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