org.codefx.libfx.collection.tree.stream

Class TreeStreams

java.lang.Object

org.codefx.libfx.collection.tree.stream.TreeStreams

public class TreeStreams
extends Object

Creates streams of nodes.

Unless otherwise noted all streams are ordered and sequential. They are generated lazily, i.e. the TreeNavigator is only used to find nodes which are known to be processed by the stream. This is implies that short-circuiting operation (like limit) will lead to the evaluation of less nodes.

The streams are only defined on trees, i.e. connected, directed, acyclic graphs. Creating them on other graphs can lead to unexpected behavior including infinite streams.

Constructor Summary

Constructors

Constructor and Description
TreeStreams()

Method Summary

Modifier and Type	Method and Description
static <N> Stream<N>	backwardDfs(TreeNavigator<N> navigator, N startNode) Returns a stream which enumerates nodes in a tree in the order of a backwards depth-first search which starts in the specified node.
static <N> Stream<N>	backwardDfsToRoot(TreeNavigator<N> navigator, N root, N startNode) Returns a stream which enumerates nodes in the (sub-)tree rooted in the specified root in the order of a backwards depth-first search which starts in the specified node.
static <N> Stream<N>	byStrategy(TreeIterationStrategy<N> strategy) Returns a stream which enumerates a tree's nodes according to the specified TreeIterationStrategy.
static <N> Stream<N>	byStrategy(TreeIterationStrategy<N> strategy, int characteristics, boolean parallel) Returns a stream which enumerates a tree's nodes according to the specified TreeIterationStrategy and stream characteristics.
static <N> Stream<N>	dfsFromRoot(TreeNavigator<N> navigator, N root) Returns a stream which enumerates nodes in the (sub-)tree rooted in the specified root in the order of a depth-first search.
static <N> Stream<N>	dfsFromWithin(TreeNavigator<N> navigator, N startNode) Returns a stream which enumerates nodes in a tree in the order of a depth-first search which starts in the specified node.
static <N> Stream<N>	dfsFromWithin(TreeNavigator<N> navigator, N root, N startNode) Returns a stream which enumerates nodes in the (sub-)tree rooted in the specified root in the order of a depth-first search which starts in the specified start node.

Methods inherited from class java.lang.Object

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

Constructor Detail

TreeStreams

public TreeStreams()

Method Detail

dfsFromRoot

public static <N> Stream<N> dfsFromRoot(TreeNavigator<N> navigator,
                                        N root)

Returns a stream which enumerates nodes in the (sub-)tree rooted in the specified root in the order of a depth-first search.

It is not necessary for the specified node to be the tree's actual root. It will be treated as the root of a subtree and only this subtree will be streamed.

Type Parameters:

N - the type of nodes contained in the tree

Parameters:

navigator - the navigator used to navigate the tree

root - the root node for the searched (sub-)tree

Returns:

a stream of nodes

dfsFromWithin

public static <N> Stream<N> dfsFromWithin(TreeNavigator<N> navigator,
                                          N startNode)

Returns a stream which enumerates nodes in a tree in the order of a depth-first search which starts in the specified node.

While the search will start in the specified node it will eventually backtrack above it, i.e. the search is not limited to the subtree rooted in the node. This is equivalent to starting a full depth-first search in the tree's root but ignoring all encountered nodes until the specified start node is found.

Type Parameters:

N - the type of nodes contained in the tree

Parameters:

navigator - the navigator used to navigate the tree

startNode - the node in which the search starts

Returns:

a stream of nodes

dfsFromWithin

public static <N> Stream<N> dfsFromWithin(TreeNavigator<N> navigator,
                                          N root,
                                          N startNode)

Returns a stream which enumerates nodes in the (sub-)tree rooted in the specified root in the order of a depth-first search which starts in the specified start node.

This is a combination of dfsFromRoot and dfsFromWithin. Only the (sub-)tree rooted in the specified root is searched (i.e. the search will never backtrack above it) but the root actually startes in the specified start node.

Type Parameters:

N - the type of nodes contained in the tree

Parameters:

navigator - the navigator used to navigate the tree

root - the root node for the searched (sub-)tree

startNode - the node in which the search starts

Returns:

a stream of nodes

backwardDfs

public static <N> Stream<N> backwardDfs(TreeNavigator<N> navigator,
                                        N startNode)

Returns a stream which enumerates nodes in a tree in the order of a backwards depth-first search which starts in the specified node.

The stream enumerates the nodes which would be encountered by starting a depth-first search in the tree's root and stopping at the specified node, but in reverse order.

Type Parameters:

N - the type of nodes contained in the tree

Parameters:

navigator - the navigator used to navigate the tree

startNode - the node in which the search starts

Returns:

a stream of nodes

backwardDfsToRoot

public static <N> Stream<N> backwardDfsToRoot(TreeNavigator<N> navigator,
                                              N root,
                                              N startNode)

Returns a stream which enumerates nodes in the (sub-)tree rooted in the specified root in the order of a backwards depth-first search which starts in the specified node.

The stream enumerates the nodes which would be encountered by starting a depth-first search in the specified root and stopping at the specified node, but in reverse order.

Type Parameters:

N - the type of nodes contained in the tree

Parameters:

navigator - the navigator used to navigate the tree

root - the root node for the searched (sub-)tree

startNode - the node in which the search starts

Returns:

a stream of nodes

byStrategy

public static <N> Stream<N> byStrategy(TreeIterationStrategy<N> strategy)

Returns a stream which enumerates a tree's nodes according to the specified TreeIterationStrategy.

Type Parameters:

N - the type of nodes contained in the tree

Parameters:

strategy - the strategy used to enumerate the tree's nodes

Returns:

a stream of nodes

byStrategy

public static <N> Stream<N> byStrategy(TreeIterationStrategy<N> strategy,
                                       int characteristics,
                                       boolean parallel)

Returns a stream which enumerates a tree's nodes according to the specified TreeIterationStrategy and stream characteristics.

Type Parameters:

N - the type of nodes contained in the tree

Parameters:

strategy - the strategy used to enumerate the tree's nodes

characteristics - the characteristics of the Spliterator used to create the stream

parallel - if true then the returned stream is a parallel stream; if false the returned stream is a sequential stream.

Returns:

a stream of nodes