Class PatternCaptureGroupTokenFilter
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Unwrappable<TokenStream>
For example, a pattern like:
"(https?://([a-zA-Z\-_0-9.]+))"
when matched against the string "http://www.foo.com/index" would return the tokens "https://www.foo.com" and "www.foo.com".
If none of the patterns match, or if preserveOriginal is true, the original token will be preserved.
Each pattern is matched as often as it can be, so the pattern "(...)"
, when
matched against "abcdefghi"
would produce ["abc","def","ghi"]
A camelCaseFilter could be written as:
"([A-Z]{2,})",
"(?<![A-Z])([A-Z][a-z]+)",
"(?:^|\\b|(?<=[0-9_])|(?<=[A-Z]{2}))([a-z]+)",
"([0-9]+)"
plus if preserveOriginal
is true, it would also return "camelCaseFilter"
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Nested Class Summary
Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource
AttributeSource.State
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate final CharTermAttribute
private int[]
private int
private final int[]
private final Matcher[]
private final PositionIncrementAttribute
private final boolean
private final CharsRefBuilder
private AttributeSource.State
Fields inherited from class org.apache.lucene.analysis.TokenFilter
input
Fields inherited from class org.apache.lucene.analysis.TokenStream
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
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Constructor Summary
ConstructorsConstructorDescriptionPatternCaptureGroupTokenFilter
(TokenStream input, boolean preserveOriginal, Pattern... patterns) -
Method Summary
Modifier and TypeMethodDescriptionboolean
Consumers (i.e.,IndexWriter
) use this method to advance the stream to the next token.private boolean
void
reset()
This method is called by a consumer before it begins consumption usingTokenStream.incrementToken()
.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, toString
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Field Details
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charTermAttr
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posAttr
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state
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matchers
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spare
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groupCounts
private final int[] groupCounts -
preserveOriginal
private final boolean preserveOriginal -
currentGroup
private int[] currentGroup -
currentMatcher
private int currentMatcher
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Constructor Details
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PatternCaptureGroupTokenFilter
public PatternCaptureGroupTokenFilter(TokenStream input, boolean preserveOriginal, Pattern... patterns) - Parameters:
input
- the inputTokenStream
preserveOriginal
- set to true to return the original token even if one of the patterns matchespatterns
- an array ofPattern
objects to match against each token
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Method Details
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nextCapture
private boolean nextCapture() -
incrementToken
Description copied from class:TokenStream
Consumers (i.e.,IndexWriter
) use this method to advance the stream to the next token. Implementing classes must implement this method and update the appropriateAttributeImpl
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)
andAttributeSource.getAttribute(Class)
, references to allAttributeImpl
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()
.- Specified by:
incrementToken
in classTokenStream
- Returns:
- false for end of stream; true otherwise
- Throws:
IOException
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reset
Description copied from class:TokenFilter
This method is called by a consumer before it begins consumption usingTokenStream.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 throwIllegalStateException
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.- Overrides:
reset
in classTokenFilter
- Throws:
IOException
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