192 lines
7.8 KiB
Java
192 lines
7.8 KiB
Java
/*
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* Copyright (C) 2014 The Android Open Source Project
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* Copyright (c) 2005, 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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*******************************************************************************
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* (C) Copyright IBM Corp. 1996-2005 - All Rights Reserved *
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* *
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* The original version of this source code and documentation is copyrighted *
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* and owned by IBM, These materials are provided under terms of a License *
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* Agreement between IBM and Sun. This technology is protected by multiple *
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* US and International patents. This notice and attribution to IBM may not *
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* to removed. *
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*******************************************************************************
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*/
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package java.text;
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import android.icu.text.Normalizer2;
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import java.util.function.Supplier;
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/**
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* This class provides the method {@code normalize} which transforms Unicode
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* text into an equivalent composed or decomposed form, allowing for easier
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* sorting and searching of text.
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* The {@code normalize} method supports the standard normalization forms
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* described in
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* <a href="https://www.unicode.org/reports/tr15/">
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* Unicode Standard Annex #15 — Unicode Normalization Forms</a>.
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* <p>
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* Characters with accents or other adornments can be encoded in
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* several different ways in Unicode. For example, take the character A-acute.
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* In Unicode, this can be encoded as a single character (the "composed" form):
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*
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* <pre>
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* U+00C1 LATIN CAPITAL LETTER A WITH ACUTE</pre>
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*
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* or as two separate characters (the "decomposed" form):
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*
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* <pre>
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* U+0041 LATIN CAPITAL LETTER A
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* U+0301 COMBINING ACUTE ACCENT</pre>
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*
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* To a user of your program, however, both of these sequences should be
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* treated as the same "user-level" character "A with acute accent". When you
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* are searching or comparing text, you must ensure that these two sequences are
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* treated as equivalent. In addition, you must handle characters with more than
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* one accent. Sometimes the order of a character's combining accents is
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* significant, while in other cases accent sequences in different orders are
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* really equivalent.
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* <p>
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* Similarly, the string "ffi" can be encoded as three separate letters:
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*
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* <pre>
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* U+0066 LATIN SMALL LETTER F
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* U+0066 LATIN SMALL LETTER F
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* U+0069 LATIN SMALL LETTER I</pre>
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*
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* or as the single character
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*
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* <pre>
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* U+FB03 LATIN SMALL LIGATURE FFI</pre>
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*
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* The ffi ligature is not a distinct semantic character, and strictly speaking
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* it shouldn't be in Unicode at all, but it was included for compatibility
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* with existing character sets that already provided it. The Unicode standard
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* identifies such characters by giving them "compatibility" decompositions
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* into the corresponding semantic characters. When sorting and searching, you
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* will often want to use these mappings.
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* <p>
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* The {@code normalize} method helps solve these problems by transforming
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* text into the canonical composed and decomposed forms as shown in the first
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* example above. In addition, you can have it perform compatibility
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* decompositions so that you can treat compatibility characters the same as
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* their equivalents.
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* Finally, the {@code normalize} method rearranges accents into the
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* proper canonical order, so that you do not have to worry about accent
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* rearrangement on your own.
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* <p>
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* The W3C generally recommends to exchange texts in NFC.
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* Note also that most legacy character encodings use only precomposed forms and
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* often do not encode any combining marks by themselves. For conversion to such
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* character encodings the Unicode text needs to be normalized to NFC.
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* For more usage examples, see the Unicode Standard Annex.
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*
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* @since 1.6
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*/
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public final class Normalizer {
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private Normalizer() {};
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/**
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* This enum provides constants of the four Unicode normalization forms
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* that are described in
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* <a href="https://www.unicode.org/reports/tr15/">
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* Unicode Standard Annex #15 — Unicode Normalization Forms</a>
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* and two methods to access them.
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*
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* @since 1.6
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*/
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// BEGIN Android-changed: remove static modifier and add mapping to equivalent ICU values.
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public enum Form {
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/**
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* Canonical decomposition.
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*/
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NFD(Normalizer2::getNFDInstance),
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/**
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* Canonical decomposition, followed by canonical composition.
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*/
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NFC(Normalizer2::getNFCInstance),
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/**
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* Compatibility decomposition.
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*/
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NFKD(Normalizer2::getNFKDInstance),
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/**
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* Compatibility decomposition, followed by canonical composition.
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*/
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NFKC(Normalizer2::getNFKCInstance);
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private final Supplier<Normalizer2> icuNormalizer;
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Form(Supplier<Normalizer2> icuNormalizer) {
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this.icuNormalizer = icuNormalizer;
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}
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}
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// END Android-changed: remove static modifier and add mapping to equivalent ICU values.
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/**
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* Normalize a sequence of char values.
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* The sequence will be normalized according to the specified normalization
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* form.
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* @param src The sequence of char values to normalize.
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* @param form The normalization form; one of
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* {@link java.text.Normalizer.Form#NFC},
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* {@link java.text.Normalizer.Form#NFD},
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* {@link java.text.Normalizer.Form#NFKC},
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* {@link java.text.Normalizer.Form#NFKD}
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* @return The normalized String
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* @throws NullPointerException If {@code src} or {@code form}
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* is null.
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*/
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public static String normalize(CharSequence src, Form form) {
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// Android-changed: Switched to ICU.
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return form.icuNormalizer.get().normalize(src);
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}
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/**
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* Determines if the given sequence of char values is normalized.
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* @param src The sequence of char values to be checked.
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* @param form The normalization form; one of
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* {@link java.text.Normalizer.Form#NFC},
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* {@link java.text.Normalizer.Form#NFD},
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* {@link java.text.Normalizer.Form#NFKC},
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* {@link java.text.Normalizer.Form#NFKD}
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* @return true if the sequence of char values is normalized;
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* false otherwise.
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* @throws NullPointerException If {@code src} or {@code form}
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* is null.
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*/
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public static boolean isNormalized(CharSequence src, Form form) {
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// Android-changed: Switched to ICU.
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return form.icuNormalizer.get().isNormalized(src);
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}
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}
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