    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      https://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.lang3;
    018
    019import java.io.Serializable;
    020import java.util.Collections;
    021import java.util.HashMap;
    022import java.util.HashSet;
    023import java.util.Map;
    024import java.util.Set;
    025import java.util.stream.Stream;
    026
    027/**
    028 * A set of characters.
    029 *
    030 * <p>Instances are immutable, but instances of subclasses may not be.</p>
    031 *
    032 * <p>#ThreadSafe#</p>
    033 * @since 1.0
    034 */
    035public class CharSet implements Serializable {
    036
    037    /**
    038     * Required for serialization support. Lang version 2.0.
    039     *
    040     * @see java.io.Serializable
    041     */
    042    private static final long serialVersionUID = 5947847346149275958L;
    043
    044    /**
    045     * A CharSet defining no characters.
    046     * @since 2.0
    047     */
    048    public static final CharSet EMPTY = new CharSet((String) null);
    049
    050    /**
    051     * A CharSet defining ASCII alphabetic characters "a-zA-Z".
    052     * @since 2.0
    053     */
    054    public static final CharSet ASCII_ALPHA = new CharSet("a-zA-Z");
    055
    056    /**
    057     * A CharSet defining ASCII alphabetic characters "a-z".
    058     * @since 2.0
    059     */
    060    public static final CharSet ASCII_ALPHA_LOWER = new CharSet("a-z");
    061
    062    /**
    063     * A CharSet defining ASCII alphabetic characters "A-Z".
    064     * @since 2.0
    065     */
    066    public static final CharSet ASCII_ALPHA_UPPER = new CharSet("A-Z");
    067
    068    /**
    069     * A CharSet defining ASCII alphabetic characters "0-9".
    070     * @since 2.0
    071     */
    072    public static final CharSet ASCII_NUMERIC = new CharSet("0-9");
    073
    074    /**
    075     * A Map of the common cases used in the factory.
    076     * Subclasses can add more common patterns if desired
    077     * @since 2.0
    078     */
    079    protected static final Map<String, CharSet> COMMON = Collections.synchronizedMap(new HashMap<>());
    080
    081    static {
    082        COMMON.put(null, EMPTY);
    083        COMMON.put(StringUtils.EMPTY, EMPTY);
    084        COMMON.put("a-zA-Z", ASCII_ALPHA);
    085        COMMON.put("A-Za-z", ASCII_ALPHA);
    086        COMMON.put("a-z", ASCII_ALPHA_LOWER);
    087        COMMON.put("A-Z", ASCII_ALPHA_UPPER);
    088        COMMON.put("0-9", ASCII_NUMERIC);
    089    }
    090
    091    /**
    092     * Factory method to create a new CharSet using a special syntax.
    093     *
    094     * <ul>
    095     *  <li>{@code null} or empty string ("")
    096     * - set containing no characters</li>
    097     *  <li>Single character, such as "a"
    098     *  - set containing just that character</li>
    099     *  <li>Multi character, such as "a-e"
    100     *  - set containing characters from one character to the other</li>
    101     *  <li>Negated, such as "^a" or "^a-e"
    102     *  - set containing all characters except those defined</li>
    103     *  <li>Combinations, such as "abe-g"
    104     *  - set containing all the characters from the individual sets</li>
    105     * </ul>
    106     *
    107     * <p>The matching order is:</p>
    108     * <ol>
    109     *  <li>Negated multi character range, such as "^a-e"
    110     *  <li>Ordinary multi character range, such as "a-e"
    111     *  <li>Negated single character, such as "^a"
    112     *  <li>Ordinary single character, such as "a"
    113     * </ol>
    114     *
    115     * <p>Matching works left to right. Once a match is found the
    116     * search starts again from the next character.</p>
    117     *
    118     * <p>If the same range is defined twice using the same syntax, only
    119     * one range will be kept.
    120     * Thus, "a-ca-c" creates only one range of "a-c".</p>
    121     *
    122     * <p>If the start and end of a range are in the wrong order,
    123     * they are reversed. Thus "a-e" is the same as "e-a".
