mirror of https://github.com/sbt/sbt.git
42 lines
1.0 KiB
Scala
42 lines
1.0 KiB
Scala
/* sbt -- Simple Build Tool
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* Copyright 2008, 2009, 2010 David MacIver, Mark Harrah
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*/
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package sbt;
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trait Dag[Node <: Dag[Node]]{
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self : Node =>
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def dependencies : Iterable[Node]
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def topologicalSort = Dag.topologicalSort(self)(_.dependencies)
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}
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object Dag
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{
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import scala.collection.{mutable, JavaConversions};
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import JavaConversions.{asIterable, asSet}
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def topologicalSort[T](root: T)(dependencies: T => Iterable[T]): List[T] = topologicalSort(root :: Nil)(dependencies)
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def topologicalSort[T](nodes: Iterable[T])(dependencies: T => Iterable[T]): List[T] =
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{
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val discovered = new mutable.HashSet[T]
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val finished = asSet(new java.util.LinkedHashSet[T])
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def visitAll(nodes: Iterable[T]) = nodes foreach visit
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def visit(dag : T){
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if (!discovered(dag)) {
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discovered(dag) = true;
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visitAll(dependencies(dag));
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finished += dag;
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}
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else if(!finished(dag))
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throw new Cyclic(dag)
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}
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visitAll(nodes);
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finished.toList;
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}
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final class Cyclic(val value: Any) extends Exception("Cyclic reference involving " + value)
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}
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