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/* NSC -- new Scala compiler
* Copyright 2005-2011 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package ast
import scala.collection.mutable.ListBuffer
import symtab.Flags._
import symtab.SymbolTable
/** XXX to resolve: TreeGen only assumes global is a SymbolTable, but
* TreeDSL at the moment expects a Global. Can we get by with SymbolTable?
*/
abstract class TreeGen extends reflect.internal.TreeGen {
val global: Global
import global._
import definitions._
def mkCheckInit(tree: Tree): Tree = {
val tpe =
if (tree.tpe != null || !tree.hasSymbol) tree.tpe
else tree.symbol.tpe
if (!global.phase.erasedTypes && settings.Xchecknull.value &&
tpe <:< NotNullClass.tpe && !tpe.isNotNull)
mkRuntimeCall(nme.checkInitialized, List(tree))
else
tree
}
// wrap the given expression in a SoftReference so it can be gc-ed
def mkSoftRef(expr: Tree): Tree = New(TypeTree(SoftReferenceClass.tpe), List(List(expr)))
def mkCached(cvar: Symbol, expr: Tree): Tree = {
val cvarRef = mkUnattributedRef(cvar)
Block(
List(
If(Apply(Select(cvarRef, nme.eq), List(Literal(Constant(null)))),
Assign(cvarRef, expr),
EmptyTree)),
cvarRef
)
}
// Builds a tree of the form "{ lhs = rhs ; lhs }"
def mkAssignAndReturn(lhs: Symbol, rhs: Tree): Tree = {
val lhsRef = mkUnattributedRef(lhs)
Block(Assign(lhsRef, rhs) :: Nil, lhsRef)
}
def mkModuleVarDef(accessor: Symbol) = {
val mval = (
accessor.owner.newVariable(accessor.pos.focus, nme.moduleVarName(accessor.name))
setInfo accessor.tpe.finalResultType
setFlag (MODULEVAR)
)
mval.addAnnotation(AnnotationInfo(VolatileAttr.tpe, Nil, Nil))
if (mval.owner.isClass) {
mval setFlag (PRIVATE | LOCAL | SYNTHETIC)
mval.owner.info.decls.enter(mval)
}
ValDef(mval)
}
// def m: T = { if (m$ eq null) m$ = new m$class(...) m$ }
// where (...) are eventual outer accessors
def mkCachedModuleAccessDef(accessor: Symbol, mvar: Symbol) =
DefDef(accessor, mkCached(mvar, newModule(accessor, mvar.tpe)))
def mkModuleAccessDef(accessor: Symbol, msym: Symbol) =
DefDef(accessor, Select(This(msym.owner), msym))
def newModule(accessor: Symbol, tpe: Type) =
New(TypeTree(tpe),
List(for (pt <- tpe.typeSymbol.primaryConstructor.info.paramTypes)
yield This(accessor.owner.enclClass)))
// def m: T;
def mkModuleAccessDcl(accessor: Symbol) =
DefDef(accessor setFlag lateDEFERRED, EmptyTree)
def mkRuntimeCall(meth: Name, args: List[Tree]): Tree =
Apply(Select(mkAttributedRef(ScalaRunTimeModule), meth), args)
def mkRuntimeCall(meth: Name, targs: List[Type], args: List[Tree]): Tree =
Apply(TypeApply(Select(mkAttributedRef(ScalaRunTimeModule), meth), targs map TypeTree), args)
/** Make a synchronized block on 'monitor'. */
def mkSynchronized(monitor: Tree, body: Tree): Tree =
Apply(Select(monitor, Object_synchronized), List(body))
def wildcardStar(tree: Tree) =
atPos(tree.pos) { Typed(tree, Ident(tpnme.WILDCARD_STAR)) }
def paramToArg(vparam: Symbol) = {
val arg = Ident(vparam)
if (isRepeatedParamType(vparam.tpe)) wildcardStar(arg)
else arg
}
def paramToArg(vparam: ValDef) = {
val arg = Ident(vparam.name)
if (treeInfo.isRepeatedParamType(vparam.tpt)) wildcardStar(arg)
else arg
}
/** Make forwarder to method `target', passing all parameters in `params' */
def mkForwarder(target: Tree, vparamss: List[List[Symbol]]) =
(target /: vparamss)((fn, vparams) => Apply(fn, vparams map paramToArg))
/** Applies a wrapArray call to an array, making it a WrappedArray.
