Package org.apache.lucene.analysis.miscellaneous

Class ASCIIFoldingFilter

    • Constructor Detail

      • ASCIIFoldingFilter

        public ASCIIFoldingFilter​(TokenStream input)

      • ASCIIFoldingFilter

        public ASCIIFoldingFilter​(TokenStream input,
                          boolean preserveOriginal)
        Create a new ASCIIFoldingFilter.
        Parameters:
        input - TokenStream to filter
        preserveOriginal - should the original tokens be kept on the input stream with a 0 position increment from the folded tokens?

    • Method Detail

      • isPreserveOriginal

        public boolean isPreserveOriginal()
        Does the filter preserve the original tokens?

      • incrementToken

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

      • reset

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

      • foldToASCII

        public void foldToASCII​(char[] input,
                        int length)
        Converts characters above ASCII to their ASCII equivalents. For example, accents are removed from accented characters.
        Parameters:
        input - The string to fold
        length - The number of characters in the input string

      • foldToASCII

        public static final int foldToASCII​(char[] input,
                                    int inputPos,
                                    char[] output,
                                    int outputPos,
                                    int length)
        Converts characters above ASCII to their ASCII equivalents. For example, accents are removed from accented characters.
        Parameters:
        input - The characters to fold
        inputPos - Index of the first character to fold
        output - The result of the folding. Should be of size >= length * 4.
        outputPos - Index of output where to put the result of the folding
        length - The number of characters to fold
        Returns:
        length of output