    124     * As a result, "a-ee-a" would create only one range,
    125     * as the "a-e" and "e-a" are the same.</p>
    126     *
    127     * <p>The set of characters represented is the union of the specified ranges.</p>
    128     *
    129     * <p>There are two ways to add a literal negation character ({@code ^}):</p>
    130     * <ul>
    131     *     <li>As the last character in a string, e.g. {@code CharSet.getInstance("a-z^")}</li>
    132     *     <li>As a separate element, e.g. {@code CharSet.getInstance("^", "a-z")}</li>
    133     * </ul>
    134     *
    135     * <p>Examples using the negation character:</p>
    136     * <pre>
    137     *     CharSet.getInstance("^a-c").contains('a') = false
    138     *     CharSet.getInstance("^a-c").contains('d') = true
    139     *     CharSet.getInstance("^^a-c").contains('a') = true // (only '^' is negated)
    140     *     CharSet.getInstance("^^a-c").contains('^') = false
    141     *     CharSet.getInstance("^a-cd-f").contains('d') = true
    142     *     CharSet.getInstance("a-c^").contains('^') = true
    143     *     CharSet.getInstance("^", "a-c").contains('^') = true
    144     * </pre>
    145     *
    146     * <p>All CharSet objects returned by this method will be immutable.</p>
    147     *
    148     * @param setStrs  Strings to merge into the set, may be null
    149     * @return a CharSet instance
    150     * @since 2.4
    151     */
    152    public static CharSet getInstance(final String... setStrs) {
    153        if (setStrs == null) {
    154            return null;
    155        }
    156        if (setStrs.length == 1) {
    157            final CharSet common = COMMON.get(setStrs[0]);
    158            if (common != null) {
    159                return common;
    160            }
    161        }
    162        return new CharSet(setStrs);
    163    }
    164
    165    /** The set of CharRange objects. */
    166    private final Set<CharRange> set = Collections.synchronizedSet(new HashSet<>());
    167
    168    /**
    169     * Constructs a new CharSet using the set syntax.
    170     * Each string is merged in with the set.
    171     *
    172     * @param set  Strings to merge into the initial set
    173     * @throws NullPointerException if set is {@code null}
    174     */
    175    protected CharSet(final String... set) {
    176        Stream.of(set).forEach(this::add);
    177    }
    178
    179    /**
    180     * Add a set definition string to the {@link CharSet}.
    181     *
    182     * @param str  set definition string
    183     */
    184    protected void add(final String str) {
    185        if (str == null) {
    186            return;
    187        }
    188
    189        final int len = str.length();
    190        int pos = 0;
    191        while (pos < len) {
    192            final int remainder = len - pos;
    193            if (remainder >= 4 && str.charAt(pos) == '^' && str.charAt(pos + 2) == '-') {
    194                // negated range
    195                set.add(CharRange.isNotIn(str.charAt(pos + 1), str.charAt(pos + 3)));
    196                pos += 4;
    197            } else if (remainder >= 3 && str.charAt(pos + 1) == '-') {
    198                // range
    199                set.add(CharRange.isIn(str.charAt(pos), str.charAt(pos + 2)));
    200                pos += 3;
    201            } else if (remainder >= 2 && str.charAt(pos) == '^') {
    202                // negated char
    203                set.add(CharRange.isNot(str.charAt(pos + 1)));
    204                pos += 2;
    205            } else {
    206                // char
    207                set.add(CharRange.is(str.charAt(pos)));
    208                pos += 1;
    209            }
    210        }
    211    }
    212
    213    /**
    214     * Does the {@link CharSet} contain the specified
    215     * character {@code ch}.
    216     *
    217     * @param ch  the character to check for
    218     * @return {@code true} if the set contains the characters
    219     */
    220    public boolean contains(final char ch) {
    221        synchronized (set) {
    222            return set.stream().anyMatch(range -> range.contains(ch));
    223        }
    224    }
    225
    226    // Basics
    227    /**
    228     * Compares two {@link CharSet} objects, returning true if they represent
    229     * exactly the same set of characters defined in the same way.
    230     *
    231     * <p>The two sets {@code abc} and {@code a-c} are <em>not</em>
    232     * equal according to this method.</p>
    233     *
    234     * @param obj  the object to compare to
    235     * @return true if equal
    236     * @since 2.0
    237     */
    238    @Override
    239    public boolean equals(final Object obj) {
    240        if (obj == this) {
    241            return true;
    242        }
    243        if (!(obj instanceof CharSet)) {
    244            return false;
    245        }
    246        final CharSet other = (CharSet) obj;
    247        return set.equals(other.set);
    248    }
    249
    250    /**
    251     * Gets the internal set as an array of CharRange objects.
    252     *
    253     * @return an array of immutable CharRange objects
    254     * @since 2.0
    255     */
    256// NOTE: This is no longer public as CharRange is no longer a public class.
    257//       It may be replaced when CharSet moves to Range.
    258    /*public*/ CharRange[] getCharRanges() {
    259        return set.toArray(CharRange.EMPTY_ARRAY);
    260    }
    261
    262    /**
    263     * Gets a hash code compatible with the equals method.
    264     *
    265     * @return a suitable hash code
    266     * @since 2.0
    267     */
    268    @Override
    269    public int hashCode() {
    270        return 89 + set.hashCode();
    271    }
    272
    273    /**
    274     * Gets a string representation of the set.
    275     *
    276     * @return string representation of the set
    277     */
    278    @Override
    279    public String toString() {
    280        return set.toString();
    281    }
    282
    283}