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java.lang.Object org.apache.lucene.util.AttributeSource org.apache.lucene.analysis.TokenStream org.apache.lucene.analysis.TokenFilter org.apache.lucene.analysis.ngram.EdgeNGramTokenFilter
public class EdgeNGramTokenFilter
Tokenizes the given token into n-grams of given size(s).
This TokenFilter
create n-grams from the beginning edge or ending edge of a input token.
Nested Class Summary | |
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static class |
EdgeNGramTokenFilter.Side
Specifies which side of the input the n-gram should be generated from |
Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource |
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AttributeSource.AttributeFactory, AttributeSource.State |
Field Summary | |
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static int |
DEFAULT_MAX_GRAM_SIZE
|
static int |
DEFAULT_MIN_GRAM_SIZE
|
static EdgeNGramTokenFilter.Side |
DEFAULT_SIDE
|
Fields inherited from class org.apache.lucene.analysis.TokenFilter |
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input |
Constructor Summary | |
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protected |
EdgeNGramTokenFilter(TokenStream input)
|
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EdgeNGramTokenFilter(TokenStream input,
EdgeNGramTokenFilter.Side side,
int minGram,
int maxGram)
Creates EdgeNGramTokenFilter that can generate n-grams in the sizes of the given range |
|
EdgeNGramTokenFilter(TokenStream input,
String sideLabel,
int minGram,
int maxGram)
Creates EdgeNGramTokenFilter that can generate n-grams in the sizes of the given range |
Method Summary | |
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boolean |
incrementToken()
Consumers (i.e., IndexWriter ) use this method to advance the stream to
the next token. |
Token |
next()
Deprecated. Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer. |
Token |
next(Token reusableToken)
Deprecated. Will be removed in Lucene 3.0. This method is final, as it should not be overridden. Delegates to the backwards compatibility layer. |
void |
reset()
Reset the filter as well as the input TokenStream. |
Methods inherited from class org.apache.lucene.analysis.TokenFilter |
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close, end |
Methods inherited from class org.apache.lucene.analysis.TokenStream |
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getOnlyUseNewAPI, setOnlyUseNewAPI |
Methods inherited from class org.apache.lucene.util.AttributeSource |
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addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, restoreState, toString |
Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Field Detail |
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public static final EdgeNGramTokenFilter.Side DEFAULT_SIDE
public static final int DEFAULT_MAX_GRAM_SIZE
public static final int DEFAULT_MIN_GRAM_SIZE
Constructor Detail |
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protected EdgeNGramTokenFilter(TokenStream input)
public EdgeNGramTokenFilter(TokenStream input, EdgeNGramTokenFilter.Side side, int minGram, int maxGram)
input
- TokenStream
holding the input to be tokenizedside
- the EdgeNGramTokenFilter.Side
from which to chop off an n-gramminGram
- the smallest n-gram to generatemaxGram
- the largest n-gram to generatepublic EdgeNGramTokenFilter(TokenStream input, String sideLabel, int minGram, int maxGram)
input
- TokenStream
holding the input to be tokenizedsideLabel
- the name of the EdgeNGramTokenFilter.Side
from which to chop off an n-gramminGram
- the smallest n-gram to generatemaxGram
- the largest n-gram to generateMethod Detail |
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public final 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)
or downcasts,
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
Note that this method will be defined abstract in Lucene 3.0.
IOException
public final Token next(Token reusableToken) throws IOException
TokenStream
This implicitly defines a "contract" between consumers (callers of this method) and producers (implementations of this method that are the source for tokens):
Token
before calling this method again.Token.clear()
before setting the fields in
it and returning itToken
after it
has been returned: the caller may arbitrarily change it. If the producer
needs to hold onto the Token
for subsequent calls, it must clone()
it before storing it. Note that a TokenFilter
is considered a
consumer.
next
in class TokenStream
reusableToken
- a Token
that may or may not be used to return;
this parameter should never be null (the callee is not required to
check for null before using it, but it is a good idea to assert that
it is not null.)
Token
in the stream or null if end-of-stream was hit
IOException
public final Token next() throws IOException
TokenStream
Token
in the stream, or null at EOS.
next
in class TokenStream
IOException
public void reset() throws IOException
TokenFilter
reset
in class TokenFilter
IOException
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