org.apache.lucene.analysis.miscellaneous

Class ASCIIFoldingFilter

java.lang.Object

org.apache.lucene.analysis.miscellaneous.ASCIIFoldingFilter

public final class ASCIIFoldingFilter
extends Object

This class converts alphabetic, numeric, and symbolic Unicode characters which are not in the first 127 ASCII characters (the "Basic Latin" Unicode block) into their ASCII equivalents, if one exists. Characters from the following Unicode blocks are converted; however, only those characters with reasonable ASCII alternatives are converted:

• C1 Controls and Latin-1 Supplement: http://www.unicode.org/charts/PDF/U0080.pdf
• Latin Extended-A: http://www.unicode.org/charts/PDF/U0100.pdf
• Latin Extended-B: http://www.unicode.org/charts/PDF/U0180.pdf
• Latin Extended Additional: http://www.unicode.org/charts/PDF/U1E00.pdf
• Latin Extended-C: http://www.unicode.org/charts/PDF/U2C60.pdf
• Latin Extended-D: http://www.unicode.org/charts/PDF/UA720.pdf
• IPA Extensions: http://www.unicode.org/charts/PDF/U0250.pdf
• Phonetic Extensions: http://www.unicode.org/charts/PDF/U1D00.pdf
• Phonetic Extensions Supplement: http://www.unicode.org/charts/PDF/U1D80.pdf
• General Punctuation: http://www.unicode.org/charts/PDF/U2000.pdf
• Superscripts and Subscripts: http://www.unicode.org/charts/PDF/U2070.pdf
• Enclosed Alphanumerics: http://www.unicode.org/charts/PDF/U2460.pdf
• Dingbats: http://www.unicode.org/charts/PDF/U2700.pdf
• Supplemental Punctuation: http://www.unicode.org/charts/PDF/U2E00.pdf
• Alphabetic Presentation Forms: http://www.unicode.org/charts/PDF/UFB00.pdf
• Halfwidth and Fullwidth Forms: http://www.unicode.org/charts/PDF/UFF00.pdf

See: http://en.wikipedia.org/wiki/Latin_characters_in_Unicode For example, 'à' will be replaced by 'a'.

Constructor Summary

Constructors

Constructor and Description
ASCIIFoldingFilter()

Method Summary

Modifier and Type	Method and Description
static int	foldToASCII(char[] input, int inputPos, char[] output, int outputPos, int length) Converts characters above ASCII to their ASCII equivalents.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ASCIIFoldingFilter

public ASCIIFoldingFilter()

Method Detail

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