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|
/* NSC -- new Scala compiler
* Copyright 2005-2012 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package transform
import symtab._
import Flags._
import scala.collection._
import scala.language.postfixOps
abstract class CleanUp extends Transform with ast.TreeDSL {
import global._
import definitions._
import CODE._
import treeInfo.StripCast
/** the following two members override abstract members in Transform */
val phaseName: String = "cleanup"
protected def newTransformer(unit: CompilationUnit): Transformer =
new CleanUpTransformer(unit)
class CleanUpTransformer(unit: CompilationUnit) extends Transformer {
private val newStaticMembers = mutable.Buffer.empty[Tree]
private val newStaticInits = mutable.Buffer.empty[Tree]
private val symbolsStoredAsStatic = mutable.Map.empty[String, Symbol]
private def clearStatics() {
newStaticMembers.clear()
newStaticInits.clear()
symbolsStoredAsStatic.clear()
}
private def savingStatics[T](body: => T): T = {
val savedNewStaticMembers : mutable.Buffer[Tree] = newStaticMembers.clone()
val savedNewStaticInits : mutable.Buffer[Tree] = newStaticInits.clone()
val savedSymbolsStoredAsStatic : mutable.Map[String, Symbol] = symbolsStoredAsStatic.clone()
val result = body
clearStatics()
newStaticMembers ++= savedNewStaticMembers
newStaticInits ++= savedNewStaticInits
symbolsStoredAsStatic ++= savedSymbolsStoredAsStatic
result
}
private def transformTemplate(tree: Tree) = {
val Template(parents, self, body) = tree
clearStatics()
val newBody = transformTrees(body)
val templ = deriveTemplate(tree)(_ => transformTrees(newStaticMembers.toList) ::: newBody)
try addStaticInits(templ) // postprocess to include static ctors
finally clearStatics()
}
private def mkTerm(prefix: String): TermName = unit.freshTermName(prefix)
//private val classConstantMeth = new HashMap[String, Symbol]
//private val symbolStaticFields = new HashMap[String, (Symbol, Tree, Tree)]
private var localTyper: analyzer.Typer = null
private object MethodDispatchType extends scala.Enumeration {
val NO_CACHE, MONO_CACHE, POLY_CACHE = Value
}
import MethodDispatchType.{ NO_CACHE, MONO_CACHE, POLY_CACHE }
private def dispatchType() = settings.refinementMethodDispatch.value match {
case "no-cache" => NO_CACHE
case "mono-cache" => MONO_CACHE
case "poly-cache" => POLY_CACHE
}
def shouldRewriteTry(tree: Try) = {
val sym = tree.tpe.typeSymbol
forMSIL && (sym != UnitClass) && (sym != NothingClass)
}
private def typedWithPos(pos: Position)(tree: Tree) =
localTyper.typedPos(pos)(tree)
/** A value class is defined to be only Java-compatible values: unit is
* not part of it, as opposed to isPrimitiveValueClass in definitions. scala.Int is
* a value class, java.lang.Integer is not. */
def isJavaValueClass(sym: Symbol) = boxedClass contains sym
def isJavaValueType(tp: Type) = isJavaValueClass(tp.typeSymbol)
/** The boxed type if it's a primitive; identity otherwise.
