Class WordDelimiterGraphFilter
java.lang.Object
org.apache.lucene.util.AttributeSource
org.apache.lucene.analysis.TokenStream
org.apache.lucene.analysis.TokenFilter
org.apache.lucene.analysis.miscellaneous.WordDelimiterGraphFilter
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Unwrappable<TokenStream>
Splits words into subwords and performs optional transformations on subword groups, producing a
correct token graph so that e.g.
PhraseQuery
can work correctly when this filter is used
in the search-time analyzer. Unlike the deprecated WordDelimiterFilter
, this token filter
produces a correct token graph as output. However, it cannot consume an input token graph
correctly. Processing is suppressed by KeywordAttribute.isKeyword()
=true.
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.
- If no CATENATE option is set, then no subword combinations are generated:
"PowerShot"
→0:"Power", 1:"Shot"
(0 and 1 are the token positions) - CATENATE_WORDS 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"
- CATENATE_NUMBERS works like CATENATE_WORDS, but for adjacent digit sequences.
- CATENATE_ALL smushes together all the token parts without distinguishing numbers and words.
WordDelimiterGraphFilter
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 CATENATE options in the analyzer
used for indexing, and not 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.State
-
Field Summary
Modifier and TypeFieldDescriptionstatic final int
Causes all subword parts to be catenated:static final int
Causes maximum runs of number parts to be catenated:static final int
Causes maximum runs of word parts to be catenated:static final int
Causes number subwords to be generated:static final int
Causes parts of words to be generated:static final int
Suppresses processing terms withKeywordAttribute.isKeyword()
=true.static final int
Causes original words are preserved and added to the subword list (Defaults to false)static final int
Causes lowercase -> uppercase transition to start a new subword.static final int
If not set, causes numeric changes to be ignored (subwords will only be generated given SUBWORD_DELIM tokens).static final int
Causes trailing "'s" to be removed for each subwordFields inherited from class org.apache.lucene.analysis.TokenFilter
input
Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
-
Constructor Summary
ConstructorDescriptionWordDelimiterGraphFilter
(TokenStream in, boolean adjustInternalOffsets, byte[] charTypeTable, int configurationFlags, CharArraySet protWords) Creates a new WordDelimiterGraphFilterWordDelimiterGraphFilter
(TokenStream in, int configurationFlags, CharArraySet protWords) Creates a new WordDelimiterGraphFilter usingWordDelimiterIterator.DEFAULT_WORD_DELIM_TABLE
as its charTypeTable -
Method Summary
Modifier and TypeMethodDescriptionstatic String
flagsToString
(int flags) Returns string representation of configuration flagsboolean
void
reset()
toString()
Methods inherited from class org.apache.lucene.analysis.TokenFilter
close, end, 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
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Field Details
-
GENERATE_WORD_PARTS
public static final int GENERATE_WORD_PARTSCauses parts of words to be generated:"PowerShot" => "Power" "Shot"
- See Also:
-
GENERATE_NUMBER_PARTS
public static final int GENERATE_NUMBER_PARTSCauses number subwords to be generated:"500-42" => "500" "42"
- See Also:
-
CATENATE_WORDS
public static final int CATENATE_WORDSCauses maximum runs of word parts to be catenated:"wi-fi" => "wifi"
- See Also:
-
CATENATE_NUMBERS
public static final int CATENATE_NUMBERSCauses maximum runs of number parts to be catenated:"500-42" => "50042"
- See Also:
-
CATENATE_ALL
public static final int CATENATE_ALLCauses all subword parts to be catenated:"wi-fi-4000" => "wifi4000"
- See Also:
-
PRESERVE_ORIGINAL
public static final int PRESERVE_ORIGINALCauses original words are preserved and added to the subword list (Defaults to false)"500-42" => "500" "42" "500-42"
- See Also:
-
SPLIT_ON_CASE_CHANGE
public static final int SPLIT_ON_CASE_CHANGECauses lowercase -> uppercase transition to start a new subword.- See Also:
-
SPLIT_ON_NUMERICS
public static final int SPLIT_ON_NUMERICSIf not set, causes numeric changes to be ignored (subwords will only be generated given SUBWORD_DELIM tokens).- See Also:
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STEM_ENGLISH_POSSESSIVE
public static final int STEM_ENGLISH_POSSESSIVECauses trailing "'s" to be removed for each subword"O'Neil's" => "O", "Neil"
- See Also:
-
IGNORE_KEYWORDS
public static final int IGNORE_KEYWORDSSuppresses processing terms withKeywordAttribute.isKeyword()
=true.- See Also:
-
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Constructor Details
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WordDelimiterGraphFilter
public WordDelimiterGraphFilter(TokenStream in, boolean adjustInternalOffsets, byte[] charTypeTable, int configurationFlags, CharArraySet protWords) Creates a new WordDelimiterGraphFilter- Parameters:
in
- TokenStream to be filteredadjustInternalOffsets
- if the offsets of partial terms should be adjustedcharTypeTable
- table containing character typesconfigurationFlags
- Flags configuring the filterprotWords
- If not null is the set of tokens to protect from being delimited
-
WordDelimiterGraphFilter
Creates a new WordDelimiterGraphFilter usingWordDelimiterIterator.DEFAULT_WORD_DELIM_TABLE
as its charTypeTable- Parameters:
in
- TokenStream to be filteredconfigurationFlags
- Flags configuring the filterprotWords
- If not null is the set of tokens to protect from being delimited
-
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Method Details
-
incrementToken
- Specified by:
incrementToken
in classTokenStream
- Throws:
IOException
-
reset
- Overrides:
reset
in classTokenFilter
- Throws:
IOException
-
flagsToString
Returns string representation of configuration flags -
toString
- Overrides:
toString
in classAttributeSource
-