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.
AttributeSource.State| Modifier and Type | Field and Description |
|---|---|
static String |
TYPE_SYNONYM |
inputDEFAULT_TOKEN_ATTRIBUTE_FACTORY| Constructor and Description |
|---|
SynonymGraphFilter(TokenStream input,
SynonymMap synonyms,
boolean ignoreCase) |
| 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, endaddAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toStringpublic static final String TYPE_SYNONYM
public SynonymGraphFilter(TokenStream input, SynonymMap synonyms, boolean ignoreCase)
public boolean incrementToken() throws IOException
TokenStreamIndexWriter) use this method to advance the stream to
the next token. Implementing classes must implement this method and update
the appropriate AttributeImpls 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 AttributeImpls 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 TokenStreamIOExceptionpublic void reset() throws IOException
TokenFilterTokenStream.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 TokenFilterIOException