com.google.common.collect

Class TreeTraverser<T>

java.lang.Object

com.google.common.collect.TreeTraverser<T>

Direct Known Subclasses:

BinaryTreeTraverser

@Beta
@GwtCompatible(emulated=true)
public abstract class TreeTraverser<T>
extends 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

Author:

Louis Wasserman

Constructor Summary

Constructors

Constructor and Description
TreeTraverser()

Method Summary

Methods

Modifier and Type	Method and Description
FluentIterable<T>	breadthFirstTraversal(T root) Returns an unmodifiable iterable over the nodes in a tree structure, using breadth-first traversal.
abstract Iterable<T>	children(T root) Returns the children of the specified node.
FluentIterable<T>	postOrderTraversal(T root) Returns an unmodifiable iterable over the nodes in a tree structure, using post-order traversal.
FluentIterable<T>	preOrderTraversal(T root) Returns an unmodifiable iterable over the nodes in a tree structure, using pre-order traversal.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TreeTraverser

public TreeTraverser()

Method Detail

children

public abstract 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.