/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Paul Phillips
*/
package scala.tools.nsc
package typechecker
import symtab.Flags._
import scala.reflect.internal.util.StringOps.ojoin
import scala.reflect.internal.util.ListOfNil
/** Logic related to method synthesis which involves cooperation between
* Namer and Typer.
*/
trait MethodSynthesis {
self: Analyzer =>
import global._
import definitions._
import CODE._
class ClassMethodSynthesis(val clazz: Symbol, localTyper: Typer) {
def mkThis = This(clazz) setPos clazz.pos.focus
def mkThisSelect(sym: Symbol) = atPos(clazz.pos.focus)(
if (clazz.isClass) Select(This(clazz), sym) else Ident(sym)
)
private def isOverride(name: TermName) =
clazzMember(name).alternatives exists (sym => !sym.isDeferred && (sym.owner != clazz))
def newMethodFlags(name: TermName) = {
val overrideFlag = if (isOverride(name)) OVERRIDE else 0L
overrideFlag | SYNTHETIC
}
def newMethodFlags(method: Symbol) = {
val overrideFlag = if (isOverride(method.name.toTermName)) OVERRIDE else 0L
(method.flags | overrideFlag | SYNTHETIC) & ~DEFERRED
}
private def finishMethod(method: Symbol, f: Symbol => Tree): Tree =
localTyper typed (
if (method.isLazy) ValDef(method, f(method))
else DefDef(method, f(method))
)
private def createInternal(name: Name, f: Symbol => Tree, info: Type): Tree = {
val name1 = name.toTermName
val m = clazz.newMethod(name1, clazz.pos.focus, newMethodFlags(name1))
finishMethod(m setInfoAndEnter info, f)
}
private def createInternal(name: Name, f: Symbol => Tree, infoFn: Symbol => Type): Tree = {
val name1 = name.toTermName
val m = clazz.newMethod(name1, clazz.pos.focus, newMethodFlags(name1))
finishMethod(m setInfoAndEnter infoFn(m), f)
}
private def cloneInternal(original: Symbol, f: Symbol => Tree, name: Name): Tree = {
val m = original.cloneSymbol(clazz, newMethodFlags(original), name) setPos clazz.pos.focus
finishMethod(clazz.info.decls enter m, f)
}
def clazzMember(name: Name) = clazz.info nonPrivateMember name
def typeInClazz(sym: Symbol) = clazz.thisType memberType sym
def deriveMethod(original: Symbol, nameFn: Name => Name)(f: Symbol => Tree): Tree =
cloneInternal(original, f, nameFn(original.name))
def createMethod(name: Name, paramTypes: List[Type], returnType: Type)(f: Symbol => Tree): Tree =
createInternal(name, f, (m: Symbol) => MethodType(m newSyntheticValueParams paramTypes, returnType))
def createMethod(name: Name, returnType: Type)(f: Symbol => Tree): Tree =
createInternal(name, f, NullaryMethodType(returnType))
def createMethod(original: Symbol)(f: Symbol => Tree): Tree =
createInternal(original.name, f, original.info)
def forwardMethod(original: Symbol, newMethod: Symbol)(transformArgs: List[Tree] => List[Tree]): Tree =
createMethod(original)(m => gen.mkMethodCall(newMethod, transformArgs(m.paramss.head map Ident)))
def createSwitchMethod(name: Name, range: Seq[Int], returnType: Type)(f: Int => Tree) = {
createMethod(name, List(IntTpe), returnType) { m =>
val arg0 = Ident(m.firstParam)
val default = DEFAULT ==> Throw(IndexOutOfBoundsExceptionClass.tpe_*, fn(arg0, nme.toString_))
val cases = range.map(num => CASE(LIT(num)) ==> f(num)).toList :+ default
Match(arg0, cases)
}
}
// def foo() = constant
def constantMethod(name: Name, value: Any): Tree = {
val constant = Constant(value)
createMethod(name, Nil, constant.tpe)(_ => Literal(constant))
}
// def foo = constant
def constantNullary(name: Name, value: Any): Tree = {
val constant = Constant(value)
createMethod(name, constant.tpe)(_ => Literal(constant))
}
}
/** There are two key methods in here.
