384 lines
14 KiB
Java
384 lines
14 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.lang3;
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/**
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* <p>Operations on {@link CharSequence} that are
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* {@code null} safe.</p>
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*
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* @see CharSequence
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* @since 3.0
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*/
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public class CharSequenceUtils {
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private static final int NOT_FOUND = -1;
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/**
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* <p>{@code CharSequenceUtils} instances should NOT be constructed in
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* standard programming. </p>
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*
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* <p>This constructor is public to permit tools that require a JavaBean
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* instance to operate.</p>
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*/
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public CharSequenceUtils() {
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}
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//-----------------------------------------------------------------------
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/**
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* <p>Returns a new {@code CharSequence} that is a subsequence of this
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* sequence starting with the {@code char} value at the specified index.</p>
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*
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* <p>This provides the {@code CharSequence} equivalent to {@link String#substring(int)}.
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* The length (in {@code char}) of the returned sequence is {@code length() - start},
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* so if {@code start == end} then an empty sequence is returned.</p>
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*
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* @param cs the specified subsequence, null returns null
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* @param start the start index, inclusive, valid
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* @return a new subsequence, may be null
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* @throws IndexOutOfBoundsException if {@code start} is negative or if
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* {@code start} is greater than {@code length()}
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*/
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public static CharSequence subSequence(final CharSequence cs, final int start) {
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return cs == null ? null : cs.subSequence(start, cs.length());
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}
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//-----------------------------------------------------------------------
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/**
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* Returns the index within {@code cs} of the first occurrence of the
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* specified character, starting the search at the specified index.
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* <p>
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* If a character with value {@code searchChar} occurs in the
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* character sequence represented by the {@code cs}
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* object at an index no smaller than {@code start}, then
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* the index of the first such occurrence is returned. For values
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* of {@code searchChar} in the range from 0 to 0xFFFF (inclusive),
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* this is the smallest value <i>k</i> such that:
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* <blockquote><pre>
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* (this.charAt(<i>k</i>) == searchChar) && (<i>k</i> >= start)
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* </pre></blockquote>
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* is true. For other values of {@code searchChar}, it is the
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* smallest value <i>k</i> such that:
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* <blockquote><pre>
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* (this.codePointAt(<i>k</i>) == searchChar) && (<i>k</i> >= start)
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* </pre></blockquote>
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* is true. In either case, if no such character occurs inm {@code cs}
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* at or after position {@code start}, then
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* {@code -1} is returned.
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*
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* <p>
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* There is no restriction on the value of {@code start}. If it
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* is negative, it has the same effect as if it were zero: the entire
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* {@code CharSequence} may be searched. If it is greater than
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* the length of {@code cs}, it has the same effect as if it were
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* equal to the length of {@code cs}: {@code -1} is returned.
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*
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* <p>All indices are specified in {@code char} values
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* (Unicode code units).
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*
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* @param cs the {@code CharSequence} to be processed, not null
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* @param searchChar the char to be searched for
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* @param start the start index, negative starts at the string start
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* @return the index where the search char was found, -1 if not found
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* @since 3.6 updated to behave more like {@code String}
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*/
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static int indexOf(final CharSequence cs, final int searchChar, int start) {
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if (cs instanceof String) {
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return ((String) cs).indexOf(searchChar, start);
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}
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final int sz = cs.length();
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if (start < 0) {
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start = 0;
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}
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if (searchChar < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
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for (int i = start; i < sz; i++) {
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if (cs.charAt(i) == searchChar) {
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return i;
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}
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}
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return NOT_FOUND;
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}
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//supplementary characters (LANG1300)
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if (searchChar <= Character.MAX_CODE_POINT) {
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final char[] chars = Character.toChars(searchChar);
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for (int i = start; i < sz - 1; i++) {
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final char high = cs.charAt(i);
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final char low = cs.charAt(i + 1);
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if (high == chars[0] && low == chars[1]) {
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return i;
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}
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}
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}
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return NOT_FOUND;
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}
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/**
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* Used by the indexOf(CharSequence methods) as a green implementation of indexOf.
