Package de.saar.chorus.domgraph.chart

Class SplitSource<E extends GraphBasedNonterminal>

java.lang.Object

de.saar.chorus.domgraph.chart.SplitSource<E>

Direct Known Subclasses:

CompleteSplitSource, OneSplitSource

public abstract class SplitSource<E extends GraphBasedNonterminal>
extends Object

An abstract superclass for classes that compute splits. A ChartSolver relies on an object of a subclass of this class to provide the splits for a subgraph. You can provide your own subclass by implementing the computeSplits method of this class.

Author:

Alexander Koller

Field Summary

Fields

Modifier and Type	Field	Description
protected DomGraph	graph

Constructor Summary

Constructors

Constructor	Description
SplitSource(DomGraph graph)

Method Summary

Modifier and Type	Method	Description
protected List<String>	computePotentialFreeRoots(E subgraph)	Computes the list of all nodes in the subgraphs which have no incoming edges.
abstract Iterator<Split<E>>	computeSplits(E subgraph)	Implement this abstract method when you write your own subclass of SplitSource.
DomGraph	getGraph()
abstract E	makeToplevelSubgraph(Set<String> graph)
abstract void	reduceIfNecessary(ConcreteRegularTreeGrammar<E> chart)	Reduces the computed RTG.

Methods inherited from class java.lang.Object

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

Field Details

graph

protected DomGraph graph

Constructor Details

SplitSource

public SplitSource(DomGraph graph)

Method Details

makeToplevelSubgraph

public abstract E makeToplevelSubgraph(Set<String> graph)

computeSplits

public abstract Iterator<Split<E>> computeSplits(E subgraph)
                                          throws UnsolvableSubgraphException

Implement this abstract method when you write your own subclass of SplitSource. The method gets a subgraph as its argument, and has the task of computing an iterator over the splits of this subgraph.

Parameters:

subgraph - a subgraph

Returns:

an iterator over some or all splits of this subgraph

Throws:

UnsolvableSubgraphException

reduceIfNecessary

public abstract void reduceIfNecessary(ConcreteRegularTreeGrammar<E> chart)

Reduces the computed RTG. If your split source is such that the RTG it computes is not automatically reduced, you should implement this method to call reduce() on the output RTG. This method is called as the last operation by the chart solver.

Parameters:

chart - the output RTG computed by the chart solver

computePotentialFreeRoots

protected List<String> computePotentialFreeRoots(E subgraph)

Computes the list of all nodes in the subgraphs which have no incoming edges. These nodes are candidates for being free roots; however, you still need to check that the holes are in different biconnected components.

Parameters:

subgraph - a subgraph

Returns:

the list of nodes without in-edges in the subgraph

getGraph

public DomGraph getGraph()