org.apache.lucene.analysis.compound

Class CompoundWordTokenFilterBase

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.compound.CompoundWordTokenFilterBase

Direct Known Subclasses:

DictionaryCompoundWordTokenFilter, HyphenationCompoundWordTokenFilter

public abstract class CompoundWordTokenFilterBase
extends TokenFilter

Base class for decomposition token filters.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

AttributeSource.AttributeFactory, AttributeSource.State

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_MAX_SUBWORD_SIZE The default for maximal length of subwords that get propagated to the output of this filter
static int	DEFAULT_MIN_SUBWORD_SIZE The default for minimal length of subwords that get propagated to the output of this filter
static int	DEFAULT_MIN_WORD_SIZE The default for minimal word length that gets decomposed
protected CharArraySet	dictionary
protected int	maxSubwordSize
protected int	minSubwordSize
protected int	minWordSize
protected boolean	onlyLongestMatch
protected LinkedList	tokens

Fields inherited from class org.apache.lucene.analysis.TokenFilter

input

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	CompoundWordTokenFilterBase(TokenStream input, Set dictionary)
protected	CompoundWordTokenFilterBase(TokenStream input, Set dictionary, boolean onlyLongestMatch)
protected	CompoundWordTokenFilterBase(TokenStream input, Set dictionary, int minWordSize, int minSubwordSize, int maxSubwordSize, boolean onlyLongestMatch)
protected	CompoundWordTokenFilterBase(TokenStream input, String[] dictionary)
protected	CompoundWordTokenFilterBase(TokenStream input, String[] dictionary, boolean onlyLongestMatch)
protected	CompoundWordTokenFilterBase(TokenStream input, String[] dictionary, int minWordSize, int minSubwordSize, int maxSubwordSize, boolean onlyLongestMatch)

Method Summary

Methods

Modifier and Type	Method and Description
protected static void	addAllLowerCase(Set target, Collection col)
protected Token	createToken(int offset, int length, Token prototype)
protected void	decompose(Token token)
protected abstract void	decomposeInternal(Token token)
boolean	incrementToken() Consumers (i.e., IndexWriter) use this method to advance the stream to the next token.
static Set	makeDictionary(String[] dictionary) Create a set of words from an array The resulting Set does case insensitive matching TODO We should look for a faster dictionary lookup approach.
protected static char[]	makeLowerCaseCopy(char[] buffer)
Token	next() Deprecated. Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer.
Token	next(Token reusableToken) Deprecated. Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer.
void	reset() Reset the filter as well as the input TokenStream.

Methods inherited from class org.apache.lucene.analysis.TokenFilter

close, end

Methods inherited from class org.apache.lucene.analysis.TokenStream

getOnlyUseNewAPI, setOnlyUseNewAPI

Methods inherited from class org.apache.lucene.util.AttributeSource

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, restoreState, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

DEFAULT_MIN_WORD_SIZE

public static final int DEFAULT_MIN_WORD_SIZE

The default for minimal word length that gets decomposed

See Also:

Constant Field Values

DEFAULT_MIN_SUBWORD_SIZE

public static final int DEFAULT_MIN_SUBWORD_SIZE

The default for minimal length of subwords that get propagated to the output of this filter

See Also:

Constant Field Values

DEFAULT_MAX_SUBWORD_SIZE

public static final int DEFAULT_MAX_SUBWORD_SIZE

The default for maximal length of subwords that get propagated to the output of this filter

See Also:

Constant Field Values

dictionary

protected final CharArraySet dictionary

tokens

protected final LinkedList tokens

minWordSize

protected final int minWordSize

minSubwordSize

protected final int minSubwordSize

maxSubwordSize

protected final int maxSubwordSize

onlyLongestMatch

protected final boolean onlyLongestMatch

Constructor Detail

CompoundWordTokenFilterBase

protected CompoundWordTokenFilterBase(TokenStream input,
                           String[] dictionary,
                           int minWordSize,
                           int minSubwordSize,
                           int maxSubwordSize,
                           boolean onlyLongestMatch)

