Class DepthFirstIterator<V,​E>

  • Type Parameters:
    V - the graph vertex type
    E - the graph edge type
    All Implemented Interfaces:
    java.util.Iterator<V>, GraphIterator<V,​E>

    public class DepthFirstIterator<V,​E>
    extends CrossComponentIterator<V,​E,​DepthFirstIterator.VisitColor>
    A depth-first iterator for a directed or undirected graph.

    For this iterator to work correctly the graph must not be modified during iteration. Currently there are no means to ensure that, nor to fail-fast. The results of such modifications are undefined.

    Author:
    Liviu Rau, Barak Naveh
    • Field Detail

      • SENTINEL

        public static final java.lang.Object SENTINEL
        Sentinel object. Unfortunately, we can't use null, because ArrayDeque won't accept those. And we don't want to rely on the caller to provide a sentinel object for us. So we have to play typecasting games.
    • Constructor Detail

      • DepthFirstIterator

        public DepthFirstIterator​(Graph<V,​E> g)
        Creates a new depth-first iterator for the specified graph.
        Parameters:
        g - the graph to be iterated.
      • DepthFirstIterator

        public DepthFirstIterator​(Graph<V,​E> g,
                                  V startVertex)
        Creates a new depth-first iterator for the specified graph. Iteration will start at the specified start vertex and will be limited to the connected component that includes that vertex. If the specified start vertex is null, iteration will start at an arbitrary vertex and will not be limited, that is, will be able to traverse all the graph.
        Parameters:
        g - the graph to be iterated.
        startVertex - the vertex iteration to be started.
      • DepthFirstIterator

        public DepthFirstIterator​(Graph<V,​E> g,
                                  java.lang.Iterable<V> startVertices)
        Creates a new depth-first iterator for the specified graph. Iteration will start at the specified start vertices and will be limited to the connected component that includes those vertices. If the specified start vertices is null, iteration will start at an arbitrary vertex and will not be limited, that is, will be able to traverse all the graph.
        Parameters:
        g - the graph to be iterated.
        startVertices - the vertices iteration to be started.
    • Method Detail

      • getStack

        public java.util.Deque<java.lang.Object> getStack()
        Retrieves the LIFO stack of vertices which have been encountered but not yet visited (WHITE). This stack also contains sentinel entries representing vertices which have been visited but are still GRAY. A sentinel entry is a sequence (v, SENTINEL), whereas a non-sentinel entry is just (v).
        Returns:
        stack