sym hasFlag SUPERACCESSOR) {
// add superaccessors
addDefDef(sym, vparams => EmptyTree)
} else {
// add forwarders
assert(sym.alias != NoSymbol, sym)
addDefDef(sym, vparams =>
Apply(staticRef(sym.alias), gen.mkAttributedThis(clazz) :: (vparams map Ident)))
}
}
}
}
stats1 = add(stats1, newDefs.toList)
if (!clazz.isTrait) stats1 = stats1 map completeSuperAccessor
stats1
}
private def nullableFields(templ: Template) = {
val nullables = new mutable.HashMap[Symbol, mutable.Set[Symbol]] with mutable.MultiMap[Symbol, Symbol] {
override def default(key: Symbol) = mutable.Set.empty
}
// if there are no lazy fields, take the fast path and save a traversal of the whole AST
if (templ.symbol.owner.info.decls.exists(_.hasFlag(LAZY))) {
// check what fields can be nulled for
val uses = singleUseFields(templ)
for ((field, users) <- uses; lazyFld <- users) {
nullables.addBinding(lazyFld, field)
}
}
nullables
}
/** The transform that gets applied to a tree after it has been completely
* traversed and possible modified by a preTransform.
* This step will
* - change every node type that refers to an implementation class to its
* corresponding interface, unless the node's symbol is an implementation class.
* - change parents of templates to conform to parents in the symbol info
* - add all new definitions to a class or interface
* - remove widening casts
* - change calls to methods which are defined only in implementation classes
* to static calls of methods in implementation modules (@see staticCall)
* - change super calls to methods in implementation classes to static calls
* (@see staticCall)
* - change `this' in implementation modules to references to the self parameter
* - refer to fields in some implementation class vie an abstract method in the interface.
*/
private def postTransform(tree: Tree): Tree = {
val sym = tree.symbol
// change every node type that refers to an implementation class to its
// corresponding interface, unless the node's symbol is an implementation class.
if (tree.tpe.typeSymbol.isImplClass &&
((tree.symbol eq null) || !tree.symbol.isImplClass))
tree.tpe = toInterface(tree.tpe);
tree match {
case Template(parents, self, body) =>
// change parents of templates to conform to parents in the symbol info
val parents1 = currentOwner.info.parents map (t => TypeTree(t) setPos tree.pos)
lazyValNullables = nullableFields(tree.asInstanceOf[Template])
// add all new definitions to current class or interface
val body1 = addNewDefs(currentOwner, body)
treeCopy.Template(tree, parents1, self, body1)
case Apply(TypeApply(sel @ Select(qual, name), List(targ)), List())
if (tree.symbol == Object_asInstanceOf && (qual.tpe <:< targ.tpe)) =>
// remove widening casts
qual
case Apply(Select(qual, _), args) =>
/** Changes <code>qual.m(args)</code> where m refers to an implementation
* class method to Q.m(S, args) where Q is the implementation module of
* <code>m</code> and S is the self parameter for the call, which
* is determined as follows:
* - if qual != super, qual itself
* - if qual == super, and we are in an implementation class,
* the current self parameter.
* - if qual == super, and we are not in an implementation class, `this'
*/
def staticCall(target: Symbol) = {
if (target == NoSymbol)
assert(false, "" + sym + ":" + sym.tpe + " " + sym.owner + " " + implClass(sym.owner) + " " + implClass(sym.owner).info.member(sym.name) + " " + atPhase(phase.prev)(implClass(sym.owner).info.member(sym.name).tpe) + " " + phase);//debug
typedPos(tree.pos)(Apply(staticRef(target), transformSuper(qual) :: args))
}
if (isStaticOnly(sym)) {
// change calls to methods which are defined only in implementation
// classes to static calls of methods in implementation modules
staticCall(sym)
} else qual match {
case Super(_, mix) =>
// change super calls to methods in implementation classes to static calls.
// Transform references super.m(args) as follows:
// - if `m' refers to a trait, insert a static call to the corresponding static
// implementation
// - otherwise return tree unchanged
if (mix == nme.EMPTY.toTypeName && currentOwner.enclClass.isImplClass)
assert(false, "illegal super in trait: " + currentOwner.enclClass + " " + tree);
if (sym.owner hasFlag lateINTERFACE) {
if (sym.hasFlag(ACCESSOR)) {
assert(args.isEmpty)
val sym1 = sym.overridingSymbol(currentOwner.enclClass)
typedPos(tree.pos)((transformSuper(qual) DOT sym1)())
}
else {
staticCall(atPhase(phase.prev)(sym.overridingSymbol(implClass(sym.owner))))
}
} else {
assert(!currentOwner.enclClass.isImplClass)
tree
}
case _ =>
tree
}
case This(_) if tree.symbol.isImplClass =>
// change `this' in implementation modules to references to the self parameter
assert(tree.symbol == currentOwner.enclClass)
selfRef(tree.pos)
case Select(Super(_, _), name) =>
tree
case Select(qual, name) if sym.owner.isImplClass && !isStaticOnly(sym) =>
assert(!sym.isMethod, "no method allowed here: %s%s %s".format(sym, sym.isImplOnly, flagsToString(sym.flags)))
// refer to fields in some implementation class via an abstract
// getter in the interface.
val iface = toInterface(sym.owner.tpe).typeSymbol
val getter = sym.getter(iface)
assert(getter != NoSymbol)
typedPos(tree.pos)((qual DOT getter)())
case Assign(Apply(lhs @ Select(qual, _), List()), rhs) =>
// assign to fields in some implementation class via an abstract
// setter in the interface.
def setter = lhs.symbol.setter(
toInterface(lhs.symbol.owner.tpe).typeSymbol,
needsExpandedSetterName(lhs.symbol)
) setPos lhs.pos
typedPos(tree.pos) { (qual DOT setter)(rhs) }
case _ =>
tree
}
}
/** The main transform method.
* This performs pre-order traversal preTransform at mixin phase;
* when coming back, it performs a postTransform at phase after.
*/
override def transform(tree: Tree): Tree = {
try { //debug
val outerTyper = localTyper
val tree1 = super.transform(preTransform(tree))
val res = atPhase(phase.next)(postTransform(tree1))
// needed when not flattening inner classes. parts after an
// inner class will otherwise be typechecked with a wrong scope
localTyper = outerTyper
res
} catch {
case ex: Throwable =>
if (settings.debug.value) Console.println("exception when traversing " + tree)
throw ex
}
}
}
}
