org.apache.lucene.analysis.miscellaneous
Class WordDelimiterFilter

java.lang.Object
  extended by org.apache.lucene.util.AttributeSource
      extended by org.apache.lucene.analysis.TokenStream
          extended by org.apache.lucene.analysis.TokenFilter
              extended by org.apache.lucene.analysis.miscellaneous.WordDelimiterFilter
All Implemented Interfaces:
Closeable

public final class WordDelimiterFilter
extends TokenFilter

Splits words into subwords and performs optional transformations on subword groups. Words are split into subwords with the following rules: - split on intra-word delimiters (by default, all non alpha-numeric characters). - "Wi-Fi" -> "Wi", "Fi" - split on case transitions - "PowerShot" -> "Power", "Shot" - split on letter-number transitions - "SD500" -> "SD", "500" - leading and trailing intra-word delimiters on each subword are ignored - "//hello---there, 'dude'" -> "hello", "there", "dude" - trailing "'s" are removed for each subword - "O'Neil's" -> "O", "Neil" - Note: this step isn't performed in a separate filter because of possible subword combinations. The combinations parameter affects how subwords are combined: - combinations="0" causes no subword combinations. - "PowerShot" -> 0:"Power", 1:"Shot" (0 and 1 are the token positions) - combinations="1" means that in addition to the subwords, maximum runs of non-numeric subwords are catenated and produced at the same position of the last subword in the run. - "PowerShot" -> 0:"Power", 1:"Shot" 1:"PowerShot" - "A's+B's&C's" -> 0:"A", 1:"B", 2:"C", 2:"ABC" - "Super-Duper-XL500-42-AutoCoder!" -> 0:"Super", 1:"Duper", 2:"XL", 2:"SuperDuperXL", 3:"500" 4:"42", 5:"Auto", 6:"Coder", 6:"AutoCoder" One use for WordDelimiterFilter is to help match words with different subword delimiters. For example, if the source text contained "wi-fi" one may want "wifi" "WiFi" "wi-fi" "wi+fi" queries to all match. One way of doing so is to specify combinations="1" in the analyzer used for indexing, and combinations="0" (the default) in the analyzer used for querying. Given that the current StandardTokenizer immediately removes many intra-word delimiters, it is recommended that this filter be used after a tokenizer that does not do this (such as WhitespaceTokenizer).


Nested Class Summary
 
Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.AttributeFactory, AttributeSource.State
 
Field Summary
static int ALPHA
           
static int ALPHANUM
           
static int CATENATE_ALL
          Causes all subword parts to be catenated:

"wi-fi-4000" => "wifi4000"

static int CATENATE_NUMBERS
          Causes maximum runs of word parts to be catenated:

"wi-fi" => "wifi"

static int CATENATE_WORDS
          Causes maximum runs of word parts to be catenated:

"wi-fi" => "wifi"

static int DIGIT
           
static int GENERATE_NUMBER_PARTS
          Causes number subwords to be generated:

"500-42" => "500" "42"

static int GENERATE_WORD_PARTS
          Causes parts of words to be generated:

"PowerShot" => "Power" "Shot"

static int LOWER
           
static int PRESERVE_ORIGINAL
          Causes original words are preserved and added to the subword list (Defaults to false)

"500-42" => "500" "42" "500-42"

static int SPLIT_ON_CASE_CHANGE
          If not set, causes case changes to be ignored (subwords will only be generated given SUBWORD_DELIM tokens)
static int SPLIT_ON_NUMERICS
          If not set, causes numeric changes to be ignored (subwords will only be generated given SUBWORD_DELIM tokens).
static int STEM_ENGLISH_POSSESSIVE
          Causes trailing "'s" to be removed for each subword

