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package scala.reflect
package internal
trait Positions extends api.Positions { self: SymbolTable =>
type Position = scala.tools.nsc.util.Position
val NoPosition = scala.tools.nsc.util.NoPosition
/** A position that wraps a set of trees.
* The point of the wrapping position is the point of the default position.
* If some of the trees are ranges, returns a range position enclosing all ranges
* Otherwise returns default position.
*/
def wrappingPos(default: Position, trees: List[Tree]): Position = default
/** A position that wraps the non-empty set of trees.
* The point of the wrapping position is the point of the first trees' position.
* If all some the trees are non-synthetic, returns a range position enclosing the non-synthetic trees
* Otherwise returns a synthetic offset position to point.
*/
def wrappingPos(trees: List[Tree]): Position = trees.head.pos
/** Ensure that given tree has no positions that overlap with
* any of the positions of `others`. This is done by
* shortening the range or assigning TransparentPositions
* to some of the nodes in `tree`.
*/
def ensureNonOverlapping(tree: Tree, others: List[Tree]) {}
trait PosAssigner extends Traverser {
var pos: Position
}
protected[this] lazy val posAssigner: PosAssigner = new DefaultPosAssigner
protected class DefaultPosAssigner extends PosAssigner {
var pos: Position = _
override def traverse(t: Tree) {
if (t eq EmptyTree) ()
else if (t.pos == NoPosition) {
t.setPos(pos)
super.traverse(t) // TODO: bug? shouldn't the traverse be outside of the if?
// @PP: it's pruning whenever it encounters a node with a
// position, which I interpret to mean that (in the author's
// mind at least) either the children of a positioned node will
// already be positioned, or the children of a positioned node
// do not merit positioning.
//
// Whatever the author's rationale, it does seem like a bad idea
// to press on through a positioned node to find unpositioned
// children beneath it and then to assign whatever happens to
// be in `pos` to such nodes. There are supposed to be some
// position invariants which I can't imagine surviving that.
}
}
}
def atPos[T <: Tree](pos: Position)(tree: T): T = {
posAssigner.pos = pos
posAssigner.traverse(tree)
tree
}
}
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