private static final class ContextSuggestField.PrefixTokenFilter extends TokenFilter
ContextSuggestField.PrefixTokenFilter
wraps a TokenStream
and adds a set
prefixes ahead. The position attribute will not be incremented for the prefixes.AttributeSource.State
Modifier and Type | Field and Description |
---|---|
private java.util.Iterator<java.lang.CharSequence> |
currentPrefix |
private PositionIncrementAttribute |
posAttr |
private java.lang.Iterable<java.lang.CharSequence> |
prefixes |
private char |
separator |
private CharTermAttribute |
termAttr |
input
DEFAULT_TOKEN_ATTRIBUTE_FACTORY
Constructor and Description |
---|
PrefixTokenFilter(TokenStream input,
char separator,
java.lang.Iterable<java.lang.CharSequence> prefixes)
Create a new
ContextSuggestField.PrefixTokenFilter |
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, end
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString
private final char separator
private final CharTermAttribute termAttr
private final PositionIncrementAttribute posAttr
private final java.lang.Iterable<java.lang.CharSequence> prefixes
private java.util.Iterator<java.lang.CharSequence> currentPrefix
public PrefixTokenFilter(TokenStream input, char separator, java.lang.Iterable<java.lang.CharSequence> prefixes)
ContextSuggestField.PrefixTokenFilter
input
- TokenStream
to wrapseparator
- Character used separate prefixes from other tokensprefixes
- Iterable
of CharSequence
which keeps all prefixespublic 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
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