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*
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* @param cs the {@code CharSequence} to be processed
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* @param searchChar the {@code CharSequence} to be searched for
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* @param start the start index
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* @return the index where the search sequence was found
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*/
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static int indexOf(final CharSequence cs, final CharSequence searchChar, final int start) {
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if (cs instanceof String) {
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return ((String) cs).indexOf(searchChar.toString(), start);
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} else if (cs instanceof StringBuilder) {
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return ((StringBuilder) cs).indexOf(searchChar.toString(), start);
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} else if (cs instanceof StringBuffer) {
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return ((StringBuffer) cs).indexOf(searchChar.toString(), start);
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}
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return cs.toString().indexOf(searchChar.toString(), start);
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// if (cs instanceof String && searchChar instanceof String) {
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// // TODO: Do we assume searchChar is usually relatively small;
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// // If so then calling toString() on it is better than reverting to
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// // the green implementation in the else block
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// return ((String) cs).indexOf((String) searchChar, start);
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// } else {
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// // TODO: Implement rather than convert to String
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// return cs.toString().indexOf(searchChar.toString(), start);
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// }
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}
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/**
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* Returns the index within {@code cs} of the last occurrence of
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* the specified character, searching backward starting at the
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* specified index. For values of {@code searchChar} in the range
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* from 0 to 0xFFFF (inclusive), the index returned is the largest
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* value <i>k</i> such that:
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* <blockquote><pre>
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* (this.charAt(<i>k</i>) == searchChar) && (<i>k</i> <= start)
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* </pre></blockquote>
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* is true. For other values of {@code searchChar}, it is the
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* largest value <i>k</i> such that:
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* <blockquote><pre>
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* (this.codePointAt(<i>k</i>) == searchChar) && (<i>k</i> <= start)
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* </pre></blockquote>
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* is true. In either case, if no such character occurs in {@code cs}
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* at or before position {@code start}, then {@code -1} is returned.
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*
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* <p>All indices are specified in {@code char} values
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* (Unicode code units).
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*
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* @param cs the {@code CharSequence} to be processed
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* @param searchChar the char to be searched for
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* @param start the start index, negative returns -1, beyond length starts at end
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* @return the index where the search char was found, -1 if not found
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* @since 3.6 updated to behave more like {@code String}
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*/
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static int lastIndexOf(final CharSequence cs, final int searchChar, int start) {
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if (cs instanceof String) {
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return ((String) cs).lastIndexOf(searchChar, start);
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}
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final int sz = cs.length();
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if (start < 0) {
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return NOT_FOUND;
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}
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if (start >= sz) {
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start = sz - 1;
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}
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if (searchChar < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
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for (int i = start; i >= 0; --i) {
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if (cs.charAt(i) == searchChar) {
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return i;
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}
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}
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return NOT_FOUND;
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}
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//supplementary characters (LANG1300)
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//NOTE - we must do a forward traversal for this to avoid duplicating code points
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if (searchChar <= Character.MAX_CODE_POINT) {
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final char[] chars = Character.toChars(searchChar);
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//make sure it's not the last index
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if (start == sz - 1) {
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return NOT_FOUND;
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}
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for (int i = start; i >= 0; i--) {
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final char high = cs.charAt(i);
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final char low = cs.charAt(i + 1);
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if (chars[0] == high && chars[1] == low) {
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return i;
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}
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}
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}
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return NOT_FOUND;
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}
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static final int TO_STRING_LIMIT = 16;
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/**
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* Used by the lastIndexOf(CharSequence methods) as a green implementation of lastIndexOf
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*
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* @param cs the {@code CharSequence} to be processed
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* @param searchChar the {@code CharSequence} to find
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* @param start the start index
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* @return the index where the search sequence was found
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*/
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static int lastIndexOf(final CharSequence cs, final CharSequence searchChar, int start) {
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if (searchChar == null || cs == null) {
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return NOT_FOUND;
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}
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if (searchChar instanceof String) {
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if (cs instanceof String) {
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return ((String) cs).lastIndexOf((String) searchChar, start);
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} else if (cs instanceof StringBuilder) {
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return ((StringBuilder) cs).lastIndexOf((String) searchChar, start);
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} else if (cs instanceof StringBuffer) {
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return ((StringBuffer) cs).lastIndexOf((String) searchChar, start);
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}
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}