"O'Neil's" => "O", "Neil"

static int SUBWORD_DELIM
           
static int UPPER
           
 
Fields inherited from class org.apache.lucene.analysis.TokenFilter
input
 
Constructor Summary
WordDelimiterFilter(TokenStream in, byte[] charTypeTable, int configurationFlags, CharArraySet protWords)
          Creates a new WordDelimiterFilter
WordDelimiterFilter(TokenStream in, int configurationFlags, CharArraySet protWords)
          Creates a new WordDelimiterFilter using WordDelimiterIterator.DEFAULT_WORD_DELIM_TABLE as its charTypeTable
 
Method Summary
 boolean incrementToken()
           
 void reset()
          
 
Methods inherited from class org.apache.lucene.analysis.TokenFilter
close, end
 
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
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

LOWER

public static final int LOWER
See Also:
Constant Field Values

UPPER

public static final int UPPER
See Also:
Constant Field Values

DIGIT

public static final int DIGIT
See Also:
Constant Field Values

SUBWORD_DELIM

public static final int SUBWORD_DELIM
See Also:
Constant Field Values

ALPHA

public static final int ALPHA
See Also:
Constant Field Values

ALPHANUM

public static final int ALPHANUM
See Also:
Constant Field Values

GENERATE_WORD_PARTS

public static final int GENERATE_WORD_PARTS
Causes parts of words to be generated:

"PowerShot" => "Power" "Shot"

See Also:
Constant Field Values

GENERATE_NUMBER_PARTS

public static final int GENERATE_NUMBER_PARTS
Causes number subwords to be generated:

"500-42" => "500" "42"

See Also:
Constant Field Values

CATENATE_WORDS

public static final int CATENATE_WORDS
Causes maximum runs of word parts to be catenated:

"wi-fi" => "wifi"

See Also:
Constant Field Values

CATENATE_NUMBERS

public static final int CATENATE_NUMBERS
Causes maximum runs of word parts to be catenated:

"wi-fi" => "wifi"

See Also:
Constant Field Values

CATENATE_ALL

public static final int CATENATE_ALL
Causes all subword parts to be catenated:

"wi-fi-4000" => "wifi4000"

See Also:
Constant Field Values

PRESERVE_ORIGINAL

public static final int PRESERVE_ORIGINAL
Causes original words are preserved and added to the subword list (Defaults to false)

"500-42" => "500" "42" "500-42"

See Also:
Constant Field Values

SPLIT_ON_CASE_CHANGE

public static final int SPLIT_ON_CASE_CHANGE
If not set, causes case changes to be ignored (subwords will only be generated given SUBWORD_DELIM tokens)

See Also:
Constant Field Values

SPLIT_ON_NUMERICS

public static final int SPLIT_ON_NUMERICS
If not set, causes numeric changes to be ignored (subwords will only be generated given SUBWORD_DELIM tokens).

See Also:
Constant Field Values

STEM_ENGLISH_POSSESSIVE

public static final int STEM_ENGLISH_POSSESSIVE
Causes trailing "'s" to be removed for each subword

"O'Neil's" => "O", "Neil"

See Also:
Constant Field Values
Constructor Detail

WordDelimiterFilter

public WordDelimiterFilter(TokenStream in,
                           byte[] charTypeTable,
                           int configurationFlags,
                           CharArraySet protWords)
Creates a new WordDelimiterFilter

Parameters:
in - TokenStream to be filtered
charTypeTable - table containing character types
configurationFlags - Flags configuring the filter
protWords - If not null is the set of tokens to protect from being delimited

WordDelimiterFilter

public WordDelimiterFilter(TokenStream in,
                           int configurationFlags,
                           CharArraySet protWords)
Creates a new WordDelimiterFilter using WordDelimiterIterator.DEFAULT_WORD_DELIM_TABLE as its charTypeTable

Parameters:
in - TokenStream to be filtered
configurationFlags - Flags configuring the filter
protWords - If not null is the set of tokens to protect from being delimited
Method Detail

incrementToken

public boolean incrementToken()
                       throws IOException
Specified by:
incrementToken in class TokenStream
Throws:
IOException

reset

public void reset()
           throws IOException

Overrides:
reset in class TokenFilter
Throws:
IOException


Copyright © 2000-2013 Apache Software Foundation. All Rights Reserved.