CompoundWordTokenFilterBase

protected CompoundWordTokenFilterBase(TokenStream input,
                           String[] dictionary,
                           boolean onlyLongestMatch)

CompoundWordTokenFilterBase

protected CompoundWordTokenFilterBase(TokenStream input,
                           Set dictionary,
                           boolean onlyLongestMatch)

CompoundWordTokenFilterBase

protected CompoundWordTokenFilterBase(TokenStream input,
                           String[] dictionary)

CompoundWordTokenFilterBase

protected CompoundWordTokenFilterBase(TokenStream input,
                           Set dictionary)

CompoundWordTokenFilterBase

protected CompoundWordTokenFilterBase(TokenStream input,
                           Set dictionary,
                           int minWordSize,
                           int minSubwordSize,
                           int maxSubwordSize,
                           boolean onlyLongestMatch)

Method Detail

makeDictionary

public static final Set makeDictionary(String[] dictionary)

Create a set of words from an array The resulting Set does case insensitive matching TODO We should look for a faster dictionary lookup approach.

Parameters:

dictionary -

Returns:

Set of lowercased terms

incrementToken

public final boolean incrementToken()
                             throws IOException

Description copied from class: TokenStream

Consumers (i.e., IndexWriter) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriate AttributeImpls with the attributes of the next token.

The producer must make no assumptions about the attributes after the method has been returned: the caller may arbitrarily change it. If the producer needs to preserve the state for subsequent calls, it can use AttributeSource.captureState() to create a copy of the current attribute state.

This method is called for every token of a document, so an efficient implementation is crucial for good performance. To avoid calls to AttributeSource.addAttribute(Class) and AttributeSource.getAttribute(Class) or downcasts, references to all AttributeImpls that this stream uses should be retrieved during instantiation.

To ensure that filters and consumers know which attributes are available, the attributes must be added during instantiation. Filters and consumers are not required to check for availability of attributes in TokenStream.incrementToken().

Overrides:

incrementToken in class TokenStream

Returns:

false for end of stream; true otherwise

Note that this method will be defined abstract in Lucene 3.0.

Throws:

IOException

next

public final Token next(Token reusableToken)
                 throws IOException

Deprecated. Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer.

Description copied from class: TokenStream

Returns the next token in the stream, or null at EOS. When possible, the input Token should be used as the returned Token (this gives fastest tokenization performance), but this is not required and a new Token may be returned. Callers may re-use a single Token instance for successive calls to this method.

This implicitly defines a "contract" between consumers (callers of this method) and producers (implementations of this method that are the source for tokens):

• A consumer must fully consume the previously returned Token before calling this method again.
• A producer must call Token.clear() before setting the fields in it and returning it

Also, the producer must make no assumptions about a Token after it has been returned: the caller may arbitrarily change it. If the producer needs to hold onto the Token for subsequent calls, it must clone() it before storing it. Note that a TokenFilter is considered a consumer.

Overrides:

next in class TokenStream

Parameters:

reusableToken - a Token that may or may not be used to return; this parameter should never be null (the callee is not required to check for null before using it, but it is a good idea to assert that it is not null.)

Returns:

next Token in the stream or null if end-of-stream was hit

Throws:

IOException

next

public final Token next()
                 throws IOException

Deprecated. Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer.

Description copied from class: TokenStream

Returns the next Token in the stream, or null at EOS.

Overrides:

next in class TokenStream

Throws:

IOException

addAllLowerCase

protected static final void addAllLowerCase(Set target,
                   Collection col)

makeLowerCaseCopy

protected static char[] makeLowerCaseCopy(char[] buffer)

createToken

protected final Token createToken(int offset,
                int length,
                Token prototype)

decompose

protected void decompose(Token token)

decomposeInternal

protected abstract void decomposeInternal(Token token)

reset

public void reset()
           throws IOException

Description copied from class: TokenFilter

Reset the filter as well as the input TokenStream.

Overrides:

reset in class TokenFilter

Throws:

IOException