public abstract class FilteringTokenFilter extends TokenFilter
accept() and return a boolean if the current
token should be preserved. incrementToken() uses this method
to decide if a token should be passed to the caller.AttributeSource.AttributeFactory, AttributeSource.Stateinput| Constructor and Description |
|---|
FilteringTokenFilter(boolean enablePositionIncrements,
TokenStream input) |
| Modifier and Type | Method and Description |
|---|---|
protected abstract boolean |
accept()
Override this method and return if the current input token should be returned by
incrementToken(). |
boolean |
getEnablePositionIncrements() |
boolean |
incrementToken()
Consumers (i.e.,
IndexWriter) use this method to advance the stream to
the next token. |
void |
reset()
Reset the filter as well as the input TokenStream.
|
void |
setEnablePositionIncrements(boolean enable)
If
true, this TokenFilter will preserve
positions of the incoming tokens (ie, accumulate and
set position increments of the removed tokens). |
close, endaddAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toStringpublic FilteringTokenFilter(boolean enablePositionIncrements,
TokenStream input)
protected abstract boolean accept()
throws IOException
incrementToken().IOExceptionpublic final 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
TokenFilterreset in class TokenFilterIOExceptionpublic boolean getEnablePositionIncrements()
setEnablePositionIncrements(boolean)public void setEnablePositionIncrements(boolean enable)
true, this TokenFilter will preserve
positions of the incoming tokens (ie, accumulate and
set position increments of the removed tokens).
Generally, true is best as it does not
lose information (positions of the original tokens)
during indexing.
When set, when a token is stopped (omitted), the position increment of the following token is incremented.
NOTE: be sure to also
set QueryParser.setEnablePositionIncrements(boolean) if
you use QueryParser to create queries.