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final int len1 = cs.length();
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final int len2 = searchChar.length();
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if (start > len1) {
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start = len1;
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}
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if (start < 0 || len2 < 0 || len2 > len1) {
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return NOT_FOUND;
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}
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if (len2 == 0) {
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return start;
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}
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if (len2 <= TO_STRING_LIMIT) {
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if (cs instanceof String) {
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return ((String) cs).lastIndexOf(searchChar.toString(), start);
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} else if (cs instanceof StringBuilder) {
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return ((StringBuilder) cs).lastIndexOf(searchChar.toString(), start);
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} else if (cs instanceof StringBuffer) {
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return ((StringBuffer) cs).lastIndexOf(searchChar.toString(), start);
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}
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}
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if (start + len2 > len1) {
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start = len1 - len2;
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}
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final char char0 = searchChar.charAt(0);
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int i = start;
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while (true) {
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while (cs.charAt(i) != char0) {
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i--;
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if (i < 0) {
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return NOT_FOUND;
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}
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}
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if (checkLaterThan1(cs, searchChar, len2, i)) {
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return i;
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}
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i--;
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if (i < 0) {
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return NOT_FOUND;
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}
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}
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}
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private static boolean checkLaterThan1(final CharSequence cs, final CharSequence searchChar, final int len2, final int start1) {
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for (int i = 1, j = len2 - 1; i <= j; i++, j--) {
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if (cs.charAt(start1 + i) != searchChar.charAt(i)
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||
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cs.charAt(start1 + j) != searchChar.charAt(j)
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) {
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return false;
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}
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}
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return true;
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}
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/**
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* Converts the given CharSequence to a char[].
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*
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* @param source the {@code CharSequence} to be processed.
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* @return the resulting char array, never null.
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* @since 3.11
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*/
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public static char[] toCharArray(final CharSequence source) {
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final int len = StringUtils.length(source);
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if (len == 0) {
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return ArrayUtils.EMPTY_CHAR_ARRAY;
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}
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if (source instanceof String) {
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return ((String) source).toCharArray();
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}
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final char[] array = new char[len];
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for (int i = 0; i < len; i++) {
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array[i] = source.charAt(i);
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}
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return array;
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}
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/**
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* Green implementation of regionMatches.
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*
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* @param cs the {@code CharSequence} to be processed
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* @param ignoreCase whether or not to be case insensitive
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* @param thisStart the index to start on the {@code cs} CharSequence
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* @param substring the {@code CharSequence} to be looked for
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* @param start the index to start on the {@code substring} CharSequence
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* @param length character length of the region
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* @return whether the region matched
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*/
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static boolean regionMatches(final CharSequence cs, final boolean ignoreCase, final int thisStart,
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final CharSequence substring, final int start, final int length) {
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if (cs instanceof String && substring instanceof String) {
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return ((String) cs).regionMatches(ignoreCase, thisStart, (String) substring, start, length);
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}
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int index1 = thisStart;
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int index2 = start;
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int tmpLen = length;
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// Extract these first so we detect NPEs the same as the java.lang.String version
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final int srcLen = cs.length() - thisStart;
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final int otherLen = substring.length() - start;
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// Check for invalid parameters
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if (thisStart < 0 || start < 0 || length < 0) {
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return false;
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}
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// Check that the regions are long enough
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if (srcLen < length || otherLen < length) {
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return false;
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}
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while (tmpLen-- > 0) {
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final char c1 = cs.charAt(index1++);
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final char c2 = substring.charAt(index2++);
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if (c1 == c2) {
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continue;
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}
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if (!ignoreCase) {
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return false;
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}
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// The real same check as in String.regionMatches():
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final char u1 = Character.toUpperCase(c1);
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final char u2 = Character.toUpperCase(c2);
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if (u1 != u2 && Character.toLowerCase(u1) != Character.toLowerCase(u2)) {
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return false;
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}
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}
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return true;
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}
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}
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