    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 *      http://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
    019/**
    020 * Operations on {@link CharSequence} that are
    021 * {@code null} safe.
    022 *
    023 * @see CharSequence
    024 * @since 3.0
    025 */
    026public class CharSequenceUtils {
    027
    028    private static final int NOT_FOUND = -1;
    029
    030    static final int TO_STRING_LIMIT = 16;
    031
    032    private static boolean checkLaterThan1(final CharSequence cs, final CharSequence searchChar, final int len2, final int start1) {
    033        for (int i = 1, j = len2 - 1; i <= j; i++, j--) {
    034            if (cs.charAt(start1 + i) != searchChar.charAt(i) || cs.charAt(start1 + j) != searchChar.charAt(j)) {
    035                return false;
    036            }
    037        }
    038        return true;
    039    }
    040
    041    /**
    042     * Used by the indexOf(CharSequence methods) as a green implementation of indexOf.
    043     *
    044     * @param cs the {@link CharSequence} to be processed
    045     * @param searchChar the {@link CharSequence} to be searched for
    046     * @param start the start index
    047     * @return the index where the search sequence was found
    048     */
    049    static int indexOf(final CharSequence cs, final CharSequence searchChar, final int start) {
    050        if (cs instanceof String) {
    051            return ((String) cs).indexOf(searchChar.toString(), start);
    052        }
    053        if (cs instanceof StringBuilder) {
    054            return ((StringBuilder) cs).indexOf(searchChar.toString(), start);
    055        }
    056        if (cs instanceof StringBuffer) {
    057            return ((StringBuffer) cs).indexOf(searchChar.toString(), start);
    058        }
    059        return cs.toString().indexOf(searchChar.toString(), start);
    060//        if (cs instanceof String && searchChar instanceof String) {
    061//            // TODO: Do we assume searchChar is usually relatively small;
    062//            //       If so then calling toString() on it is better than reverting to
    063//            //       the green implementation in the else block
    064//            return ((String) cs).indexOf((String) searchChar, start);
    065//        } else {
    066//            // TODO: Implement rather than convert to String
    067//            return cs.toString().indexOf(searchChar.toString(), start);
    068//        }
    069    }
    070
    071    /**
    072     * Returns the index within {@code cs} of the first occurrence of the
    073     * specified character, starting the search at the specified index.
    074     * <p>
    075     * If a character with value {@code searchChar} occurs in the
    076     * character sequence represented by the {@code cs}
    077     * object at an index no smaller than {@code start}, then
    078     * the index of the first such occurrence is returned. For values
    079     * of {@code searchChar} in the range from 0 to 0xFFFF (inclusive),
    080     * this is the smallest value <i>k</i> such that:
    081     * </p>
    082     * <blockquote><pre>
    083     * (this.charAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &gt;= start)
    084     * </pre></blockquote>
    085     * is true. For other values of {@code searchChar}, it is the
    086     * smallest value <i>k</i> such that:
    087     * <blockquote><pre>
    088     * (this.codePointAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &gt;= start)
    089     * </pre></blockquote>
    090     * <p>
    091     * is true. In either case, if no such character occurs inm {@code cs}
    092     * at or after position {@code start}, then
    093     * {@code -1} is returned.
    094     * </p>
    095     * <p>
    096     * There is no restriction on the value of {@code start}. If it
    097     * is negative, it has the same effect as if it were zero: the entire
    098     * {@link CharSequence} may be searched. If it is greater than
    099     * the length of {@code cs}, it has the same effect as if it were
    100     * equal to the length of {@code cs}: {@code -1} is returned.
    101     * </p>
    102     * <p>All indices are specified in {@code char} values
    103     * (Unicode code units).
