/* NSC -- new Scala compiler
* Copyright 2005-2011 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package transform
import symtab._
import Flags._
import scala.collection.{ mutable, immutable }
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 | notOVERRIDE
/** 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 = perRunCaches.newMap[Symbol, Type]()
/** Map a lazy, mixedin field accessor to it's trait member accessor */
private val initializer = perRunCaches.newMap[Symbol, Symbol]
/** Deferred bitmaps that will be added during the transformation of a class */
private val deferredBitmaps = perRunCaches.newMap[Symbol, List[Tree]]() withDefaultValue Nil
// --------- 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.isLazy)
)
/** 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
private def isFieldWithBitmap(field: Symbol) = {
field.info // ensure that nested objects are transformed
// For checkinit consider normal value getters
// but for lazy values only take into account lazy getters
field.isLazy && field.isMethod && !field.isDeferred
}
/** Does this field require an initialized bit?
* Note: fields of classes inheriting DelayedInit are not checked.
* This is because the they are neither initialized in the constructor
* nor do they have a setter (not if they are vals anyway). The usual
* logic for setting bitmaps does therefor not work for such fields.
* That's why they are excluded.
*/
private def needsInitFlag(sym: Symbol) = (
settings.checkInit.value
&& sym.isGetter
&& !sym.isInitializedToDefault
&& !sym.hasFlag(PARAMACCESSOR | SPECIALIZED | LAZY)
&& !sym.accessed.hasFlag(PRESUPER)
&& !sym.isOuterAccessor
&& !(sym.owner isSubClass DelayedInitClass)
)
/** 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
debuglog("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.hasAccessorFlag && (!member.isDeferred || (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 = {
debuglog("new member of " + clazz + ":" + member.defString)
clazz.info.decls enter member setFlag MIXEDIN
}
def needsExpandedSetterName(field: Symbol) = !field.isLazy && (
if (field.isMethod) field.hasStableFlag
else !field.isMutable
)
/** 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))
val newFlags = field.flags & ~PrivateLocal | ACCESSOR | lateDEFERRED | ( if (field.isMutable) 0 else STABLE )
// TODO preserve pre-erasure info?
clazz.newMethod(nme.getterName(field.name), field.pos, newFlags) setInfo MethodType(Nil, field.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 newFlags = field.flags & ~PrivateLocal | ACCESSOR | lateDEFERRED
val setter = clazz.newMethod(setterName, field.pos, newFlags)
// TODO preserve pre-erasure info?
setter setInfo MethodType(setter.newSyntheticValueParams(List(field.info)), UnitClass.tpe)
if (needsExpandedSetterName(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) {
if (!member.isMethod && !member.isModule && !member.isModuleVar) {
assert(member.isTerm && !member.isDeferred, member)
if (member.getter(impl).isPrivate) {
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.isLazy) {
val setter = member.setter(clazz, needsExpandedSetterName(member))
if (setter == NoSymbol) addMember(clazz, newSetter(member))
}
}
}
debuglog("new defs of " + clazz + " = " + clazz.info.decls);
}
}
/** 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.nonEmpty, 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(
// XXX this should be impl.isImplClass, except that we get impl classes
// coming through under -optimise which do not agree that they are (because
// the IMPLCLASS flag is unset, I believe.) See ticket #4285.
nme.isImplClassName(impl.name) || impl.isImplClass,
"%s (%s) is not a an implementation class, it cannot mix in %s".format(
impl, impl.defaultFlagString, iface)
)
if (!impl.isImplClass) {
debugwarn("!!! " + impl + " has an impl class name, but !isImplClass: " + impl.defaultFlagString + ", mixing in " + iface)
}
for (member <- impl.info.decls) {
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) {
if (isConcreteAccessor(member)) {
if (isOverriddenAccessor(member, clazz.info.baseClasses)) {
debugwarn("!!! is overridden val: "+member.fullLocationString)
}
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.isLazy) {
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(nme.getterToLocal(member.name), member.pos).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 (PrivateLocal | member.getFlag(MUTABLE | LAZY))
setFlag (if (!member.hasStableFlag) MUTABLE else 0)
setAnnotations accessed.annotations)
}
}
} else if (member.isSuperAccessor) { // 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.hasNoFlags(LIFTED | BRIDGE)) {
// mixin objects: todo what happens with abstract objects?
addMember(clazz, member.cloneSymbol(clazz, member.flags & ~(DEFERRED | lateDEFERRED)) setPos clazz.pos)
}
}
}
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.
