diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/interactive/scala/tools/nsc/interactive/ContextTrees.scala | 64 |
1 files changed, 40 insertions, 24 deletions
diff --git a/src/interactive/scala/tools/nsc/interactive/ContextTrees.scala b/src/interactive/scala/tools/nsc/interactive/ContextTrees.scala index 93ef4c4d6c..4f67a22b8f 100644 --- a/src/interactive/scala/tools/nsc/interactive/ContextTrees.scala +++ b/src/interactive/scala/tools/nsc/interactive/ContextTrees.scala @@ -6,6 +6,7 @@ package scala.tools.nsc package interactive import scala.collection.mutable.ArrayBuffer +import scala.annotation.tailrec trait ContextTrees { self: Global => @@ -28,44 +29,59 @@ trait ContextTrees { self: Global => override def toString = "ContextTree("+pos+", "+children+")" } - /** Optionally returns the smallest context that contains given `pos`, or None if none exists. + /** Returns the most precise context possible for the given `pos`. + * + * It looks for the finest ContextTree containing `pos`, and then look inside + * this ContextTree for a child ContextTree located immediately before `pos`. + * If such a child exists, returns its context, otherwise returns the context of + * the parent ContextTree. + * + * This is required to always return a context which contains the all the imports + * declared up to `pos` (see SI-7280 for a test case). + * + * Can return None if `pos` is before any valid Scala code. */ def locateContext(contexts: Contexts, pos: Position): Option[Context] = synchronized { - def locateNearestContextTree(contexts: Contexts, pos: Position, recent: Array[ContextTree]): Option[ContextTree] = { - locateContextTree(contexts, pos) match { - case Some(x) => - recent(0) = x - locateNearestContextTree(x.children, pos, recent) - case None => recent(0) match { - case null => None - case x => Some(x) - } + @tailrec + def locateFinestContextTree(context: ContextTree): ContextTree = { + if (context.pos includes pos) { + locateContextTree(context.children, pos) match { + case Some(x) => + locateFinestContextTree(x) + case None => + context + } + } else { + context } } - locateNearestContextTree(contexts, pos, new Array[ContextTree](1)) map (_.context) + locateContextTree(contexts, pos) map locateFinestContextTree map (_.context) } + /** Returns the ContextTree containing `pos`, or the ContextTree positioned just before `pos`, + * or None if `pos` is located before all ContextTrees. + */ def locateContextTree(contexts: Contexts, pos: Position): Option[ContextTree] = { if (contexts.isEmpty) None else { - val hi = contexts.length - 1 - if ((contexts(hi).pos properlyPrecedes pos) || (pos properlyPrecedes contexts(0).pos)) None - else { - def loop(lo: Int, hi: Int): Option[ContextTree] = { + @tailrec + def loop(lo: Int, hi: Int, previousSibling: Option[ContextTree]): Option[ContextTree] = { + if (pos properlyPrecedes contexts(lo).pos) + previousSibling + else if (contexts(hi).pos properlyPrecedes pos) + Some(contexts(hi)) + else { val mid = (lo + hi) / 2 val midpos = contexts(mid).pos - if ((pos precedes midpos) && (mid < hi)) - loop(lo, mid) - else if ((midpos precedes pos) && (lo < mid)) - loop(mid, hi) - else if (midpos includes pos) + if (midpos includes pos) Some(contexts(mid)) - else if (contexts(mid+1).pos includes pos) - Some(contexts(mid+1)) - else None + else if (midpos properlyPrecedes pos) + loop(mid + 1, hi, Some(contexts(mid))) + else + loop(lo, mid, previousSibling) } - loop(0, hi) } + loop(0, contexts.length - 1, None) } } |