public final class WordDelimiterFilter extends TokenFilter
"Wi-Fi"
→ "Wi", "Fi"
"PowerShot"
→
"Power", "Shot"
"SD500"
→
"SD", "500"
"//hello---there, 'dude'"
→
"hello", "there", "dude"
"O'Neil's"
→ "O", "Neil"
"PowerShot"
→ 0:"Power", 1:"Shot"
(0 and 1 are the token positions)"PowerShot"
→
0:"Power", 1:"Shot" 1:"PowerShot"
"A's+B's&C's"
-gt; 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"
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
).AttributeSource.AttributeFactory, AttributeSource.State
Modifier and Type | Field and Description |
---|---|
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 |
Constructor and Description |
---|
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 |
Modifier and Type | Method and Description |
---|---|
boolean |
incrementToken()
Consumers (i.e.,
IndexWriter ) use this method to advance the stream to
the next token. |
void |
reset()
This method is called by a consumer before it begins consumption using
TokenStream.incrementToken() . |
close, end
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toString
public static final int LOWER
public static final int UPPER
public static final int DIGIT
public static final int SUBWORD_DELIM
public static final int ALPHA
public static final int ALPHANUM
public static final int GENERATE_WORD_PARTS
public static final int GENERATE_NUMBER_PARTS
public static final int CATENATE_WORDS
public static final int CATENATE_NUMBERS
public static final int CATENATE_ALL
public static final int PRESERVE_ORIGINAL
public static final int SPLIT_ON_CASE_CHANGE
public static final int SPLIT_ON_NUMERICS
public static final int STEM_ENGLISH_POSSESSIVE
public WordDelimiterFilter(TokenStream in, byte[] charTypeTable, int configurationFlags, CharArraySet protWords)
in
- TokenStream to be filteredcharTypeTable
- table containing character typesconfigurationFlags
- Flags configuring the filterprotWords
- If not null is the set of tokens to protect from being delimitedpublic WordDelimiterFilter(TokenStream in, int configurationFlags, CharArraySet protWords)
WordDelimiterIterator.DEFAULT_WORD_DELIM_TABLE
as its charTypeTablein
- TokenStream to be filteredconfigurationFlags
- Flags configuring the filterprotWords
- If not null is the set of tokens to protect from being delimitedpublic boolean incrementToken() throws IOException
TokenStream
IndexWriter
) use this method to advance the stream to
the next token. Implementing classes must implement this method and update
the appropriate AttributeImpl
s 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 AttributeImpl
s 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()
.
incrementToken
in class TokenStream
IOException
public void reset() throws IOException
TokenStream.incrementToken()
.
Resets this stream to a clean state. Stateful implementations must implement this method so that they can be reused, just as if they had been created fresh.
If you override this method, always call super.reset()
, otherwise
some internal state will not be correctly reset (e.g., Tokenizer
will
throw IllegalStateException
on further usage).
NOTE:
The default implementation chains the call to the input TokenStream, so
be sure to call super.reset()
when overriding this method.
reset
in class TokenFilter
IOException
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