Java tutorial
/* * 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; /** * <p>A set of characters.</p> * * <p>Instances are immutable, but instances of subclasses may not be.</p> * * <p>#ThreadSafe#</p> * @since 1.0 * @version $Id$ */ 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<String, CharSet>()); static { COMMON.put(null, EMPTY); COMMON.put("", 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); } /** The set of CharRange objects. */ private final Set<CharRange> set = Collections.synchronizedSet(new HashSet<CharRange>()); //----------------------------------------------------------------------- /** * <p>Factory method to create a new CharSet using a special syntax.</p> * * <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); } //----------------------------------------------------------------------- /** * <p>Constructs a new CharSet using the set syntax. * Each string is merged in with the set.</p> * * @param set Strings to merge into the initial set * @throws NullPointerException if set is {@code null} */ protected CharSet(final String... set) { super(); final int sz = set.length; for (int i = 0; i < sz; i++) { add(set[i]); } } //----------------------------------------------------------------------- /** * <p>Add a set definition string to the {@code CharSet}.</p> * * @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; } } } //----------------------------------------------------------------------- /** * <p>Gets the internal set as an array of CharRange objects.</p> * * @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(new CharRange[set.size()]); } //----------------------------------------------------------------------- /** * <p>Does the {@code CharSet} contain the specified * character {@code ch}.</p> * * @param ch the character to check for * @return {@code true} if the set contains the characters */ public boolean contains(final char ch) { for (final CharRange range : set) { if (range.contains(ch)) { return true; } } return false; } // Basics //----------------------------------------------------------------------- /** * <p>Compares two {@code CharSet} objects, returning true if they represent * exactly the same set of characters defined in the same way.</p> * * <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 == false) { return false; } final CharSet other = (CharSet) obj; return set.equals(other.set); } /** * <p>Gets a hash code compatible with the equals method.</p> * * @return a suitable hash code * @since 2.0 */ @Override public int hashCode() { return 89 + set.hashCode(); } /** * <p>Gets a string representation of the set.</p> * * @return string representation of the set */ @Override public String toString() { return set.toString(); } }