*/
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.newModuleSymbol(sym.name.toTermName, sym.pos, MODULE | FINAL)
setModuleClass sym.asInstanceOf[ClassSymbol]
)
clazz.owner.info.decls enter sourceModule
}
sourceModule setInfo sym.tpe
// Companion module isn't visible for anonymous class at this point anyway
assert(clazz.sourceModule != NoSymbol || clazz.isAnonymousClass,
clazz + " has no sourceModule: sym = " + sym + " sym.tpe = " + sym.tpe)
parents1 = List()
decls1 = newScopeWith(decls.toList filter isImplementedStatically: _*)
} else if (!parents.isEmpty) {
parents1 = parents.head :: (parents.tail map toInterface)
}
}
//decls1 = atPhase(phase.next)(newScopeWith(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
}
/** 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.hasAccessorFlag || (sym.isTerm && !sym.isMethod))
&& sym.isPrivate
&& !(currentOwner.isGetter && currentOwner.accessed == sym) // getter
&& !definitions.isValueClass(sym.tpe.resultType.typeSymbol)
&& sym.owner == templ.symbol.owner
&& !sym.isLazy
&& !tree.isDef) {
log("added use in: " + currentOwner + " -- " + tree)
usedIn(sym) ::= currentOwner
}
}
super.traverse(tree)
}
}
}
SingleUseTraverser(templ)
log("usedIn: " + usedIn)
usedIn filter {
case (_, member :: Nil) => member.isValue && member.isLazy
case _ => false
}
}
// --------- 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, newScope)
/** The typer */
private var localTyper: erasure.Typer = _
private def typedPos(pos: Position)(tree: Tree) = localTyper typed { atPos(pos)(tree) }
private def localTyped(pos: Position, tree: Tree, pt: Type) = localTyper.typed(atPos(pos)(tree), pt)
/** Map lazy values to the fields they should null after initialization. */
private var lazyValNullables: Map[Symbol, Set[Symbol]] = _
/** 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 = perRunCaches.newMap[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 && !isValueClass(currentOwner))
addMixedinMembers(currentOwner, unit)
else if (currentOwner hasFlag lateINTERFACE)
addLateInterfaceMembers(currentOwner)
tree
case DefDef(_, _, _, vparams :: Nil, _, _) =>
if (currentOwner.isImplClass) {
if (isImplementedStatically(sym)) {
sym setFlag notOVERRIDE
self = sym.newValueParameter(nme.SELF, sym.pos) setInfo toInterface(currentOwner.typeOfThis)
val selfdef = ValDef(self) setType NoType
copyDefDef(tree)(vparamss = List(selfdef :: vparams))
}
else EmptyTree
}
else {
if (currentOwner.isTrait && sym.isSetter && !atPhase(currentRun.picklerPhase)(sym.isDeferred)) {
sym.addAnnotation(TraitSetterAnnotationClass)
}
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.
*/
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(tree: Tree) = tree match {
case Super(qual, _) =>
transformThis(qual)
case _ =>
tree
}
/** Replace a this reference to the current implementation class by the self
* parameter. Leave all other trees unchanged.
*/
private def transformThis(tree: Tree) = tree match {
case This(_) if tree.symbol.isImplClass =>
assert(tree.symbol == currentOwner.enclClass)
selfRef(tree.pos)
case _ =>
tree
}
/** Create a static reference to given symbol sym of the
* form M.sym 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?
assert(
sym.owner.sourceModule ne NoSymbol,
"" + sym.fullLocationString + " in " + sym.owner.owner + " " + sym.owner.owner.info.decls
)
REF(sym.owner.sourceModule) DOT sym
}
def needsInitAndHasOffset(sym: Symbol) =
needsInitFlag(sym) && (fieldOffset contains sym)
/** Examines the symbol and returns a name indicating what brand of
* bitmap it requires. The possibilities are the BITMAP_* vals
* defined in StdNames. If it needs no bitmap, nme.NO_NAME.
