Package opennlp.tools.util.featuregen

Class GeneratorFactory

java.lang.Object

opennlp.tools.util.featuregen.GeneratorFactory

public class GeneratorFactory
extends Object

Creates a set of feature generators based on a provided XML descriptor. Example of an XML descriptor:

<featureGenerators name="namefind"> <generator class="opennlp.tools.util.featuregen.CachedFeatureGeneratorFactory"> <generator class="opennlp.tools.util.featuregen.WindowFeatureGeneratorFactory"> <int name="prevLength">2</int> <int name="nextLength">2</int> <generator class="opennlp.tools.util.featuregen.TokenClassFeatureGeneratorFactory"/> </generator> <generator class="opennlp.tools.util.featuregen.WindowFeatureGeneratorFactory"> <int name="prevLength">2</int> <int name="nextLength">2</int> <generator class="opennlp.tools.util.featuregen.TokenFeatureGeneratorFactory"/> </generator> <generator class="opennlp.tools.util.featuregen.DefinitionFeatureGeneratorFactory"/> <generator class="opennlp.tools.util.featuregen.PreviousMapFeatureGeneratorFactory"/> <generator class="opennlp.tools.util.featuregen.BigramNameFeatureGeneratorFactory"/> <generator class="opennlp.tools.util.featuregen.SentenceFeatureGeneratorFactory"> <bool name="begin">true</bool> <bool name="end">false</bool> </generator> </generator> </featureGenerators>

Each XML element is mapped to a GeneratorFactory.XmlFeatureGeneratorFactory which is responsible to process the element and create the specified AdaptiveFeatureGenerator. Elements can contain other elements in this case it is the responsibility of the mapped factory to process the child elements correctly. In some factories this leads to recursive calls the GeneratorFactory.XmlFeatureGeneratorFactory.create(Element, FeatureGeneratorResourceProvider) method. In the example above the generators element is mapped to the AggregatedFeatureGeneratorFactory which then creates all the aggregated AdaptiveFeatureGenerators to accomplish this it evaluates the mapping with the same mechanism and gives the child element to the corresponding factories. All created generators are added to a new instance of the AggregatedFeatureGenerator which is then returned.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	GeneratorFactory.AbstractXmlFeatureGeneratorFactory

Constructor Summary

Constructors

Constructor	Description
GeneratorFactory()

Method Summary

Modifier and Type	Method	Description
static AdaptiveFeatureGenerator	create(InputStream xmlDescriptorIn, FeatureGeneratorResourceProvider resourceManager)	Creates an AdaptiveFeatureGenerator from an provided XML descriptor.
static Map<String,ArtifactSerializer<?>>	extractArtifactSerializerMappings(InputStream xmlDescriptorIn)
static List<Element>	getDescriptorElements(InputStream xmlDescriptorIn)	Provides a list with all the elements in the xml feature descriptor.

Methods inherited from class java.lang.Object

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

Constructor Detail

GeneratorFactory

public GeneratorFactory()

Method Detail

create

public static AdaptiveFeatureGenerator create(InputStream xmlDescriptorIn,
                                              FeatureGeneratorResourceProvider resourceManager)
                                       throws IOException

Creates an AdaptiveFeatureGenerator from an provided XML descriptor. Usually this XML descriptor contains a set of nested feature generators which are then used to generate the features by one of the opennlp components.

Parameters:

xmlDescriptorIn - the InputStream from which the descriptor is read, the stream remains open and must be closed by the caller.

resourceManager - the resource manager which is used to resolve resources referenced by a key in the descriptor

Returns:

created feature generators

Throws:

IOException - if an error occurs during reading from the descriptor InputStream

extractArtifactSerializerMappings

public static Map<String,ArtifactSerializer<?>> extractArtifactSerializerMappings(InputStream xmlDescriptorIn)
                                                                                 throws IOException

Throws:

IOException

getDescriptorElements

public static List<Element> getDescriptorElements(InputStream xmlDescriptorIn)
                                           throws IOException

Provides a list with all the elements in the xml feature descriptor.

Parameters:

xmlDescriptorIn - the xml feature descriptor

Returns:

a list containing all elements

Throws:

IOException - if inputstream cannot be open

InvalidFormatException - if xml is not well-formed