    104     * </p>
    105     *
    106     * @param cs  the {@link CharSequence} to be processed, not null
    107     * @param searchChar  the char to be searched for
    108     * @param start  the start index, negative starts at the string start
    109     * @return the index where the search char was found, -1 if not found
    110     * @since 3.6 updated to behave more like {@link String}
    111     */
    112    static int indexOf(final CharSequence cs, final int searchChar, int start) {
    113        if (cs instanceof String) {
    114            return ((String) cs).indexOf(searchChar, start);
    115        }
    116        final int sz = cs.length();
    117        if (start < 0) {
    118            start = 0;
    119        }
    120        if (searchChar < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
    121            for (int i = start; i < sz; i++) {
    122                if (cs.charAt(i) == searchChar) {
    123                    return i;
    124                }
    125            }
    126            return NOT_FOUND;
    127        }
    128        //supplementary characters (LANG1300)
    129        if (searchChar <= Character.MAX_CODE_POINT) {
    130            final char[] chars = Character.toChars(searchChar);
    131            for (int i = start; i < sz - 1; i++) {
    132                final char high = cs.charAt(i);
    133                final char low = cs.charAt(i + 1);
    134                if (high == chars[0] && low == chars[1]) {
    135                    return i;
    136                }
    137            }
    138        }
    139        return NOT_FOUND;
    140    }
    141
    142    /**
    143     * Used by the lastIndexOf(CharSequence methods) as a green implementation of lastIndexOf
    144     *
    145     * @param cs the {@link CharSequence} to be processed
    146     * @param searchChar the {@link CharSequence} to find
    147     * @param start the start index
    148     * @return the index where the search sequence was found
    149     */
    150    static int lastIndexOf(final CharSequence cs, final CharSequence searchChar, int start) {
    151        if (searchChar == null || cs == null) {
    152            return NOT_FOUND;
    153        }
    154        if (searchChar instanceof String) {
    155            if (cs instanceof String) {
    156                return ((String) cs).lastIndexOf((String) searchChar, start);
    157            }
    158            if (cs instanceof StringBuilder) {
    159                return ((StringBuilder) cs).lastIndexOf((String) searchChar, start);
    160            }
    161            if (cs instanceof StringBuffer) {
    162                return ((StringBuffer) cs).lastIndexOf((String) searchChar, start);
    163            }
    164        }
    165
    166        final int len1 = cs.length();
    167        final int len2 = searchChar.length();
    168
    169        if (start > len1) {
    170            start = len1;
    171        }
    172
    173        if (start < 0 || len2 > len1) {
    174            return NOT_FOUND;
    175        }
    176
    177        if (len2 == 0) {
    178            return start;
    179        }
    180
    181        if (len2 <= TO_STRING_LIMIT) {
    182            if (cs instanceof String) {
    183                return ((String) cs).lastIndexOf(searchChar.toString(), start);
    184            }
    185            if (cs instanceof StringBuilder) {
    186                return ((StringBuilder) cs).lastIndexOf(searchChar.toString(), start);
    187            }
    188            if (cs instanceof StringBuffer) {
    189                return ((StringBuffer) cs).lastIndexOf(searchChar.toString(), start);
    190            }
    191        }
    192
    193        if (start + len2 > len1) {
    194            start = len1 - len2;
    195        }
    196
    197        final char char0 = searchChar.charAt(0);
    198
    199        int i = start;
    200        while (true) {
    201            while (cs.charAt(i) != char0) {
    202                i--;
    203                if (i < 0) {
    204                    return NOT_FOUND;
    205                }
    206            }
    207            if (checkLaterThan1(cs, searchChar, len2, i)) {
    208                return i;
    209            }
    210            i--;
    211            if (i < 0) {
    212                return NOT_FOUND;
    213            }
    214        }
    215    }
    216
    217    /**
    218     * Returns the index within {@code cs} of the last occurrence of
    219     * the specified character, searching backward starting at the
    220     * specified index. For values of {@code searchChar} in the range
    221     * from 0 to 0xFFFF (inclusive), the index returned is the largest
    222     * value <i>k</i> such that:
    223     * <blockquote><pre>
    224     * (this.charAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &lt;= start)
    225     * </pre></blockquote>
    226     * is true. For other values of {@code searchChar}, it is the
    227     * largest value <i>k</i> such that:
    228     * <blockquote><pre>
    229     * (this.codePointAt(<i>k</i>) == searchChar) &amp;&amp; (<i>k</i> &lt;= start)
    230     * </pre></blockquote>
    231     * is true. In either case, if no such character occurs in {@code cs}
    232     * at or before position {@code start}, then {@code -1} is returned.
    233     *
    234     * <p>
    235     * All indices are specified in {@code char} values
    236     * (Unicode code units).
    237     * </p>
    238     *
    239     * @param cs  the {@link CharSequence} to be processed
    240     * @param searchChar  the char to be searched for
    241     * @param start  the start index, negative returns -1, beyond length starts at end
    242     * @return the index where the search char was found, -1 if not found
    243     * @since 3.6 updated to behave more like {@link String}
    244     */
    245    static int lastIndexOf(final CharSequence cs, final int searchChar, int start) {
    246        if (cs instanceof String) {
    247            return ((String) cs).lastIndexOf(searchChar, start);
    248        }
    249        final int sz = cs.length();
    250        if (start < 0) {
    251            return NOT_FOUND;
    252        }
    253        if (start >= sz) {
    254            start = sz - 1;
    255        }
    256        if (searchChar < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
    257            for (int i = start; i >= 0; --i) {
    258                if (cs.charAt(i) == searchChar) {
    259                    return i;
    260                }
    261            }
    262            return NOT_FOUND;
    263        }
    264        //supplementary characters (LANG1300)
    265        //NOTE - we must do a forward traversal for this to avoid duplicating code points
    266        if (searchChar <= Character.MAX_CODE_POINT) {
    267            final char[] chars = Character.toChars(searchChar);
    268            //make sure it's not the last index
    269            if (start == sz - 1) {
    270                return NOT_FOUND;
    271            }
    272            for (int i = start; i >= 0; i--) {
    273                final char high = cs.charAt(i);
    274                final char low = cs.charAt(i + 1);
    275                if (chars[0] == high && chars[1] == low) {
    276                    return i;
    277                }
    278            }
    279        }
    280        return NOT_FOUND;
    281    }
    282
    283    /**
    284     * Green implementation of regionMatches.