*/
def bitmapCategory(field: Symbol): Name = {
import nme._
val isNormal = (
if (isFieldWithBitmap(field)) true
// bitmaps for checkinit fields are not inherited
else if (needsInitFlag(field) && !field.isDeferred) false
else return NO_NAME
)
if (field.accessed hasAnnotation TransientAttr) {
if (isNormal) BITMAP_TRANSIENT
else BITMAP_CHECKINIT_TRANSIENT
}
else if (field hasFlag PRIVATE | notPRIVATE) {
if (isNormal) BITMAP_PRIVATE
else BITMAP_CHECKINIT
}
else {
if (isNormal) BITMAP_NORMAL
else BITMAP_CHECKINIT
}
}
/** 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 = mutable.ListBuffer[Tree]()
/** Attribute given tree and anchor at given position */
def attributedDef(pos: Position, tree: Tree): Tree = {
debuglog("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 symbol.
* @param rhs The method body.
*/
def addDefDef(sym: Symbol, rhs: Tree = EmptyTree) = addDef(position(sym), DefDef(sym, rhs))
def addValDef(sym: Symbol, rhs: Tree = EmptyTree) = addDef(position(sym), ValDef(sym, rhs))
/** Add `newdefs` to `stats`, removing any abstract method definitions
* in stats that are matched by some symbol defined in
* newDefs.
*/
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)
}
def addDeferredBitmap(clazz: Symbol, tree: Tree) {
// Append the set of deferred defs
deferredBitmaps(clazz) ::= typedPos(clazz.pos)(tree)
}
/** 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(_, _, _, vparams :: Nil, _, EmptyTree) if stat.symbol.isSuperAccessor =>
val rhs0 = (Super(clazz, tpnme.EMPTY) DOT stat.symbol.alias)(vparams map (v => Ident(v.symbol)): _*)
val rhs1 = localTyped(stat.pos, rhs0, stat.symbol.tpe.resultType)
debuglog(
"complete super acc " + stat.symbol.fullLocationString +
" " + rhs1 + " " + stat.symbol.alias.fullLocationString +
"/" + stat.symbol.alias.owner.hasFlag(lateINTERFACE)
)//debug
deriveDefDef(stat)(_ => atPhase(currentRun.mixinPhase)(transform(rhs1)))
case _ =>
stat
}
import lazyVals._
/**
* Private or transient lazy vals use bitmaps that are private for the class context,
* unlike public or protected vals, which can use inherited bitmaps.
* Similarly fields in the checkinit mode use private bitmaps.
*/
def isLocalBitmapField(field: Symbol) = (
field.accessed.hasAnnotation(TransientAttr)
|| field.hasFlag(PRIVATE | notPRIVATE)
|| isCheckInitField(field)
)
/**
* Return the bitmap field for 'offset'. Depending on the hierarchy it is possible to reuse
* the bitmap of its parents. If that does not exist yet we create one.
*/
def bitmapFor(clazz0: Symbol, offset: Int, field: Symbol, searchParents: Boolean = true): Symbol = {
val category = bitmapCategory(field)
val bitmapName = nme.newBitmapName(category, offset / FLAGS_PER_WORD)
val sym = clazz0.info.member(bitmapName)
assert(!sym.isOverloaded, sym)
def createBitmap: Symbol = {
val sym = clazz0.newVariable(bitmapName, clazz0.pos) setInfo IntClass.tpe
atPhase(currentRun.typerPhase)(sym addAnnotation VolatileAttr)
category match {
case nme.BITMAP_TRANSIENT | nme.BITMAP_CHECKINIT_TRANSIENT => sym addAnnotation TransientAttr
case _ =>
}
category match {
case nme.BITMAP_NORMAL if field.isLazy => sym setFlag PROTECTED
case _ => sym setFlag PrivateLocal
}
clazz0.info.decls.enter(sym)
if (clazz0 == clazz)
addDef(clazz.pos, VAL(sym) === ZERO)
else {
//FIXME: the assertion below will not work because of the way bitmaps are added.
// They should be added during infoTransform, so that in separate compilation, bitmap
// is a member of clazz and doesn't fail the condition couple lines below.
// This works, as long as we assume that the previous classes were compiled correctly.