*/
def toBoxedType(tp: Type) = if (isJavaValueType(tp)) boxedClass(tp.typeSymbol).tpe else tp
def transformApplyDynamic(ad: ApplyDynamic) = {
val qual0 = ad.qual
val params = ad.args
if (settings.logReflectiveCalls.value)
unit.echo(ad.pos, "method invocation uses reflection")
val typedPos = typedWithPos(ad.pos) _
assert(ad.symbol.isPublic)
var qual: Tree = qual0
/* ### CREATING THE METHOD CACHE ### */
def addStaticVariableToClass(forName: TermName, forType: Type, forInit: Tree, isFinal: Boolean): Symbol = {
val flags = PRIVATE | STATIC | SYNTHETIC | (
if (isFinal) FINAL else 0
)
val varSym = currentClass.newVariable(mkTerm("" + forName), ad.pos, flags) setInfoAndEnter forType
if (!isFinal)
varSym.addAnnotation(VolatileAttr)
val varDef = typedPos( VAL(varSym) === forInit )
newStaticMembers append transform(varDef)
val varInit = typedPos( REF(varSym) === forInit )
newStaticInits append transform(varInit)
varSym
}
def addStaticMethodToClass(forBody: (Symbol, Symbol) => Tree): Symbol = {
val methSym = currentClass.newMethod(mkTerm(nme.reflMethodName), ad.pos, STATIC | SYNTHETIC)
val params = methSym.newSyntheticValueParams(List(ClassClass.tpe))
methSym setInfoAndEnter MethodType(params, MethodClass.tpe)
val methDef = typedPos(DefDef(methSym, forBody(methSym, params.head)))
newStaticMembers append transform(methDef)
methSym
}
def fromTypesToClassArrayLiteral(paramTypes: List[Type]): Tree =
ArrayValue(TypeTree(ClassClass.tpe), paramTypes map LIT)
/* ... */
def reflectiveMethodCache(method: String, paramTypes: List[Type]): Symbol = dispatchType match {
case NO_CACHE =>
/* Implementation of the cache is as follows for method "def xyz(a: A, b: B)":
var reflParams$Cache: Array[Class[_]] = Array[JClass](classOf[A], classOf[B])
def reflMethod$Method(forReceiver: JClass[_]): JMethod =
forReceiver.getMethod("xyz", reflParams$Cache)
*/
val reflParamsCacheSym: Symbol =
addStaticVariableToClass(nme.reflParamsCacheName, arrayType(ClassClass.tpe), fromTypesToClassArrayLiteral(paramTypes), true)
addStaticMethodToClass((_, forReceiverSym) =>
gen.mkMethodCall(REF(forReceiverSym), Class_getMethod, Nil, List(LIT(method), REF(reflParamsCacheSym)))
)
case MONO_CACHE =>
/* Implementation of the cache is as follows for method "def xyz(a: A, b: B)"
(but with a SoftReference wrapping reflClass$Cache, similarly in the poly Cache) :
var reflParams$Cache: Array[Class[_]] = Array[JClass](classOf[A], classOf[B])
var reflMethod$Cache: JMethod = null
var reflClass$Cache: JClass[_] = null
def reflMethod$Method(forReceiver: JClass[_]): JMethod = {
if (reflClass$Cache != forReceiver) {
reflMethod$Cache = forReceiver.getMethod("xyz", reflParams$Cache)
reflClass$Cache = forReceiver
}
reflMethod$Cache
}
*/
val reflParamsCacheSym: Symbol =
addStaticVariableToClass(nme.reflParamsCacheName, arrayType(ClassClass.tpe), fromTypesToClassArrayLiteral(paramTypes), true)
val reflMethodCacheSym: Symbol =
addStaticVariableToClass(nme.reflMethodCacheName, MethodClass.tpe, NULL, false)
val reflClassCacheSym: Symbol =
addStaticVariableToClass(nme.reflClassCacheName, SoftReferenceClass.tpe, NULL, false)
