Module org.apache.lucene.analysis.common

Package org.apache.lucene.analysis.miscellaneous

Class DelimitedTermFrequencyTokenFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.lucene.analysis.miscellaneous.DelimitedTermFrequencyTokenFilter

All Implemented Interfaces:

Closeable, AutoCloseable, Unwrappable<TokenStream>

public final class DelimitedTermFrequencyTokenFilter
extends TokenFilter

Characters before the delimiter are the "token", the textual integer after is the term frequency. To use this TokenFilter the field must be indexed with IndexOptions.DOCS_AND_FREQS but no positions or offsets.

For example, if the delimiter is '|', then for the string "foo|5", "foo" is the token and "5" is a term frequency. If there is no delimiter, the TokenFilter does not modify the term frequency.

Note make sure your Tokenizer doesn't split on the delimiter, or this won't work

Nested Class Summary

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

AttributeSource.State

Field Summary

Fields

Modifier and Type	Field	Description
static final char	DEFAULT_DELIMITER
private final char	delimiter
private final CharTermAttribute	termAtt
private final TermFrequencyAttribute	tfAtt

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

input

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

DEFAULT_TOKEN_ATTRIBUTE_FACTORY

Constructor Summary

Constructors

Constructor	Description
DelimitedTermFrequencyTokenFilter(TokenStream input)
DelimitedTermFrequencyTokenFilter(TokenStream input, char delimiter)

Method Summary

Modifier and Type	Method	Description
boolean	incrementToken()	Consumers (i.e., IndexWriter) use this method to advance the stream to the next token.

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

close, end, reset, unwrap

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

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT_DELIMITER

public static final char DEFAULT_DELIMITER

See Also:

• Constant Field Values

delimiter

private final char delimiter

termAtt

private final CharTermAttribute termAtt

tfAtt

private final TermFrequencyAttribute tfAtt

Constructor Details

DelimitedTermFrequencyTokenFilter

public DelimitedTermFrequencyTokenFilter(TokenStream input)

DelimitedTermFrequencyTokenFilter

public DelimitedTermFrequencyTokenFilter(TokenStream input,
 char delimiter)

Method Details

incrementToken

public 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), 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().

Specified by:

incrementToken in class TokenStream

Returns:

false for end of stream; true otherwise

Throws:

IOException