//assert(clazz0.sourceFile != null)
addDeferredBitmap(clazz0, VAL(sym) === ZERO)
}
sym
}
if (sym ne NoSymbol)
sym
else if (searchParents && !isLocalBitmapField(field))
bitmapForParents(clazz0, offset, field) getOrElse createBitmap
else
createBitmap
}
def bitmapForParents(clazz0: Symbol, offset: Int, valSym: Symbol): Option[Symbol] = {
def requiredBitmaps(fs: Int): Int = if (fs == 0) -1 else (fs - 1) / FLAGS_PER_WORD
val bitmapNum = offset / FLAGS_PER_WORD
// filter private and transient
// since we do not inherit normal values (in checkinit mode) also filter them out
// !!! Not sure how that comment relates to this code...
superClassesToCheck(clazz0) foreach { cl =>
val fields0 = usedBits(cl)
if (requiredBitmaps(fields0) < bitmapNum) {
val fields1 = cl.info.decls filter isNonLocalFieldWithBitmap size;
return {
if (requiredBitmaps(fields0 + fields1) >= bitmapNum)
Some(bitmapFor(cl, offset, valSym, false))
else None // Don't waste time, since we won't find bitmap anyway
}
}
}
None
}
/** Return an (untyped) tree of the form 'Clazz.this.bmp = Clazz.this.bmp | mask'. */
def mkSetFlag(clazz: Symbol, offset: Int, valSym: Symbol): Tree = {
val bmp = bitmapFor(clazz, offset, valSym)
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 = )
* @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$ =
* 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) = Select(This(clazz), sym.accessedOrSelf) === LIT(null)
val bitmapSym = bitmapFor(clazz, offset, lzyVal)
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, lzyVal), UNIT)
log("nulling fields inside " + lzyVal + ": " + nulls)
val result = gen.mkDoubleCheckedLocking(clazz, cond, syncBody, nulls)
typedPos(init.head.pos)(BLOCK(result, retVal))
}
def mkInnerClassAccessorDoubleChecked(attrThis: Tree, rhs: Tree): Tree =
rhs match {
case Block(List(assign), returnTree) =>
val Assign(moduleVarRef, _) = assign
val cond = Apply(Select(moduleVarRef, nme.eq), List(NULL))
val doubleSynchrTree = gen.mkDoubleCheckedLocking(attrThis, cond, List(assign), Nil)
Block(List(doubleSynchrTree), returnTree)
case _ =>
assert(false, "Invalid getter " + rhs + " for module in class " + clazz)
EmptyTree
}
def mkCheckedAccessor(clazz: Symbol, retVal: Tree, offset: Int, pos: Position, fieldSym: Symbol): Tree = {
val bitmapSym = bitmapFor(clazz, offset, fieldSym.getter(fieldSym.owner))
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] = {
def dd(stat: DefDef) = {
val sym = stat.symbol
def isUnit = sym.tpe.resultType.typeSymbol == UnitClass
def isEmpty = stat.rhs == EmptyTree
if (sym.isLazy && !isEmpty && !clazz.isImplClass) {
assert(fieldOffset contains sym, sym)
deriveDefDef(stat)(rhs =>
if (isUnit)
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))
}
)
}
else if (needsInitFlag(sym) && !isEmpty && !clazz.hasFlag(IMPLCLASS | TRAIT)) {
assert(fieldOffset contains sym, sym)
deriveDefDef(stat)(rhs =>
(mkCheckedAccessor(clazz, _: Tree, fieldOffset(sym), stat.pos, sym))(
if (sym.tpe.resultType.typeSymbol == UnitClass) UNIT
else rhs
)
)
}
else if (sym.isConstructor) {
deriveDefDef(stat)(addInitBits(clazz, _))
}
else if (settings.checkInit.value && !clazz.isTrait && sym.isSetter) {
val getter = sym.getter(clazz)
if (needsInitFlag(getter) && fieldOffset.isDefinedAt(getter))
deriveDefDef(stat)(rhs => Block(List(rhs, localTyper.typed(mkSetFlag(clazz, fieldOffset(getter), getter))), UNIT))
else stat
}
else if (sym.isModule && (!clazz.isTrait || clazz.isImplClass) && !sym.isBridge) {
deriveDefDef(stat)(rhs =>
typedPos(stat.pos)(
mkInnerClassAccessorDoubleChecked(
// Martin to Hubert: I think this can be replaced by selfRef(tree.pos)
// @PP: It does not seem so, it crashes for me trying to bootstrap.