* Don't let a reference type parameter be inferred, in case it's a singleton:
* apply the element type directly.
*/
def mkWrapArray(tree: Tree, elemtp: Type) = {
val sym = elemtp.typeSymbol
val meth: Name =
if (isValueClass(sym)) "wrap"+sym.name+"Array"
else if ((elemtp <:< AnyRefClass.tpe) && !isPhantomClass(sym)) "wrapRefArray"
else "genericWrapArray"
if (isValueClass(sym))
Apply(Select(mkAttributedRef(PredefModule), meth), List(tree))
else
Apply(TypeApply(Select(mkAttributedRef(PredefModule), meth), List(TypeTree(elemtp))), List(tree))
}
/** Generate a cast for tree Tree representing Array with
* elem type elemtp to expected type pt.
*/
def mkCastArray(tree: Tree, elemtp: Type, pt: Type) =
if (elemtp.typeSymbol == AnyClass && isValueClass(tree.tpe.typeArgs.head.typeSymbol))
mkCast(mkRuntimeCall("toObjectArray", List(tree)), pt)
else
mkCast(tree, pt)
/** Translate names in Select/Ident nodes to type names.
*/
def convertToTypeName(tree: Tree): Option[RefTree] = tree match {
case Select(qual, name) => Some(Select(qual, name.toTypeName))
case Ident(name) => Some(Ident(name.toTypeName))
case _ => None
}
/** Try to convert Select(qual, name) to a SelectFromTypeTree.
*/
def convertToSelectFromType(qual: Tree, origName: Name) = convertToTypeName(qual) match {
case Some(qual1) => SelectFromTypeTree(qual1 setPos qual.pos, origName.toTypeName)
case _ => EmptyTree
}
/** Used in situations where you need to access value of an expression several times
*/
def evalOnce(expr: Tree, owner: Symbol, unit: CompilationUnit)(within: (() => Tree) => Tree): Tree = {
var used = false
if (treeInfo.isPureExpr(expr)) {
within(() => if (used) expr.duplicate else { used = true; expr })
} else {
val temp = owner.newValue(expr.pos.makeTransparent, unit.freshTermName("ev$"))
.setFlag(SYNTHETIC).setInfo(expr.tpe)
val containing = within(() => Ident(temp) setPos temp.pos.focus setType expr.tpe)
ensureNonOverlapping(containing, List(expr))
Block(List(ValDef(temp, expr)), containing) setPos (containing.pos union expr.pos)
}
}
def evalOnceAll(exprs: List[Tree], owner: Symbol, unit: CompilationUnit)(within: (List[() => Tree]) => Tree): Tree = {
val vdefs = new ListBuffer[ValDef]
val exprs1 = new ListBuffer[() => Tree]
val used = new Array[Boolean](exprs.length)
var i = 0
for (expr <- exprs) {
if (treeInfo.isPureExpr(expr)) {
exprs1 += {
val idx = i
() => if (used(idx)) expr.duplicate else { used(idx) = true; expr }
}
} else {
val temp = owner.newValue(expr.pos.makeTransparent, unit.freshTermName("ev$"))
.setFlag(SYNTHETIC).setInfo(expr.tpe)
vdefs += ValDef(temp, expr)
exprs1 += (() => Ident(temp) setPos temp.pos.focus setType expr.tpe)
}
i += 1
}
val prefix = vdefs.toList
val containing = within(exprs1.toList)
ensureNonOverlapping(containing, exprs)
if (prefix.isEmpty) containing
else Block(prefix, containing) setPos (prefix.head.pos union containing.pos)
}
/** Return a double-checked locking idiom around the syncBody tree. It guards with 'cond' and
* synchronizez on 'clazz.this'. Additional statements can be included after initialization,
* (outside the synchronized block).
*
* The idiom works only if the condition is using a volatile field.
* @see http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html
*/
def mkDoubleCheckedLocking(clazz: Symbol, cond: Tree, syncBody: List[Tree], stats: List[Tree]): Tree =
mkDoubleCheckedLocking(mkAttributedThis(clazz), cond, syncBody, stats)
def mkDoubleCheckedLocking(attrThis: Tree, cond: Tree, syncBody: List[Tree], stats: List[Tree]): Tree = {
If(cond,
Block(
mkSynchronized(
attrThis,
If(cond, Block(syncBody: _*), EmptyTree)) ::
stats: _*),
EmptyTree)
}
}
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