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|
/* NSC -- new Scala compiler
* Copyright 2005-2007 LAMP/EPFL
* @author
*/
// $Id$
package scala.tools.nsc.transform
import scala.collection.mutable.ListBuffer
import symtab.Flags._
import util.TreeSet
abstract class Constructors extends Transform {
import global._
import definitions._
import posAssigner.atPos
/** the following two members override abstract members in Transform */
val phaseName: String = "constructors"
protected def newTransformer(unit: CompilationUnit): Transformer =
new ConstructorTransformer
class ConstructorTransformer extends Transformer {
def transformClassTemplate(impl: Template): Template = {
val clazz = impl.symbol.owner
val stats = impl.body
val localTyper = typer.atOwner(impl, clazz)
var constr: DefDef = null
var constrParams: List[Symbol] = null
var constrBody: Block = null
// decompose primary constructor into the three entities above.
for (stat <- stats) {
stat match {
case ddef @ DefDef(_, _, _, List(vparams), _, rhs @ Block(_, Literal(_))) =>
if (ddef.symbol.isPrimaryConstructor) {
constr = ddef
constrParams = vparams map (_.symbol)
constrBody = rhs
}
case _ =>
}
}
assert((constr ne null) && (constrBody ne null), impl)
val paramAccessors = clazz.constrParamAccessors
def parameter(acc: Symbol): Symbol =
parameterNamed(nme.getterName(acc.originalName))
def parameterNamed(name: Name): Symbol = {
def matchesName(param: Symbol) =
param.name == name ||
param.name.startsWith(name) && param.name(name.length) == '$'
val ps = constrParams filter matchesName
if (ps.isEmpty) assert(false, "" + name + " not in " + constrParams)
ps.head
}
var thisRefSeen: Boolean = false
val intoConstructorTransformer = new Transformer {
override def transform(tree: Tree): Tree = tree match {
case Apply(Select(This(_), _), List()) =>
if ((tree.symbol hasFlag PARAMACCESSOR) && tree.symbol.owner == clazz)
gen.mkAttributedIdent(parameter(tree.symbol.accessed)) setPos tree.pos
else if (tree.symbol.outerSource == clazz && !clazz.isImplClass)
gen.mkAttributedIdent(parameterNamed(nme.OUTER)) setPos tree.pos
else
super.transform(tree)
case Select(This(_), _)
if ((tree.symbol hasFlag PARAMACCESSOR) && !tree.symbol.isSetter && tree.symbol.owner == clazz) =>
gen.mkAttributedIdent(parameter(tree.symbol)) setPos tree.pos
case Select(_, _) =>
thisRefSeen = true
super.transform(tree)
case This(_) =>
thisRefSeen = true
super.transform(tree)
case Super(_, _) =>
thisRefSeen = true
super.transform(tree)
case _ =>
super.transform(tree)
}
}
def intoConstructor(oldowner: Symbol, tree: Tree) =
intoConstructorTransformer.transform(
new ChangeOwnerTraverser(oldowner, constr.symbol)(tree))
def canBeMoved(tree: Tree) = tree match {
//todo: eliminate thisRefSeen
case ValDef(mods, _, _, _) => (mods hasFlag PRESUPER | PARAMACCESSOR) || !thisRefSeen
case _ => false
}
def mkAssign(to: Symbol, from: Tree): Tree =
atPos(to.pos) {
localTyper.typed {
Assign(Select(This(clazz), to), from)
}
}
def copyParam(to: Symbol, from: Symbol): Tree = {
var result = mkAssign(to, Ident(from))
if (from.name == nme.OUTER)
result =
atPos(to.pos) {
localTyper.typed {
If(Apply(Select(Ident(from), nme.eq), List(Literal(Constant(null)))),
Throw(New(TypeTree(NullPointerExceptionClass.tpe), List(List()))),
result);
}
}
result
}
val defBuf = new ListBuffer[Tree]
val constrStatBuf = new ListBuffer[Tree]
val constrPrefixBuf = new ListBuffer[Tree]
val presupers = treeInfo.preSuperFields(stats)
for (stat <- constrBody.stats) {
constrStatBuf += stat
stat match {
case ValDef(mods, name, _, _) if (mods hasFlag PRESUPER) =>
constrStatBuf +=
localTyper.typed {
atPos(stat.pos) {
val fields = presupers filter (
vdef => nme.localToGetter(vdef.name) == name)
assert(fields.length == 1)
Assign(
gen.mkAttributedRef(clazz.thisType, fields.head.symbol),
Ident(stat.symbol))
}
}
case _ =>
}
}
for (stat <- stats) stat match {
case DefDef(mods, name, tparams, vparamss, tpt, rhs) =>
stat.symbol.tpe match {
case MethodType(List(), tp @ ConstantType(c)) =>
defBuf += copy.DefDef(
stat, mods, name, tparams, vparamss, tpt,
Literal(c) setPos rhs.pos setType tp)
case _ =>
if (!stat.symbol.isPrimaryConstructor) defBuf += stat
}
case ValDef(mods, name, tpt, rhs) =>
if (stat.symbol.tpe.isInstanceOf[ConstantType])
assert(stat.symbol.getter(stat.symbol.owner) != NoSymbol, stat)
else {
if (rhs != EmptyTree && !stat.symbol.hasFlag(LAZY)) {
val rhs1 = intoConstructor(stat.symbol, rhs);
(if (canBeMoved(stat)) constrPrefixBuf else constrStatBuf) += mkAssign(
stat.symbol, rhs1)
}
defBuf += copy.ValDef(stat, mods, name, tpt, EmptyTree)
}
case ClassDef(_, _, _, _) =>
defBuf += (new ConstructorTransformer).transform(stat)
case _ =>
constrStatBuf += intoConstructor(impl.symbol, stat)
}
val accessed = new TreeSet[Symbol]((x, y) => x isLess y)
def isAccessed(sym: Symbol) =
sym.owner != clazz ||
!(sym hasFlag PARAMACCESSOR) ||
!sym.isPrivateLocal ||
(accessed contains sym)
val accessTraverser = new Traverser {
override def traverse(tree: Tree) = {
tree match {
case Select(_, _) =>
if (!isAccessed(tree.symbol)) accessed addEntry tree.symbol
case _ =>
}
super.traverse(tree)
}
}
for (stat <- defBuf.elements) accessTraverser.traverse(stat)
val paramInits = for (acc <- paramAccessors if isAccessed(acc))
yield copyParam(acc, parameter(acc))
defBuf += copy.DefDef(
constr, constr.mods, constr.name, constr.tparams, constr.vparamss, constr.tpt,
copy.Block(
constrBody,
paramInits ::: constrPrefixBuf.toList ::: constrStatBuf.toList,
constrBody.expr));
for (sym <- clazz.info.decls.toList)
if (!isAccessed(sym)) clazz.info.decls unlink sym
copy.Template(impl, impl.parents, impl.self,
defBuf.toList filter (stat => isAccessed(stat.symbol)))
}
override def transform(tree: Tree): Tree = {
tree match {
case ClassDef(mods, name, tparams, impl) if !tree.symbol.hasFlag(INTERFACE) =>
copy.ClassDef(tree, mods, name, tparams, transformClassTemplate(impl))
case _ =>
super.transform(tree)
}
}
} // ConstructorTransformer
}
|