def isCacheEmpty(receiver: Symbol): Tree =
reflClassCacheSym.IS_NULL() OR (reflClassCacheSym.GET() OBJ_NE REF(receiver))
addStaticMethodToClass((_, forReceiverSym) =>
BLOCK(
IF (isCacheEmpty(forReceiverSym)) THEN BLOCK(
REF(reflMethodCacheSym) === ((REF(forReceiverSym) DOT Class_getMethod)(LIT(method), REF(reflParamsCacheSym))) ,
REF(reflClassCacheSym) === gen.mkSoftRef(REF(forReceiverSym)),
UNIT
) ENDIF,
REF(reflMethodCacheSym)
)
)
case POLY_CACHE =>
/* Implementation of the cache is as follows for method "def xyz(a: A, b: B)"
(SoftReference so that it does not interfere with classloader garbage collection, see ticket
#2365 for details):
var reflParams$Cache: Array[Class[_]] = Array[JClass](classOf[A], classOf[B])
var reflPoly$Cache: SoftReference[scala.runtime.MethodCache] = new SoftReference(new EmptyMethodCache())
def reflMethod$Method(forReceiver: JClass[_]): JMethod = {
var method: JMethod = reflPoly$Cache.find(forReceiver)
if (method != null)
return method
else {
method = ScalaRunTime.ensureAccessible(forReceiver.getMethod("xyz", reflParams$Cache))
reflPoly$Cache = new SoftReference(reflPoly$Cache.get.add(forReceiver, method))
return method
}
}
*/
val reflParamsCacheSym: Symbol =
addStaticVariableToClass(nme.reflParamsCacheName, arrayType(ClassClass.tpe), fromTypesToClassArrayLiteral(paramTypes), true)
def mkNewPolyCache = gen.mkSoftRef(NEW(TypeTree(EmptyMethodCacheClass.tpe)))
val reflPolyCacheSym: Symbol = (
addStaticVariableToClass(nme.reflPolyCacheName, SoftReferenceClass.tpe, mkNewPolyCache, false)
)
def getPolyCache = gen.mkCast(fn(REF(reflPolyCacheSym), nme.get), MethodCacheClass.tpe)
addStaticMethodToClass((reflMethodSym, forReceiverSym) => {
val methodSym = reflMethodSym.newVariable(mkTerm("method"), ad.pos) setInfo MethodClass.tpe
BLOCK(
IF (getPolyCache OBJ_EQ NULL) THEN (REF(reflPolyCacheSym) === mkNewPolyCache) ENDIF,
VAL(methodSym) === ((getPolyCache DOT methodCache_find)(REF(forReceiverSym))) ,
IF (REF(methodSym) OBJ_!= NULL) .
THEN (Return(REF(methodSym)))
ELSE {
def methodSymRHS = ((REF(forReceiverSym) DOT Class_getMethod)(LIT(method), REF(reflParamsCacheSym)))
def cacheRHS = ((getPolyCache DOT methodCache_add)(REF(forReceiverSym), REF(methodSym)))
BLOCK(
REF(methodSym) === (REF(ensureAccessibleMethod) APPLY (methodSymRHS)),
REF(reflPolyCacheSym) === gen.mkSoftRef(cacheRHS),
Return(REF(methodSym))
)
}
)
})
}
/* ### HANDLING METHODS NORMALLY COMPILED TO OPERATORS ### */
def testForName(name: Name): Tree => Tree = t => (
if (nme.CommonOpNames(name))
gen.mkMethodCall(definitions.Boxes_isNumberOrBool, t :: Nil)
else if (nme.BooleanOpNames(name))
t IS_OBJ BoxedBooleanClass.tpe
else
gen.mkMethodCall(definitions.Boxes_isNumber, t :: Nil)
)
/** The Tree => Tree function in the return is necessary to prevent the original qual
* from being duplicated in the resulting code. It may be a side-effecting expression,
* so all the test logic is routed through gen.evalOnce, which creates a block like
* { val x$1 = qual; if (x$1.foo || x$1.bar) f1(x$1) else f2(x$1) }
* (If the compiler can verify qual is safe to inline, it will not create the block.)
