CharSet.java
/*
* 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;
import java.io.Serializable;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.stream.Stream;
/**
* A set of characters.
*
* <p>Instances are immutable, but instances of subclasses may not be.</p>
*
* <p>#ThreadSafe#</p>
* @since 1.0
*/
public class CharSet implements Serializable {
/**
* Required for serialization support. Lang version 2.0.
*
* @see java.io.Serializable
*/
private static final long serialVersionUID = 5947847346149275958L;
/**
* A CharSet defining no characters.
* @since 2.0
*/
public static final CharSet EMPTY = new CharSet((String) null);
/**
* A CharSet defining ASCII alphabetic characters "a-zA-Z".
* @since 2.0
*/
public static final CharSet ASCII_ALPHA = new CharSet("a-zA-Z");
/**
* A CharSet defining ASCII alphabetic characters "a-z".
* @since 2.0
*/
public static final CharSet ASCII_ALPHA_LOWER = new CharSet("a-z");
/**
* A CharSet defining ASCII alphabetic characters "A-Z".
* @since 2.0
*/
public static final CharSet ASCII_ALPHA_UPPER = new CharSet("A-Z");
/**
* A CharSet defining ASCII alphabetic characters "0-9".
* @since 2.0
*/
public static final CharSet ASCII_NUMERIC = new CharSet("0-9");
/**
* A Map of the common cases used in the factory.
* Subclasses can add more common patterns if desired
* @since 2.0
*/
protected static final Map<String, CharSet> COMMON = Collections.synchronizedMap(new HashMap<>());
static {
COMMON.put(null, EMPTY);
COMMON.put(StringUtils.EMPTY, EMPTY);
COMMON.put("a-zA-Z", ASCII_ALPHA);
COMMON.put("A-Za-z", ASCII_ALPHA);
COMMON.put("a-z", ASCII_ALPHA_LOWER);
COMMON.put("A-Z", ASCII_ALPHA_UPPER);
COMMON.put("0-9", ASCII_NUMERIC);
}
/**
* Factory method to create a new CharSet using a special syntax.
*
* <ul>
* <li>{@code null} or empty string ("")
* - set containing no characters</li>
* <li>Single character, such as "a"
* - set containing just that character</li>
* <li>Multi character, such as "a-e"
* - set containing characters from one character to the other</li>
* <li>Negated, such as "^a" or "^a-e"
* - set containing all characters except those defined</li>
* <li>Combinations, such as "abe-g"
* - set containing all the characters from the individual sets</li>
* </ul>
*
* <p>The matching order is:</p>
* <ol>
* <li>Negated multi character range, such as "^a-e"
* <li>Ordinary multi character range, such as "a-e"
* <li>Negated single character, such as "^a"
* <li>Ordinary single character, such as "a"
* </ol>
*
* <p>Matching works left to right. Once a match is found the
* search starts again from the next character.</p>
*
* <p>If the same range is defined twice using the same syntax, only
* one range will be kept.
* Thus, "a-ca-c" creates only one range of "a-c".</p>
*
* <p>If the start and end of a range are in the wrong order,
* they are reversed. Thus "a-e" is the same as "e-a".
* As a result, "a-ee-a" would create only one range,
* as the "a-e" and "e-a" are the same.</p>
*
* <p>The set of characters represented is the union of the specified ranges.</p>
*
* <p>There are two ways to add a literal negation character ({@code ^}):</p>
* <ul>
* <li>As the last character in a string, e.g. {@code CharSet.getInstance("a-z^")}</li>
* <li>As a separate element, e.g. {@code CharSet.getInstance("^", "a-z")}</li>
* </ul>
*
* <p>Examples using the negation character:</p>
* <pre>
* CharSet.getInstance("^a-c").contains('a') = false
* CharSet.getInstance("^a-c").contains('d') = true
* CharSet.getInstance("^^a-c").contains('a') = true // (only '^' is negated)
* CharSet.getInstance("^^a-c").contains('^') = false
* CharSet.getInstance("^a-cd-f").contains('d') = true
* CharSet.getInstance("a-c^").contains('^') = true
* CharSet.getInstance("^", "a-c").contains('^') = true
* </pre>
*
* <p>All CharSet objects returned by this method will be immutable.</p>
*
* @param setStrs Strings to merge into the set, may be null
* @return a CharSet instance
* @since 2.4
*/
public static CharSet getInstance(final String... setStrs) {
if (setStrs == null) {
return null;
}
if (setStrs.length == 1) {
final CharSet common = COMMON.get(setStrs[0]);
if (common != null) {
return common;
}
}
return new CharSet(setStrs);
}
/** The set of CharRange objects. */
private final Set<CharRange> set = Collections.synchronizedSet(new HashSet<>());
/**
* Constructs a new CharSet using the set syntax.
* Each string is merged in with the set.
*
* @param set Strings to merge into the initial set
* @throws NullPointerException if set is {@code null}
*/
protected CharSet(final String... set) {
Stream.of(set).forEach(this::add);
}
/**
* Add a set definition string to the {@link CharSet}.
*
* @param str set definition string
*/
protected void add(final String str) {
if (str == null) {
return;
}
final int len = str.length();
int pos = 0;
while (pos < len) {
final int remainder = len - pos;
if (remainder >= 4 && str.charAt(pos) == '^' && str.charAt(pos + 2) == '-') {
// negated range
set.add(CharRange.isNotIn(str.charAt(pos + 1), str.charAt(pos + 3)));
pos += 4;
} else if (remainder >= 3 && str.charAt(pos + 1) == '-') {
// range
set.add(CharRange.isIn(str.charAt(pos), str.charAt(pos + 2)));
pos += 3;
} else if (remainder >= 2 && str.charAt(pos) == '^') {
// negated char
set.add(CharRange.isNot(str.charAt(pos + 1)));
pos += 2;
} else {
// char
set.add(CharRange.is(str.charAt(pos)));
pos += 1;
}
}
}
/**
* Does the {@link CharSet} contain the specified
* character {@code ch}.
*
* @param ch the character to check for
* @return {@code true} if the set contains the characters
*/
public boolean contains(final char ch) {
synchronized (set) {
return set.stream().anyMatch(range -> range.contains(ch));
}
}
// Basics
/**
* Compares two {@link CharSet} objects, returning true if they represent
* exactly the same set of characters defined in the same way.
*
* <p>The two sets {@code abc} and {@code a-c} are <i>not</i>
* equal according to this method.</p>
*
* @param obj the object to compare to
* @return true if equal
* @since 2.0
*/
@Override
public boolean equals(final Object obj) {
if (obj == this) {
return true;
}
if (!(obj instanceof CharSet)) {
return false;
}
final CharSet other = (CharSet) obj;
return set.equals(other.set);
}
/**
* Gets the internal set as an array of CharRange objects.
*
* @return an array of immutable CharRange objects
* @since 2.0
*/
// NOTE: This is no longer public as CharRange is no longer a public class.
// It may be replaced when CharSet moves to Range.
/*public*/ CharRange[] getCharRanges() {
return set.toArray(CharRange.EMPTY_ARRAY);
}
/**
* Gets a hash code compatible with the equals method.
*
* @return a suitable hash code
* @since 2.0
*/
@Override
public int hashCode() {
return 89 + set.hashCode();
}
/**
* Gets a string representation of the set.
*
* @return string representation of the set
*/
@Override
public String toString() {
return set.toString();
}
}