- Type Parameters:
N- Node parameter type
- All Known Subinterfaces:
- All Known Implementing Classes:
@Beta @DoNotMock("Implement with a lambda, or use GraphBuilder to build a Graph with the desired edges") public interface SuccessorsFunction<N>A functional interface for graph-structured data.
This interface is meant to be used as the type of a parameter to graph algorithms (such as breadth first traversal) that only need a way of accessing the successors of a node in a graph.
UsageGiven an algorithm, for example:
you will invoke it depending on the graph representation you're using.
public <N> someGraphAlgorithm(N startNode, SuccessorsFunction<N> successorsFunction);
This works because those types each implement
SuccessorsFunction. It will also work with any other implementation of this interface.
If you have your own graph implementation based around a custom node type
MyNode, which has a method
getChildren()that retrieves its successors in a graph:
If you have some other mechanism for returning the successors of a node, or one that doesn't return an
Iterable<? extends N>, then you can use a lambda to perform a more general transformation:
someGraphAlgorithm(startNode, node -> ImmutableList.of(node.leftChild(), node.rightChild()));
Graph algorithms that need additional capabilities (accessing both predecessors and successors, iterating over the edges, etc.) should declare their input to be of a type that provides those capabilities, such as
- Joshua O'Madadhain, Jens Nyman
Iterable<? extends N> successors(N node)Returns all nodes in this graph adjacent to
nodewhich can be reached by traversing
node's outgoing edges in the direction (if any) of the edge.
This is not the same as "all nodes reachable from
nodeby following outgoing edges". For that functionality, see
Some algorithms that operate on a
SuccessorsFunctionmay produce undesired results if the returned
Iterablecontains duplicate elements. Implementations of such algorithms should document their behavior in the presence of duplicates.
The elements of the returned
Iterablemust each be:
- Usable as
Mapkeys (see the Guava User Guide's section on graph elements for details)
nodeis not an element of this graph