*
* 1) Enter methods such as enterGetterSetter are called
* from Namer with a tree which may generate further trees such as accessors or
* implicit wrappers. Some setup is performed. In general this creates symbols
* and enters them into the scope of the owner.
*
* 2) addDerivedTrees is called from Typer when a Template is typed.
* It completes the job, returning a list of trees with their symbols
* set to those created in the enter methods. Those trees then become
* part of the typed template.
*/
trait MethodSynth {
self: Namer =>
import NamerErrorGen._
def enterImplicitWrapper(tree: ClassDef): Unit = {
enterSyntheticSym(ImplicitClassWrapper(tree).derivedTree)
}
// trees are later created by addDerivedTrees (common logic is encapsulated in field/standardAccessors/beanAccessors)
def enterGetterSetter(tree: ValDef): Unit = {
val getter = Getter(tree)
val getterSym = getter.createSym
val setterSym = if (getter.needsSetter) Setter(tree).createSym else NoSymbol
// a lazy field is linked to its lazy accessor (TODO: can we do the same for field -> getter -> setter)
val fieldSym = if (Field.noFieldFor(tree)) NoSymbol else Field(tree).createSym(getterSym)
// only one symbol can have `tree.pos`, the others must focus their position
// normally the field gets the range position, but if there is none, give it to the getter
tree.symbol = fieldSym orElse (getterSym setPos tree.pos)
val namer = if (fieldSym != NoSymbol) namerOf(fieldSym) else namerOf(getterSym)
// There's no reliable way to detect all kinds of setters from flags or name!!!
// A BeanSetter's name does not end in `_=` -- it does begin with "set", but so could the getter
// for a regular Scala field... TODO: can we add a flag to distinguish getter/setter accessors?
val getterCompleter = namer.accessorTypeCompleter(tree, isSetter = false)
val setterCompleter = namer.accessorTypeCompleter(tree, isSetter = true)
getterSym setInfo getterCompleter
setterSym andAlso (_ setInfo setterCompleter)
fieldSym andAlso (_ setInfo namer.valTypeCompleter(tree))
enterInScope(getterSym)
setterSym andAlso (enterInScope(_))
fieldSym andAlso (enterInScope(_))
deriveBeanAccessors(tree, namer)
}
private def deriveBeanAccessors(tree: ValDef, namer: Namer): Unit = {
// TODO: can we look at the annotations symbols? (name-based introduced in 8cc477f8b6, see neg/t3403)
val hasBeanProperty = tree.mods hasAnnotationNamed tpnme.BeanPropertyAnnot
val hasBoolBP = tree.mods hasAnnotationNamed tpnme.BooleanBeanPropertyAnnot
if (hasBeanProperty || hasBoolBP) {
if (!tree.name.charAt(0).isLetter) BeanPropertyAnnotationFieldWithoutLetterError(tree)
// avoids name clashes with private fields in traits
else if (tree.mods.isPrivate) BeanPropertyAnnotationPrivateFieldError(tree)
val derivedPos = tree.pos.focus
val missingTpt = tree.tpt.isEmpty
def deriveBeanAccessor(prefix: String): Symbol = {
val isSetter = prefix == "set"
val name = newTermName(prefix + tree.name.toString.capitalize)
val setterParam = nme.syntheticParamName(1)
