org.apache.solr.analysis

Class ReversedWildcardFilter

java.lang.Object

org.apache.lucene.util.AttributeSource

org.apache.lucene.analysis.TokenStream

org.apache.lucene.analysis.TokenFilter

org.apache.solr.analysis.ReversedWildcardFilter

All Implemented Interfaces:

Closeable

public final class ReversedWildcardFilter
extends TokenFilter

This class produces a special form of reversed tokens, suitable for better handling of leading wildcards. Tokens from the input TokenStream are reversed and prepended with a special "reversed" marker character. If withOriginal argument is true then first the original token is returned, and then the reversed token (with positionIncrement == 0) is returned. Otherwise only reversed tokens are returned.

Note: this filter doubles the number of tokens in the input stream when withOriginal == true, which proportionally increases the size of postings and term dictionary in the index.

Nested Class Summary

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

AttributeSource.AttributeFactory, AttributeSource.State

Field Summary

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

input

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ReversedWildcardFilter(TokenStream input, boolean withOriginal, char markerChar)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	incrementToken()
static void	reverse(char[] buffer, int start, int len) Partially reverses the given input buffer in-place from the given offset up to the given length, keeping surrogate pairs in the correct (non-reversed) order.

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

close, end, reset

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

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

Methods inherited from class java.lang.Object

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

Constructor Detail

ReversedWildcardFilter

protected ReversedWildcardFilter(TokenStream input,
                      boolean withOriginal,
                      char markerChar)

Method Detail

incrementToken

public boolean incrementToken()
                       throws IOException

Specified by:

incrementToken in class TokenStream

Throws:

IOException

reverse

public static void reverse(char[] buffer,
           int start,
           int len)

Partially reverses the given input buffer in-place from the given offset up to the given length, keeping surrogate pairs in the correct (non-reversed) order.

Parameters:

buffer - the input char array to reverse

start - the offset from where to reverse the buffer

len - the length in the buffer up to where the buffer should be reversed