Class HunspellStemFilter

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable

    public final class HunspellStemFilter
    extends TokenFilter
    TokenFilter that uses hunspell affix rules and words to stem tokens. Since hunspell supports a word having multiple stems, this filter can emit multiple tokens for each consumed token

    Note: This filter is aware of the KeywordAttribute. To prevent certain terms from being passed to the stemmer KeywordAttribute.isKeyword() should be set to true in a previous TokenStream. Note: For including the original term as well as the stemmed version, see KeywordRepeatFilterFactory

    • Constructor Detail

      • HunspellStemFilter

        public HunspellStemFilter​(TokenStream input,
                                  HunspellDictionary dictionary,
                                  int recursionCap)
        Creates a new HunspellStemFilter that will stem tokens from the given TokenStream using affix rules in the provided HunspellDictionary
        Parameters:
        input - TokenStream whose tokens will be stemmed
        dictionary - HunspellDictionary containing the affix rules and words that will be used to stem the tokens
        recursionCap - maximum level of recursion stemmer can go into, defaults to 2
      • HunspellStemFilter

        public HunspellStemFilter​(TokenStream input,
                                  HunspellDictionary dictionary,
                                  boolean dedup,
                                  int recursionCap)
        Creates a new HunspellStemFilter that will stem tokens from the given TokenStream using affix rules in the provided HunspellDictionary
        Parameters:
        input - TokenStream whose tokens will be stemmed
        dictionary - HunspellDictionary containing the affix rules and words that will be used to stem the tokens
        dedup - true if only unique terms should be output.
        recursionCap - maximum level of recursion stemmer can go into, defaults to 2
    • Method Detail

      • incrementToken

        public boolean incrementToken()
                               throws java.io.IOException
        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:
        java.io.IOException
      • reset

        public void reset()
                   throws java.io.IOException
        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:
        java.io.IOException