*/
def getPrimitiveReplacementForStructuralCall(name: Name): Option[(Symbol, Tree => Tree)] = {
val methodName = (
if (params.isEmpty) nme.primitivePostfixMethodName(name)
else if (params.tail.isEmpty) nme.primitiveInfixMethodName(name)
else nme.NO_NAME
)
definitions.getDeclIfDefined(BoxesRunTimeClass, methodName) match {
case NoSymbol => None
case sym => assert(!sym.isOverloaded, sym) ; Some((sym, testForName(name)))
}
}
/* ### BOXING PARAMS & UNBOXING RESULTS ### */
/* Transforms the result of a reflective call (always an AnyRef) to
* the actual result value (an AnyRef too). The transformation
* depends on the method's static return type.
* - for units (void), the reflective call will return null: a new
* boxed unit is generated.
* - otherwise, the value is simply casted to the expected type. This
* is enough even for value (int et al.) values as the result of
* a dynamic call will box them as a side-effect. */
/* ### CALLING THE APPLY ### */
def callAsReflective(paramTypes: List[Type], resType: Type): Tree = {
gen.evalOnce(qual, currentOwner, unit) { qual1 =>
/* Some info about the type of the method being called. */
val methSym = ad.symbol
val boxedResType = toBoxedType(resType) // Int -> Integer
val resultSym = boxedResType.typeSymbol
// If this is a primitive method type (like '+' in 5+5=10) then the
// parameter types and the (unboxed) result type should all be primitive types,
// and the method name should be in the primitive->structural map.
def isJavaValueMethod = (
(resType :: paramTypes forall isJavaValueType) && // issue #1110
(getPrimitiveReplacementForStructuralCall(methSym.name).isDefined)
)
// Erasure lets Unit through as Unit, but a method returning Any will have an
// erased return type of Object and should also allow Unit.
def isDefinitelyUnit = (resultSym == UnitClass)
def isMaybeUnit = (resultSym == ObjectClass) || isDefinitelyUnit
// If there's any chance this signature could be met by an Array.
val isArrayMethodSignature = {
def typesMatchApply = paramTypes match {
case List(tp) => tp <:< IntClass.tpe
case _ => false
}
def typesMatchUpdate = paramTypes match {
case List(tp1, tp2) => (tp1 <:< IntClass.tpe) && isMaybeUnit
case _ => false
}
(methSym.name == nme.length && params.isEmpty) ||
(methSym.name == nme.clone_ && params.isEmpty) ||
(methSym.name == nme.apply && typesMatchApply) ||
(methSym.name == nme.update && typesMatchUpdate)
}
/* Some info about the argument at the call site. */
val qualSym = qual.tpe.typeSymbol
val args = qual1() :: params
def isDefinitelyArray = (qualSym == ArrayClass)
def isMaybeArray = (qualSym == ObjectClass) || isDefinitelyArray
def isMaybeBoxed = platform isMaybeBoxed qualSym
// This is complicated a bit by trying to handle Arrays correctly.
// Under normal circumstances if the erased return type is Object then
// we're not going to box it to Unit, but that is the situation with
// a signature like def f(x: { def update(x: Int, y: Long): Any })
//
// However we only want to do that boxing if it has been determined
// to be an Array and a method returning Unit. But for this fixResult
// could be called in one place: instead it is called separately from the
// unconditional outcomes (genValueCall, genArrayCall, genDefaultCall.)
def fixResult(tree: Tree, mustBeUnit: Boolean = false) =
if (mustBeUnit || resultSym == UnitClass) BLOCK(tree, REF(BoxedUnit_UNIT)) // boxed unit
else if (resultSym == ObjectClass) tree // no cast necessary
else gen.mkCast(tree, boxedResType) // cast to expected type
/** Normal non-Array call */
def genDefaultCall = {
// reflective method call machinery
val invokeName = MethodClass.tpe member nme.invoke_ // scala.reflect.Method.invoke(...)
def cache = REF(reflectiveMethodCache(ad.symbol.name.toString, paramTypes)) // cache Symbol
def lookup = Apply(cache, List(qual1() GETCLASS)) // get Method object from cache
def invokeArgs = ArrayValue(TypeTree(ObjectClass.tpe), params) // args for invocation
def invocation = (lookup DOT invokeName)(qual1(), invokeArgs) // .invoke(qual1, ...)
