Package edu.umd.cs.findbugs.graph

Class AbstractDepthFirstSearch<GraphType extends Graph<EdgeType,VertexType>,EdgeType extends GraphEdge<EdgeType,VertexType>,VertexType extends GraphVertex<VertexType>>

java.lang.Object
edu.umd.cs.findbugs.graph.AbstractDepthFirstSearch<GraphType,EdgeType,VertexType>
All Implemented Interfaces:
DFSEdgeTypes
Direct Known Subclasses:
DepthFirstSearch, ReverseDepthFirstSearch
public abstract class AbstractDepthFirstSearch<GraphType extends Graph<EdgeType,VertexType>,EdgeType extends GraphEdge<EdgeType,VertexType>,VertexType extends GraphVertex<VertexType>> extends Object implements DFSEdgeTypes
Perform a depth first search on a graph. Algorithm based on Cormen, et. al, Introduction to Algorithms, p. 478. Currently, this class
  • assigns DFS edge types (see DFSEdgeTypes)
  • assigns discovery and finish times for each vertex
  • produces a topological sort of the vertices, if and only if the graph is acyclic

Concrete subclasses implement forward and reverse versions of depth first search.

Author:
David Hovemeyer
See Also:

  • Field Details

    • DEBUG

      public static final boolean DEBUG
      See Also:

    • WHITE

      protected static final int WHITE
      Color of a vertex which hasn't been visited yet.
      See Also:

    • GRAY

      protected static final int GRAY
      Color of a vertex which has been visited, but not all of whose descendents have been visited.
      See Also:

    • BLACK

      protected static final int BLACK
      Color of a vertex whose entire search tree has been visited.
      See Also:

  • Constructor Details

    • AbstractDepthFirstSearch

      public AbstractDepthFirstSearch(GraphType graph)
      Constructor.
      Parameters:
      graph - the graph to be searched
      Throws:
      IllegalArgumentException - if the graph has not had edge ids assigned yet

  • Method Details

    • outgoingEdgeIterator

      protected abstract Iterator<EdgeType> outgoingEdgeIterator(GraphType graph, VertexType vertex)
      Get Iterator over "logical" outgoing edges.

    • getTarget

      protected abstract VertexType getTarget(EdgeType edge)
      Get "logical" target of edge.

    • getSource

      protected abstract VertexType getSource(EdgeType edge)
      Get "logical" source of edge.

    • getNextSearchTreeRoot

      protected VertexType getNextSearchTreeRoot()
      Choose the next search tree root. By default, this method just scans for a WHITE vertex. Subclasses may override this method in order to choose which vertices are used as search tree roots.
      Returns:
      the next search tree root

    • unvisitedVertices

      public Collection<VertexType> unvisitedVertices()

    • setVertexChooser

      public void setVertexChooser(VertexChooser<VertexType> vertexChooser)
      Specify a VertexChooser object to be used to selected which vertices are visited by the search. This is useful if you only want to search a subset of the vertices in the graph.
      Parameters:
      vertexChooser - the VertexChooser to use

    • setSearchTreeCallback

      public void setSearchTreeCallback(SearchTreeCallback<VertexType> searchTreeCallback)
      Set a search tree callback.
      Parameters:
      searchTreeCallback - the search tree callback

    • search

      public AbstractDepthFirstSearch<GraphType,EdgeType,VertexType> search()
      Perform the depth first search.
      Returns:
      this object

    • containsCycle

      public boolean containsCycle()
      Return whether or not the graph contains a cycle: i.e., whether it contains any back edges. This should only be called after search() has been called (since that method actually executes the search).
      Returns:
      true if the graph contains a cycle, false otherwise

    • getDFSEdgeType

      public int getDFSEdgeType(EdgeType edge)
      Get the type of edge in the depth first search.
      Parameters:
      edge - the edge
      Returns:
      the DFS type of edge: TREE_EDGE, FORWARD_EDGE, CROSS_EDGE, or BACK_EDGE
      See Also:

    • getDiscoveryTime

      public int getDiscoveryTime(VertexType vertex)
      Return the timestamp indicating when the given vertex was discovered.
      Parameters:
      vertex - the vertex

    • getFinishTime

      public int getFinishTime(VertexType vertex)
      Return the timestamp indicating when the given vertex was finished (meaning that all of its descendents were visited recursively).
      Parameters:
      vertex - the vertex

    • getFinishTimeList

      public int[] getFinishTimeList()
      Get array of finish times, indexed by vertex label.
      Returns:
      the array of finish times

    • topologicalSortIterator

      public Iterator<VertexType> topologicalSortIterator()
      Get an iterator over the vertexs in topological sort order. This works if and only if the graph is acyclic.

    • getColor

      protected int getColor(VertexType vertex)
      Get the current color of given vertex.
      Parameters:
      vertex - the vertex
      Returns:
      the color (WHITE, BLACK, or GRAY)

    • visitMe

      protected boolean visitMe(VertexType vertex)
      Predicate to determine which vertices should be visited as the search progresses. Takes both vertex color and the vertex chooser (if any) into account.
      Parameters:
      vertex - the vertex to possibly be visited
      Returns:
      true if the vertex should be visited, false if not