All Implemented Interfaces:
Closeable, AutoCloseable, Unwrappable<TokenStream>

@Deprecated public final class SynonymFilter extends TokenFilter
Deprecated.
Use SynonymGraphFilter instead, but be sure to also use FlattenGraphFilter at index time (not at search time) as well.
Matches single or multi word synonyms in a token stream. This token stream cannot properly handle position increments != 1, ie, you should place this filter before filtering out stop words.

Note that with the current implementation, parsing is greedy, so whenever multiple parses would apply, the rule starting the earliest and parsing the most tokens wins. For example if you have these rules:

   a -> x
   a b -> y
   b c d -> z
 
Then input a b c d e parses to y b c d, ie the 2nd rule "wins" because it started earliest and matched the most input tokens of other rules starting at that point.

A future improvement to this filter could allow non-greedy parsing, such that the 3rd rule would win, and also separately allow multiple parses, such that all 3 rules would match, perhaps even on a rule by rule basis.

NOTE: when a match occurs, the output tokens associated with the matching rule are "stacked" on top of the input stream (if the rule had keepOrig=true) and also on top of another matched rule's output tokens. This is not a correct solution, as really the output should be an arbitrary graph/lattice. For example, with the above match, you would expect an exact PhraseQuery "y b c" to match the parsed tokens, but it will fail to do so. This limitation is necessary because Lucene's TokenStream (and index) cannot yet represent an arbitrary graph.

NOTE: If multiple incoming tokens arrive on the same position, only the first token at that position is used for parsing. Subsequent tokens simply pass through and are not parsed. A future improvement would be to allow these tokens to also be matched.

  • Field Details

    • TYPE_SYNONYM

      public static final String TYPE_SYNONYM
      Deprecated.
      See Also:
    • synonyms

      private final SynonymMap synonyms
      Deprecated.
    • ignoreCase

      private final boolean ignoreCase
      Deprecated.
    • rollBufferSize

      private final int rollBufferSize
      Deprecated.
    • captureCount

      private int captureCount
      Deprecated.
    • termAtt

      private final CharTermAttribute termAtt
      Deprecated.
    • posIncrAtt

      private final PositionIncrementAttribute posIncrAtt
      Deprecated.
    • posLenAtt

      private final PositionLengthAttribute posLenAtt
      Deprecated.
    • typeAtt

      private final TypeAttribute typeAtt
      Deprecated.
    • offsetAtt

      private final OffsetAttribute offsetAtt
      Deprecated.
    • inputSkipCount

      private int inputSkipCount
      Deprecated.
    • futureInputs

      private final SynonymFilter.PendingInput[] futureInputs
      Deprecated.
    • bytesReader

      private final ByteArrayDataInput bytesReader
      Deprecated.
    • futureOutputs

      private final SynonymFilter.PendingOutputs[] futureOutputs
      Deprecated.
    • nextWrite

      private int nextWrite
      Deprecated.
    • nextRead

      private int nextRead
      Deprecated.
    • finished

      private boolean finished
      Deprecated.
    • scratchArc

      private final FST.Arc<BytesRef> scratchArc
      Deprecated.
    • fst

      private final FST<BytesRef> fst
      Deprecated.
    • fstReader

      private final FST.BytesReader fstReader
      Deprecated.
    • scratchBytes

      private final BytesRef scratchBytes
      Deprecated.
    • scratchChars

      private final CharsRefBuilder scratchChars
      Deprecated.
    • lastStartOffset

      private int lastStartOffset
      Deprecated.
    • lastEndOffset

      private int lastEndOffset
      Deprecated.
  • Constructor Details

    • SynonymFilter

      public SynonymFilter(TokenStream input, SynonymMap synonyms, boolean ignoreCase)
      Deprecated.
      Parameters:
      input - input tokenstream
      synonyms - synonym map
      ignoreCase - 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
  • Method Details

    • capture

      private void capture()
      Deprecated.
    • parse

      private void parse() throws IOException
      Deprecated.
      Throws:
      IOException
    • addOutput

      private void addOutput(BytesRef bytes, int matchInputLength, int matchEndOffset)
      Deprecated.
    • rollIncr

      private int rollIncr(int count)
      Deprecated.
    • getCaptureCount

      int getCaptureCount()
      Deprecated.
    • incrementToken

      public boolean incrementToken() throws IOException
      Deprecated.
      Description copied from class: TokenStream
      Consumers (i.e., IndexWriter) 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().

      Specified by:
      incrementToken in class TokenStream
      Returns:
      false for end of stream; true otherwise
      Throws:
      IOException
    • reset

      public void reset() throws IOException
      Deprecated.
      Description copied from class: TokenFilter
      This method is called by a consumer before it begins consumption using 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.

      Overrides:
      reset in class TokenFilter
      Throws:
      IOException