author | wenzelm |
Fri, 10 Aug 2012 13:33:07 +0200 | |
changeset 48754 | c2c1e5944536 |
parent 48648 | f13eeeea1a69 |
child 49560 | 11430dd89e35 |
permissions | -rw-r--r-- |
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/* Title: Pure/General/graph.scala |
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Module: PIDE |
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Author: Makarius |
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Directed graphs. |
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*/ |
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package isabelle |
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prefer sorted Map/Set for canonical order of results -- pass ordering via fresh copy of empty;
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parents:
46659
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changeset
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import scala.collection.immutable.{SortedMap, SortedSet} |
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import scala.annotation.tailrec |
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object Graph |
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{ |
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class Duplicate[Key](val key: Key) extends Exception |
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class Undefined[Key](val key: Key) extends Exception |
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class Cycles[Key](val cycles: List[List[Key]]) extends Exception |
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prefer sorted Map/Set for canonical order of results -- pass ordering via fresh copy of empty;
wenzelm
parents:
46659
diff
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def empty[Key, A](implicit ord: Ordering[Key]): Graph[Key, A] = |
d2ac78ba805e
prefer sorted Map/Set for canonical order of results -- pass ordering via fresh copy of empty;
wenzelm
parents:
46659
diff
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new Graph[Key, A](SortedMap.empty(ord)) |
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def string[A]: Graph[String, A] = empty(Ordering.String) |
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def int[A]: Graph[Int, A] = empty(Ordering.Int) |
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def long[A]: Graph[Long, A] = empty(Ordering.Long) |
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} |
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final class Graph[Key, A] private(rep: SortedMap[Key, (A, (SortedSet[Key], SortedSet[Key]))]) |
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{ |
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wenzelm
parents:
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type Keys = SortedSet[Key] |
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type Entry = (A, (Keys, Keys)) |
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prefer sorted Map/Set for canonical order of results -- pass ordering via fresh copy of empty;
wenzelm
parents:
46659
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def ordering: Ordering[Key] = rep.ordering |
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prefer sorted Map/Set for canonical order of results -- pass ordering via fresh copy of empty;
wenzelm
parents:
46659
diff
changeset
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def empty_keys: Keys = SortedSet.empty[Key](ordering) |
d2ac78ba805e
prefer sorted Map/Set for canonical order of results -- pass ordering via fresh copy of empty;
wenzelm
parents:
46659
diff
changeset
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46666
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clarified signature -- avoid oddities of Iterable like Iterator.map;
wenzelm
parents:
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b01b6977a5e8
clarified signature -- avoid oddities of Iterable like Iterator.map;
wenzelm
parents:
46661
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changeset
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/* graphs */ |
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def is_empty: Boolean = rep.isEmpty |
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def defined(x: Key): Boolean = rep.isDefinedAt(x) |
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clarified signature -- avoid oddities of Iterable like Iterator.map;
wenzelm
parents:
46661
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def entries: Iterator[(Key, Entry)] = rep.iterator |
b01b6977a5e8
clarified signature -- avoid oddities of Iterable like Iterator.map;
wenzelm
parents:
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def keys: Iterator[Key] = entries.map(_._1) |
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def dest: List[(Key, List[Key])] = |
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clarified signature -- avoid oddities of Iterable like Iterator.map;
wenzelm
parents:
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(for ((x, (_, (_, succs))) <- entries) yield (x, succs.toList)).toList |
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wenzelm
parents:
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override def toString: String = |
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clarified signature -- avoid oddities of Iterable like Iterator.map;
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parents:
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dest.map(p => p._1.toString + " -> " + p._2.map(_.toString).mkString("{", ", ", "}")) |
b01b6977a5e8
clarified signature -- avoid oddities of Iterable like Iterator.map;
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parents:
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.mkString("Graph(", ", ", ")") |
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private def get_entry(x: Key): Entry = |
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rep.get(x) match { |
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case Some(entry) => entry |
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case None => throw new Graph.Undefined(x) |
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} |
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private def map_entry(x: Key, f: Entry => Entry): Graph[Key, A] = |
