WeightedWalkable<E> class abstract mixin Graphs

A collection of nodes and edges that can be traversed incrementally.

The nodes of the walkable collection are accessed by calling the successors method with a source vertex as an argument, which returns an Iterable of vertices and their respective weights that are accessible from the source node.

The WeightedWalkable declaration provides a default implementation, which can be extended or mixed-in to implement the WeightedWalkable interface. It implements every member other than successors and roots. An implementation of WeightedWalkable should provide a more efficient implementation of members of WeightedWalkable when it can do so.

Adapting

Example

Here is a sample implementation of a weighted graph using pattern matching:

final class AbcGraph with WeightedWalkable<String> {
  @override
  Iterable<(String, int)> successors(String node) {
    return switch (node) {
      'a' => const [('b', 1), ('c', 2)],
      'b' => const [('c', 3)],
      'c' => const [('d', 4)],
      _ => const [],
    };
  }

  @override
  Iterable<String> get roots => ['a', 'b', 'c'];
}

void main() {
  final graph = AbcGraph();
  print(graph.successors('a')); // [('b', 1), ('c', 2.0)]
  print(graph.roots); // ['a', 'b', 'c']
}