if (clazz.isImplClass) gen.mkAttributedIdent(stat.vparamss.head.head.symbol) else gen.mkAttributedThis(clazz),
rhs
)
)
)
}
else stat
}
stats map {
case defn: DefDef => dd(defn)
case stat => stat
}
}
class AddInitBitsTransformer(clazz: Symbol) extends Transformer {
private def checkedGetter(lhs: Tree) = {
val sym = clazz.info decl lhs.symbol.getterName suchThat (_.isGetter)
if (needsInitAndHasOffset(sym)) {
log("adding checked getter for: " + sym + " " + lhs.symbol.defaultFlagString)
List(localTyper typed mkSetFlag(clazz, fieldOffset(sym), sym))
}
else Nil
}
override def transformStats(stats: List[Tree], exprOwner: Symbol) = {
// !!! Ident(self) is never referenced, is it supposed to be confirming
// that self is anything in particular?
super.transformStats(
stats flatMap {
case stat @ Assign(lhs @ Select(This(_), _), rhs) => stat :: checkedGetter(lhs)
// remove initialization for default values
case Apply(lhs @ Select(Ident(self), _), List(EmptyTree)) if lhs.symbol.isSetter => Nil
case stat => List(stat)
},
exprOwner
)
}
}
/** 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 AddInitBitsTransformer(clazz) transform rhs
def isNonLocalFieldWithBitmap(field: Symbol) =
isFieldWithBitmap(field) && !isLocalBitmapField(field)
def isCheckInitField(field: Symbol) =
needsInitFlag(field) && !field.isDeferred
def superClassesToCheck(clazz: Symbol) =
clazz.ancestors filterNot (_ hasFlag TRAIT | JAVA)
/**
* Return the number of bits used by superclass fields.
*/
def usedBits(clazz0: Symbol): Int =
superClassesToCheck(clazz0) flatMap (_.info.decls) count { f =>
f.owner != clazz0 && isNonLocalFieldWithBitmap(f)
}
// begin addNewDefs
/** 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 buildBitmapOffsets() {
def fold(zero: Int, fields: List[Symbol]) = {
var idx = zero
fields foreach { f =>
idx += 1
fieldOffset(f) = idx
}
}
clazz.info.decls.toList groupBy bitmapCategory foreach {
case (nme.NO_NAME, _) => ()
case (nme.BITMAP_NORMAL, fields) => fold(usedBits(clazz), fields)
case (_, fields) => fold(0, fields)
}
}
buildBitmapOffsets()
var stats1 = addCheckedGetters(clazz, stats)
// add deferred bitmaps
deferredBitmaps remove clazz foreach { d => stats1 = add(stats1, d) }
def accessedReference(sym: Symbol) = sym.tpe match {
case MethodType(Nil, ConstantType(c)) => Literal(c)
case _ =>
// if it is a mixed-in lazy value, complete the accessor
if (sym.isLazy && sym.isGetter) {
val isUnit = sym.tpe.resultType.typeSymbol == UnitClass
val initCall = Apply(staticRef(initializer(sym)), gen.mkAttributedThis(clazz) :: Nil)
val selection = Select(This(clazz), sym.accessed)
val init = if (isUnit) initCall else atPos(sym.pos)(Assign(selection, initCall))
val returns = if (isUnit) UNIT else selection
mkLazyDef(clazz, sym, List(init), returns, fieldOffset(sym))
}
else sym.getter(sym.owner).tpe.resultType.typeSymbol match {
case UnitClass => UNIT
case _ => Select(This(clazz), sym.accessed)
}
}
def isOverriddenSetter(sym: Symbol) =
nme.isTraitSetterName(sym.name) && {
val other = sym.nextOverriddenSymbol
isOverriddenAccessor(other.getter(other.owner), clazz.info.baseClasses)
}
// for all symbols `sym` in the class definition, which are mixed in:
for (sym <- clazz.info.decls ; if sym hasFlag MIXEDIN) {
// if current class is a trait interface, add an abstract method for accessor `sym`
if (clazz hasFlag lateINTERFACE) {
addDefDef(sym)
}
// if class is not a trait add accessor definitions
else if (!clazz.isTrait) {
if (sym.hasAccessorFlag && (!sym.isDeferred || sym.hasFlag(lateDEFERRED))) {
// add accessor definitions
addDefDef(sym, {
val accessedRef = accessedReference(sym)
if (sym.isSetter) {
if (isOverriddenSetter(sym)) UNIT
else accessedRef match {
case Literal(_) => accessedRef