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new Graph[Key, A](rep + (x -> f(get_entry(x)))) |
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/* nodes */ |
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def get_node(x: Key): A = get_entry(x)._1 |
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def map_node(x: Key, f: A => A): Graph[Key, A] = |
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map_entry(x, { case (i, ps) => (f(i), ps) }) |
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/* reachability */ |
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/*nodes reachable from xs -- topologically sorted for acyclic graphs*/ |
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def reachable(next: Key => Keys, xs: List[Key]): (List[List[Key]], Keys) = |
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{ |
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wenzelm
parents:
48348
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def reach(x: Key, reached: (List[Key], Keys)): (List[Key], Keys) = |
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val (rs, r_set) = reached |
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if (r_set(x)) reached |
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else { |
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48350
09bf3b73e446
clarified topological ordering: preserve order of adjacency via reverse fold;
wenzelm
parents:
48348
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changeset
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val (rs1, r_set1) = (next(x) :\ (rs, r_set + x))(reach) |
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(x :: rs1, r_set1) |
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} |
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} |
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def reachs(reached: (List[List[Key]], Keys), x: Key): (List[List[Key]], Keys) = |
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{ |
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val (rss, r_set) = reached |
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48350
09bf3b73e446
clarified topological ordering: preserve order of adjacency via reverse fold;
wenzelm
parents:
48348
diff
changeset
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val (rs, r_set1) = reach(x, (Nil, r_set)) |
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(rs :: rss, r_set1) |
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} |
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d2ac78ba805e
prefer sorted Map/Set for canonical order of results -- pass ordering via fresh copy of empty;
wenzelm
parents:
46659
diff
changeset
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((List.empty[List[Key]], empty_keys) /: xs)(reachs) |
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} |
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/*immediate*/ |
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def imm_preds(x: Key): Keys = get_entry(x)._2._1 |
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def imm_succs(x: Key): Keys = get_entry(x)._2._2 |
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/*transitive*/ |
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def all_preds(xs: List[Key]): List[Key] = reachable(imm_preds, xs)._1.flatten |
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def all_succs(xs: List[Key]): List[Key] = reachable(imm_succs, xs)._1.flatten |
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/*strongly connected components; see: David King and John Launchbury, |
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"Structuring Depth First Search Algorithms in Haskell"*/ |
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def strong_conn: List[List[Key]] = |
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46666
b01b6977a5e8
clarified signature -- avoid oddities of Iterable like Iterator.map;
wenzelm
parents:
46661
diff
changeset
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reachable(imm_preds, all_succs(keys.toList))._1.filterNot(_.isEmpty).reverse |
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/* minimal and maximal elements */ |
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def minimals: List[Key] = |
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(List.empty[Key] /: rep) { |
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case (ms, (m, (_, (preds, _)))) => if (preds.isEmpty) m :: ms else ms } |
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def maximals: List[Key] = |
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(List.empty[Key] /: rep) { |
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case (ms, (m, (_, (_, succs)))) => if (succs.isEmpty) m :: ms else ms } |
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def is_minimal(x: Key): Boolean = imm_preds(x).isEmpty |
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def is_maximal(x: Key): Boolean = imm_succs(x).isEmpty |
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/* node operations */ |
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def new_node(x: Key, info: A): Graph[Key, A] = |
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{ |
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if (defined(x)) throw new Graph.Duplicate(x) |
46661
d2ac78ba805e
prefer sorted Map/Set for canonical order of results -- pass ordering via fresh copy of empty;
wenzelm
parents:
46659
diff
changeset
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else new Graph[Key, A](rep + (x -> (info, (empty_keys, empty_keys)))) |
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} |
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def default_node(x: Key, info: A): Graph[Key, A] = |
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if (defined(x)) this else new_node(x, info) |
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prefer sorted Map/Set for canonical order of results -- pass ordering via fresh copy of empty;
wenzelm
parents:
46659
diff
changeset
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private def del_adjacent(fst: Boolean, x: Key)(map: SortedMap[Key, Entry], y: Key) |
d2ac78ba805e
prefer sorted Map/Set for canonical order of results -- pass ordering via fresh copy of empty;