// note: tree.tpt may be EmptyTree, which will be a problem when use as the tpt of a parameter
// the completer will patch this up (we can't do this now without completing the field)
val tptToPatch = if (missingTpt) TypeTree() else tree.tpt.duplicate
val (vparams, tpt) =
if (isSetter) (List(ValDef(Modifiers(PARAM | SYNTHETIC), setterParam, tptToPatch, EmptyTree)), TypeTree(UnitTpe))
else (Nil, tptToPatch)
val rhs =
if (tree.mods.isDeferred) EmptyTree
else if (isSetter) Apply(Ident(tree.name.setterName), List(Ident(setterParam)))
else Select(This(owner), tree.name)
val sym = createMethod(tree, name, derivedPos, tree.mods.flags & BeanPropertyFlags)
context.unit.synthetics(sym) = newDefDef(sym, rhs)(tparams = Nil, vparamss = List(vparams), tpt = tpt)
sym
}
val getterCompleter = namer.beanAccessorTypeCompleter(tree, missingTpt, isSetter = false)
enterInScope(deriveBeanAccessor(if (hasBeanProperty) "get" else "is") setInfo getterCompleter)
if (tree.mods.isMutable) {
val setterCompleter = namer.beanAccessorTypeCompleter(tree, missingTpt, isSetter = true)
enterInScope(deriveBeanAccessor("set") setInfo setterCompleter)
}
}
}
import AnnotationInfo.{mkFilter => annotationFilter}
def addDerivedTrees(typer: Typer, stat: Tree): List[Tree] = stat match {
case vd @ ValDef(mods, name, tpt, rhs) if deriveAccessors(vd) && !vd.symbol.isModuleVar =>
stat.symbol.initialize // needed!
val getter = Getter(vd)
getter.validate()
val accessors = getter :: (if (getter.needsSetter) Setter(vd) :: Nil else Nil)
(Field(vd) :: accessors).map(_.derivedTree).filter(_ ne EmptyTree)
case cd @ ClassDef(mods, _, _, _) if mods.isImplicit =>
val annotations = stat.symbol.initialize.annotations
// TODO: need to shuffle annotations between wrapper and class.
val wrapper = ImplicitClassWrapper(cd)
val meth = wrapper.derivedSym
context.unit.synthetics get meth match {
case Some(mdef) =>
context.unit.synthetics -= meth
meth setAnnotations (annotations filter annotationFilter(MethodTargetClass, defaultRetention = false))
cd.symbol setAnnotations (annotations filter annotationFilter(ClassTargetClass, defaultRetention = true))
List(cd, mdef)
case _ =>
// Shouldn't happen, but let's give ourselves a reasonable error when it does
context.error(cd.pos, s"Internal error: Symbol for synthetic factory method not found among ${context.unit.synthetics.keys.mkString(", ")}")
// Soldier on for the sake of the presentation compiler
List(cd)
}
case _ =>
stat :: Nil
}
sealed trait Derived {
/** The derived symbol. It is assumed that this symbol already exists and has been
* entered in the parent scope when derivedSym is called
*/
def derivedSym: Symbol
/** The definition tree of the derived symbol. */
def derivedTree: Tree
}
/** A synthetic method which performs the implicit conversion implied by
* the declaration of an implicit class.
*/
case class ImplicitClassWrapper(tree: ClassDef) extends Derived {
def derivedSym = {
val enclClass = tree.symbol.owner.enclClass
// Only methods will do! Don't want to pick up any stray
// companion objects of the same name.