    285     *
    286     * @param cs the {@link CharSequence} to be processed
    287     * @param ignoreCase whether or not to be case-insensitive
    288     * @param thisStart the index to start on the {@code cs} CharSequence
    289     * @param substring the {@link CharSequence} to be looked for
    290     * @param start the index to start on the {@code substring} CharSequence
    291     * @param length character length of the region
    292     * @return whether the region matched
    293     */
    294    static boolean regionMatches(final CharSequence cs, final boolean ignoreCase, final int thisStart,
    295            final CharSequence substring, final int start, final int length)    {
    296        if (cs instanceof String && substring instanceof String) {
    297            return ((String) cs).regionMatches(ignoreCase, thisStart, (String) substring, start, length);
    298        }
    299        int index1 = thisStart;
    300        int index2 = start;
    301        int tmpLen = length;
    302
    303        // Extract these first so we detect NPEs the same as the java.lang.String version
    304        final int srcLen = cs.length() - thisStart;
    305        final int otherLen = substring.length() - start;
    306
    307        // Check for invalid parameters
    308        if (thisStart < 0 || start < 0 || length < 0) {
    309            return false;
    310        }
    311
    312        // Check that the regions are long enough
    313        if (srcLen < length || otherLen < length) {
    314            return false;
    315        }
    316
    317        while (tmpLen-- > 0) {
    318            final char c1 = cs.charAt(index1++);
    319            final char c2 = substring.charAt(index2++);
    320
    321            if (c1 == c2) {
    322                continue;
    323            }
    324
    325            if (!ignoreCase) {
    326                return false;
    327            }
    328
    329            // The real same check as in String.regionMatches():
    330            final char u1 = Character.toUpperCase(c1);
    331            final char u2 = Character.toUpperCase(c2);
    332            if (u1 != u2 && Character.toLowerCase(u1) != Character.toLowerCase(u2)) {
    333                return false;
    334            }
    335        }
    336
    337        return true;
    338    }
    339
    340    /**
    341     * Returns a new {@link CharSequence} that is a subsequence of this
    342     * sequence starting with the {@code char} value at the specified index.
    343     *
    344     * <p>This provides the {@link CharSequence} equivalent to {@link String#substring(int)}.
    345     * The length (in {@code char}) of the returned sequence is {@code length() - start},
    346     * so if {@code start == end} then an empty sequence is returned.</p>
    347     *
    348     * @param cs  the specified subsequence, null returns null
    349     * @param start  the start index, inclusive, valid
    350     * @return a new subsequence, may be null
    351     * @throws IndexOutOfBoundsException if {@code start} is negative or if
    352     *  {@code start} is greater than {@code length()}
    353     */
    354    public static CharSequence subSequence(final CharSequence cs, final int start) {
    355        return cs == null ? null : cs.subSequence(start, cs.length());
    356    }
    357
    358    /**
    359     * Converts the given CharSequence to a char[].
    360     *
    361     * @param source the {@link CharSequence} to be processed.
    362     * @return the resulting char array, never null.
    363     * @since 3.11
    364     */
    365    public static char[] toCharArray(final CharSequence source) {
    366        final int len = StringUtils.length(source);
    367        if (len == 0) {
    368            return ArrayUtils.EMPTY_CHAR_ARRAY;
    369        }
    370        if (source instanceof String) {
    371            return ((String) source).toCharArray();
    372        }
    373        final char[] array = new char[len];
    374        for (int i = 0; i < len; i++) {
    375            array[i] = source.charAt(i);
    376        }
    377        return array;
    378    }
    379
    380    /**
    381     * {@link CharSequenceUtils} instances should NOT be constructed in
    382     * standard programming.
    383     *
    384     * <p>This constructor is public to permit tools that require a JavaBean
    385     * instance to operate.</p>
    386     */
    387    public CharSequenceUtils() {
    388    }
    389}