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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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/*
*******************************************************************************
* (C) Copyright IBM Corp. 1996-2005 - All Rights Reserved *
* *
* The original version of this source code and documentation is copyrighted *
* and owned by IBM, These materials are provided under terms of a License *
* Agreement between IBM and Sun. This technology is protected by multiple *
* US and International patents. This notice and attribution to IBM may not *
* to removed. *
*******************************************************************************
*/
package java.text;
import sun.text.normalizer.NormalizerBase;
import sun.text.normalizer.NormalizerImpl;
/**
* This class provides the method <code>normalize</code> which transforms Unicode
* text into an equivalent composed or decomposed form, allowing for easier
* sorting and searching of text.
* The <code>normalize</code> method supports the standard normalization forms
* described in
* <a href="http://www.unicode.org/unicode/reports/tr15/tr15-23.html">
* Unicode Standard Annex #15 — Unicode Normalization Forms</a>.
* <p>
* Characters with accents or other adornments can be encoded in
* several different ways in Unicode. For example, take the character A-acute.
* In Unicode, this can be encoded as a single character (the "composed" form):
*
* <p><pre>
* U+00C1 LATIN CAPITAL LETTER A WITH ACUTE</pre>
* </p>
*
* or as two separate characters (the "decomposed" form):
*
* <p><pre>
* U+0041 LATIN CAPITAL LETTER A
* U+0301 COMBINING ACUTE ACCENT</pre>
* </p>
*
* To a user of your program, however, both of these sequences should be
* treated as the same "user-level" character "A with acute accent". When you
* are searching or comparing text, you must ensure that these two sequences are
* treated as equivalent. In addition, you must handle characters with more than
* one accent. Sometimes the order of a character's combining accents is
* significant, while in other cases accent sequences in different orders are
* really equivalent.
* <p>
* Similarly, the string "ffi" can be encoded as three separate letters:
*
* <p><pre>
* U+0066 LATIN SMALL LETTER F
* U+0066 LATIN SMALL LETTER F
* U+0069 LATIN SMALL LETTER I</pre>
* </p>
*
* or as the single character
*
* <p><pre>
* U+FB03 LATIN SMALL LIGATURE FFI</pre>
* </p>
*
* The ffi ligature is not a distinct semantic character, and strictly speaking
* it shouldn't be in Unicode at all, but it was included for compatibility
* with existing character sets that already provided it. The Unicode standard
* identifies such characters by giving them "compatibility" decompositions
* into the corresponding semantic characters. When sorting and searching, you
* will often want to use these mappings.
* <p>
* The <code>normalize</code> method helps solve these problems by transforming
* text into the canonical composed and decomposed forms as shown in the first
* example above. In addition, you can have it perform compatibility
* decompositions so that you can treat compatibility characters the same as
* their equivalents.
* Finally, the <code>normalize</code> method rearranges accents into the
* proper canonical order, so that you do not have to worry about accent
* rearrangement on your own.
* <p>
* The W3C generally recommends to exchange texts in NFC.
* Note also that most legacy character encodings use only precomposed forms and
* often do not encode any combining marks by themselves. For conversion to such
* character encodings the Unicode text needs to be normalized to NFC.
* For more usage examples, see the Unicode Standard Annex.
*
* @since 1.6
*/
public final class Normalizer {
private Normalizer() {};
/**
* This enum provides constants of the four Unicode normalization forms
* that are described in
* <a href="http://www.unicode.org/unicode/reports/tr15/tr15-23.html">
* Unicode Standard Annex #15 — Unicode Normalization Forms</a>
* and two methods to access them.
*
* @since 1.6
*/
public static enum Form {
/**
* Canonical decomposition.
*/
NFD,
/**
* Canonical decomposition, followed by canonical composition.
*/
NFC,
/**
* Compatibility decomposition.
*/
NFKD,
/**
* Compatibility decomposition, followed by canonical composition.
*/
NFKC
}
/**
* Normalize a sequence of char values.
* The sequence will be normalized according to the specified normalization
* from.
* @param src The sequence of char values to normalize.
* @param form The normalization form; one of
* {@link java.text.Normalizer.Form#NFC},
* {@link java.text.Normalizer.Form#NFD},
* {@link java.text.Normalizer.Form#NFKC},
* {@link java.text.Normalizer.Form#NFKD}
* @return The normalized String
* @throws NullPointerException If <code>src</code> or <code>form</code>
* is null.
*/
public static String normalize(CharSequence src, Form form) {
return NormalizerBase.normalize(src.toString(), form);
}
/**
* Determines if the given sequence of char values is normalized.
* @param src The sequence of char values to be checked.
* @param form The normalization form; one of
* {@link java.text.Normalizer.Form#NFC},
* {@link java.text.Normalizer.Form#NFD},
* {@link java.text.Normalizer.Form#NFKC},
* {@link java.text.Normalizer.Form#NFKD}
* @return true if the sequence of char values is normalized;
* false otherwise.
* @throws NullPointerException If <code>src</code> or <code>form</code>
* is null.
*/
public static boolean isNormalized(CharSequence src, Form form) {
return NormalizerBase.isNormalized(src.toString(), form);
}
}