Package com.google.common.collect

Class TreeTraverser<T>

  • Direct Known Subclasses:
    BinaryTreeTraverser
    @Beta
@GwtCompatible(emulated=true)
public abstract class TreeTraverser<T>
extends java.lang.Object
    Views elements of a type T as nodes in a tree, and provides methods to traverse the trees induced by this traverser.

    For example, the tree 

              
          h
        / | \
       /  e  \
      d       g
     /|\      |
    / | \     f
   a  b  c

    can be iterated over in preorder (hdabcegf), postorder (abcdefgh), or breadth-first order (hdegabcf).

    Null nodes are strictly forbidden.

    Since:
    15.0

    • Constructor Detail

      • TreeTraverser

        public TreeTraverser()

    • Method Detail

      • children

        public abstract java.lang.Iterable<T> children​(T root)
        Returns the children of the specified node. Must not contain null.

      • preOrderTraversal

        public final FluentIterable<T> preOrderTraversal​(T root)
        Returns an unmodifiable iterable over the nodes in a tree structure, using pre-order traversal. That is, each node's subtrees are traversed after the node itself is returned.

        No guarantees are made about the behavior of the traversal when nodes change while iteration is in progress or when the iterators generated by children(T) are advanced.

      • postOrderTraversal

        public final FluentIterable<T> postOrderTraversal​(T root)
        Returns an unmodifiable iterable over the nodes in a tree structure, using post-order traversal. That is, each node's subtrees are traversed before the node itself is returned.

        No guarantees are made about the behavior of the traversal when nodes change while iteration is in progress or when the iterators generated by children(T) are advanced.

      • breadthFirstTraversal

        public final FluentIterable<T> breadthFirstTraversal​(T root)
        Returns an unmodifiable iterable over the nodes in a tree structure, using breadth-first traversal. That is, all the nodes of depth 0 are returned, then depth 1, then 2, and so on.

        No guarantees are made about the behavior of the traversal when nodes change while iteration is in progress or when the iterators generated by children(T) are advanced.