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Apache Commons Lang, a package of Java utility classes for the
classes that are in java.lang's hierarchy, or are considered to be so
standard as to justify existence in java.lang.
/*
* 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 org.apache.commons.lang3;
/**
* Operations on {@code CharSet} instances.
*
* This class handles {@code null} input gracefully.
* An exception will not be thrown for a {@code null} input.
* Each method documents its behaviour in more detail.
*
* #ThreadSafe#
* @see CharSet
* @since 1.0
* @version $Id: CharSetUtils.java 1144916 2011-07-10 17:50:21Z ggregory $
*/
public class CharSetUtils {
/**
* CharSetUtils instances should NOT be constructed in standard programming.
* Instead, the class should be used as {@code CharSetUtils.evaluateSet(null);}.
*
* This constructor is public to permit tools that require a JavaBean instance
* to operate.
*/
public CharSetUtils() {
super();
}
// Squeeze
//-----------------------------------------------------------------------
/**
* Squeezes any repetitions of a character that is mentioned in the
* supplied set.
*
*
* CharSetUtils.squeeze(null, *) = null
* CharSetUtils.squeeze("", *) = ""
* CharSetUtils.squeeze(*, null) = *
* CharSetUtils.squeeze(*, "") = *
* CharSetUtils.squeeze("hello", "k-p") = "helo"
* CharSetUtils.squeeze("hello", "a-e") = "hello"
*
*
* @see CharSet#getInstance(java.lang.String...) for set-syntax.
* @param str the string to squeeze, may be null
* @param set the character set to use for manipulation, may be null
* @return the modified String, {@code null} if null string input
*/
public static String squeeze(String str, String... set) {
if (StringUtils.isEmpty(str) || deepEmpty(set)) {
return str;
}
CharSet chars = CharSet.getInstance(set);
StringBuilder buffer = new StringBuilder(str.length());
char[] chrs = str.toCharArray();
int sz = chrs.length;
char lastChar = ' ';
char ch = ' ';
for (int i = 0; i < sz; i++) {
ch = chrs[i];
// Compare with contains() last for performance.
if (ch == lastChar && i != 0 && chars.contains(ch)) {
continue;
}
buffer.append(ch);
lastChar = ch;
}
return buffer.toString();
}
// Count
//-----------------------------------------------------------------------
/**
* Takes an argument in set-syntax, see evaluateSet,
* and returns the number of characters present in the specified string.
*
*
* CharSetUtils.count(null, *) = 0
* CharSetUtils.count("", *) = 0
* CharSetUtils.count(*, null) = 0
* CharSetUtils.count(*, "") = 0
* CharSetUtils.count("hello", "k-p") = 3
* CharSetUtils.count("hello", "a-e") = 1
*
*
* @see CharSet#getInstance(java.lang.String...) for set-syntax.
* @param str String to count characters in, may be null
* @param set String[] set of characters to count, may be null
* @return the character count, zero if null string input
*/
public static int count(String str, String... set) {
if (StringUtils.isEmpty(str) || deepEmpty(set)) {
return 0;
}
CharSet chars = CharSet.getInstance(set);
int count = 0;
for (char c : str.toCharArray()) {
if (chars.contains(c)) {
count++;
}
}
return count;
}
// Keep
//-----------------------------------------------------------------------
/**
* Takes an argument in set-syntax, see evaluateSet,
* and keeps any of characters present in the specified string.
*
*
* CharSetUtils.keep(null, *) = null
* CharSetUtils.keep("", *) = ""
* CharSetUtils.keep(*, null) = ""
* CharSetUtils.keep(*, "") = ""
* CharSetUtils.keep("hello", "hl") = "hll"
* CharSetUtils.keep("hello", "le") = "ell"
*
*
* @see CharSet#getInstance(java.lang.String...) for set-syntax.
* @param str String to keep characters from, may be null
* @param set String[] set of characters to keep, may be null
* @return the modified String, {@code null} if null string input
* @since 2.0
*/
public static String keep(String str, String... set) {
if (str == null) {
return null;
}
if (str.length() == 0 || deepEmpty(set)) {
return "";
}
return modify(str, set, true);
}
// Delete
//-----------------------------------------------------------------------
/**
* Takes an argument in set-syntax, see evaluateSet,
* and deletes any of characters present in the specified string.
*
*
* CharSetUtils.delete(null, *) = null
* CharSetUtils.delete("", *) = ""
* CharSetUtils.delete(*, null) = *
* CharSetUtils.delete(*, "") = *
* CharSetUtils.delete("hello", "hl") = "eo"
* CharSetUtils.delete("hello", "le") = "ho"
*
*
* @see CharSet#getInstance(java.lang.String...) for set-syntax.
* @param str String to delete characters from, may be null
* @param set String[] set of characters to delete, may be null
* @return the modified String, {@code null} if null string input
*/
public static String delete(String str, String... set) {
if (StringUtils.isEmpty(str) || deepEmpty(set)) {
return str;
}
return modify(str, set, false);
}
//-----------------------------------------------------------------------
/**
* Implementation of delete and keep
*
* @param str String to modify characters within
* @param set String[] set of characters to modify
* @param expect whether to evaluate on match, or non-match
* @return the modified String, not null
*/
private static String modify(String str, String[] set, boolean expect) {
CharSet chars = CharSet.getInstance(set);
StringBuilder buffer = new StringBuilder(str.length());
char[] chrs = str.toCharArray();
int sz = chrs.length;
for(int i=0; i