// exception catching machinery
val invokeExc = currentOwner.newValue(mkTerm(""), ad.pos) setInfo InvocationTargetExceptionClass.tpe
def catchVar = Bind(invokeExc, Typed(Ident(nme.WILDCARD), TypeTree(InvocationTargetExceptionClass.tpe)))
def catchBody = Throw(Apply(Select(Ident(invokeExc), nme.getCause), Nil))
// try { method.invoke } catch { case e: InvocationTargetExceptionClass => throw e.getCause() }
fixResult(TRY (invocation) CATCH { CASE (catchVar) ==> catchBody } ENDTRY)
}
/** A possible primitive method call, represented by methods in BoxesRunTime. */
def genValueCall(operator: Symbol) = fixResult(REF(operator) APPLY args)
def genValueCallWithTest = {
getPrimitiveReplacementForStructuralCall(methSym.name) match {
case Some((operator, test)) =>
IF (test(qual1())) THEN genValueCall(operator) ELSE genDefaultCall
case _ =>
genDefaultCall
}
}
/** A native Array call. */
def genArrayCall = fixResult(
methSym.name match {
case nme.length => REF(boxMethod(IntClass)) APPLY (REF(arrayLengthMethod) APPLY args)
case nme.update => REF(arrayUpdateMethod) APPLY List(args(0), (REF(unboxMethod(IntClass)) APPLY args(1)), args(2))
case nme.apply => REF(arrayApplyMethod) APPLY List(args(0), (REF(unboxMethod(IntClass)) APPLY args(1)))
case nme.clone_ => REF(arrayCloneMethod) APPLY List(args(0))
},
mustBeUnit = methSym.name == nme.update
)
/** A conditional Array call, when we can't determine statically if the argument is
* an Array, but the structural type method signature is consistent with an Array method
* so we have to generate both kinds of code.
*/
def genArrayCallWithTest =
IF ((qual1() GETCLASS()) DOT nme.isArray) THEN genArrayCall ELSE genDefaultCall
localTyper typed (
if (isMaybeBoxed && isJavaValueMethod) genValueCallWithTest
else if (isArrayMethodSignature && isDefinitelyArray) genArrayCall
else if (isArrayMethodSignature && isMaybeArray) genArrayCallWithTest
else genDefaultCall
)
}
}
if (settings.refinementMethodDispatch.value == "invoke-dynamic") {
/* val guardCallSite: Tree = {
val cachedClass = addStaticVariableToClass("cachedClass", definitions.ClassClass.tpe, EmptyTree)
val tmpVar = currentOwner.newVariable(ad.pos, unit.freshTermName(ad.pos, "x")).setInfo(definitions.AnyRefClass.tpe)
atPos(ad.pos)(Block(List(
ValDef(tmpVar, transform(qual))),
If(Apply(Select(gen.mkAttributedRef(cachedClass), nme.EQ), List(getClass(Ident(tmpVar)))),
Block(List(Assign(gen.mkAttributedRef(cachedClass), getClass(Ident(tmpVar)))),
treeCopy.ApplyDynamic(ad, Ident(tmpVar), transformTrees(params))),
EmptyTree)))
}
//println(guardCallSite)
*/
localTyper.typed(treeCopy.ApplyDynamic(ad, transform(qual), transformTrees(params)))
}
else {
/* ### BODY OF THE TRANSFORMATION -> remember we're in case ad@ApplyDynamic(qual, params) ### */
/* This creates the tree that does the reflective call (see general comment
* on the apply-dynamic tree for its format). This tree is simply composed
* of three successive calls, first to getClass on the callee, then to
* getMethod on the class, then to invoke on the method.