case _ =>
val init = Assign(accessedRef, Ident(sym.firstParam))
val getter = sym.getter(clazz)
if (!needsInitFlag(getter)) init
else Block(init, mkSetFlag(clazz, fieldOffset(getter), getter), UNIT)
}
}
else if (needsInitFlag(sym))
mkCheckedAccessor(clazz, accessedRef, fieldOffset(sym), sym.pos, sym)
else
gen.mkCheckInit(accessedRef)
})
}
else if (sym.isModule && !(sym hasFlag LIFTED | BRIDGE)) {
// add modules
val vdef = gen.mkModuleVarDef(sym)
addDef(position(sym), vdef)
val rhs = gen.newModule(sym, vdef.symbol.tpe)
val assignAndRet = gen.mkAssignAndReturn(vdef.symbol, rhs)
val attrThis = gen.mkAttributedThis(clazz)
val rhs1 = mkInnerClassAccessorDoubleChecked(attrThis, assignAndRet)
addDefDef(sym, rhs1)
}
else if (!sym.isMethod) {
// add fields
addValDef(sym)
}
else if (sym.isSuperAccessor) {
// add superaccessors
addDefDef(sym)
}
else {
// add forwarders
assert(sym.alias != NoSymbol, sym)
// debuglog("New forwarder: " + sym.defString + " => " + sym.alias.defString)
addDefDef(sym, Apply(staticRef(sym.alias), gen.mkAttributedThis(clazz) :: sym.paramss.head.map(Ident)))
}
}
}
stats1 = add(stats1, newDefs.toList)
if (!clazz.isTrait) stats1 = stats1 map completeSuperAccessor
stats1
}
private def nullableFields(templ: Template): Map[Symbol, Set[Symbol]] = {
val scope = templ.symbol.owner.info.decls
// if there are no lazy fields, take the fast path and save a traversal of the whole AST
if (scope exists (_.isLazy)) {
val map = mutable.Map[Symbol, Set[Symbol]]() withDefaultValue Set()
// check what fields can be nulled for
for ((field, users) <- singleUseFields(templ); lazyFld <- users)
map(lazyFld) += field
map.toMap
}
else Map()
}
/** 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 via an abstract method in the interface.
*/
private def postTransform(tree: Tree): Tree = {
val sym = tree.symbol
// assert(tree.tpe ne null, tree.getClass +" : "+ tree +" in "+ localTyper.context.tree)
// 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 && ((sym eq null) || !sym.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)
// mark fields which can be nulled afterward
lazyValNullables = nullableFields(tree.asInstanceOf[Template]) withDefaultValue Set()
// add all new definitions to current class or interface
treeCopy.Template(tree, parents1, self, addNewDefs(currentOwner, body))
// remove widening casts
case Apply(TypeApply(Select(qual, _), targ :: _), _) if isCastSymbol(sym) && (qual.tpe <:< targ.tpe) =>
qual
case Apply(Select(qual, _), args) =>
/** Changes qual.m(args) where m refers to an implementation
* class method to Q.m(S, args) where Q is the implementation module of
* m 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) = {
def implSym = implClass(sym.owner).info.member(sym.name)
assert(target ne NoSymbol,
List(sym + ":", sym.tpe, sym.owner, implClass(sym.owner), implSym,
atPhase(phase.prev)(implSym.tpe), phase) mkString " "
)
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 == tpnme.EMPTY && currentOwner.enclClass.isImplClass)
assert(false, "illegal super in trait: " + currentOwner.enclClass + " " + tree);
if (sym.owner hasFlag lateINTERFACE) {
if (sym.hasAccessorFlag) {
assert(args.isEmpty, args)
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, currentOwner.enclClass)
tree
}
case _ =>
tree
}
case This(_) =>
transformThis(tree)
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, sym)
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 = {
val saved = localTyper
val tree1 = super.transform(preTransform(tree))
// localTyper needed when not flattening inner classes. parts after an
// inner class will otherwise be typechecked with a wrong scope
try atPhase(phase.next)(postTransform(tree1))
finally localTyper = saved
}
}
}