org.apache.lucene.analysis

Class CharacterUtils

java.lang.Object

org.apache.lucene.analysis.CharacterUtils

public final class CharacterUtils
extends Object

Utility class to write tokenizers or token filters.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CharacterUtils.CharacterBuffer A simple IO buffer to use with fill(CharacterBuffer, Reader).

Method Summary

Modifier and Type	Method and Description
static boolean	fill(CharacterUtils.CharacterBuffer buffer, Reader reader) Convenience method which calls fill(buffer, reader, buffer.buffer.length).
static boolean	fill(CharacterUtils.CharacterBuffer buffer, Reader reader, int numChars) Fills the CharacterUtils.CharacterBuffer with characters read from the given reader Reader.
static CharacterUtils.CharacterBuffer	newCharacterBuffer(int bufferSize) Creates a new CharacterUtils.CharacterBuffer and allocates a char[] of the given bufferSize.
static int	toChars(int[] src, int srcOff, int srcLen, char[] dest, int destOff) Converts a sequence of unicode code points to a sequence of Java characters.
static int	toCodePoints(char[] src, int srcOff, int srcLen, int[] dest, int destOff) Converts a sequence of Java characters to a sequence of unicode code points.
static void	toLowerCase(char[] buffer, int offset, int limit) Converts each unicode codepoint to lowerCase via Character.toLowerCase(int) starting at the given offset.
static void	toUpperCase(char[] buffer, int offset, int limit) Converts each unicode codepoint to UpperCase via Character.toUpperCase(int) starting at the given offset.

Methods inherited from class java.lang.Object

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

Method Detail

newCharacterBuffer

public static CharacterUtils.CharacterBuffer newCharacterBuffer(int bufferSize)

Creates a new CharacterUtils.CharacterBuffer and allocates a char[] of the given bufferSize.

Parameters:

bufferSize - the internal char buffer size, must be >= 2

Returns:

a new CharacterUtils.CharacterBuffer instance.

toLowerCase

public static void toLowerCase(char[] buffer,
                               int offset,
                               int limit)

Converts each unicode codepoint to lowerCase via Character.toLowerCase(int) starting at the given offset.

Parameters:

buffer - the char buffer to lowercase

offset - the offset to start at

limit - the max char in the buffer to lower case

toUpperCase

public static void toUpperCase(char[] buffer,
                               int offset,
                               int limit)

Converts each unicode codepoint to UpperCase via Character.toUpperCase(int) starting at the given offset.

Parameters:

buffer - the char buffer to UPPERCASE

offset - the offset to start at

limit - the max char in the buffer to lower case

toCodePoints

public static int toCodePoints(char[] src,
                               int srcOff,
                               int srcLen,
                               int[] dest,
                               int destOff)

Converts a sequence of Java characters to a sequence of unicode code points.

Returns:

the number of code points written to the destination buffer

toChars

public static int toChars(int[] src,
                          int srcOff,
                          int srcLen,
                          char[] dest,
                          int destOff)

Converts a sequence of unicode code points to a sequence of Java characters.

Returns:

the number of chars written to the destination buffer

fill

public static boolean fill(CharacterUtils.CharacterBuffer buffer,
                           Reader reader,
                           int numChars)
                    throws IOException

Fills the CharacterUtils.CharacterBuffer with characters read from the given reader Reader. This method tries to read numChars characters into the CharacterUtils.CharacterBuffer, each call to fill will start filling the buffer from offset 0 up to numChars. In case code points can span across 2 java characters, this method may only fill numChars - 1 characters in order not to split in the middle of a surrogate pair, even if there are remaining characters in the Reader.

This method guarantees that the given CharacterUtils.CharacterBuffer will never contain a high surrogate character as the last element in the buffer unless it is the last available character in the reader. In other words, high and low surrogate pairs will always be preserved across buffer boarders.

A return value of false means that this method call exhausted the reader, but there may be some bytes which have been read, which can be verified by checking whether buffer.getLength() > 0.

Parameters:

buffer - the buffer to fill.

reader - the reader to read characters from.

numChars - the number of chars to read

Returns:

false if and only if reader.read returned -1 while trying to fill the buffer

Throws:

IOException - if the reader throws an IOException.

fill

public static boolean fill(CharacterUtils.CharacterBuffer buffer,
                           Reader reader)
                    throws IOException

Convenience method which calls fill(buffer, reader, buffer.buffer.length).

Throws:

IOException