diff options
Diffstat (limited to 'src/reflect')
| -rw-r--r-- | src/reflect/scala/reflect/api/Trees.scala | 18 | ||||
| -rw-r--r-- | src/reflect/scala/reflect/internal/Positions.scala | 2 | ||||
| -rw-r--r-- | src/reflect/scala/reflect/internal/Printers.scala | 2 | ||||
| -rw-r--r-- | src/reflect/scala/reflect/internal/Trees.scala | 15 |
4 files changed, 26 insertions, 11 deletions
diff --git a/src/reflect/scala/reflect/api/Trees.scala b/src/reflect/scala/reflect/api/Trees.scala index 9a65ddaa96..3837517a3b 100644 --- a/src/reflect/scala/reflect/api/Trees.scala +++ b/src/reflect/scala/reflect/api/Trees.scala @@ -75,11 +75,26 @@ trait Trees { self: Universe => def isDef: Boolean /** Is this tree one of the empty trees? + * * Empty trees are: the `EmptyTree` null object, `TypeTree` instances that don't carry a type * and the special `emptyValDef` singleton. + * + * In the compiler the `isEmpty` check and the derived `orElse` method are mostly used + * as a check for a tree being a null object (`EmptyTree` for term trees and empty TypeTree for type trees). + * + * Unfortunately `emptyValDef` is also considered to be `isEmpty`, but this is deemed to be + * a conceptual mistake pending a fix in https://issues.scala-lang.org/browse/SI-6762. + * + * @see `canHaveAttrs` */ def isEmpty: Boolean + /** Can this tree carry attributes (i.e. symbols, types or positions)? + * Typically the answer is yes, except for the `EmptyTree` null object and + * two special singletons: `emptyValDef` and `pendingSuperCall`. + */ + def canHaveAttrs: Boolean + /** The canonical way to test if a Tree represents a term. */ def isTerm: Boolean @@ -2852,7 +2867,8 @@ trait Trees { self: Universe => trees mapConserve (tree => transform(tree).asInstanceOf[TypeDef]) /** Transforms a `ValDef`. */ def transformValDef(tree: ValDef): ValDef = - if (tree.isEmpty) tree else transform(tree).asInstanceOf[ValDef] + if (tree eq emptyValDef) tree + else transform(tree).asInstanceOf[ValDef] /** Transforms a list of `ValDef` nodes. */ def transformValDefs(trees: List[ValDef]): List[ValDef] = trees mapConserve (transformValDef(_)) diff --git a/src/reflect/scala/reflect/internal/Positions.scala b/src/reflect/scala/reflect/internal/Positions.scala index b65df0e70b..f8c670827a 100644 --- a/src/reflect/scala/reflect/internal/Positions.scala +++ b/src/reflect/scala/reflect/internal/Positions.scala @@ -38,7 +38,7 @@ trait Positions extends api.Positions { self: SymbolTable => protected class DefaultPosAssigner extends PosAssigner { var pos: Position = _ override def traverse(t: Tree) { - if (t.isDummy) () + if (!t.canHaveAttrs) () else if (t.pos == NoPosition) { t.setPos(pos) super.traverse(t) // TODO: bug? shouldn't the traverse be outside of the if? diff --git a/src/reflect/scala/reflect/internal/Printers.scala b/src/reflect/scala/reflect/internal/Printers.scala index 6f834803c4..a8085a4c58 100644 --- a/src/reflect/scala/reflect/internal/Printers.scala +++ b/src/reflect/scala/reflect/internal/Printers.scala @@ -435,7 +435,7 @@ trait Printers extends api.Printers { self: SymbolTable => case tree => xprintTree(this, tree) } - if (printTypes && tree.isTerm && !tree.isEmpty) { + if (printTypes && tree.isTerm && tree.canHaveAttrs) { print("{", if (tree.tpe eq null) "<null>" else tree.tpe.toString, "}") } } diff --git a/src/reflect/scala/reflect/internal/Trees.scala b/src/reflect/scala/reflect/internal/Trees.scala index 5b7afdf5dd..dceec18e57 100644 --- a/src/reflect/scala/reflect/internal/Trees.scala +++ b/src/reflect/scala/reflect/internal/Trees.scala @@ -36,7 +36,7 @@ trait Trees extends api.Trees { self: SymbolTable => def isDef = false def isEmpty = false - def isDummy = false + def canHaveAttrs = true /** The canonical way to test if a Tree represents a term. */ @@ -955,9 +955,8 @@ trait Trees extends api.Trees { self: SymbolTable => def ValDef(sym: Symbol): ValDef = ValDef(sym, EmptyTree) - trait DummyTree extends Tree { - override def isEmpty = true - override def isDummy = true + trait CannotHaveAttrs extends Tree { + override def canHaveAttrs = false private def unsupported(what: String, args: Any*) = throw new UnsupportedOperationException(s"$what($args) inapplicable for "+self.toString) @@ -969,9 +968,9 @@ trait Trees extends api.Trees { self: SymbolTable => override def tpe_=(t: Type) = if (t != NoType) unsupported("tpe_=", t) } - case object EmptyTree extends TermTree with DummyTree { val asList = List(this) } - object emptyValDef extends ValDef(Modifiers(PRIVATE), nme.WILDCARD, TypeTree(NoType), EmptyTree) with DummyTree - object pendingSuperCall extends Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR), List()) with DummyTree + case object EmptyTree extends TermTree with CannotHaveAttrs { override def isEmpty = true; val asList = List(this) } + object emptyValDef extends ValDef(Modifiers(PRIVATE), nme.WILDCARD, TypeTree(NoType), EmptyTree) with CannotHaveAttrs + object pendingSuperCall extends Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR), List()) with CannotHaveAttrs def DefDef(sym: Symbol, mods: Modifiers, vparamss: List[List[ValDef]], rhs: Tree): DefDef = atPos(sym.pos) { @@ -1123,7 +1122,7 @@ trait Trees extends api.Trees { self: SymbolTable => traverse(annot); traverse(arg) case Template(parents, self, body) => traverseTrees(parents) - if (!self.isEmpty) traverse(self) + if (self ne emptyValDef) traverse(self) traverseStats(body, tree.symbol) case Block(stats, expr) => traverseTrees(stats); traverse(expr) |