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/* NSC -- new Scala compiler
* Copyright 2009-2013 Typesafe/Scala Solutions and LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package interactive
import scala.collection.mutable.ArrayBuffer
trait ContextTrees { self: Global =>
type Context = analyzer.Context
lazy val NoContext = analyzer.NoContext
type Contexts = ArrayBuffer[ContextTree]
/** A context tree contains contexts that are indexed by positions.
* It satisfies the following properties:
* 1. All context come from compiling the same unit.
* 2. Child contexts have parent contexts in their outer chain.
* 3. The `pos` field of a context is the same as `context.tree.pos`, unless that
* position is transparent. In that case, `pos` equals the position of
* one of the solid descendants of `context.tree`.
* 4. Children of a context have non-overlapping increasing positions.
* 5. No context in the tree has a transparent position.
*/
class ContextTree(val pos: Position, val context: Context, val children: ArrayBuffer[ContextTree]) {
def this(pos: Position, context: Context) = this(pos, context, new ArrayBuffer[ContextTree])
override def toString = "ContextTree("+pos+", "+children+")"
}
/** Optionally returns the smallest context that contains given `pos`, or None if none exists.
*/
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)
}
}
}
locateNearestContextTree(contexts, pos, new Array[ContextTree](1)) map (_.context)
}
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] = {
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)
Some(contexts(mid))
else if (contexts(mid+1).pos includes pos)
Some(contexts(mid+1))
else None
}
loop(0, hi)
}
}
}
/** Insert a context at correct position into a buffer of context trees.
* If the `context` has a transparent position, add it multiple times
* at the positions of all its solid descendant trees.
*/
def addContext(contexts: Contexts, context: Context): Unit = {
val cpos = context.tree.pos
if (cpos.isTransparent)
for (t <- context.tree.children flatMap solidDescendants)
addContext(contexts, context, t.pos)
else
addContext(contexts, context, cpos)
}
/** Insert a context with non-transparent position `cpos`
* at correct position into a buffer of context trees.
*/
def addContext(contexts: Contexts, context: Context, cpos: Position): Unit = synchronized {
try {
if (!cpos.isRange) {}
else if (contexts.isEmpty) contexts += new ContextTree(cpos, context)
else {
val hi = contexts.length - 1
if (contexts(hi).pos precedes cpos)
contexts += new ContextTree(cpos, context)
else if (contexts(hi).pos properlyIncludes cpos) // fast path w/o search
addContext(contexts(hi).children, context, cpos)
else if (cpos precedes contexts(0).pos)
new ContextTree(cpos, context) +=: contexts
else {
def insertAt(idx: Int): Boolean = {
val oldpos = contexts(idx).pos
if (oldpos sameRange cpos) {
contexts(idx) = new ContextTree(cpos, context, contexts(idx).children)
true
} else if (oldpos includes cpos) {
addContext(contexts(idx).children, context, cpos)
true
} else if (cpos includes oldpos) {
val start = contexts.indexWhere(cpos includes _.pos)
val last = contexts.lastIndexWhere(cpos includes _.pos)
contexts(start) = new ContextTree(cpos, context, contexts.slice(start, last + 1))
contexts.remove(start + 1, last - start)
true
} else false
}
def loop(lo: Int, hi: Int) {
if (hi - lo > 1) {
val mid = (lo + hi) / 2
val midpos = contexts(mid).pos
if (cpos precedes midpos)
loop(lo, mid)
else if (midpos precedes cpos)
loop(mid, hi)
else
addContext(contexts(mid).children, context, cpos)
} else if (!insertAt(lo) && !insertAt(hi)) {
val lopos = contexts(lo).pos
val hipos = contexts(hi).pos
if ((lopos precedes cpos) && (cpos precedes hipos))
contexts.insert(hi, new ContextTree(cpos, context))
else
inform("internal error? skewed positions: "+lopos+" !< "+cpos+" !< "+hipos)
}
}
loop(0, hi)
}
}
} catch {
case ex: Throwable =>
println(ex)
ex.printStackTrace()
println("failure inserting "+cpos+" into "+contexts+"/"+contexts(contexts.length - 1).pos+"/"+
(contexts(contexts.length - 1).pos includes cpos))
throw ex
}
}
}
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