* - getMethod needs an array of classes for choosing one amongst many
* overloaded versions of the method. This is provided by paramTypeClasses
* and must be done on the static type as Scala's dispatching is static on
* the parameters.
* - invoke needs an array of AnyRefs that are the method's arguments. The
* erasure phase guarantees that any parameter passed to a dynamic apply
* is compatible (through boxing). Boxed ints et al. is what invoke expects
* when the applied method expects ints, hence no change needed there.
* - in the end, the result of invoke must be fixed, again to deal with arrays.
* This is provided by fixResult. fixResult will cast the invocation's result
* to the method's return type, which is generally ok, except when this type
* is a value type (int et al.) in which case it must cast to the boxed version
* because invoke only returns object and erasure made sure the result is
* expected to be an AnyRef. */
val t: Tree = {
val (mparams, resType) = ad.symbol.tpe match {
case MethodType(mparams, resType) =>
assert(params.length == mparams.length, ((params, mparams)))
(mparams, resType)
case tpe @ OverloadedType(pre, alts) =>
unit.warning(ad.pos, s"Overloaded type reached the backend! This is a bug in scalac.\n Symbol: ${ad.symbol}\n Overloads: $tpe\n Arguments: " + ad.args.map(_.tpe))
alts filter (_.paramss.flatten.size == params.length) map (_.tpe) match {
case mt @ MethodType(mparams, resType) :: Nil =>
unit.warning(NoPosition, "Only one overload has the right arity, proceeding with overload " + mt)
(mparams, resType)
case _ =>
unit.error(ad.pos, "Cannot resolve overload.")
(Nil, NoType)
}
}
typedPos {
val sym = currentOwner.newValue(mkTerm("qual"), ad.pos) setInfo qual0.tpe
qual = REF(sym)
BLOCK(
VAL(sym) === qual0,
callAsReflective(mparams map (_.tpe), resType)
)
}
}
/* For testing purposes, the dynamic application's condition
* can be printed-out in great detail. Remove? */
if (settings.debug.value) {
def paramsToString(xs: Any*) = xs map (_.toString) mkString ", "
val mstr = ad.symbol.tpe match {
case MethodType(mparams, resType) =>
"""| with
| - declared parameter types: '%s'
| - passed argument types: '%s'
| - result type: '%s'""" .
stripMargin.format(
paramsToString(mparams),
paramsToString(params),
resType.toString
)
case _ => ""
}
log(
"""Dynamically application '%s.%s(%s)' %s - resulting code: '%s'""".format(
qual, ad.symbol.name, paramsToString(params), mstr, t
)
)
}
/* We return the dynamic call tree, after making sure no other
* clean-up transformation are to be applied on it. */
transform(t)
}
/* ### END OF DYNAMIC APPLY TRANSFORM ### */
}
override def transform(tree: Tree): Tree = tree match {
/* Transforms dynamic calls (i.e. calls to methods that are undefined
* in the erased type space) to -- dynamically -- unsafe calls using
* reflection. This is used for structural sub-typing of refinement
* types, but may be used for other dynamic calls in the future.
* For 'a.f(b)' it will generate something like:
* 'a.getClass().
* ' getMethod("f", Array(classOf[b.type])).
* ' invoke(a, Array(b))
* plus all the necessary casting/boxing/etc. machinery required
* for type-compatibility (see fixResult).
*
* USAGE CONTRACT:
* There are a number of assumptions made on the way a dynamic apply
* is used. Assumptions relative to type are handled by the erasure
* phase.
* - The applied arguments are compatible with AnyRef, which means
* that an argument tree typed as AnyVal has already been extended
* with the necessary boxing calls. This implies that passed
* arguments might not be strictly compatible with the method's
* parameter types (a boxed integer while int is expected).
* - The expected return type is an AnyRef, even when the method's
* return type is an AnyVal. This means that the tree containing the
* call has already been extended with the necessary unboxing calls
* (or is happy with the boxed type).
