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:
    Graph, DepthFirstSearch, ReverseDepthFirstSearch

    • Field Detail

      • WHITE

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

      • 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:
        Constant Field Values

      • BLACK

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

    • Constructor Detail

      • 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 Detail

      • 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

      • 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

      • 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:
        DFSEdgeTypes

      • 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

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