wenzelm
parents:
46659
diff
changeset
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: SortedMap[Key, Entry] = |
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map.get(y) match { |
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case None => map |
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case Some((i, (preds, succs))) => |
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map + (y -> (i, if (fst) (preds - x, succs) else (preds, succs - x))) |
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} |
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def del_node(x: Key): Graph[Key, A] = |
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{ |
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val (preds, succs) = get_entry(x)._2 |
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new Graph[Key, A]( |
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(((rep - x) /: preds)(del_adjacent(false, x)) /: succs)(del_adjacent(true, x))) |
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} |
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def restrict(pred: Key => Boolean): Graph[Key, A] = |
46666
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clarified signature -- avoid oddities of Iterable like Iterator.map;
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parents:
46661
diff
changeset
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(this /: entries){ case (graph, (x, _)) => if (!pred(x)) graph.del_node(x) else graph } |
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clarified Graph.restrict (formerly Graph.subgraph) based on public graph operations;
wenzelm
parents:
46613
diff
changeset
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/* edge operations */ |
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def is_edge(x: Key, y: Key): Boolean = |
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defined(x) && defined(y) && imm_succs(x)(y) |
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def add_edge(x: Key, y: Key): Graph[Key, A] = |
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if (is_edge(x, y)) this |
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else |
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map_entry(y, { case (i, (preds, succs)) => (i, (preds + x, succs)) }). |
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map_entry(x, { case (i, (preds, succs)) => (i, (preds, succs + y)) }) |
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def del_edge(x: Key, y: Key): Graph[Key, A] = |
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if (is_edge(x, y)) |
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map_entry(y, { case (i, (preds, succs)) => (i, (preds - x, succs)) }). |
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map_entry(x, { case (i, (preds, succs)) => (i, (preds, succs - y)) }) |
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else this |
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/* irreducible paths -- Hasse diagram */ |
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46661
d2ac78ba805e
prefer sorted Map/Set for canonical order of results -- pass ordering via fresh copy of empty;
wenzelm
parents:
46659
diff
changeset
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private def irreducible_preds(x_set: Keys, path: List[Key], z: Key): List[Key] = |
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{ |
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def red(x: Key)(x1: Key) = is_edge(x, x1) && x1 != z |
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@tailrec def irreds(xs0: List[Key], xs1: List[Key]): List[Key] = |
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xs0 match { |
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case Nil => xs1 |
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case x :: xs => |
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if (!(x_set(x)) || x == z || path.contains(x) || |
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xs.exists(red(x)) || xs1.exists(red(x))) |
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irreds(xs, xs1) |
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else irreds(xs, x :: xs1) |
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} |
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irreds(imm_preds(z).toList, Nil) |
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} |
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def irreducible_paths(x: Key, y: Key): List[List[Key]] = |
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{ |
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val (_, x_set) = reachable(imm_succs, List(x)) |
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def paths(path: List[Key])(ps: List[List[Key]], z: Key): List[List[Key]] = |
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if (x == z) (z :: path) :: ps |
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else (ps /: irreducible_preds(x_set, path, z))(paths(z :: path)) |
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if ((x == y) && !is_edge(x, x)) List(Nil) else paths(Nil)(Nil, y) |
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} |
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/* maintain acyclic graphs */ |
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def add_edge_acyclic(x: Key, y: Key): Graph[Key, A] = |
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if (is_edge(x, y)) this |
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else { |
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irreducible_paths(y, x) match { |
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case Nil => add_edge(x, y) |
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case cycles => throw new Graph.Cycles(cycles.map(x :: _)) |
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} |
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} |
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def add_deps_acyclic(y: Key, xs: List[Key]): Graph[Key, A] = |
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(this /: xs)(_.add_edge_acyclic(_, y)) |
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def topological_order: List[Key] = all_succs(minimals) |
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} |