* - The type-checker has prevented dynamic applies on methods which
* parameter's erased types are not statically known at the call site.
* This is necessary to allow dispatching the call to the correct
* method (dispatching on parameters is static in Scala). In practice,
* this limitation only arises when the called method is defined as a
* refinement, where the refinement defines a parameter based on a
* type variable. */
case tree: ApplyDynamic =>
transformApplyDynamic(tree)
/* Some cleanup transformations add members to templates (classes, traits, etc).
* When inside a template (i.e. the body of one of its members), two maps
* (newStaticMembers and newStaticInits) are available in the tree transformer. Any mapping from
* a symbol to a MemberDef (DefDef, ValDef, etc.) that is in newStaticMembers once the
* transformation of the template is finished will be added as a member to the
* template. Any mapping from a symbol to a tree that is in newStaticInits, will be added
* as a statement of the form "symbol = tree" to the beginning of the default
* constructor. */
case Template(parents, self, body) =>
localTyper = typer.atOwner(tree, currentClass)
if (forMSIL) savingStatics( transformTemplate(tree) )
else transformTemplate(tree)
case Literal(c) if (c.tag == ClazzTag) && !forMSIL=>
val tpe = c.typeValue
typedWithPos(tree.pos) {
if (isPrimitiveValueClass(tpe.typeSymbol)) {
if (tpe.typeSymbol == UnitClass)
REF(BoxedUnit_TYPE)
else
Select(REF(boxedModule(tpe.typeSymbol)), nme.TYPE_)
}
else tree
}
/* MSIL requires that the stack is empty at the end of a try-block.
* Hence, we here rewrite all try blocks with a result != {Unit, All} such that they
* store their result in a local variable. The catch blocks are adjusted as well.
* The try tree is subsituted by a block whose result expression is read of that variable. */
case theTry @ Try(block, catches, finalizer) if shouldRewriteTry(theTry) =>
def transformTry = {
val tpe = theTry.tpe.widen
val tempVar = currentOwner.newVariable(mkTerm(nme.EXCEPTION_RESULT_PREFIX), theTry.pos).setInfo(tpe)
def assignBlock(rhs: Tree) = super.transform(BLOCK(Ident(tempVar) === transform(rhs)))
val newBlock = assignBlock(block)
val newCatches = for (CaseDef(pattern, guard, body) <- catches) yield
(CASE(super.transform(pattern)) IF (super.transform(guard))) ==> assignBlock(body)
val newTry = Try(newBlock, newCatches, super.transform(finalizer))
typedWithPos(theTry.pos)(BLOCK(VAL(tempVar) === EmptyTree, newTry, Ident(tempVar)))
}
transformTry
/*
* This transformation should identify Scala symbol invocations in the tree and replace them
* with references to a static member. Also, whenever a class has at least a single symbol invocation
* somewhere in its methods, a new static member should be created and initialized for that symbol.
* For instance, say we have a Scala class:
*
* class Cls {
* // ...
* def someSymbol = `symbolic
* // ...
* }
*
* After transformation, this class looks like this:
*
* class Cls {
* private "static" val <some_name>$symbolic = Symbol("symbolic")
* // ...
* def someSymbol = <some_name>$symbolic
* // ...
* }
*
* The reasoning behind this transformation is the following. Symbols get interned - they are stored
* in a global map which is protected with a lock. The reason for this is making equality checks
* quicker. But calling Symbol.apply, although it does return a unique symbol, accesses a locked object,
* making symbol access slow. To solve this, the unique symbol from the global symbol map in Symbol
* is accessed only once during class loading, and after that, the unique symbol is in the static
* member. Hence, it is cheap to both reach the unique symbol and do equality checks on it.
*
* And, finally, be advised - scala symbol literal and the Symbol class of the compiler
* have little in common.
