org.apache.lucene.util

Class UnicodeUtil

java.lang.Object

org.apache.lucene.util.UnicodeUtil

public final class UnicodeUtil
extends Object

Class to encode java's UTF16 char[] into UTF8 byte[] without always allocating a new byte[] as String.getBytes(StandardCharsets.UTF_8) does.

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

Field Summary

Fields

Modifier and Type	Field and Description
static BytesRef	BIG_TERM A binary term consisting of a number of 0xff bytes, likely to be bigger than other terms (e.g.
static int	UNI_REPLACEMENT_CHAR
static int	UNI_SUR_HIGH_END
static int	UNI_SUR_HIGH_START
static int	UNI_SUR_LOW_END
static int	UNI_SUR_LOW_START

Method Summary

Methods

Modifier and Type	Method and Description
static int	codePointCount(BytesRef utf8) Returns the number of code points in this UTF8 sequence.
static String	newString(int[] codePoints, int offset, int count) Cover JDK 1.5 API.
static String	toHexString(String s)
static void	UTF16toUTF8(char[] source, int offset, int length, BytesRef result) Encode characters from a char[] source, starting at offset for length chars.
static void	UTF16toUTF8(CharSequence s, int offset, int length, BytesRef result) Encode characters from this String, starting at offset for length characters.
static void	UTF8toUTF16(byte[] utf8, int offset, int length, CharsRef chars) Interprets the given byte array as UTF-8 and converts to UTF-16.
static void	UTF8toUTF16(BytesRef bytesRef, CharsRef chars) Utility method for UTF8toUTF16(byte[], int, int, CharsRef)
static void	UTF8toUTF32(BytesRef utf8, IntsRef utf32) This method assumes valid UTF8 input.
static boolean	validUTF16String(char[] s, int size)
static boolean	validUTF16String(CharSequence s)

Methods inherited from class java.lang.Object

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

Field Detail

BIG_TERM

public static final BytesRef BIG_TERM

A binary term consisting of a number of 0xff bytes, likely to be bigger than other terms (e.g. collation keys) one would normally encounter, and definitely bigger than any UTF-8 terms.

WARNING: This is not a valid UTF8 Term

UNI_SUR_HIGH_START

public static final int UNI_SUR_HIGH_START

See Also:

Constant Field Values

UNI_SUR_HIGH_END

public static final int UNI_SUR_HIGH_END

See Also:

Constant Field Values

UNI_SUR_LOW_START

public static final int UNI_SUR_LOW_START

See Also:

Constant Field Values

UNI_SUR_LOW_END

public static final int UNI_SUR_LOW_END

See Also:

Constant Field Values

UNI_REPLACEMENT_CHAR

public static final int UNI_REPLACEMENT_CHAR

See Also:

Constant Field Values

Method Detail

UTF16toUTF8

public static void UTF16toUTF8(char[] source,
               int offset,
               int length,
               BytesRef result)

Encode characters from a char[] source, starting at offset for length chars. After encoding, result.offset will always be 0.

UTF16toUTF8

public static void UTF16toUTF8(CharSequence s,
               int offset,
               int length,
               BytesRef result)

Encode characters from this String, starting at offset for length characters. After encoding, result.offset will always be 0.

validUTF16String

public static boolean validUTF16String(CharSequence s)

validUTF16String

public static boolean validUTF16String(char[] s,
                       int size)

codePointCount

public static int codePointCount(BytesRef utf8)

Returns the number of code points in this UTF8 sequence.

This method assumes valid UTF8 input. This method does not perform full UTF8 validation, it will check only the first byte of each codepoint (for multi-byte sequences any bytes after the head are skipped).

Throws:

IllegalArgumentException - If invalid codepoint header byte occurs or the content is prematurely truncated.

UTF8toUTF32

public static void UTF8toUTF32(BytesRef utf8,
               IntsRef utf32)

This method assumes valid UTF8 input. This method does not perform full UTF8 validation, it will check only the first byte of each codepoint (for multi-byte sequences any bytes after the head are skipped).

Throws:

IllegalArgumentException - If invalid codepoint header byte occurs or the content is prematurely truncated.

newString

public static String newString(int[] codePoints,
               int offset,
               int count)

Cover JDK 1.5 API. Create a String from an array of codePoints.

Parameters:

codePoints - The code array

offset - The start of the text in the code point array

count - The number of code points

Returns:

a String representing the code points between offset and count

Throws:

IllegalArgumentException - If an invalid code point is encountered

IndexOutOfBoundsException - If the offset or count are out of bounds.

toHexString

public static String toHexString(String s)

UTF8toUTF16

public static void UTF8toUTF16(byte[] utf8,
               int offset,
               int length,
               CharsRef chars)

Interprets the given byte array as UTF-8 and converts to UTF-16. The CharsRef will be extended if it doesn't provide enough space to hold the worst case of each byte becoming a UTF-16 codepoint.

NOTE: Full characters are read, even if this reads past the length passed (and can result in an ArrayOutOfBoundsException if invalid UTF-8 is passed). Explicit checks for valid UTF-8 are not performed.

UTF8toUTF16

public static void UTF8toUTF16(BytesRef bytesRef,
               CharsRef chars)

Utility method for UTF8toUTF16(byte[], int, int, CharsRef)

See Also:

UTF8toUTF16(byte[], int, int, CharsRef)