100 lines
3.4 KiB
Java
100 lines
3.4 KiB
Java
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/*
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* Copyright (c) 2002, 2004, 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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package sun.misc;
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import java.util.Comparator;
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/** Implements a locale and case insensitive comparator suitable for
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strings that are known to only contain ASCII characters. Some
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tables internal to the JDK contain only ASCII data and are using
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the "generalized" java.lang.String case-insensitive comparator
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which converts each character to both upper and lower case. */
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public class ASCIICaseInsensitiveComparator implements Comparator<String> {
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public static final Comparator<String> CASE_INSENSITIVE_ORDER =
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new ASCIICaseInsensitiveComparator();
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public int compare(String s1, String s2) {
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int n1=s1.length(), n2=s2.length();
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int minLen = n1 < n2 ? n1 : n2;
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for (int i=0; i < minLen; i++) {
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char c1 = s1.charAt(i);
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char c2 = s2.charAt(i);
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assert c1 <= '\u007F' && c2 <= '\u007F';
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if (c1 != c2) {
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c1 = (char)toLower(c1);
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c2 = (char)toLower(c2);
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if (c1 != c2) {
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return c1 - c2;
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}
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}
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}
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return n1 - n2;
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}
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/**
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* A case insensitive hash code method to go with the case insensitive
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* compare() method.
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*
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* Returns a hash code for this ASCII string as if it were lower case.
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*
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* returns same answer as:<p>
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* <code>s.toLowerCase(Locale.US).hashCode();</code><p>
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* but does not allocate memory (it does NOT have the special
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* case Turkish rules).
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*
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* @param s a String to compute the hashcode on.
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* @return a hash code value for this object.
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*/
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public static int lowerCaseHashCode(String s) {
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int h = 0;
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int len = s.length();
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for (int i = 0; i < len; i++) {
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h = 31*h + toLower(s.charAt(i));
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}
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return h;
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}
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/* If java.util.regex.ASCII ever becomes public or sun.*, use its code instead:*/
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static boolean isLower(int ch) {
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return ((ch-'a')|('z'-ch)) >= 0;
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}
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static boolean isUpper(int ch) {
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return ((ch-'A')|('Z'-ch)) >= 0;
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}
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static int toLower(int ch) {
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return isUpper(ch) ? (ch + 0x20) : ch;
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}
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static int toUpper(int ch) {
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return isLower(ch) ? (ch - 0x20) : ch;
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}
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}
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