val result = enclClass.info decl derivedName filter (x => x.isMethod && x.isSynthetic)
if (result == NoSymbol || result.isOverloaded)
context.error(tree.pos, s"Internal error: Unable to find the synthetic factory method corresponding to implicit class $derivedName in $enclClass / ${enclClass.info.decls}")
result
}
def derivedTree = factoryMeth(derivedMods, derivedName, tree)
def derivedName = tree.name.toTermName
def derivedMods = tree.mods & AccessFlags | METHOD | IMPLICIT | SYNTHETIC
}
trait DerivedAccessor extends Derived {
def tree: ValDef
def derivedName: TermName
def derivedFlags: Long
def derivedPos = tree.pos.focus
def createSym = createMethod(tree, derivedName, derivedPos, derivedFlags)
}
case class Getter(tree: ValDef) extends DerivedAccessor {
def derivedName = tree.name
def derivedSym =
if (tree.mods.isLazy) tree.symbol.lazyAccessor
else if (Field.noFieldFor(tree)) tree.symbol
else tree.symbol.getterIn(tree.symbol.enclClass)
def derivedFlags = tree.mods.flags & GetterFlags | ACCESSOR.toLong | ( if (needsSetter) 0 else STABLE )
def needsSetter = tree.mods.isMutable // implies !lazy
override def derivedTree =
if (tree.mods.isLazy) deriveLazyAccessor
else newDefDef(derivedSym, if (Field.noFieldFor(tree)) tree.rhs else Select(This(tree.symbol.enclClass), tree.symbol))(tpt = derivedTpt)
/** Implements lazy value accessors:
* - for lazy values of type Unit and all lazy fields inside traits,
* the rhs is the initializer itself, because we'll just "compute" the result on every access
* ("computing" unit / constant type is free -- the side-effect is still only run once, using the init bitmap)
* - for all other lazy values z the accessor is a block of this form:
* { z = <rhs>; z } where z can be an identifier or a field.
*/
private def deriveLazyAccessor: DefDef = {
val ValDef(_, _, tpt0, rhs0) = tree
val rhs1 = context.unit.transformed.getOrElse(rhs0, rhs0)
val body =
if (tree.symbol.owner.isTrait || Field.noFieldFor(tree)) rhs1 // TODO move tree.symbol.owner.isTrait into noFieldFor
else gen.mkAssignAndReturn(tree.symbol, rhs1)
derivedSym setPos tree.pos // TODO: can we propagate `tree.pos` to `derivedSym` when the symbol is created?
val ddefRes = DefDef(derivedSym, new ChangeOwnerTraverser(tree.symbol, derivedSym)(body))
// ValDef will have its position focused whereas DefDef will have original correct rangepos
// ideally positions would be correct at the creation time but lazy vals are really a special case
// here so for the sake of keeping api clean we fix positions manually in LazyValGetter
ddefRes.tpt.setPos(tpt0.pos)
tpt0.setPos(tpt0.pos.focus)
ddefRes
}
// TODO: more principled approach -- this is a bit bizarre
private def derivedTpt = {
// For existentials, don't specify a type for the getter, even one derived
// from the symbol! This leads to incompatible existentials for the field and
// the getter. Let the typer do all the work. You might think "why only for
// existentials, why not always," and you would be right, except: a single test
// fails, but it looked like some work to deal with it. Test neg/t0606.scala
// starts compiling (instead of failing like it's supposed to) because the typer
// expects to be able to identify escaping locals in typedDefDef, and fails to
// spot that brand of them. In other words it's an artifact of the implementation.
val getterTp = derivedSym.tpe_*.finalResultType
val tpt = getterTp.widen match {
// Range position errors ensue if we don't duplicate this in some
// circumstances (at least: concrete vals with existential types.)
