public final class SynonymGraphFilter extends TokenFilter
SynonymMap
to an incoming TokenStream
, producing a fully correct graph
output. This is a replacement for SynonymFilter
, which produces
incorrect graphs for multi-token synonyms.
However, if you use this during indexing, you must follow it with
FlattenGraphFilter
to squash tokens on top of one another
like SynonymFilter
, because the indexer can't directly
consume a graph. To get fully correct positional queries when your
synonym replacements are multiple tokens, you should instead apply
synonyms using this TokenFilter
at query time and translate
the resulting graph to a TermAutomatonQuery
e.g. using
TokenStreamToTermAutomatonQuery
.
NOTE: this cannot consume an incoming graph; results will be undefined.
Modifier and Type | Class and Description |
---|---|
(package private) static class |
SynonymGraphFilter.BufferedInputToken |
(package private) static class |
SynonymGraphFilter.BufferedOutputToken |
AttributeSource.State
Modifier and Type | Field and Description |
---|---|
private ByteArrayDataInput |
bytesReader |
private int |
captureCount |
private boolean |
finished |
private FST<BytesRef> |
fst |
private FST.BytesReader |
fstReader |
private boolean |
ignoreCase |
private int |
lastNodeOut |
private boolean |
liveToken |
private RollingBuffer<SynonymGraphFilter.BufferedInputToken> |
lookahead |
private int |
lookaheadNextRead |
private int |
lookaheadNextWrite |
private int |
matchEndOffset |
private int |
matchStartOffset |
private int |
maxLookaheadUsed |
private int |
nextNodeOut |
private OffsetAttribute |
offsetAtt |
private java.util.LinkedList<SynonymGraphFilter.BufferedOutputToken> |
outputBuffer |
private PositionIncrementAttribute |
posIncrAtt |
private PositionLengthAttribute |
posLenAtt |
private FST.Arc<BytesRef> |
scratchArc |
private BytesRef |
scratchBytes |
private CharsRefBuilder |
scratchChars |
private SynonymMap |
synonyms |
private CharTermAttribute |
termAtt |
static java.lang.String |
TYPE_SYNONYM |
private TypeAttribute |
typeAtt |
input
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
Constructor and Description |
---|
SynonymGraphFilter(TokenStream input,
SynonymMap synonyms,
boolean ignoreCase)
Apply previously built synonyms to incoming tokens.
|
Modifier and Type | Method and Description |
---|---|
private void |
bufferOutputTokens(BytesRef bytes,
int matchInputLength)
Expands the output graph into the necessary tokens, adding
synonyms as side paths parallel to the input tokens, and
buffers them in the output token buffer.
|
private void |
capture()
Buffers the current input token into lookahead buffer.
|
(package private) int |
getCaptureCount() |
(package private) int |
getMaxLookaheadUsed() |
boolean |
incrementToken()
Consumers (i.e.,
IndexWriter ) use this method to advance the stream to
the next token. |
private boolean |
parse()
Scans the next input token(s) to see if a synonym matches.
|
private void |
releaseBufferedToken() |
void |
reset()
This method is called by a consumer before it begins consumption using
TokenStream.incrementToken() . |
close, end
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString
public static final java.lang.String TYPE_SYNONYM
private final CharTermAttribute termAtt
private final PositionIncrementAttribute posIncrAtt
private final PositionLengthAttribute posLenAtt
private final TypeAttribute typeAtt
private final OffsetAttribute offsetAtt
private final SynonymMap synonyms
private final boolean ignoreCase
private final FST.BytesReader fstReader
private final ByteArrayDataInput bytesReader
private final BytesRef scratchBytes
private final CharsRefBuilder scratchChars
private final java.util.LinkedList<SynonymGraphFilter.BufferedOutputToken> outputBuffer
private int nextNodeOut
private int lastNodeOut
private int maxLookaheadUsed
private int captureCount
private boolean liveToken
private int matchStartOffset
private int matchEndOffset
private boolean finished
private int lookaheadNextRead
private int lookaheadNextWrite
private RollingBuffer<SynonymGraphFilter.BufferedInputToken> lookahead
public SynonymGraphFilter(TokenStream input, SynonymMap synonyms, boolean ignoreCase)
input
- input tokenstreamsynonyms
- synonym mapignoreCase
- case-folds input for matching with Character.toLowerCase(int)
.
Note, if you set this to true, it's your responsibility to lowercase
the input entries when you create the SynonymMap
public boolean incrementToken() throws java.io.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
java.io.IOException
private void releaseBufferedToken() throws java.io.IOException
java.io.IOException
private boolean parse() throws java.io.IOException
java.io.IOException
private void bufferOutputTokens(BytesRef bytes, int matchInputLength)
private void capture()
public void reset() throws java.io.IOException
TokenFilter
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
java.io.IOException
int getCaptureCount()
int getMaxLookaheadUsed()