cz.auderis.tools.collection.topo

Class TopoSorter<K,V>

java.lang.Object

cz.auderis.tools.collection.topo.TopoSorter<K,V>

Type Parameters:

K - type of key (usually identifier) of the sorted item

V - type of sorted item

public final class TopoSorter<K,V>
extends Object

Implements topological sorting algorithm that ensures dependencies are listed before their dependants in the resulting list. Formally, for every pair X <-- Y (i.e. Y depends on X) the algorithm generates a sorted list L where L.indexOf(X) < L.indexOf(Y).

In case the input structure contain one or more cycles, the algorithm does its best to sort the non-cyclic part but throws TopoCycleException at the end. The sorted items as well as nodes found in cycles can be obtained from the exception.

To allow a wide spectrum of applications, the algorithm assumes that every item is identified by a unique key. Dependencies of an item are subsequently defined as a set of other items' keys.

Version:

1.0

Author:

Boleslav Bobcik <bbobcik@gmail.com>

Method Summary

Modifier and Type	Method and Description
static <K,V> List<V>	sort(Collection<? extends TopoNode<? extends K,? extends V>> sourceNodes) Processes the given collection of TopoNode nodes and returns the topologically sorted list of items represented by input nodes or, if a cycle in dependency graph is detected, throws TopoCycleException.
static <K,V> void	sortTo(Collection<? extends TopoNode<? extends K,? extends V>> sourceNodes, List<? super V> target) Processes the given collection of TopoNode nodes and appends the topologically sorted items represented by input nodes to the end of target list.

Methods inherited from class java.lang.Object

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

Method Detail

sort

public static <K,V> List<V> sort(Collection<? extends TopoNode<? extends K,? extends V>> sourceNodes)
                          throws TopoCycleException

Processes the given collection of TopoNode nodes and returns the topologically sorted list of items represented by input nodes or, if a cycle in dependency graph is detected, throws TopoCycleException.

Type Parameters:

K - type of key (usually identifier) of the sorted item

V - type of sorted item

Parameters:

sourceNodes - collection of source nodes encapsulating sorted items and their dependencies

Returns:

list of topologically sorted items

Throws:

TopoCycleException - if a cycle is detected in dependency relations

sortTo

public static <K,V> void sortTo(Collection<? extends TopoNode<? extends K,? extends V>> sourceNodes,
                                List<? super V> target)
                         throws TopoCycleException

Processes the given collection of TopoNode nodes and appends the topologically sorted items represented by input nodes to the end of target list. If a cycle in dependency graph is detected, throws TopoCycleException; the target list may or may not have been modified.

Type Parameters:

K - type of key (usually identifier) of the sorted item

V - type of sorted item

Parameters:

sourceNodes - collection of source nodes encapsulating sorted items and their dependencies

target - target list to which the sorted items are appended

Throws:

TopoCycleException - the topo cycle exception

NullPointerException - if target list is null