case _: ExistentialType => TypeTree() setOriginal (tree.tpt.duplicate setPos tree.tpt.pos.focus)
case _ if tree.mods.isDeferred => TypeTree() setOriginal tree.tpt // keep type tree of original abstract field
case _ => TypeTree(getterTp)
}
tpt setPos tree.tpt.pos.focus
}
def validate() = {
assert(derivedSym != NoSymbol, tree)
if (derivedSym.isOverloaded)
GetterDefinedTwiceError(derivedSym)
}
}
case class Setter(tree: ValDef) extends DerivedAccessor {
def derivedName = tree.setterName
def derivedSym = tree.symbol.setterIn(tree.symbol.enclClass)
def derivedFlags = tree.mods.flags & SetterFlags | ACCESSOR
def derivedTree =
derivedSym.paramss match {
case (setterParam :: Nil) :: _ =>
// assert(!derivedSym.isOverloaded, s"Unexpected overloaded setter $derivedSym for ${tree.symbol} in ${tree.symbol.enclClass}")
val rhs =
if (Field.noFieldFor(tree) || derivedSym.isOverloaded) EmptyTree
else Assign(Select(This(tree.symbol.enclClass), tree.symbol), Ident(setterParam))
DefDef(derivedSym, rhs)
case _ => EmptyTree
}
}
object Field {
// No field for these vals (either never emitted or eliminated later on):
// - abstract vals have no value we could store (until they become concrete, potentially)
// - lazy vals of type Unit
// - concrete vals in traits don't yield a field here either (their getter's RHS has the initial value)
// Constructors will move the assignment to the constructor, abstracting over the field using the field setter,
// and Fields will add a field to the class that mixes in the trait, implementing the accessors in terms of it
// - [Emitted, later removed during Constructors] a concrete val with a statically known value (ConstantType)
// performs its side effect according to lazy/strict semantics, but doesn't need to store its value
// each access will "evaluate" the RHS (a literal) again
// We would like to avoid emitting unnecessary fields, but the required knowledge isn't available until after typer.
// The only way to avoid emitting & suppressing, is to not emit at all until we are sure to need the field, as dotty does.
// NOTE: do not look at `vd.symbol` when called from `enterGetterSetter` (luckily, that call-site implies `!mods.isLazy`),
// similarly, the `def field` call-site breaks when you add `|| vd.symbol.owner.isTrait` (detected in test suite)
// as the symbol info is in the process of being created then.
// TODO: harmonize tree & symbol creation
// the middle `&& !owner.isTrait` is needed after `isLazy` because non-unit-typed lazy vals in traits still get a field -- see neg/t5455.scala
def noFieldFor(vd: ValDef) = (vd.mods.isDeferred
|| (vd.mods.isLazy && !owner.isTrait && isUnitType(vd.symbol.info))
|| (owner.isTrait && !traitFieldFor(vd)))
// TODO: never emit any fields in traits -- only use getter for lazy/presuper ones as well
private def traitFieldFor(vd: ValDef): Boolean = vd.mods.hasFlag(PRESUPER | LAZY)
}
case class Field(tree: ValDef) extends Derived {
private val isLazy = tree.mods.isLazy
// If the owner is not a class, this is a lazy val from a method,
// with no associated field. It has an accessor with $lzy appended to its name and
// its flags are set differently. The implicit flag is reset because otherwise
// a local implicit "lazy val x" will create an ambiguity with itself
// via "x$lzy" as can be seen in test #3927.
private val localLazyVal = isLazy && !owner.isClass
private val nameSuffix =
if (!localLazyVal) reflect.NameTransformer.LOCAL_SUFFIX_STRING
else reflect.NameTransformer.LAZY_LOCAL_SUFFIX_STRING
def derivedName = tree.name.append(nameSuffix)
def createSym(getter: MethodSymbol) = {
val sym = owner.newValue(derivedName, tree.pos, derivedMods.flags)
if (isLazy) sym setLazyAccessor getter
sym
}
def derivedSym = tree.symbol
def derivedMods =
if (!localLazyVal) tree.mods & FieldFlags | PrivateLocal | (if (isLazy) MUTABLE else 0)
else (tree.mods | ARTIFACT | MUTABLE) & ~IMPLICIT
// TODO: why is this different from the symbol!?
private def derivedModsForTree = tree.mods | PrivateLocal
def derivedTree =
if (Field.noFieldFor(tree)) EmptyTree
else if (isLazy) copyValDef(tree)(mods = derivedModsForTree, name = derivedName, rhs = EmptyTree).setPos(tree.pos.focus)
else copyValDef(tree)(mods = derivedModsForTree, name = derivedName)
}
}
}