Class EdgeNGramTokenFilter

  • All Implemented Interfaces:
    Closeable, AutoCloseable

    public final class EdgeNGramTokenFilter
    extends TokenFilter
    Tokenizes the given token into n-grams of given size(s).

    This TokenFilter create n-grams from the beginning edge or ending edge of a input token.

    • Constructor Detail

      • EdgeNGramTokenFilter

        public EdgeNGramTokenFilter​(TokenStream input,
                                    EdgeNGramTokenFilter.Side side,
                                    int minGram,
                                    int maxGram)
        Creates EdgeNGramTokenFilter that can generate n-grams in the sizes of the given range
        Parameters:
        input - TokenStream holding the input to be tokenized
        side - the EdgeNGramTokenFilter.Side from which to chop off an n-gram
        minGram - the smallest n-gram to generate
        maxGram - the largest n-gram to generate
      • EdgeNGramTokenFilter

        public EdgeNGramTokenFilter​(TokenStream input,
                                    String sideLabel,
                                    int minGram,
                                    int maxGram)
        Creates EdgeNGramTokenFilter that can generate n-grams in the sizes of the given range
        Parameters:
        input - TokenStream holding the input to be tokenized
        sideLabel - the name of the EdgeNGramTokenFilter.Side from which to chop off an n-gram
        minGram - the smallest n-gram to generate
        maxGram - the largest n-gram to generate
    • Method Detail

      • incrementToken

        public final boolean incrementToken()
                                     throws IOException
        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