*/
case Apply(fn, (arg @ Literal(Constant(symname: String))) :: Nil) if fn.symbol == Symbol_apply =>
def transformApply = {
// add the symbol name to a map if it's not there already
val rhs = gen.mkMethodCall(Symbol_apply, arg :: Nil)
val staticFieldSym = getSymbolStaticField(tree.pos, symname, rhs, tree)
// create a reference to a static field
val ntree = typedWithPos(tree.pos)(REF(staticFieldSym))
super.transform(ntree)
}
transformApply
// Replaces `Array(Predef.wrapArray(ArrayValue(...).$asInstanceOf[...]), <tag>)`
// with just `ArrayValue(...).$asInstanceOf[...]`
//
// See SI-6611; we must *only* do this for literal vararg arrays.
case Apply(appMeth, List(Apply(wrapRefArrayMeth, List(arg @ StripCast(ArrayValue(_, _)))), _))
if wrapRefArrayMeth.symbol == Predef_wrapRefArray && appMeth.symbol == ArrayModule_genericApply =>
super.transform(arg)
case Apply(appMeth, List(elem0, Apply(wrapArrayMeth, List(rest @ ArrayValue(elemtpt, _)))))
if wrapArrayMeth.symbol == Predef_wrapArray(elemtpt.tpe) && appMeth.symbol == ArrayModule_apply(elemtpt.tpe) =>
super.transform(rest.copy(elems = elem0 :: rest.elems))
case _ =>
super.transform(tree)
}
/* Returns the symbol and the tree for the symbol field interning a reference to a symbol 'synmname'.
* If it doesn't exist, i.e. the symbol is encountered the first time,
* it creates a new static field definition and initialization and returns it.
*/
private def getSymbolStaticField(pos: Position, symname: String, rhs: Tree, tree: Tree): Symbol = {
symbolsStoredAsStatic.getOrElseUpdate(symname, {
val theTyper = typer.atOwner(tree, currentClass)
// create a symbol for the static field
val stfieldSym = (
currentClass.newVariable(mkTerm("symbol$"), pos, PRIVATE | STATIC | SYNTHETIC | FINAL)
setInfo SymbolClass.tpe
)
currentClass.info.decls enter stfieldSym
// create field definition and initialization
val stfieldDef = theTyper.typedPos(pos)(VAL(stfieldSym) === rhs)
val stfieldInit = theTyper.typedPos(pos)(REF(stfieldSym) === rhs)
// add field definition to new defs
newStaticMembers append stfieldDef
newStaticInits append stfieldInit
stfieldSym
})
}
/* finds the static ctor DefDef tree within the template if it exists. */
private def findStaticCtor(template: Template): Option[Tree] =
template.body find {
case defdef @ DefDef(_, nme.CONSTRUCTOR, _, _, _, _) => defdef.symbol.hasStaticFlag
case _ => false
}
/* changes the template for the class so that it contains a static constructor with symbol fields inits,
* augments an existing static ctor if one already existed.
*/
private def addStaticInits(template: Template): Template = {
if (newStaticInits.isEmpty)
template
else {
val newCtor = findStaticCtor(template) match {
// in case there already were static ctors - augment existing ones
// currently, however, static ctors aren't being generated anywhere else
case Some(ctor @ DefDef(_,_,_,_,_,_)) =>
// modify existing static ctor
deriveDefDef(ctor) {
case block @ Block(stats, expr) =>
// need to add inits to existing block
treeCopy.Block(block, newStaticInits.toList ::: stats, expr)
case term: TermTree =>
// need to create a new block with inits and the old term
treeCopy.Block(term, newStaticInits.toList, term)
}
case _ =>
// create new static ctor
val staticCtorSym = currentClass.newStaticConstructor(template.pos)
val rhs = Block(newStaticInits.toList, Literal(Constant(())))
localTyper.typedPos(template.pos)(DefDef(staticCtorSym, rhs))
}
deriveTemplate(template)(newCtor :: _)
}
}
} // CleanUpTransformer
}
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