mirror of https://github.com/sbt/sbt.git
52 lines
1.1 KiB
Scala
52 lines
1.1 KiB
Scala
|
package sbt.inc
|
||
|
|
|
||
|
|
// stolen from Josh
|
||
|
|
object StronglyConnected
|
||
|
|
{
|
||
|
|
def apply[N](nodes: Iterable[N])(dependencies: N => Iterable[N]): Set[Set[N]] =
|
||
|
|
{
|
||
|
|
val stack = new collection.mutable.Stack[N]
|
||
|
|
val onStack = new collection.mutable.HashSet[N]
|
||
|
|
val scc = new collection.mutable.ArrayBuffer[Set[N]]
|
||
|
|
val index = new collection.mutable.ArrayBuffer[N]
|
||
|
|
val lowLink = new collection.mutable.HashMap[N, Int]
|
||
|
|
|
||
|
|
def tarjanImpl(v: N)
|
||
|
|
{
|
||
|
|
index += v
|
||
|
|
lowLink(v) = index.size-1
|
||
|
|
stack.push(v)
|
||
|
|
onStack += v
|
||
|
|
for(n <- dependencies(v))
|
||
|
|
{
|
||
|
|
if( !index.contains(n) )
|
||
|
|
{
|
||
|
|
tarjanImpl(n)
|
||
|
|
lowLink(v) = math.min(lowLink(v), lowLink(n))
|
||
|
|
}
|
||
|
|
else if(onStack(n))
|
||
|
|
lowLink(v) = math.min(lowLink(v), index.indexOf(n))
|
||
|
|
}
|
||
|
|
|
||
|
|
if(lowLink(v) == index.indexOf(v))
|
||
|
|
{
|
||
|
|
val components = new collection.mutable.ArrayBuffer[N]
|
||
|
|
def popLoop()
|
||
|
|
{
|
||
|
|
val popped = stack.pop()
|
||
|
|
onStack -= popped
|
||
|
|
components.append(popped)
|
||
|
|
if(popped != v) popLoop()
|
||
|
|
}
|
||
|
|
popLoop()
|
||
|
|
scc.append(components.toSet)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
for(node <- nodes)
|
||
|
|
if( !index.contains(node) )
|
||
|
|
tarjanImpl(node)
|
||
|
|
scc.toSet
|
||
|
|
}
|
||
|
|
}
|