org.apache.lucene.analysis.miscellaneous
Class WordDelimiterFilter

java.lang.Object
  org.apache.lucene.util.AttributeSource
      org.apache.lucene.analysis.TokenStream
          org.apache.lucene.analysis.TokenFilter
              org.apache.lucene.analysis.miscellaneous.WordDelimiterFilter

All Implemented Interfaces:

Closeable

public final class WordDelimiterFilter
extends org.apache.lucene.analysis.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

org.apache.lucene.util.AttributeSource.AttributeFactory, org.apache.lucene.util.AttributeSource.State

Field Summary

static int	ALPHA
static int	ALPHANUM
static int	DIGIT
static int	LOWER
static int	SUBWORD_DELIM
static int	UPPER

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

input

Constructor Summary

WordDelimiterFilter(org.apache.lucene.analysis.TokenStream in, byte[] charTypeTable, int generateWordParts, int generateNumberParts, int catenateWords, int catenateNumbers, int catenateAll, int splitOnCaseChange, int preserveOriginal, int splitOnNumerics, int stemEnglishPossessive, org.apache.lucene.analysis.CharArraySet protWords)

WordDelimiterFilter(org.apache.lucene.analysis.TokenStream in, int generateWordParts, int generateNumberParts, int catenateWords, int catenateNumbers, int catenateAll, int splitOnCaseChange, int preserveOriginal, int splitOnNumerics, int stemEnglishPossessive, org.apache.lucene.analysis.CharArraySet protWords)

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, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, 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

Constructor Detail

WordDelimiterFilter

public WordDelimiterFilter(org.apache.lucene.analysis.TokenStream in,
                           byte[] charTypeTable,
                           int generateWordParts,
                           int generateNumberParts,
                           int catenateWords,
                           int catenateNumbers,
                           int catenateAll,
                           int splitOnCaseChange,
                           int preserveOriginal,
                           int splitOnNumerics,
                           int stemEnglishPossessive,
                           org.apache.lucene.analysis.CharArraySet protWords)

Parameters:

in - Token stream to be filtered.

charTypeTable -

generateWordParts - If 1, causes parts of words to be generated: "PowerShot" => "Power" "Shot"

generateNumberParts - If 1, causes number subwords to be generated: "500-42" => "500" "42"

catenateWords - 1, causes maximum runs of word parts to be catenated: "wi-fi" => "wifi"

catenateNumbers - If 1, causes maximum runs of number parts to be catenated: "500-42" => "50042"

catenateAll - If 1, causes all subword parts to be catenated: "wi-fi-4000" => "wifi4000"

splitOnCaseChange - 1, causes "PowerShot" to be two tokens; ("Power-Shot" remains two parts regards)

preserveOriginal - If 1, includes original words in subwords: "500-42" => "500" "42" "500-42"

splitOnNumerics - 1, causes "j2se" to be three tokens; "j" "2" "se"

stemEnglishPossessive - If 1, causes trailing "'s" to be removed for each subword: "O'Neil's" => "O", "Neil"

protWords - If not null is the set of tokens to protect from being delimited

WordDelimiterFilter

public WordDelimiterFilter(org.apache.lucene.analysis.TokenStream in,
                           int generateWordParts,
                           int generateNumberParts,
                           int catenateWords,
                           int catenateNumbers,
                           int catenateAll,
                           int splitOnCaseChange,
                           int preserveOriginal,
                           int splitOnNumerics,
                           int stemEnglishPossessive,
                           org.apache.lucene.analysis.CharArraySet protWords)

Parameters:

in - Token stream to be filtered.

generateWordParts - If 1, causes parts of words to be generated: "PowerShot", "Power-Shot" => "Power" "Shot"

generateNumberParts - If 1, causes number subwords to be generated: "500-42" => "500" "42"

catenateWords - 1, causes maximum runs of word parts to be catenated: "wi-fi" => "wifi"

catenateNumbers - If 1, causes maximum runs of number parts to be catenated: "500-42" => "50042"

catenateAll - If 1, causes all subword parts to be catenated: "wi-fi-4000" => "wifi4000"

splitOnCaseChange - 1, causes "PowerShot" to be two tokens; ("Power-Shot" remains two parts regards)

preserveOriginal - If 1, includes original words in subwords: "500-42" => "500" "42" "500-42"

splitOnNumerics - 1, causes "j2se" to be three tokens; "j" "2" "se"

stemEnglishPossessive - If 1, causes trailing "'s" to be removed for each subword: "O'Neil's" => "O", "Neil"

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 org.apache.lucene.analysis.TokenStream

Throws:

IOException

reset

public void reset()
           throws IOException

Overrides:

reset in class org.apache.lucene.analysis.TokenFilter

Throws:

IOException